Saturday, September 25, 2004

A proper job!

I've been working at Sharp for three weeks now, and all I can say is, "Wow!"

It's a pretty amazing place: I park my bicycle next to two giant tanks of liquid nitrogen, there are sets of breathing apparatus on the walls, the place has a high-level cleanroom, and there are laser warning strobes above half of the doors. I keep on being reminded of when I used to play Half-Life a lot...

I turned up on the first day, expecting loads of administrative stuff and not even to have a desk until the afternoon. To my suprise, the first thing I had to do was to unpack my brand new workstation with a 19-inch flat panel monitor onto a huge desk in my development team's offices. My personal space at work is nearly as big as our sitting room at home! I've now succeeded in getting a good set of GNU tools installed on my computer, thanks to Cygwin.

I've done two mini-projects so far: one involved making some printed circuit boards (PCBs) and the other was an investigation into Dickson charge pumps, a type of (very inefficient, we found) DC to DC convertor.

I started my big project on Thursday, so in the next few months I've got the joys of learning VHDL, playing with FPGAs, designing some very complicated circuit boards, and then hoping it all works...

Friday, August 27, 2004

Update time

So, having sorely neglected this journal for far too long (not for the first time, I might add) I thought it might be a good plan to write an update for a change.

Although it didn't feel like my A-level papers went as well as I wanted them too, I didn't do too badly. In fact I did very well - I got A-grades in all the modules I took in the summer session, and thus A-grades in all of my A-levels! That means I'm going to Cambridge!

In July I went on a OCYO tour to Germany - my first tour as principal horn. Regrettably, it didn't go too well - I messed up at least once in each concert. The major contributor to that was the fact that I managed to break my horn - somehow, I succeeded bending the leadpipe in by about 20°, resulting in a huge kink in the leadpipe and a bigger dent in the bell flair. It's going to cost too much to repair, and the worst thing is that I'm going to have to play my brother Alex's horn in the really important OCYO concert in two weeks' time because mine won't be fixed until the end of September, which isn't going to improve the quality of my playing.

Since getting back from tour, I've been working at Keble College as a student helper during the conference season, and playing Achaea a lot.

Although I did my best to get the MBDA Engineering Scholarship, I didn't, unfortunately. However, that means I'll be spending my gap year working for Sharp, starting soon. Bizarrely, one of students I'm currently working with at Keble is sharing a house with an Engineering student who's working on the same team I'm going to be working on.

Anyway, that's all for now. I'll write again soon, no doubt.

Thursday, June 24, 2004

I'm currently in the happy position of having just completely messed up two A-Level Chemistry papers. Fortunately, Chemistry isn't particularly critical for me, so I can afford to get a B, but it would be nice not to. On the other hand, my Maths papers have been going well so far. The beginning of next week is going to be traumatic though: Physics synoptic paper on Monday afternoon, Chemistry synoptic on Tuesday morning and Pure Maths 4 and 5 on Tuesday afternoon. I'm not looking forward to that little lot at all.

Wednesday, June 23, 2004

Learning Lisp

I've been learning Lisp - after all, it's not as if I have anything else to do. It's very different to any other programming language I've learnt, and in a way it's very cool. I especially like the feature that the language itself can be used to modify the language, but I haven't really got to the stage where I can make use of that yet. Today I wrote a program:

(defun countdown (&rest args)
  (let ((target (apply #'encode-universal-time args))
    (do ((finished nil)) (finished)
        (sleep 1)
        (setf left (- target (get-universal-time)))
        (if (< left 0)
            (setf finished t)
          (format t "~a:~a:~a~%"
                  (floor (/ left 3600))
                  (floor (/ (mod left 3600) 60))
                  (mod left 60))))))

I've been finding ANSI Common Lisp by Paul Graham very handy (once Amazon finally decided to deliver it), and I've been using SBCL as my compiler.

Update: The history of Lisp, for anyone who's interested.

Monday, June 21, 2004


The first flight[] of Scaled Composites' SpaceShipOne to 100km[] was successful[]!

Yay! My money's definitely on them to win the X-Prize.

Update: More info here[], here[], and here[].

Friday, June 18, 2004

More about Magnum

I mentioned a month or so ago that I'd been told that NASA was developing a new launcher called Magnum, and that I was going to investigate. Here's where I've got to.

Firstly, searching for the keyword "Magnum" in a space-related context brings up a lot of results referring to NASA launching a series of ELINT satellites in the late 1980s, which isn't very helpful. It's also hard to filter out references to the Colt Magnum series of pistols.

A document from 1998 provides some interesting information:

  • Design is derived from that of the space-shuttle (this could be a replacement for the Shuttle-Z programme)
  • Performance is 80 tonnes to ~400 km altitude LEO at 28.5° inclination
  • Core is 8.4 m diameter to allow Magnum to launch from existing shuttle facilities (cost-cutting measure, I guess)
  • Target cost is $1000 per kg (and if you believe that you'll believe anything)
The document also mentions something that I hadn't picked up before, that NASA are planning to replace the current solid-fuel shuttle boosters with liquid-fueled boosters capable of autonomous fly-back and landing. I'll believe it when I see it.

Quite a lot of these details are corroborated by this article, which also contains some snazzy publicity imagery - including Lockheed-Martin and Boeing concept renders of what the fly-back boosters might look like.

Earliest information I've found is a set of 1997 lecture slides which, although interesting, are probably hopelessly out-of-date by now.

I've also found some comments from various people, many of which run along the lines of, "Why are we spending all this money on massive launchers so we can send spacecraft straight to Mars Apollo-style, when we could use [insert name of current, low performance launcher here] and assemble at ISS?" The fact that the ISS is in a hopeless orbit for insertion into a Martian transfer orbit, and the fact that we don't have the know-how to be able to assemble large structures in microgravity, makes this viewpoint rather an odd one.

And that's pretty much it. I've been able to find very little or no useful information dating more recently that 2000. I'm going to try e-mail MSFC directly, and see what they can tell me. It's worth a try.

Wednesday, June 16, 2004

100 km

SpaceShipOne is an Ansari X-Prize project that I've been following with great interest over the last few months. On June 21st, Scaled are going to try their first flight to the X-Prize qualifying height of 100 km, from Mojave Civilian Flight Test Center. I will be watching with great interest. If only I could be there!

Although SpaceShipOne will be going up to 100 km, Scaled still won't win the X-Prize, because the X-Prize rules stipulate that the winning craft must carry 3 people (or just a pilot and ballast equivalent to the other two crew), and the same spacecraft must trip twice in the space of 2 weeks.

Time's running out for X-Prize competitors: the prize is only available until 1st January 2005.

On a personal note, I'm not a big fan of the X-Prize. Although it seems to have succeeded to a certain extent in stimulating the development of private spaceflight, even the winning spacecraft will not be capable even of getting to orbit. The next prize would be awarded to the first private enterprise to put a man in 500 km orbit and then recover him safely, if I had any say in it. Then you've automatically got a competitive launch vehicle.

Tuesday, June 15, 2004


For the first time in my life, I'm actually revising properly for an exam. I've got Pure Maths 5 on Monday (if I remember correctly), and I've realised that although I can actually do most of the questions, I can't do them fast enough. So I'm currently hacking through the practice papers I've been given as fast as I can in the hope that I can get a reasonable mark in the exam.

Inbetween writing my blog, reading Slashdot, eating, working out on the school ergos, shooting etc, of course.

Update: Opened the fifth of my pracice papers, looked at the first question, and didn't have a clue how to do it. So I looked at the answer, and couldn't make head nor tail of it. Am currently feeling tired and depressed.

Sunday, June 13, 2004


I had a conversation with a friend of mine, where I made the point that I really don't like IQ tests because all they measure is how good you are at IQ tests. However, since I've never actually taken an IQ test in anger, I thought I'd take a few today to compare and contrast.Quite a range - I rest my case. While randomly surfing, I also discovered that my personality type is Visionary (Extraverted Intuition with Introverted Thinking).

Tuesday, June 08, 2004


I went to the summer members' event at the Royal Institution last night. It was a balloon debate, with four eminent scientists each taking the role of a famous director of the RI. Represented were Count Rumford (founder of the RI), Michael Faraday, Lawrence Bragg (inventor of X-ray crystallography) and George Porter (discoverer of the ozone layer hole).

I left home late, and was thus late getting to the RI (the train from Oxford being half an hour late didn't help much), but fortunately I only missed the introductory comments. Lawrence Bragg's suggestion that he hadn't actually got anything left to contribute to the world of science resulted in him being thrown out first, and George Porter got thrown out second for being too smarmy, though I thought it would have been good to have a final between George Porter and Count Rumford. Count Rumford won; although some could claim the result was rigged because Count Rumford was being played by the current director, Baronness Susan Greenfield, she was to most confident and funniest of the group.

After the debate, there were Pimm's and strawberries in the library, which was nice.

Getting home was traumatic. First I decided to wait at Paddington for a fast train to Oxford, because I didn't feel like slumming it for hours on one of the inevitable dirty and smelly local stopping trains, and so, having left the RI at half-past nine I finally left London at quarter to eleven. Then there was a points failure at Reading, so I didn't get into Oxford until quarter past midnight, whereupon I had to wait for the last bus home.

Result being that although it took me two and a half hours to get to the RI from home, it took me nearly four to get home from the RI. Understandably, this morning I feel knackered.

Saturday, June 05, 2004

The joy of Blockbuster

On Thursday I decided to become a member of Blockbuster, so that I could rent The Return of the King and finally get to watch it.

All went swimmingly until about halfway through the battle of Pelennor Field, when there was a corrupt sector on the disc. So I took the DVD back to the branch, and got another box in return - but upon returning home, found it had two Special Features discs in it.

I took the box back on Friday afternoon, and got it exchanged, and got an extra day and a free rental for my trouble. But upon getting home late on Friday evening, I found the box had two Special Features discs in again. You can imagine how pleased I was about that.

Anyway, so today I've finally got it replaced again, and I'm looking forward to watching the rest of the movie. I might start again from the beginning now, coming to think about it.

As an aside, I'm using MPlayer to play DVDs, but sometimes it gets really stuttery and I have to reboot before it'll play the DVD smoothly. I also sometimes get "Your computer is too slow, sucker" messages as well, which are annoying. I really like the text-mode DVD playback though...

My website is on EV1?

Interesting and more interesting: I just put my website's domain name into Netcraft's "What's That Site Running" page, and found out that my site's IP address is within EV1's netblock. This is interesting: EV1 bought a SCOSource "license" from the SCO fudsters earlier this year, and then regretted doing so. Anyway, I'm quite suprised: I'm not hosted by EV1, I'm hosted by TWU.

Tuesday, June 01, 2004

Pranking around

Traditionally at our school, the week before the summer half term (and, therefore, the school open day) is heavily disrupted by the Upper 6th fooling about. So, not being the sort of people who break an established tradition, we carried out the following atrocities.

On Monday, a number of people dressed in combats and masks ran into whole school assembly and stole the school captain.

On Wednesday, I had my last Physics lesson with Mr. H. I sauntered in 20 minutes late, wearing none of the right school uniform, swigging from a vodka bottle. I think he found it funny.

On Wednesday night, we put a clapped out little Citroen into the main hall of Norris House. Unfortunately I wasn't involved in that, because I was ill in bed. Apparently it was the first car-moving prank for about two decades, so that was good.

Thursday night was our big prank. All week, the school refectory staff had been locking up really carefully, closing all the windows and chaining up the doors. Not to ignore a good challenge, we broke in in the middle of the night, and moved all the furniture onto the school croquet lawn. Not yet satisfied, we also moved the Citroen and all the staff dining room's furniture into the refectory. Then we removed all traces of our way in, as far as was possible. We are legends.

On Friday I did some random busking, running into rooms with my violin, playing at people, and then running off. That was funny too.


I've got a job for the summer now: working as a housekeeper at Keble College in Oxford for five or six weeks in the summer. I had an interview with the Facilities Manager there this morning, and it sounds like very hard work, but hey - it's a good opportunity to earn some dough. I'm starting the day after I get back from OCYO. Man, that's going to be tiring. I think I'm going to look for some evening work as well. The more the merrier!

Wednesday, May 26, 2004

Scientifically challenged

Last Friday I had my Physics practical exam, and today I had my Chemistry practical. It's interesting to contrast them. The Physics exam was 105 minutes, and that was barely enough time to carry out the experiments and write them up. In fact, I messed up one experiment because I was having to rush it. Not to mention the fact that one of the experiments really didn't work very well. By contrast, even though the Chemistry exam was the same length, it was far easier, with experiments that worked first time and loads of time to do the writing up. All very strange, bearing in mind that I'm generally far better at Physics than I am at Chemistry. No more exams now until 17th June!

Wednesday, May 19, 2004

No toy operating systems, please

I posted my keyboard-death plight to the Oxford Linux User Group, OxLUG, and there was a deluge of suggestions. Apart from the obvious and impractical ones (get a new keyboard), someone suggested using Ctrl-M, which enabled me to get LILO to boot into LFS. Score! Having logged in and loaded KDE, I discovered that Ctrl-M doesn't work as an Enter replacement in X11. Once again, I sought assistance, and someone mentioned xmodmap. I immediately had a poke around, discovered it was a standard tool included with X, and upon reading man page found that it was exactly what I was looking for! So now, courtesy of the command xmodmap -e "keycode 113 = Return", Alt-Gr does the job of the Enter key. I have a usable system once more! But although it's great as an interim measure, I can't live with it permanently. Once my dad gets back from Austria I'll investigate getting it fixed properly. Bet it'll be expensive.

Tuesday, May 18, 2004

New look

I want to use the new Blogger features - specifically, built-in commenting and postings on their own pages - but I don't have the time to redesign my nice blue template for them right now. So I'm stuck with this thing for now.

Disaster strikes

After getting KDE working (beautifully) by this morning, I set about downloading and installing OpenOffice in order to facilitate writing some business letters. I installed the dependencies (Java Development Kit 1.4, Apache Ant, etc, etc...), started the build, and left it to run over lunch and the early afternoon. I got back from Chemistry at about three o'clock, brought up the KDE password prompt to unlock the screen, and hit Enter. Nothing happened, so I hit Enter again. After a few seconds, the prompt timed out and disappeared. I brought it up again, typed in my password and pressed Enter. Still no response. Little placeholder stars were appearing when I typed in my password characters, but the Enter key seemed to be having no effect. I hit Alt-F1 to change to a different virtual console, and tried to log in, but still nothing from the Enter key. Rebooting to the BIOS, I found by a process of trial and error that my Enter, Up, Down and Right keys have failed. At least. And without those keys I can't even boot into my LFS system, let alone log in or do anything else useful. I have a feeling I'm going to be shopping for a new computer sometime soon...

Friday, May 14, 2004

Midnight ramblings

Interesting things going on. It was our school Inter-House Music Competition this evening. Although I was nominally in charge of our entry, I delegated the responsibility to my brother, who not only wrote a piece for the impromptu jazz ensemble we put together (in which he played trumpet), but also sang the solo item and set up the the chapel for the event. Leaving me nothing to do apart from turn up on the night and clap loudly when we won. The "sixth form centre" opened today as well. Basically, it's an area in the sports centre with comfy chairs and tables (think starbucks) and a bar. So I went up there and drank some beer and chatted to some people about sundry things, before coming back here... ...and discovering that the new version of Blogger has support for comments built in! So now I don't have to use Enetation (which isn't very cross-browser compatible), and I can have a separate page per blog entry! Tomorrow I'll rewrite my template. I'm not sure if that will be before or after doing my Statistics prep (for tomorrow morning) or compiling an X server for my LFS installation. I just remembered we've got a shooting match tomorrow, so I probably ought to go to bed and sleep off the alcohol.

Wednesday, May 12, 2004

The Next Small Step

I went to the Royal Institution last night to hear a talk by Dr. Kevin Fong, an anaesthetist who actively studies the health problems associated with spaceflight, and who has just returned from a period spent studying at the Johnson Space Centre.

The main point he made was that the best strategy for a Mars mission was a thousand-day mission, entailing a nine-month outward flight. He explained that after that length of time in microgravity conditions, the crew of such a mission would be in no fit state to carry out any science, let alone to get out of their landing capsule and set up a base. He mentioned such problems as motion sickness, skeletal mineral loss (2% per month, apparently) and muscular degradation.

While describing these issues, Dr. Fong also described the differences between going for a ride on NASA's "Vomit Comet" and going for a ride on the Russian equivalent. NASA require you to turn up a week before, and go through all sorts of medical checks and briefings over the course of four days before you actually go for a one-and-a-half hour flight. In Russia, they sling you in the back of the plane, say something along the lines of, "Here's a parachute, if something goes wrong, open the door and jump out and try not to land in water," and then off you go.

He also described the current design for a manned Mars spacecraft. Essentially, it's a fold out scaffold 125 m in length, with a TransHab-type module at one end, a SP-100 class nuclear reactor at the other, and engines and antennae in the middle. He also mentioned that liquid hydrogen is being considered for use as the habitable module's radiation shield, but I remain sceptical.

I felt that the talk didn't really go into enough techical detail for me. Talking to some scientists beforehand, I discovered that I'd missed a very interesting lecture at the Royal Society last Thursday. Oh well.

Dr. Fong made several references to the Space Shuttle being withdrawn from service in 2010, and after the talk I asked him what sort of things were being considered as a replacement. He mentioned the Crew Exploration Vehicle (which I'd already heard about) and also a cargo launcher called Magnum (which I hadn't). Cursory Googling brings up the fact that it's being developed by MSFC, and not much other useful stuff. I'll investigate.

Sunday, May 09, 2004


So, time to reveal what I've been working on for the last week. Basically, I've got so fed up of Microsoft's monopoly leveraging and underhand business tactics, not to mention the ever-present threat of virus infection on such an insecure platform as Windows XP, that I've decided to put my money where my mouth is and switch completely to Linux. To cut a long story short, I've been installing Linux from scratch. I've now got a system that boots; the only issues are a slight problem with my Ethernet connection and DVD/CD-RW drive. Oh yes, and the fact that I've only got command-line mode at the moment. I'm using my Mandrake 8.2 installation as a kind of backup operating system. I'm still amazed by how little space Linux takes up. On my Mandrake partitions, I've got KDE, the Sun JDK, umpteen tools, the kernel, loads of docs,, random other junk; and yet I'm still only using 1.5 GB of my root partition.

Sunday, May 02, 2004

Busy again

I'm working on something complicated at the moment, and have no time to write much here.

Tuesday, April 27, 2004

Disgruntled of Woodcote

Having been asked to do the lecture again by Dr. H., and having been assured that there'd be an audience, I turned up to the venue, whereupon one person turned up. I don't appreciate it when people waste my time. Nevertheless, I will post the slides on my website (minus the video clip). It might be a couple of weeks though: uploading stuff from school is a real pain.

Busy day

No proper article today: I'm doing my Lunar colonization lecture again this evening, so I'm having to spend time this morning getting ahead. This time I'm going to record the lecture, and post the slides and a transcript on my website.

Monday, April 26, 2004

Atmospheric management

Here's a random idea. Remember the Kyoto Protocol was an international agreement to cut CO2 emissions in an effort to curb global warning? Granted that it's dead now, thanks to the Bush administration (I've never understood what the problem was there), but it was a good idea while it lasted. Back to the point: I had a completely off-the-wall idea as to how net CO2 emissions could be reduced by a country, even if not eliminated.

Recent proposals for a Mars mission have recommended that an away team do not take oxidiser or propellant for the way back, but rather generate them in situ. The preferred way of doing this seems to be to take hydrogen to Mars (it has a low molar mass, so you can take a large amount of it for a relatively small mass), and then use the hydrogen to "crack" the CO2 in the Martian atmosphere to make methane and oxygen, which would be used to fuel the homebound trip. Note that this process:

  • generates 1 mole of methane for every 4 moles of hydrogen
  • generates 11 kg of reaction mass for each kilogram of hydrogen
  • requires some technology to store the generated gases
  • is pretty power-hungry.
So how does this apply to the situation on Earth? Well, I can envision a system that:
  1. electrolyses water to generate hydrogen and oxygen
  2. stores the oxygen, and uses the hydrogen to "crack" carbon dioxide
  3. stores the generated methane and oxygen
. The methane and oxygen could be then be sold as fuel, perhaps. It would be necessary to make sure that the power source for the process doesn't generate carbon dioxide: nuclear power or, better, solar power would fit the bill. It would also be necessary to make sure that the process of building the system didn't generate more than a small fraction of the CO2 expected to be scrubbed from the atmosphere by the system during its working lifetime (or there's no point).

Advantages over growing forests: methane can be burnt a lot more cleanly than wood can (lower soot output), and the system can be used in areas where vegetation can't be grown easily. Disadvantages: forests look nicer, they can be used to generate secondary income (through visitors etc), they're good for the local ecology, they have lower maintainance requirements and building them doesn't generate pollution. Basically, if I had the choice I'd plant trees rather than use the scrubber.

The sad thing is that I can envision getting governments to adopt the scrubber a lot more easily than getting them to plant extensive forests.

Sunday, April 25, 2004


I was on Amazon today, and after adding a couple of items to my basket, I looked at what I'd got so far.
  • Moonwar (The Moonbase Saga) - Ben Bova
  • The Moon Is a Harsh Mistress - Robert A. Heinlein
  • Gatecrasher - Experience - Various Artists
Looking at at the bottom of the page, what do I see? "Customers who bought the items in your Shopping Basket also bought: ... PHP and MySQL Web Development, 2nd edition by Luke Welling." Talk about accurate profiling.

Friday, April 23, 2004

Concert at St. Martin in the Fields

The school took the string players on a trip today to hear the New London Soloists' Orchestra and the Allegri String Quartet play at St. Martin in the Fields tonight - I just got back. The programme included Eine Kleine Nachtmusic and one of the Salzburg divertimenti by W. A. Mozart, Elgar's Serenade for Strings and Introduction and Allegro, two string movements from Henry V by Walton, and Vaughan Williams' Variations on a Theme by Tallis. All the pieces were played with extreme accuracy and excellent intonation, but I felt that the Mozart in particular felt a little tired. In contrast, the Introduction and Allegro was fantastic, really captivating. What particular amused me was that in some pieces the orchestra seemed to just be playing the music pretty much without thinking about it, and the conductor was almost surplus to requirements, whereas in others he was clearly having to work very hard. Niggles aside, it was one of the best concerts I've been to for a while.

Silly hat

We had our school photographs this morning and, prior to going out for the St. John house photo, our housemaster awarded colours. I was awarded full house colours: a maroon tie with pink stripes, and a sort of wierd, tasselled cap in the same colours. Quite bizarre. The leavers had both an informal and a formal photograph, of which I'll be buying the formal one. The informal photo was just a bit too wierd. I personally wore jeans, a shirt, a labcoat and a fez, with the necessary pencil and notebook.

Solar Radiation

Now my Easter break is over , I'm going to pick up with a more detailed analysis of the Solar radiation environment [1].

The Sun's outer three layers are responsible for the majority its electromagnetic radiation. The photosphere, at about 5900 K, emits visible wavelengths; the chromosphere above emits more intense ultra-violet radiation; and the corona, the Sun's outer layer, gives out X-rays. The chromosphere has temperatures up to 10,000 K, and the corona reaches temperatures greater than 2x106 K.

The radiation pressure of the Sun's electromagnetic emissions is sufficient to drive of huge amounts of matter in the form of the solar wind. At one AU, the solar wind has a flux of about 9 protons cm-3, travelling at an approximate mean velocity of 450 kms-1.

Disturbances in the Sun's atmosphere are the cause of solar flares, large plumes of material thrust out from the Sun's surface. Associated with flares are increases both in radiation and high energy particle fluxes. Near the Earth the first observable change is a sudden and relatively brief increase in solar radiation about 20 minutes after the flare occurs, and then about a day later a longer burst of high energy particles, similar to the solar wind but more intense and at higher velocities, typically 103 kms-1.

As discussed previously, the enhanced electromagnetic and particle emissions pose a substantial risk to exposed equipment and personnel.


J. P. W. Stark (2003) The Spacecraft Environment and its Effect on Design. In Spacecraft Systems Engineering (J. P. W. Stark, G. G. Swinerd & P. W. Fortescue, ed.), pp. 11-47. John Wiley & Sons Ltd, Chichester.

Thursday, April 22, 2004

Lazy times

Looking back, it's a very long time since I last updated this weblog! So much has happened since then.

Wednesday 31st March to Saturday 3rd April was the run for Bye Bye Birdie. That was an amazing show, though I say it from a participant's point of view. The music was rythmical, catchy and in tune; the choreography was unbelievably precise, and the actors truly lived their roles. I have never been involved with a more professional youth production. I was really sad when it was all over - but then again, the cast party after the last performance was tremendous fun! Mr & Mrs H. came to see it, and they both said that they really enjoyed it.

We got home from the party at about quarter to two in the morning on Sunday 4th April, a mere 6 hours before we had to leave home to go to our OCYO course at Sibford School near Banbury. Needless to say, I found playing the horn rather taxing that morning. But despite the fact that the OCYO course was on a shoestring budget and very hard work, I had a great time. For the first time when I've been on OCYO, I felt that I was with a group of real friends, T., E., L., & J., who I spent nearly all of my time with while I was there.

An amusing thing happened during the OCYO course. As I've previously mentioned, we're playing Shostakovich's 5th Symphony, and I'm playing first horn. Now, the first entry in the symphony for the first horn (after 36 bars rest) is a top G followed by a descending passage. All through the first couple of days of the residential course, I didn't get it right once - my lips just let me down, probably still tired from the exertions required by the show. On the last night of the residential course, we had the OCYO cabaret, and one of the features was the presentation of humourous awards to members of the orchestra. I won the much-coveted title of "Most Enthusiastic Player", and upon mounting the stage in a very keen manner was urged to play something. I immediately launched into that very entry - and got it perfectly right. I think I was even more suprised than our conductor!

Regrettably, having had two weeks of great fun, I was due some bad luck, and on Maundy Thursday Lizzie and I split up. It had been clear to me that our relationship was foundering - and, apparently, she'd been thinking of splitting with me since New Year - but unfortunately she still hasn't actually explained to me exactly what I was doing wrong. I really wish she had.

Anyway, so that's all the notable stuff that happened over the Easter break, apart from pre-season shooting immediately before we returned to school yesterday evening. We went to Pirbright and shot for three days. And that's about it, really. Apart from my suprise at the impeccable behaviour of the juniors - we didn't have any trouble from them at all!

Ah yes, I nearly forgot. On Friday 2nd of April I had a Year in Industry interview at Sharp Laboratories of Europe, following which they offered me a job which I've accepted. So next year I'm going to be designing LCD screens! Not quite what I was expecting to be doing, but it sounds like it's going to be great fun all the same.

So, having managed not to do any significant amounts of revision or horn practice for far too long, I must now stop typing random gibberish and do some of both. Or either.

UPDATE: Other stuff that happened of note included cycling to Cheltenham and halfway back; finally visiting Lisa (in Cheltenham); meeting Zoe on the aforementioned trip; and playing Achaea a lot. And if your interested, the team I'm going to be working with next year have a website here.

Monday, March 29, 2004

Long over-due

It's about time I updated this thing. I've been so busy since this time last week I just haven't had the time do anything, really. Wednesday was the job interview at Snell & Wilcox. I found out a lot about the company during the day: basically, they make digital signal processing equipment for TV broadcasters. For instance, they make equipment for converting between various standards (e.g. PAL-NTSC, SDTV-HDTV), and they've got some pretty cool kit for that. They've also got a piece of equipment called Archangel for restoring archive film: they showed us a demonstration of some pretty appalling footage being restored very convincingly, removing loads of defects such as banding, shaking, interference, all sorts. Very very impressive. Unfortunately, they were running late, meaning that I left two hours late, and only got back to school at 2100 (after leaving school at 0630 in the morning); by which time I was so knackered that I just went to bed. Then on Thursday I had lessons and school mass in the morning, and then after a token showing at CCF to keep up appearances, I went home in order to go to a party in the evening: my friend G. was having her 17th birthday party at a bar in the town we've just moved to. And that was great fun, apart from... ...having to get up at 0545 in the morning to get to school in time for roll call. Then I slept through the usual boring drivel at end of term assembly (hours of pointless football statistics, mostly), before having a single lesson with Mr. P. where we just had a chat. And apart from that I just haven't really been bothered, even though I've had the time... just about... to write something here. I might find the time sometime later today, before I have to go to rehearse for Bye Bye Birdie.

Tuesday, March 23, 2004

Moon lecture

As I mentioned last Thursday, I gave a lecture today entitled "Going back to the Moon to Stay" for the school's Astronomy and Cosmology Society. Unfortunately only a few people turned up; I gave the lecture anyway, but the master who runs the society has asked me to do it again next term, so I'll do a transcript and put the slides online then. I've got a job interview tomorrow! This time it's at Snell & Wilcox. It doesn't look like exactly what I want to do, but it does look interesting. Their websites not hugely informative; hopefully whatever they say tomorrow should clarify what exactly the work would entail. Time for bed now - I need to get up at 0600 tomorrow!

Big ion propulsion systems

On Saturday I investigated SEP systems for spacecraft going from LEO to the Moon and having a relatively small LEO mass of 20 tonnes. In hindsight, some of my numbers were a bit dodgy; more realistic values are for 15 tonnes of non-propulsion equipment.

But what happens when there's a possible initial mass of 100 tonnes, as could be launched to LEO by a Saturn V?

At this scale, SEP doesn't make sense. Sticking to my maximum transfer time of 2 years, the math works out as follows: mf / m0 = 0.843, so 84.3 tonnes of payload and systems and 15.7 tonnes of fuel. Using just one ion thruster as before, a Δv of 6.33x103 ms-1 would take 100 years. That means that to transfer in 2 years, I'd need 50 thrusters, corresponding to 250 kW of power consumption.

That's an awful lot of power, and a solar panel array that big is just ridiculous, without even taking radiation degradation into account. So, nuclear power could be used instead. Up to 1993 as part of the Space Defence Initiative NASA developed a reactor designated the SP-100 [1]. This was capable of delivering power levels up to about a MW at between 10-50 kgkW-1 (better specific mass at higher power). By the way: for the environmentalists, the SP100's nuclear fuel container is designed to reach the ground intact in the event of the reactor unexpectedly breaking up in the atmosphere. Additionally, I'm assuming a 1000 km starting orbit, and an orbital height of 700 km is considered by NASA to be "nuclear safe".

Pulling figures out of thin air, let's assume that a 250 kW reactor can be built at 30 kg/kW. That means that 7.5 tonnes would be power source. Additionally, I'd need 250 kW of ion thrusters, at about (yep, more made-up numbers) 13 kg/kW, another 3.3 tonnes.

Adding all that up, for 100 tonnes at LEO, I'd get 15.7 tonnes of fuel, 7.5 tonnes of nuclear reactor and 3.3 tonnes of thrusters, leaving 73.5 tonnes for payload. Very nice.

The real problem with what I'm doing here is the fact that no-one's done any research on really big spacecraft in the last decade or so, because there's been no requirement for such research. Everything's been kept small, cheap and efficient as far as possible (apart from the ISS, which is big, expensive and inefficient). I want to see things that are big, not too expensive and extremely efficient.


[1] 'SP100 Power Source', NASA SpaceLink

Monday, March 22, 2004


This year's academic prizewinners have been announced. I have won three:
  • Further Maths
  • Physics
  • Music
This is the same number as I won last year. Winning the Music prize is particularly bizarre, as I don't study Music. However, I enjoy suprises, and it's nice that the amount of effort I put into my music has had some recognition.

Sunday, March 21, 2004

A day off?

I'm having a day off today. I'm trying to get through the whole day without doing anything that resembles work in anyway. Yay! ...Shaft is on tonight on Channel 4 at 22:00. I'm going to watch it.

Saturday, March 20, 2004

Power for ion propulsion

There's a few problems with ion propulsion from LEO to the Moon that I hadn't considered. The first problem is in providing the electrical power required.

Last week I suggested using solar panels. The problem with that idea is that the spacecraft will be travelling through the Van Allen belts, where there is a high level of ionising radiation. Ionising radiation destroys solar panels, so it's best to minimise the amount of time spent in the Van Allen belts.

Here's a rough approximation. The ion thruster I described last week (Isp of 3800 s) had a thrust of 0.2 N [1]. Suppose the spacecraft has an initial mass of 20,000 kg (20 tonnes). That means the acceleration from this 5 kW thruster will be of the order of 1x10-5 ms-2. It'd take a long, long time (~ 20 years) to make a velocity change of 6.33x103 ms-1 at that rate of acceleration. 20 years, a large number of which would be spent in the Van Allen belts.

So what about increasing the number of thrusters? Let's say 2 years for a transfer is reasonable. Then 10 thrusters are needed, corresponding to 50 kW of power needed. If a solar array is degraded by 10-50% on a single transit through the Van Allen belt - and my spacecraft is spending quite a while there - I would need an initial capability of 100 kW. Unfortunately, the technology doesn't currently exist to make a deployable array that big. Additionally, the spacecraft would only be able to make one trip from Earth to the Moon.

Assuming that somehow there's been such a deployable array constructed and used, and since these (very heavy) arrays have been taken all the way to the Moon, it wouldn't be unreasonable to want to use them again. It would make sense to land them and use them to power a base. Only problem is, they'd need to be undeployed first. A good demonstration of the reason for that is as follows: take a strip of card (a bookmark, perhaps). Make a fist, and grip the middle of the strip between your thumb and the side of your index finger. With the strip horizontal, hold your fist a couple of inches above a table and allow it to drop. Watch what happens to the strip as your fist hits the table. Now imagine what would happen to the deployed solar array under an even larger shock. No-one's ever built a multiply-deployable array either: there's another challenge.

There is one possible solution to the Van Allen problem: run the solar panels at a high temperature (~ 400 K), when, in theory, they may be able to self-heal.

Next issue is mass. Once again, assuming 20 tonne initial mass and mf / m0 = 0.843, there is a requirement 3.14 tonnes of fuel. I'll round that to 3.5 tonnes to allow for the tankage factor. Typical specific masses for solar electric propulsion (SEP) systems are of the order of 20 kg/kW (I really think this is seriously underestimated), so a 100 kW system would have a hardware mass of 2 tonnes. That leaves 14.5 tonnes for payload and subsystems for lunar landing.

Now, what happens when the system scales up? A Saturn V was capable of sending 47 tonnes to the moon, and a hundred tonnes to LEO. What happens then?


[1] JPL Advanced Propulsion Technology Group, 'Advanced Propulsion Concepts', Island One Society

Friday, March 19, 2004

Muir Mathieson Memorial Competition

Well, that was it: what I've been working towards all term. There were seven of us playing this evening: a flautist, a cellist, a bassoonist, a percussionist, a clarinettist, a violinist and myself. The standard was extraordinarily high: it was undoubtedly one of the highest quality concerts I've played in, if not the highest.

I played the Adagio und Allegro again, and unfortunately it didn't go very well. In fact, it was the worst I'd played it in weeks. I missed the top C in the Adagio; my tripletty bits were a mess; and at the end, my mouth went completely dry, and I couldn't get the right notes out at all.


Anyway, the runner-up was R., my friend the clarinettist (she played really stylishly) and the overall winner was S., who played the marimba amazingly. I was very impressed.

I'm glad I entered. It was definitely worth it, because not only has it really motivated my to practise a lot this term - I'm now playing as well as I've ever been, if not better - but it means that I've got a pretty convincing piece worked up ready for the school Open Day concert next term.

Anyway, it's in the past now. This week I'm going to be doing a lot of practise on my part for Bye Bye Birdie.

Thursday, March 18, 2004


Don't expect anything much from me before next Tuesday: I'm preparing a talk/presentation for the schools' Astronomy and Cosmology Society on lunar colonisation. I will of course place said presentation on the Internet once I've done it.

Wednesday, March 17, 2004

Planet or satellite

I had first lesson off this morning, so while doing some prep I listened to the Chris Moyles show on Radio One. Now, at 09:00 every day, Comedy Dave does a spiel called 'Tedious Link', where he has to connect the previous day's Tedious Link track to the current day's via a series of seemingly arbitrary (and extremely clever) coincidences. Now, today Dave made some reference to the Moon being a planet, which caused no end of uproar. Chris said that the Moon was a satellite, and Dave stuck by his statement that the Moon was a planet. And guess who they called up to resolve the issue? Sir Patrick Moore, the venerable astronomer, and presenter of "The Sky at Night". It was surreal, and very funny, because for 10 minutes it seemed as if Radio One had suddenly turned into Radio Four. Naturally, Sir Patrick clarified the issue: planets orbit stars, and satellites orbit planets. Chris was naturally very pleased with himself. I'm quite impressed by how willing Sir Patrick is to get stuck in and set the record straight, even at his age. He's a legend.

Lava tube feasibility

On Friday, the British Library finally sent me the paper on lava tubes [1] I'd been referred to by Tom Billings (getting hold of it was a non-trivial exercise). It was definitely worth the effort, however: it's very interesting indeed.

As I suggested on 2nd March, the problem with designing a lava tube-based outpost is that, at the moment, we've no way of knowing whether there actually is a lava tube where we think there is one. I was pleasantly suprised to find my speculation confirmed by Coombes & Hawke; they say, "There is one major problem to consider... the difficulty in confirming, absolutely, that a tube does in fact exist... and determining what its exact proportions are."

The best thing about this paper, however, is that it provides a table of very strong lava tube candidates, some more than a kilometre in width. Some of these lava tubes could be ideal sites, except for the unfortunate fact that none of the tubes assessed as 'prime candidates' are close to the equator. That's a shame, because an equatorial position would be the most fuel-efficient to get to.

Even so, it's possible that strategists might decide it better to go with a lava tube we know rather than spend a lot of money on techniques such as SPR in the hope of finding a more conveniently located site.


[1] Coombs, C.R., and B.R. Hawke, 'A Search for Intact Lava Tubes on the Moon: Possible Lunar Base Habitats', in The Second Conference on Lunar Bases and Space Activities of the 21st Century (W.W.Mendell, Ed.), NASA CP-3166, Vol. I, p. 219, 1992

Tuesday, March 16, 2004

Homo sapiens

So on Saturday, someone decided to tell me that I need to get a life. 'Who cares,' they said, 'about all this rubbish you talk about?' Maybe I should explain why I'm so interested in space. I remember first becoming fascinated with space travel when I read a book by Arthur C. Clarke entitled Islands in the Sky. I almost forgot about it then for a few years, until when I was 14 or 15 I realized something that seems to me as if it should be obvious.

The human race is going to die. It's going to happen, one way or another. We will be extinct one day, and nothing that we can do about that: all we can do is delay that day as long as possible. But I look around me in the world today and I see that what's going to kill us will inevitably be the consequence of our sins.

Now, although that sentence was couched in religious terminology, I mean it in a totally non-religious way. Thinking about the way I behave, I realize that I am in a continual war between what I should do and what I want to do, and more often than not I do what I want. For example, last night after the Maths trip I should have done some horn practice, but instead I went to bed and read a book. This morning I should have got up at quarter past six so as to have enough time to do the things I need to get done before lessons, but I stayed in bed to twenty-five to seven. These are minor examples, of course, but they illustrate what I'm talking about.

Unfortunately, when taken at the scale of a nation, the pre-occupation with 'me' has terrifying consequences. Because a government continually feels the pressure of 'what the people want', it is forced to give the people what the people want rather than what they need. Take the USA for example. Its self-serving import/export policies and propaganda about the benefits of 'free trade' (we sell stuff to you happily, but won't buy your stuff except at huge rates of taxation) are born out of the desires of Americans to own big cars, comfortable houses and still to have plenty of time to drink beer in their local. Of course, that's not to say that people all over the world don't have the same basic desire to live in comfort. I do. But while we feather our nests, people all over the world haven't enough food to eat and barely enough water. That's neither right nor fair. I know good people who do many charitable things; a few who have given up a lot in the name of charity. But I know that they make up the minority of people; would that they were less exceptional. Perhaps what I'm talking about is the 'human condition'.

So what does that have to do with me? Because everyone is too preoccupied with what people want, rather than what they need, important things are being neglected and money that needs to be spent on scientific research is being directed elsewhere. We've known that Yellowstone National Park in USA is a giant semi-active caldera for a long time but because the chances of an eruption are so remote, less research is being done on it than should be. The fact seems to be ignored that an eruption of that particular volcano would result in the outright destruction of a large area of the USA, and would have extinction-level effects. Likewise, take an asteroid impact: we've known for thirty years that a large asteroid or comet hitting the Earth would be an extinction-level event. But such is the state of affairs that frequently-reported near misses aren't taken as a warning, but as another example of 'those crazy scientists crying wolf again'. As Terry Pratchett puts it, we are "...a race that watched million ton slabs of ice crashing into a planet which was in astronomical terms just next door, and then did nothing about it, because that sort of thing only happens in Outer Space".

But although I hope that through my future work I may be able to help with the danger to our race from outer space, I have really been plagued by the realisation that we have too many eggs in one basket. Although the Earth is a big, our survival is a fragile thing, and as we make the world smaller by our transport and communication infrastructures becoming continually more sophisticated, I see that we just increase the likelihood that something will kill us all. People first saw the effects of that in the SARS virus last year. Having seen the numbers, we were very lucky: the rate of infection was low enough that a serious epidemic was averted. If SARS had been a little more potent, a pandemic could have been on the cards. Another manifestation is terrorism. Terrorists can communicate so effectively nowadays, and that contributes to the potency of their attacks. Although I condemn terrorists and their activities, they do serve an important role in society: they remind us of how fragile our perceived security is. While we stay locked into one rapidly shrinking planet, these problems of war, disease, and the poor-rich divide will only get worse. What homo sapiens needs is some redundancy, so that if Earth suddenly ceases to be a going concern there will still be some of us somewhere to keep up the struggle.

This is my mission, to make our species capable of surviving an extinction-level event on Earth, or an infectious disease, or a nuclear war. But I won't be able to do that unless I can persuade people to do what they should rather than what they want, and governments to think not about the next five years but the next fifty. It won't be easy, but it is necessary. This will be my life's work.

Saturday, March 13, 2004

Terrible weekend

I'm really fed up this morning. Because there's no CMS this morning (there's a concert this evening instead) I'm stuck at school for just one lesson, Physics with Mr H., right at the end of the morning. So once I finally get out of here after lunch, it's going to be about 2 hours on the bus to get home, and then I have to go straight out to get a bus to the concert. If it wasn't for Chopper's lesson (sure to be dull as ditchwater), I could have gone home last night, and spent most of the day with Lizzie. As it is, I've slaved over some nasty calculus, done a bit of horn practise, and updated my website.

Tomorrow should be better though: although I'll have to make my own way home from my horn lesson, in the afternoon I'm going to get my bike out, fix the flat tyre, and go off cycling: I'm going to find the best cycling route from our new house to Lizzie's place. Hopefully walking from Horspath to Cowley won't take too long... I'm glad I've managed to get out of singing in the Bach St. John Passion on Sunday, or it really would be a terrible weekend.

Speaking of website updates, I've added quite a bit: a new section about shooting, including my 2003 reports for the Buzz (the school newspaper). I've also added a concert diary, outlining some upcoming concerts I'm playing in.

Friday, March 12, 2004

Using ion propulsion

So supposing I've potentially got 20 tonnes into LEO, but I actually want to get something to the Moon, what's the fraction of that 20 tonnes that has to be propellant?

I'm going to assume that I can have my 20 tonnes in an orbit parallel with that of the Moon, at an altitude of 1000 km. I'm also going to assume that the only problem is getting out of the Earth's gravitational field, to a target orbit the same as the Moon's (i.e. an orbital radius of 384000 km). So from the equations for a circular orbit (see for instance an A-level Physics textbook) initial velocity v0 = 7.35 kms-1 and final velocity vf = 1.02 kms-1, giving Δv = 6.33x103 ms-1.

I'm going to make the blatant assumption that as much electrical power is available as I require, and use a high-powered ion thruster. Now, the example I looked up on the Internet [1] had a quoted specific impulse Isp of 3800 s. I can use the fact that exhaust velocity is equal to specific impulse divided by the gravitational field strength on the Earth's surface (g = 9.81 ms-2) to find exhaust velocity ve = 37240 ms-1. Then from the rocket equation in the form e-Δv / ve = mf / m0 the ratio of final mass to initial mass is 0.843.

This is interesting, because it implies that out of 20 tonnes in LEO 16 tonnes will make it to lunar orbit: a much better ratio than for a conventional booster! Assuming, however, the payload is destined for the Moon's surface, that sixteen tonnes must include: the ion engines themselves and fuel tankage; the solar panels required to power the ion engines; the landing retrorockets and enough fuel to land the payload; and the landing gear. So it's probable that less than half of the original 20 tonnes would consist of non-propulsion payload. But the setup would probably still be an improvement on a conventional chemical-rocket-only system.


[1] IslandOne, Advanced Propulsion Concepts

Better with a 12-gauge

I'm finding indoor shooting incredibly frustrating at the moment. When shooting practise cards, I can do really well: I've got a really good 98 last week. But when it comes to match cards, I just shoot completely rubbishly. The last three cards have been 89, 90, 87 (today). It's infuriating: I don't know what's wrong with me. Sorry for lack of journal today: I'm still working on it.

Thursday, March 11, 2004

Fly, flying away

I to RAF Benson during CCF today, to fly Tutors (the RAF's current initial training aircraft). This was my last time flying them as a cadet: we don't have any more flying sessions there booked this year. I had a half hour sortie. After takeoff, we flew towards Didcot, and then just about managed to find enough clear air to do some aerobatics. Doing a loop is very strange: you pull lots of Gs while you climb, and then you look upwards and backwards and see the ground come into view - a wierd feeling. There's a kind of momentary feeling of hanging, and then you're heading straight towards the ground, pulling heavy Gs again. It's even wierder when you're flying the plane yourself. We also did some upside-down flying, which was truly bizarre, hanging from your harness while looking up at the ground. I had a major headache for the rest of the day though, because my helmet was too tight. Oh well.

January results

Pure Mathematics 3: 79% (B) Mechanics 3: 88% (A) That really isn't good enough. I must work harder. Although I do have an A overall in A-level Maths now, which is a good thing really.

Heavy lift (sort of)

I've been trying to work out which single-shot launcher provides best performance to LEO, by looking at the Ariane [1] and Boeing Delta-IV [2] launchers (no particular reason; these are just the launchers I thought of as being capable). I got the latest versions of the documents I referred to available, but I suspect they may be a little out of date (four years old).

Another thing to note is that the Delta-IV is only available for US government launches now, because Boeing was finding the commercial market insufficiently lucrative.

I'm interested in the maximum lift capability to LEO, pretty obviously, and for my purposes I'll consider a 45° inclination orbit at an altitude of 1000 km.

The Ariane 5 ES costs about $150,000,000 a shot (probably more). It consists of two solid fuel boosters and a cryogenic (liquid hydrogen/oxygen) main stage, with a solid fuel upper stage. Its performance to a LEO as described is just over 18,000 kg.

The heavy variant of the Delta-IV (Delta-IVH) costs in excess of $120,000,000. This is the only figure I could find, and it's even more outdated than my documentation for the launcher; I suspect the true price is closer to $200,000,000. The launcher consists of three Delta-IV CBCs (cryogenic main stages) strapped together, with a cryogenic second stage. It's a pretty big launcher. Performance to the aforementioned orbit is about 22,500 kg, in a payload bay of comparable size to the Space Shuttle's.

So for sheer mass capability, the Delta-IVH beats the most capable current member of the Ariane family hands down, and has a comparable price tag.


[1] Arianespace, 'Ariane 5 User's Manual', Issue 3 Revision 0, March 2000

[2] The Boeing Company, 'Delta IV Payload Planner's Guide', October 2000

Wednesday, March 10, 2004

Big and slow or small and fast

Yesterday I mentioned that I thought "development of the Moon should proceed... with most of the equipment and supplies being taken to the Moon in big, slow containers, while crew exchange happens in lightweight, fast spacecraft." What did I mean?

The ESA have a current project named SMART-1, a very small lunar orbiter mission. It was launched on the back of a big commercial satellite, into an orbit much closer in than that of the Moon. What's interesting is that it is currently using an ion drive to climb out of the Earth's gravity well to the moon, while hardly using any propellant at all (ion drives have a very high specific impulse). The downside is, of course, that it takes a very long time: SMART-1 will take eighteen months to move from the orbit it was inserted into at launch to its final lunar orbit.

I find this very interesting, because it suggests an interesting scheme for getting kit to the Moon. Big containers of non-perishable equipment and supplies could be thrown into a relatively low orbit, and then could engage ion drives to move themselves into lunar orbit (probably taking a couple of years or so), before using conventional methods for landing on the Moon. That would make most efficient use of the launcher's lifting capacity by minimizing the amount of propellant needed in the cargo. On the downside, it means two different types of engine and two different sets of propellant tanks are needed, as well some way of producing quite a lot of power.

Fortunately, power isn't too much of a problem: solar panels couild be designed to first be used to power an ion drive, and then detached as part of the unloading process and used at a lunar base.

Unfortunately, perishable goods (like astronauts) couldn't use that transit method, so an Apollo-style spacecraft would be needed to transfer personnel from Earth to Moon and back again. Ideally, the L/AV would be left at the Moon and refueled by visiting astronauts, to save on Earth launch mass. My slight worry is that we currently do not have a suitable launcher for this type of mission, unless the Russian Energia launcher is available or the Saturn V could be resurrected.

This scheme is an example of Lunar Surface Rendezvous (LSR) for freight, and Lunar Orbit Rendezvous (LOR) for personnel/perishable goods.

Tuesday, March 09, 2004


I just thought that I've been so preoccupied with writing journal articles recently that I haven't thought about describing the things I've been up to recently.

Back in January I mentioned that I was working up Schumann's Adagio und Allegro for the school Instrumental Competition, and that my horn teacher thought I couldn't do it. The competition was on Friday, and contrary to his expectations, I did win! That makes it twice I've won now (I won it in 2001 playing Nocturne by Franz Strauss).

Of course, the big gig is on Friday 19th March, when I'm going to be competing against several of my friends from CMS. There are going to be seven of us competing, and the standard will probably be very high, so it could be quite exciting! Lizzie's coming along to listen, as are most of my family.

On Sunday Greg and I had a band call for a show we're playing in with OYMT, Bye Bye Birdie. The music's very hard, but it's good fun as well, and lots of people I know are involved. Evening performances are on the 31st March, and 1st, 2nd and 3rd of April at St. Helen and St. Catherine's School Abingdon. There are matinees on the 1st and 3rd of April. Come and see it, because it's going to be very good.

On Friday night Lizzie's family took me to the National Guild of Master Bakers' Oxford branch's annual dinner dance. Which was interesting: the food was very nice, but unfortunately the music and dancing was definitely somewhat dubious.

Next Saturday I'm playing in a CMS concert at Burford school...

I'm far too busy.

The Lunar Hostel scheme

Over the last few days I've been referring frequently to Kokh et al. [1] in their paper on the Lunar Hostel concept. But on Friday I stated that I disagreed with the main thrust of the paper. Why?

In essence, what they propose is to provide a "big dumb volume" on the Moon's surface (a "hostel") with absolutely minimal amenities, and have all the necessary life support systems etc. provided by visiting spacecraft.

I believe this to economically foolish, and I don't think any agency would fund this scheme. The problem is mass. Landing on the Moon takes a certain mass of propellant, and it's necessary to take the propellant needed to get back into orbit again with you. It's desirable to keep the amount of propellant you need to take onto the surface with you to a minimum, so that you can take more supplies, equipment etc. with you instead.

So if you're visiting a base, you want to leave as much as possible of the stuff you take with you behind. You don't want to land a huge piece of hardware for recycling the air inside the hostel, and lug it back into orbit again. The same goes for water systems. It'd be much more desirable to land a big tankful of water and then take an empty tank back to orbit than to land a toilet, a shower, a water recycling system, and so on, and then have to launch it all back.

In complete opposition to the LRS's idea, I think the way development of the Moon should proceed is with most of the equipment and supplies being taken to the Moon in big, slow containers, while crew exchange happens in lightweight, fast spacecraft with minimal functionality (a la Soyuz or Apollo).


[1] P. Kokh, D. Armstrong, M.R. Kaehny, and J. Suszynski, 'THE LUNAR "HOSTEL": An Alternate Concept for First Beachhead and Secondary Outposts', The Lunar Reclamation Society, 1991

Monday, March 08, 2004

Applying the Moonbagel - 2

On Friday I began a discussion of how to apply the Moonbase hybrid-inflatable design.

I took the opportunity to draw a quick diagram to visualise what I was trying to describe. Access it from the Space section of my website. Please take a look.

As I mentioned on Friday, placing a floor inside a Moonbagel a third of the way up its diameter maximises usable floorspace, and this diagram illustrates the concept quite well. To me, the positioning looks like the optimal configuration for such a small module; in a larger module, I would put two floors in, at a third and at two thirds of the way up inside.

By now you've no doubt noticed the caption: "Moonbagel/Space Shuttle". That's because I chose the dimensions for this example quite carefully to fit into the Space Shuttle's main bay: the module as shown would fit into exactly a quarter of the bay, uninflated (the dashed outline).

I tackled another problem with this sketch. The bulkiest part of a module is the central core, which must contain hardware (wet & environmental systems) and the envelope, when uninflated. The original sketches show the core being held above a vacuum space by the pressure in the inflatable section. I don't like that configuration, because it would impose unnecessary stresses on the points where the ring meets the core. As shown, I've chosen a configuration where the base of the core is on a level with the base of the ring, and rests on the same surface.

Those are the main points I tried to fit into the diagram. Once I'd drawn it problems with it started appearing to me: I'm forever self-analysing. For instance, where should an airlock go? In this design, I can't find a suitable place to fit one. And where could the flooring be stored while in transit? Where could power cables connect to the module? The expansion coefficient isn't as big as it could be, either. However, I can't see a module much larger than this in its uninflated form being practical to move around on the Moon.

Friday, March 05, 2004

Applying the Moonbagel

Yesterday I said that the Moonbagel hybrid-inflatable [1] looked like a good design for basing a Moonbase design around. However, as I said, there are a few specifics that I feel should be addressed. Please refer to Kokh et al. so that you know what I'm talking about.

First, dimensions. Consider the floor to ceiling distance of the room you are (probably) seated in now. I expect that you will observe that the ceiling is 8' to 10' above the floor, i.e. 2.5 m to 3 m. This is because that is the amount of vertical space people feel comfortable in, so it would make sense to have that much headroom in a Moonbagel. But remember that the floor of an unmodified Moonbagel would be curved, like the inside of half-pipe. Unless the Moonbagel is decked, it would be difficult to make efficient and comfortable use of the space inside. If the Moonbagel was decked, it would be good place the decking about a third of the way up, so as to get the best trade-off between floorspace and headroom. The lower third of the space available could then be used, for example, for stowage.

But this brings me neatly on to the problem of radiation shielding. In order to get the most efficient possible usage of cargo mass as well as to improve the expansion ratio it would be sensible to have the walls as lightweight as possible. But there is no way that such lightweight walls - for the sake of argument 5 cm thick - would provide sufficient radiation shielding for the Moonbagel's inhabitants. Shielding would have to be provided by a lava tube or by regolith heaped over the inflatable. Assuming there is no accessible lava tube, and that the Moonbagel is 1.5 * 3 = 4.5 m tall, that means digging a hole 2.25 m deep, putting the Moonbagel in and inflating it, and then piling the regolith back over the top. There have been builders at my school recently. It took quite a long time for them to dig a hole 2 m deep, and required some heavy equipment[*].

Back to dimensions. For maximum strength and best unexpanded to expanded volume ratio, a 'slice' of a Moonbagel should be as close to circular as possible. However, the container fills the 'hole' of the torus.

I'm going to need a diagram to be able to elucidate my ideas further. A task for the weekend, maybe.


[*] It's starting to seem inevitable that heavy earthmoving equipment will be needed for the construction of any size of permanent base, so I'm not going to dwell on it.


[1] P. Kokh, D. Armstrong, M.R. Kaehny, and J. Suszynski, 'THE LUNAR "HOSTEL": An Alternate Concept for First Beachhead and Secondary Outposts', The Lunar Reclamation Society, 1991

Thursday, March 04, 2004

Inflatable habitats

When thinking about the practical design of a Moonbase, the thing that always bothers me is the need for space. Unlike the ISS, a Moonbase would be under the influence of gravity, and so the usage of volume would be very different.

Reasons for needing the extra space apart (having provided it, it's certain that activities would expand to fill it) inflatable modules seem the best way to go about creating it. Why?

The shuttle has a limited volume in its main bay - hence the relatively small size of the ISS modules, but inflatables could provide a much more efficient use of the volume. Consider a balloon and a matchbox. Uninflated, you can fit the balloon inside the matchbox, but when inflated, the volume of the balloon is much, much larger than that of the matchbox. This isn't the best analogy - the anticipated inflation ratio is smaller, and the inflatable module would unfold rather than stretch to its inflated size, but it provides the necessary example.

The original proponents of inflatables for a Moonbase were Kokh et al. [1], who suggested several designs. One of their most important points is that pure inflatable designs are impractical because they require a lot of outfitting - they can have no built in furnishings, and because pure inflatables only come in spherical, cylindrical and toroidical configurations, there is always an inconvenient curved surface underfoot which needs to be decked over for comfort.

Kokh et al. suggest a 'hybrid inflatable', which consists of some hard elements which have inflatable volume expanding between them or out of them. Their favourite design was dubbed the 'Moonbagel': a hard cylinder containing equipment and inflatable walls that expanded out into a torus, the original cylinder filling the 'hole' of the torus.

As meritous as their work was, I personally disagree with the main purpose of their paper, and I will discuss that at a later date.

NASA later took an interest in the Moonbagel design with respect to providing living space for astronauts on the way to and from Mars. Their adaptation, called TransHab, incorporated foot-thick walls for radiation shielding and a central structure fabricated from a lightweight honeycomb material [2].

The Moonbagel concept seems very promising to me, with a few adaptations. I will discuss these tomorrow.


[1] P. Kokh, D. Armstrong, M.R. Kaehny, and J. Suszynski, 'THE LUNAR "HOSTEL": An Alternate Concept for First Beachhead and Secondary Outposts', The Lunar Reclamation Society, 1991

[2] P. Kokh, 'TransHab and the Prehistory of its Architecture', The Lunar Reclamation Society, 1999

Wednesday, March 03, 2004

Lava tube initial steps

I've thought further about the problem of actually gaining access to a lava tube, and assuming it's the plan to build a long-term base in a lava tube, mission planners have two options:

  1. Send a surface scouting mission - probably a rover - to a potential site, to ascertain whether the chosen lava tube is accessible. If not, a different site could be investigated, or a hardened shelter and excavation equipment could be sent with a crew to dig their way into the tube.

    Once an accessible site is found or access to a tube is cleared, send kit for setting up a base inside.

    Advantages: You don't go to the expense of sending a hardened shelter and heavy excavation equipment unless you have to.

    Disadvantages: For each site, an extra launch is necessary for a rover just to scout out the local area. Also, the project will take longer to get off the ground because of having to wait for the results of the rover's survey.

  2. Assume lava tube access will be blocked, and send a hardened shelter, excavation equipment, and stuff for populating a tube immediately. If access is blocked, the crew will clear it, and set up a base.

    Advantages: doesn't require a surface scouting mission in advance, so quicker to implement.

    Disadvantages: the extra mass of a hardened shelter and heavy plant has to be sent every time.

Neither of these options are ideal, especially from a financial point of view. However, there are lava tubes on Earth which are directly accessible (the Oregon L5 Society uses such a lava tube as a moonbase simulation facility), so it's not unreasonable to assume that there are such lava tubes on the Moon. The problem is, how to locate them?

I expect that, at least initially, financial constraints will dictate that a beachhead will be a hardened shelter near to a lava tube, and that equipment for either gaining access to the lava tube or for establishing an inflatable-modules-covered-with-regolith base would come later, if the lava tube is inaccessible. Of course, if the lava tube is accessible immediately, then that's an added bonus.

Tuesday, March 02, 2004


My website is now back online at its new host! I've added a new section, 'Space', where I'm going to put space-related articles and resources I've written. The first thing I've made available is the talk I gave to the Windhover about the Columbia space shuttle accident.

Missing the obvious

Yesterday I outlined some design constraints for a beachhead Moonbase. Unfortunately, I've been missing a crucial fact over the last couple of weeks; this is a good example of why these journal entries are a learning experience.

While looking at some data on lava tube sites that have already been identified, something struck me: all the lava tubes that have been located so far have been rille discontinuities, i.e. the lava tube has collapsed at each end of the possible lava tube, probably leaving a lot of debris that would hinder access to the tube. I then also finally realised that entirely uncollapsed tubes would have no way in - they would be completely underground. The fact is that even if a lava tube was found from orbit that looked absolutely perfect for inhabitation, it is most probable that the tube would be inaccessible.

So, in order to gain access to a lava tube some heavy plant would very likely be required: bulldozers, excavators and possibly tunnelling equipment, none of which is going to be on the cards for a beachhead Moonbase (although I have some ideas about how some of this stuff could be made available).

So, having established that a beachhead Moonbase cannot be assumed to be located in a lava tube, I'm back to square one: how to protect astronauts from solar particle events and cosmic rays while they clear access to a lava tube. Well, one way would be with a metre or so of regolith. But heavy equipment is needed to move the regolith on top of the base. I really don't like the thought of astronauts being unprotected so far from home: if a big solar flare occurred, they would be to far away to return before it hit, and could easily suffer a fatal dose of radiation.

Which came first, chicken or egg? I will need to ponder this further.

Monday, March 01, 2004

Beachhead Moonbase design constraints

On Friday I suggested methods for supplying power to a Moonbase. But what would a Moonbase look like? To do this, I must first define what the requirements are, and what restricts my options.

Firstly, I am considering a "beachhead" Moonbase; that is, a first landing base with no current infrastructure. I am considering the minimum requirement.

Secondly, recall that we are going to site the base inside a lava tube. Because an orbital drop is never going to be able to land inside a lava tube, there's a requirement already: the base must be portable without too much inconvenience.

Thirdly, astronauts will need to get into and out of the base to carry out activities on the Moon's surface. So an airlock will be required.

Although power generation will be farmed out to a separate fuel cell generator (probably a sensible idea for safety's sake) there is still a lot of heavy equipment needed. Atmosphere regeneration, of course, and water management: what happens to water from showering or going to the toilet?

Additionally, a lot of other hardware is required: communications equipment, cooking equipment, furniture, medical kit; the list goes on and on.

According to my scheme, all of the features above must be available in my beachhead Moonbase. Tomorrow I will discuss the problems with some current proposed Moonbase designs.

Sunday, February 29, 2004


Sorry for the interruption over the weekend: I've been moving house, and we don't have Internet access at our new place yet. By the way, if I haven't told you my new address yet and you think I should have, e-mail me.

Friday, February 27, 2004

Powering a moon base

Yesterday I said I'd start talking about problems with lunar colonisation, and their possible solutions. To start at a completely arbitrary point, how do we power our hypothetical moonbase? Without power, your life support system goes down and you're dead. So quite an important problem, then.

Interestingly, despite quite a lot of Googling last night, I couldn't really find any good suggestions of how to solve this particular issue - lots of complaining about the problem, but no coherent thought about possible solutions.

The primary power source envisaged for a Moon base is solar energy from photovoltaic cells. The Moon doesn't have an atmosphere to get in the way of the Sun's light, so the intensity of the light is pretty much constant for the whole of the lunar day, and more intense than even direct sunlight on Earth. Big advantages for solar power. But then you have to take into account the length of the lunar day.

A lunar day is the same length as a Earth month: 14 Earth days of light, followed by 14 Earth days of darkness. If your base relies solely on solar power, you're in big trouble. This means that if you want to use solar power, you need to couple it with some form of energy storage.

Enough batteries to heat and light a base for a fortnight will weigh tonnes. So batteries aren't much good unless you have a vast launch budget. Neither are flywheels a good prospect: over the course of two weeks, a lot of energy will be lost to friction. Not to mention that a flywheel big enough to store that kind of energy will also weigh tonnes. The most promising technique at the moment seems to be fuel cells: devices that generate electricity directly from a chemical reaction. These would be especially good if they could be made to run in reverse, because they could then be used in a similar fashion to batteries. Even better would be if the fuel from the base crews landing/ascent module was the same as the fuel for the fuel cells: it would considerably simplify storing the fuel. Only one set of tanks needed!

You can tell that my favourite solution for solar power is PV cells with fuel cells. But the ideal solution would be a small nuclear reactor. Although it would weigh a lot, it would be able to power a much larger base than the equivalent mass of PV cells and fuel cells, and would therefore be a much more efficient use of launch capacity. Unfortunately, the political climate is such that you'd never get permission to launch a nuclear reactor for fear of what would happen if something went wrong.

So the base has power, but what form would the base take?

References:* (numerous threads)* (numerous threads)

Thursday, February 26, 2004

Moving hosting!

I've finally got my act together, and I'm in the process of moving my website to The Web Union. In the process, I've managed to find a very, very good online FTP client that's free to use - so I thought I'd share the joy.

Lava tubes: summary

So, to summarise what I've been writing over the last week:

  1. Lava tubes are natural tunnels formed by flowing lava.
  2. In some places, they have collapsed to form rilles.
  3. On the Moon they are roughly an order of magnitude larger than their equivalents on Earth.
  4. They offer considerable protection for a manned base from a variety of environmental dangers.
  5. Lava tubes would provide an ideal location for a the base for a mission lasting longer than a couple of days.
  6. Satellite photography can be used to look for intact lava tubes indirectly by looking for discontinuities in rilles.
  7. GPR can see lava tubes directly, but has serious problems associated.
  8. Geophones can generate precise data on lava tubes, but require a network of sensors and a number of shock waves in different places.
  9. "EMP thumpers" combine the advantages of geophones and GPR, but is still under development as a technique.
Tomorrow I will begin to discuss problems (and their possible solutions) associated with staying on the Moon for any length of time.

By the way, a disclaimer: writing these articles is part of a learning process for me. I don't suggest that they're even factually correct (although I do my best). If you find them useful, then great! And if you find any problems with them please let me know.

Wednesday, February 25, 2004

Lava tubes, seismic survey and EMR

Yesterday I outlined the ground-penetrating radar technique for finding lava tubes on the Moon. Another two methods have been suggested [1], and I will briefly describe them.

Firstly, seismic survey. This involves deploying a network of seismic sensors (geophones) in the area you wish to search for lava tubes; essentially, microphones embedded in the ground. Then you send shock waves through the ground, like a miniature earthquake. You can generate the vibrations either by explosive charges, or by impacts (i.e. crashing something into the ground from orbit).

Although seismic survey provides excellent resolution and good penetration of the surface, there are problems: you have to non-destructively land your sensors and then embed them. That limits you to a small area. If you're using explosives, you need to set them up as well, or if you're chucking stuff from orbit you need to have some sort of accurate delivery system. To generate good data, you need to have lots of sensors and lots of shock waves from different places. I think that this technique would be good for mapping an area you've already identified as interesting.

The final method is still theoretical, and combines the ideas of GPR and seismic survey. You lob devices from orbit - devices that, when they hit the Moon's surface, behave a bit like EMP bombs, converting their kinetic energy into a very powerful radar pulse. The radar pulse bounces off features in the Moon - such as lava tubes - and the reflections are detected by a very long baseline array of receivers, and converted into 3D geographical data.


[1] D. Stephenson et al., 'lunar resources/lava tubes',, 22-01-1996

Tuesday, February 24, 2004

Our Father

From This was much too hilarious not to put up on here!

<Firefly> Time for my prayers:
<Firefly> Our Father, who 0wnz heaven, j00 r0ck!
<Firefly> May all 0ur base someday be belong to you!
<Firefly> May j00 0wn earth just like j00 0wn heaven.
<Firefly> Give us this day our warez, mp3z, and pr0n through a phat pipe.
<Firefly> And cut us some slack when we act like n00b lamerz, just as we teach n00bz when they act lame on us.
<Firefly> Please don't give us root access on some poor d00d'z box when we're too pissed off to think about what's right and wrong, and if you could keep the fbi off our backs, we'd appreciate it.
<Firefly> For j00 0wn r00t on all our b0x3s 4ever and ever, 4m3n.

Lava tubes and surface-penetrating radar

Yesterday I discussed satellite photography. As I mentioned, there are problems with this technique, but there are others that might do the job just as well.

Consider a very simplified radar: you send out a pulse of radio waves, and you wait for reflections to come back. The longer the reflection takes, the farther away the thing that's reflecting.

During the Cold War, the US satellite reconnaisance researchers developed radar into a way to find concealed underground missile silos, and then as a demonstration published images of the network of underground rivers beneath the Nile delta, if I remember correctly. This worked by getting reflections back off features progressively deeper into the ground.

So this could work for looking for lava tubes. Mount a big radar on a Moon-orbiting satellite, and then set it looking at the surface of the Moon. Most of the time it'll get one reflection back, from the surface, but when it encounters a lava tube it'll get another reflection back from the tube roof, and then a third from the tube floor. This proposed mission would in fact provide two useful sets of data: a three-dimensional map of the Moons surface, which could be useful in mission-planning or geological studies, and then lava tube positions as a by-product.

There are naturally a couple of problems to overcome with this technique: on a basic level, resolution, penetration, and signal to noise ratio [1]. Resolution is very important, as to find the sorts of lava tubes we're interested in we need a 10 m resolution, or even finer. Penetration is also important, as we want to find lava tubes even quite deep down, and a low signal to noise ration is vital if we want to extract any useful data at all! To get a high resolution, you need a high frequency, but increasing the frequency of the radar signal reduced the penetrating power. It's a thorny issue. Additionally, to get a 10 m resolution you'd need to know the position of the spacecraft to within 10 m.

Even with those problems, this seems to me to be the most economical way of getting the sort of data that would be useful for finding the sort of lava tubes suitable for locating a Moon base in.

So what are the last two methods?


[1] T.L. Billings, 'Re: lunar resources/lava tubes',, 25-01-1996

Monday, February 23, 2004

Lava tubes and satellite photography

So, after yesterday's interlude, I will address the problem of how to find lava tubes on the Moon.

There are several techniques available to use. The first one I will consider is satellite photography.

Initially this may seem more than a little silly: how can (visible spectrum) photographs show lava tubes, when they're underground? Fortunately, we can use indirect methods to find lava tubes. If you recall, last Thursday I explained that rima are collapsed lava tubes, and this fact can be used to find intact lava tubes: all you need to do is look for gaps, or more precisely discontinuities, in a visible rille.

A detailed study was done by Coombs and Hawke [1] of imagery from the Apollo missions and the Lunar Orbiter spacecraft, which turned up more than ninety possible lava tubes. An analysis of the data from the 1994 Clementine mission has yet to be carried out [2]. Which brings us neatly to another problem with visible spectrum photography.

The easiest way to pick out rima is by the shadows of their walls - nice dark lines on a light background. Unfortunately, the Clementine mission was geared toward providing good data for geochemical data, and so they arranged to have all its photos taken at local noon - when the shadows are at their least significant. This is a pretty annoying obstacle to using Clementine data to find lava tubes. That and the rather low resolution.

But there are of course ways to look for lava tubes other than satellite photos.


[1] Coombs, C.R., and B.R. Hawke, 'A Search for Intact Lava Tubes on the Moon: Possible Lunar Base Habitats', in The Second Conference on Lunar Bases and Space Activities of the 21st Century (W.W.Mendell, Ed.), NASA CP-3166, Vol. I, p. 219, 1992.

[2] T.L. Billings, 'Lunar Lava Tubes via Clementine',, 17-02-2004


T.L. Billings, Oregon L-5 Society Portland Chapter

Sunday, February 22, 2004

Lava tube sizes

Yesterday I brought you to the conclusion that lava tubes look like good locations for manned lunar bases. But before I tackle the thorny problem of finding lava tubes in the first place, I feel I ought to give some idea of scale of these lava tubes. I said that you could put a village down inside the largest ones. This was probably an exaggeration, although there's at least one rille 3 km wide. Here's some example data[1]:

A small lava tube might be 20 m under ground, 20 m across and 15 m high.

A large tube might be 500 m under ground, 300 m across and 100 m high. So pretty large.

A good rule of thumb is that lunar lava tubes grow to about 10 times the size of their Terran equivalents.

Another aside: in Latin, the plural of rille is rima, and lava tubes are ducta. So if I start babbling about rima and ducta, you know what I'm on about.

Anyway, back to the point: how do we go about finding intact lava tubes?


[1] Artemis Project: Lunar Lava Tube Dimensions

Saturday, February 21, 2004

Other lava tube advantages

Yesterday we saw how lava tubes would act as a radiation shelter for astronauts on the moon. There are, however, several other potential advantages in putting a base in a lava tube[1].

Firstly, protection from meteoroids. The moon is constantly pounded by meteors weighing tiny fractions of a gram (we call them micrometeors), as well as meteor showers of larger meteors now and again. Although the micrometeorites are an unfortunate annoyance and can be compensated for by building equipment slightly bulkier than ideal, the larger meteor showers would be a serious danger to an exposed base. Placing a base inside a lava tube would protect it from meteor showers, thus making anti-meteor armour less of a necessity, and the tube would also provide a shelter for delicate equipment that would be easily damaged by meteors.

Second are thermal considerations. The lunar surface varies from ≅100 K in the nighttime to ≅400 K in the day, which means that thermal regulation of a base in order to keep it comfortable for humans could be a bit of a nightmare. If a base is placed in a lava tube, protection from heat is no longer a problem - all you need to do would is try your utmost to keep heat in, and we have experience of dealing with that kind of problem from polar research bases.

Finally is the problem of lunar dust. Formed from lunar rock by millions of years of bombardment by meteors, lunar dust is a serious headache. It's a very fine powder that gets into everything, clogging up motors, covering solar panels and shorting out electronics. But because lava tube interiors have been protected from meteors, we expect them to be relative dust free. Of course, by the time we've been walking and driving in and out for a couple of weeks it won't be.

So we've established that putting a lunar base inside a lava tube would be a good idea. So how do we go about finding a good site?


[1] Moon Miners' Manifesto: 12 Questions About Lunar Lava Tubes

Friday, February 20, 2004

All singing, all dancing, totally electric

(I think) I have managed to iron out all the remaining issues with my website. That includes a brand new design for my weblog! It's quite a bit more lightweight, and has the additional advantage that it won't need to be updated every time my main website's design is updated.

The NEWTS website is now an exercise in geekery. I run NEWTS (a PHP application) over the source tree. It invokes Ant (a Java application), which in turn invokes Docutils (a Python application). But it does what it's meant to do just about perfectly, which is to check out the NEWTS sources from CVS, build a CVS snapshot, build the documentation, and build all that into the website.

If you see any problems with my website (before you point it out, yes, I know MSIE has a broken CSS implementation) scream. I will be.

Can of worms

Yep, I've unwittingly broken my website again. I'll see if I can fix it later today.

Lava tubes and radiation shielding

Yesterday I described lava tubes, and the current evidence for their existence. But why are lava tubes so interesting for engineers investigating the possibility of a manned, long-term lunar base?

The reason is safety - principally with regard to radiation exposure, but other factors come into it as well.

Hazardous radiation in space in the inner solar system divides into two main categories: galactic cosmic rays (GCR) and solar particle events, but for our purposes we can summarize them as high energy particles and low energy particles. On Earth we are protected from the radiation by the Van Allen belts (part of the Earths magnetic field), which trap most of the radiation before it gets to us. We see the interaction between the magnetic field and the particles as the Northern Lights. That's why the Van Allen belts are particularly extensive when there's a solar flare, for instance. But the Moon has no magnetic field, and not even an atmosphere to shield astronauts from radiation. If there was a solar flare that hit the Earth-Moon system, any astronauts on the Moons surface would most likely receive a lethal radiation dose.

Using data from samples brought back from the Moon on the Apollo missions, detailed studies have shown that placing a base in a lava tube with 6 metres of lunar rock and regolith above it would filter out almost all the high energy particles. Less than a metre's depth would shield the base from the effects of a solar flare (De Angelis et al. [1])

So putting the base inside a lava tube would mean that the lunar base would be cheaper to set up, because it would not be necessary to take heavy and bulky radiation shielding to the moon. It would also mean that astronauts on the Moon would be able to continue to work during a solar flare, instead of cowering inside a hardened radiation shelter (although they couldn't go outside, of course).

So what secondary reasons are there for putting a base inside a lava tube?


[1] De Angelis, J.W.Wilson, M.S.Clowdsley, J.E.Nealy, D.Humes and J.M.Clem, 'Lunar Lava Tube Radiation Safety Analysis'