Quaecunque

Stumbling into controversies

2009-08-24T22:19:50Z

There could be something interesting to say about the whole US healthcare saga ... though I'm sure that others are covering it well elsewhere. I don't see a lot of meeting of minds so far in the blog comments I've seen - supporters of the NHS post in one place, detractors another (usually). Having had the UK decried on account of the NHS, the release of Megrahi seems to be the big bugbear at the moment. Apparently the plan is to stop drinking Whisky and visiting Scotland. Will they stop playing golf too?

I stumbled across another "great debate" in the last couple of days. The government is keen to encourage urban dwellers to take up beekeeping and I was interested to see what it involved. I've already been lent someone's daughter's school project(!) as an introduction but I've been looking around the web ... and this was where I stumbled across another controversy. I came across a couple of analyses) of the Vegan Society's position paper on honey(unfortunately references give a 404!). There were also numerous forum postings where people battle out whether beekeeping is necessarily exploitative. Presumably, if one kept hives to maintain populations and pollination, but threw away the excess honey[*] and didn't eat it, that wouldn't be exploitation?

I'm not vegan (I am vegetarian but now as a matter of habit/taste/discipline more than principle) so maybe it's not surprising that I've missed out on all theheated forum threads... Do I need heated discussions? Probably not!

[*] It appears that some amount of free space needs to be maintained in a hive to prevent the queen running out of cells in which to lay eggs - if the queen swarms the likelihood of the swarmed colony surviving long-term is lower.

After 18 years and 267 days...

2009-07-02T22:41:52Z

<181.15:35:00 DSS-63 BOT	
   181.15:40:00 DSS-63 TX ON	
   181.15:46:00 DSS-63 CMD MOD ON	
   181.15:50:00 Send time-tagged cmd with RX 1 on, 64BPS ENG, TX2/RX2 to LGA/R, TX1/RX1 to LGA/F (19:00 SCET)
   181.15:55:00 Send time-tagged cmd with AOCS configuration, open LV 2, ME-2 on, SS gain to low, CE-1 off (18:45 SCET)
   181.16:05:00 Switch off SIM HV (KET HV1 OFF)
   181.16:06:00 Switch off SIM HV (KET HV2 to Step 0)
   181.16:07:00 Switch off SIM HV (KET HV2 OFF)
   181.16:15:00 Switch on the X Wing Heaters
   181.16:20:00 Deschedule CONJ
   181.16:25:00 Switch off DSU
   181.16:30:00 Update PT and BT
   181.17:00:00 Monitor BAM-I HV off (BY TT)
   181.17:34:00 Monitor SIM HV off
   181.17:44:00 Monitor X Wing Heaters on
   181.17:49:00 Monitor CONJ descheduling
   181.17:54:00 Monitor DSU switch off
   181.17:59:00 Monitor the updating of PT and BT
   181.19:30:00 Monitor AOCS configuration changes
   181.19:45:00 Monitor RX 1 on, 64bps, some data collection at 64bps followed by RFDU reconfiguration
   181.20:05:00 DSS-63 CMD MOD OFF	
   181.20:10:00 DSS-63 TX OFF	
   181.20:15:00 Monitor S/C TX 1 off (loss of carrier)
   181.20:20:00 DSS-63 EOT

(In more detail than is often provided...):

http://ulysses-ops.jpl.esa.int/ulsfct/the_odyssey_continues.html#12

http://ulysses-ops.jpl.esa.int/ulsfct/ulysses-ops-blog.html

http://ulysses-ops.jpl.esa.int/ulsfct/opsfiles/current_ops.html#end-of-mission

Low key lottery...

2009-05-22T11:26:17Z

In case you thought that everything had to be high-tech these days, especially in government...

This was sent to me by one of my colleagues. It is for an entirely serious matter, see http://www.ofcom.org.uk/radio/ifi/rbl/rsls/ramadanstations09/. How else do you pick them?

Thanks, and this should actually be fun. Well as fun as anything gets if you’re a manifest dweeb.

2008-08-29T23:52:00Z

After a letter written by three US senators (including John McCain) requesting that NASA takes no further steps towards shuttle decommissioning [*], the feasibility of shuttle extension to 2015 is being looked at... because of politics. The dispute between Russia and Georgia makes it less likely that the US Congress will approve the waiver to the US Non-proliferation Act (that prevents the US buying things from Russia) which allows NASA to pay for Soyuz flights to the ISS. So given the money sunk into the ISS, what is the US going to do until 2015 (or possibly later) when their successor vehicle is ready? Answer: stretch the shuttle (possibly): www.nasaspaceflight.com/content/?cid=5504

The Columbia Accident Investigation Board recommended that the shuttle did not fly beyound 2010 without a "full recertification" though what that means is in itself an interesting debate. However, the idea of having no US access to space for 5 years seems to be making politicians a bit jumpy in the national pride stakes. If the shuttle was continued (even if they dropped to 2 orbiters and used one for spare parts[*]) then they would have some means of transport to and from the ISS. However, they'd still rely on the Soyuz as their emergency return vehicle, and it's not clear about payment for that...

The constraints on a new, extended flight manifest beyond the remaining ten currently planned (from the original email)[@]:

- We cant just spread out the 10 flights to 2015, that does not support ISS requirements
- We will need some new ETs and that’s the long lead item so we may need a little "streching".
- We will have to put orbiters in OMDP
- We don’t want to get in the way of Cx development by holding on to facilities they need (HB3, MLP, Pad , Crawler, Engine Test stands etc)...

The email does conclude on a lighter note:

Thanks, and this should actually be fun. Well as fun as anything gets if you’re a manifest dweeb.

[*] The rundown of shuttle production has already begun. Quite a number of engine parts are no longer made, but as the engines are reused they need fewer spares. They have already run into issues with other systems where (for example) they have two functioning VHF radios between three orbiters (though they're getting a spare through flight certification, I believe)... For a post on the issues with keeping the shuttle going, see Wayne Hale's blog entry . As the external tank (ET) is not reused, they'd have to make more of those to support extra flights, and they were about to scrap the equipment for that this autumn having completed sufficient for the remaining flights. Thus the reference to stretching (i.e. the existing 10 flights might be spaced out a little more to account for the lead time in getting a tank for the 11th).

[@]Abbreviation decoder: Cx -Constellation, the successor; OMDP - Orbiter Maintenance Down Period (major overhaul/upgrade session that happens after every 8 (IIRC) flights or x years of an orbiter); HB3 - High Bay 3 - where they mate the shuttle, tank and boosters together, which will be used for assembling the Ares rocket; MLP - Mobile Launcher Platform (what they stack the items on - this is then picked up by the crawler and transported to the pad)

The waiting is over...

2008-07-24T22:25:08Z

...I received my rejection email from ESA today, though they do point me in the direction of their other careers. It shouldn't come as any great surprise that in cutting down from 8000-odd applicants to 700-1000 (the figure quoted for the next stage) they have to adopt a fairly strict regime. It's a disappointment but I have the good fortune to have a job that I really enjoy despite the lack of space focus or an amusing microgravity environment!

I suspect that the initial sift was at least in part done on some scoring of the multiple-choice answers: perhaps being a better swimmer, accepting a round-trip long-haul flight once a week or weighing less would have helped? Speaking Russian? If the intention is only to recruit every ten years then they may not give away too much by offering some general feedback on the criteria that mattered in the end and how they scored them. The perils of writing online: that last sentence might sound sourer than it's meant to. I genuinely am interested in how you select reliably from such a large field - it's not as if the process for 20 applicants of reading every form through is going to scale to 8000!

Their mention of other careers is an interesting thing to think about: the other posts they are currently advertising require a degree of specialism or experience in areas of space science or technology that I don't possess - as an adaptable generalist, being an astronaut is probably the ESA position I am most qualified for :-). Maybe that should tell me something...

In a marginally related story, my colleague realised today that he was going to be on leave for the interview day for our current vacancy and would I consider sitting in on the panel if necessary? - well, of course I'll help out. However, we have formal training for people who do selection and I haven't been on it, so I don't think I'm expected to choose a candidate from the field, just to be ready to answer any of the candidate's ultra-specific questions about how many cups of tea we have each day on average. Obviously the short-listing and selection has already been done and that is done by scoring candidates on specific aspects - I think the interviews are done in the same sort of way. However, we have only had 50 or so applicants - I don't think our systems would function very well for 8000!

And last, but very certainly not least, our beloved Corky's health worsened significantly (and unexpectedly) over the weekend and he is no longer with us. We had to make the decision in the car back from Kutna Hora to Dobrovice on Sunday - we would have liked to have been there but under the circumstances it would have been unnecessary suffering to have waited the 24 hours until we were back from the Czech Republic. We miss him lots.

Next time: a jollier entry?

Firing up the ancient technology (advisory: some geeky content)

2008-05-19T23:18:48Z

We possess a venerable scanner, that I'm sure cost £200 when we bought it quite a number of years ago - it was bought somewhat at the last minute to scan photos for the first issue of Dark Times in 1996. I had not been going out with cally_tmk for very long back then...

So we bought it to attach to my PC - then a P75 dual-booting between Windows 95 and Linux (0.99.15 followed shortly after by 1.2.13). The scanner is a SCSI scanner so it comes with an ISA card to drive it. Well, the scanner is still used on the oldest PC we have working here now (the P133 that replaced Cally_tmk's Dell 386) whose sole purpose now is to drive the scanner. Of course, typically, the network lead I found for it was faulty and Win95 is not very forthcoming with diagnostics on the networking front.

We accept we probably ought to get a new scanner sometime - we do actually have a couple of USB ones sitting on the floor here that might be worth a try...

Anyway, the medical certificate from the last entry ago has been scanned and dispatched. I await a confirmation email...

In other news of rather more modern technology, I have come to the conclusion that it is probably best to use computers for decompressing audio files. I have spent the best part of 8 hours (across two days, it would be too much otherwise) getting to grips with mpeg audio (layer 2 so it is a bit old fashioned). I reckon once you got up to speed it would only take a couple of hours per 24ms frame to decompress by hand... In case you're wondering I have been asked to explain why one audio file works and the other doesn't...

The real revelation was that it is quite hard work tracking down bit-stream level documentation of MPEG formats - it does exist, but the actual codec implementations are not fabulously well commented - and it seems pretty clear that most people would rather just use codecs as black boxes (sensible!) and don't necessarily understand how the bytes in an audio file (or on DAB or Digital TV - same audio format) get decompressed. That bit is left for geeks like me to babble about bit allocation and scale factor selection.

Just as well I do audio - I reckon video is probably lots worse!

Medicals (episode 2 ...)

2008-05-03T00:06:50Z

Well, I went for the promised medical. Aside from the serious diagnostics, it seems that quite a number of things are tested less formally...

There was a fair bit of form-filling (medical history stuff) which the doctor typed into an interactive application. (Bizarrely it at first didn't want to accept "Pneumonia" as a valid condition - I had it when I was 8, so it wasn't likely to be an issue.)

There was more eye testing - this time with quite specific near-vision reading tests, a squint test (My eyes do point in the same direction) and a "tell me when you can see me waving my fingers" peripheral vision test. Balance was tested by standing on one leg with my eyes closed; hearing by covering one ear while the doctor whispered some digits at the other end of the room.

I had a many-lead (12? 10? I should have paid more attention!) ECG (normal) - I didn't expect leads attached to my knees...

It's probably the most detailed medical I've had, and I passed - so I now have a JAA Class 2 medical certificate (valid for five years) which was the point of the whole exercise and spending £141 in the process...

Thanks for all your interesting comments about sight - I shan't rush into any unusual eye exercises...

Oh, and you have probably all seen LOLCatBible and heard of LOLCode - now also available as a language for PostgreSQL - Real Example

Episode 1 of a sort...

2008-04-30T17:44:39Z

... I had an eye test today - the first time since I had an over-the-top-thorough eye test in 1993 (when I needed one to confirm the state of my sight in case I subsequently ruined it with a big laser and sued). That test involved peripheral vision testing and retinal photography, and was at least in part an exercise for optometry students to practice!

Today's test was a more basic affair...

first with some automatic machine with a little picture of a road and house (administered by a staff member best described as "sternly efficient" or brusque) and then a somewhat more detailed and traditional examination from a limping optometrist.

Why? I decided that as I have a medical involving a sight test on Friday[*] I'd better check that I would pass it (and get glasses beforehand if I needed them) but it seems I have 6/6 left eye and 6/7.5 right eye (good enough) - I am aware that my sight has worsened since I was a teenager, when I indulged in feats of prodigious distant visual acuity - compared to then, it's very poor. Compared to the population in general it's reasonable. However, the prescription I was given today was quite gentle and suggested only for near work (i.e. the hours I spend peering at a computer). I haven't bought any glasses (would feel weird wearing them) and wondered in conversation at lunchtime whether I should buy some or not[@].

One of my colleagues rather contrarily suggested that glasses were a bad idea - he used to have them and then stopped, because he thought it could only worsen his sight and make his eyes lazy[+]. The world looks better in soft focus, he said, and the women are all pretty.

[*] Which I may cover on Friday if it's not too gruesome. I'm uncertain whether to friend-lock this or not - knowing my visual acuity is an unlikely direction for blackmail or identity theft but I might protect later episodes.

[@] Laser vision correction is (basically) ruled out, though I know quite a few people who have had it recently.

[+] I have no idea whether this is true - opthalmology is not something I know lots about.

On the internet, [fill in blank]

2008-02-05T20:42:31Z

After a moment, it stopped walking into my wall, and turned to stare at me. - obviously if you get fond of your patch in Second Life, the robot menace may be a bit much,

There's a lot of stuff to say about game engines for exploring archaeology. And I really must write something about the "systems game" concept.

Being technical...

2008-01-30T00:23:35Z

[x]
(and if that didn't work:

http://www.youtube.com/watch?v=6EJ8r9Rhfw8

(Found via the presenter's wife's blog: http://www.giagia.co.uk/?p=248 along with other outtakes indicating a little "surfer dude producer vs. particle physicist" creative tension!)

"I want to know what a ripple in spacetime would mean to this sandwich"

(Whole programme (not containing that quote, it's from an outtake) can be found for the next few days at http://www.bbc.co.uk/programmes/b008w9kp [y] )

[x] evilmattikinz started it round here...
[y] These are permanent URLs i.e. for ever for every episode of every programme. They now link to Flash iPlayer where available.

Specialist publication

2008-01-17T00:56:38Z

Orbital Debris Quarterly News - well someone was bound to write such a thing. (Warning: contains details of gross irresponsibility on the part of the People's Republic of China and a bullet-wound to a shuttle)

Strange game Looks like the kind of thing that evilmattikinz would get up to...

Secrets of various sorts

2008-01-08T00:21:55Z

An interesting article on what space mission patches for classified US satellites tell you. (found via www.nasaspaceflight.com)

This reminded me of Richard Lamont's Capenhurst investigation where the purpose of the "Radio Introduction Unit" was somewhat given away by the description of their coat of arms!

I also note that elsewhere on his site, Richard Lamont has been requesting (via FoIA) details of the BBC network radio problems last August. It has been redacted so that you don't know where circuits go or where exactly the faulty air-conditioning unit was... I can confess to having seen the unredacted version of one of these (always funny to see things turn up "on the outside"), but it's not worth torturing me for the details because I can't remember any of them anyway.

Historical Surveying / Geeky Theorising

2008-01-05T02:25:59Z

You all must know how I love geeky stuff, so when evilmattikinz sent me a note about a couple of old OS photos with an enquiry about what they meant.... and I couldn't resist, and replied...

The photos are obviously OS photos as part of the records for the marks concerned. As for whether they are horizontal controls (triangulation stations) or vertical controls (benchmarks) I'd go for the latter
despite of the "STN" (station; implying horizontal) labelling at the top of one of the pictures. The dating corresponds with the Third Geodetic Levelling - evidence from OS annual report (http://www.deformedweb.co.uk/trigs/annual.cgi) suggests that Lancaster tertiary levelling (exactly this sort of thing) was completed prior to April 1954 - so I think these may be the third-order benchmarks being recorded. For further argument in favour of this, see below:

Obviously the date is at the top of the board - the next numbers (09A or 71B ) I think are just the designation of the mark in the current grid square - which is the next line: SD4861 (in Lancaster) a square which interestingly also contains a fundamental bench mark. Denis Street is identifiable in google maps and is indeed in that square. The other is possibly a shot of Williamson Park (where the FBM is and which has many benchmarks in it). There's a fair bit of parkland in the area and it's a bit anonymous.

I had a theory that if they were benchmarks then the last line was a serial number of the mark in the levelling - levelling line 55 was Hoghton to Lancaster. An individual levelling line and attendant
campaign might be significant effort, so the 55/ would be painted on the board because everything along that line would need it (not 100% convinced on this!)

Note that the marks on the photos suggest they have been destroyed - unsurprising really as benchmarks are lost all the time and there is little reason to replace them.

Enough!

Benchmark spotting geekery HQ

Digitising the data from the 1922 report

Yes, they were doing surreal photos in 1922, too

Out of Step or Out of Sorts? (On vocations)

2007-10-31T00:48:22Z

I have this feeling I'm going grumpy. I'm turning into an arch-skeptic before my time. Or maybe I'm not getting enough sleep...

I had a very stimulating meal yesterday with friends (well, it was officially a meeting) and "Transition Towns" were mentioned (these being a way for a community to prepare in advance for peak oil and climate change). Related to this, a vision was presented of a stronger local communities who (for example) didn't have to have the technology and the power demands that our society had; who would be happy to live without that technology [*]

...and I had quite a strong reaction. Why would I want a simple, low-tech world? What would I do without computers?

The second question is often answered the wrong way - it presumes that I have and use computers because our culture and society makes me and I would be happier without such troubles. This is quite an understandable reaction to have if you feel that complex systems torment you (as they do many people). My perspective is different: I can live my life, I can survive without computers or technology. I can live in a tent; my everyday life is not filled with gadgets that I depend on. But my vocation is systems engineering and to find one's vocation rendered inappropriate can be galling, to say the least. Were society to decide that rock music was inappropriately loud and that we shouldn't be making drum kits or electric guitars, how would rock musicians feel?

But that's not what people mean about the low-tech world. It's only half low-tech. People will still use electronics, they'll just pretend not to! We'll still have people who plug their guitar amp into their wind turbine (controlled using semiconductors) to sing songs abou escaping the pressure of technology. Now where are these devices to come from?

...And then I start to think - what about all the others who have vocations in "dirty" trades - aerospace engineers, for example. What will happen to them?

I met a couple a few months back who were both engineers; he was a heating/ventilation designer for a local authority and she was a systems engineer. I asked what sort of systems, and when she replied "weapons systems" I wasn't sure where you took the conversation from there. We had arrived at dinner and the subject changed. The following morning I said that there hadn't been any particular motive to me not asking any more other than that I wasn't sure that I could ask any questions she would be allowed to answer. Basically true - but she could say that most of what she did was paper studies and operational analysis of systems that would never be built. "Well", she said, "at least you're still talking to me. A couple of people refuse to talk to me since they discovered what I do".

Vocations are strange and mysterious things.

[*] This is a wild paraphrase and not necessarily an accurate reflection of what my friend[**] suggested.
[**] who can name themselevs should they wish, but it's really not important[+] for this story who they are.
[+] By which I don't mean they're not important. They are. But their identity is not relevant here.

Way behind the times...

2007-10-16T00:52:41Z

It is typical of life that while I was suffering a cold that led to me sleeping most of Thursday and a bit of Friday; that lots of those who live near the (obvious now though I never knew before) entertainment hub which is Huntingdon were riding their horses and having swordfights and all the kind of derring-do that my dashing friends get up to.

My vague sense of missing out on things was rather heightened last night. I have a tendency to wander my way round the web and after various random[ ] sources of information[!] and ended up reading something about national anthems. Amongst this I spotted the results of a poll for a suitable anthem for Scotland - the top two entries (Flower of Scotland and Scotland the Brave["]) were familiar, but the third one was "Highland Cathedral" which I had never heard of. Apparently it's been used all over the place and is quite well known.

Trying to find out more (and in particular, to hear this piece I had missed), I discovered that it is Chris Patten's favourite pipe tune. I had paid little attention at the time to the handover of Hong Kong in 1997[$], but in tracking down Highland Cathedral I found the footage of Chris Patten leaving Government House on the 30th June 1997; having the Union Flag piped down to the Last Post and standing on a small podium in the garden in the heavy rain (without an umbrella)[%]. The police band play Highland Cathedral for him (this might not have been by his arrangement - he acknowledges them with a smile when he hears it) as the flag is taken through the house from the roof. Finally, the flag is presented and he is a little too quick to take it. This is the last governor of the wealthiest and most populous dominion of Britain; but also a man in a grey suit getting wet in the rain. There is a verse of God Save the Queen. Then, to Auld Lang Syne, he is driven away to the main ceremony. (best video I've found of this, possibly fom someone's 10-year anniversary programme)

Finally, as his last act of office he sends the telegram to the Foreign Office:
I have relinquished the administration of this Government. God save the Queen. Patten

...and they leave on Britannia. They get a 21-gun salute in Indonesia, but when he gets off the plane at Heathrow, he's back with his family in the rain at the taxi rank to find their own way home.

I'm just a sentimentalist, but it seems a strangely poignant way to represent the end of an empire - not with a bang but a whimper.

[ ] Am I trying to overwrite secret information?

[!] Last nights' top hit was the Shuttle DPS (Data Processing System) Console Operators Handbook rev F. - the quite chatty documentation of GPC error 43 (Data bus MIA XMIT-ENA register disagree) and the wrong things that might have happened before they fixed a bug... Yes, you can all sigh and roll your eyes!

["] The argument against it is that no-one knows the words. Ever since my mum told me that as a child (in Ayrshire) who occasionally went up to Glasgow, her contemporaries would sing "Wha's seen the tattie howkers(x3)/Coming up the Broomielaw" to the tune[#]. This may make sense to Scottish readers :)

[#] I know there is also a song "Wha saw the tattie howkers".

[$] If I'd written this entry in June or July I could have claimed that it was timed for the anniversary. I don't even manage that!

[%] Later events were to show that privilege and rank meant nothing. Someone held an umbrella over Cherie Blair at the handover ceremony, but Patten and Prince Charles just had to deliver their speeches soaking wet.

A bit random

2007-10-02T21:45:28Z

Fed up with off-the-shelf light-up clothing? Why not combine your sewing skills with electronics and make your own?(Lots of projects including some DIY instructions). SparkFun are now selling a range of components with holes big enough to stich through...

In other hacking news, my rover project still plods away - I have my single-board computer (A Technologic Systems TS-7260) but it became pretty obvious pretty quickly that Python (my original plan) is not an ideal language to use for this application, for two reasons:

It doesn't like cross-compilation, because its configure script keeps wanting to run programs.
More significantly, for a machine with 32MB flash, it occupies about 11-20MB.

So I did a bit of hunting for scripting languages with a small footprint, and have chosen Lua (about a 60-120k footprint). I have since discovered that it is the fastest-rising language in the Tiobe charts (but be wary of polls). I'm currently porting my JPEG camera driver code into a micture of C and Lua (though my use of the TS-7260 probably means I could use a USB webcam instead!).

Boring stuff over. Exciting tales next...

Ah. Maybe next week?

Throwing things away in orbit...

2007-09-14T20:07:14Z

Nice description of he implications of disposing of things in orbit:

SuitSat trajectory

New designs are available

2007-08-19T22:57:02Z

I discover somewhat to my surprise, that new designs of milkfloat are still being developed[a].

Also, from the same site, "A serviceable, second-hand milk float, with half-decent batteries, will set you back around 500 pounds. A float in good condition with good batteries may cost more than twice that."

Is that all?

[a] And I thought they were going to ship them to Kathmandu to solve pollution problems, but apparently the drive system is rather old-fashioned.

Representations (being prolific today)

2007-08-19T00:47:51Z

We have, as some of you will know, been working our way through Adam Adamant Lives and tonight's episode was "The Village of Evil" - aside from the increasing frequency with which hooded ceremonies seem to be appearing[1], there was one other thing that really surprised me.

While the satanic rituals will be taking place at the old mill, Sims is told to keep Georgina safe by taking her out. In the absence of anything else to do in the village, Adamant suggests taking her to church (surely, he says when Sims sounds surprised by this suggestion, we have Evensong still in England). SSo Sims and Georgina go, and the shots of the ritual at the mill are intercut with Georgina and Sims in church.

The writer was obviously keen to draw parallels, so the "form" of the satanic ritual is quite responsorial. The thing that astonished me was the portrayal of the Evensong. Unsurprisingly for the 60s (and possibly not a surprise today!) it was a sung BCP[3] Evensong - but rather than adopting the now-commonplace approach to church services as consisting of a hymn (well-known) and a sernon (either terribly earnest or slightly sinister), we had the introductory responses, some of the psalm and the Magnificat. Of course, Georgina keeps perstering Sims throughout - and they both stumble with the setting of the psalm (this was the clincher for realism and really made us laugh!).

They couldn't resist one concession to cliché - the vicar is a round-faced elderly man who, beaming beneficently at them as they leave, criticises the materialism of London, and asserts that the country folk have a simple faith!

(Typically vicars in TV drama or film are either kind but dim or deeply sinister. They are rarely ordinary[4]. Liturgy, aside from the well-known bits of weddings and funerals, doesn't exist).

Can anyone identify any other cases of real liturgy other than the above appearing "straight" in TV drama or film?

[1] The previous episode, The League of Uncharitable Ladies[2] had this too, along with sound hypnosis - a popular topic for the writers as it appeared in Sing a Song of Murder too.
[2] Directed by Ridley Scott - I have noticed they're getting more funky moving camerawork as we go along.
[3] Book of Common Prayer (1662) - but most commonly it's actually the 1928 edition famously not approved by Parliament (see the CofE site for details - the curse of being the established church is that MPs who don't like your attempts to modernise can veto it ...
[4] The Archers is a radio programme, and thus allowed a normal vicar.

The joys of expanding foam...

2007-08-18T16:05:05Z

While all this talk of high-tech repair in space is going on, I have been fitting a new shower "enclosure" (I'm sure they were cubicles when I was a child, though cubicle means something different now[1]). After much consideration about whether the instruction to bed the shower tray in cement was really necessary to support it - or just a way of making it much more difficult to fix leaks later - I decided against. The metal bit is built the tray is plumbed in, the walls aren't square... so out comes the magic sticky foam.

I dispensed in cleanly round the shower, then suddenly got the idea that it might help to seal our leaky roof[2]. In the process I managed to get some of it on my hands (yes, there were instructions about wearing gloves, I know) and as I've just discovered, my elbow... it's stopped being sticky now at least ("tack free in 20 minutes!").

At least it might stop the drips.

[1] The BBC used the term "Studio" for a room with microphones in; a room in which a programme was mixed (containing a mixing desk etc.) was a cubicle. The old terminology in local radio was that their central (and only) studio was "Studio 1" and they had Cubicles 1A and 1B either side. They don't do this now, they just call them studio 1, 2, 3 etc. and "talks studio" if they do the old-fashioned thing.
[2] The wrong sort of tiles for a roof with as shallow a pitch as ours[4]. I was surprised, peering through the hole in our bedroom ceiling[3] that I could see daylight.
[3] We had water dripping through the sodden/sodding plasterboard and the loft is about 12 inches high at that point so I cut a whole in the ceiling to get to the underside of the roof.
[4] About 30 degrees,12 m by 8m facing sue south... which would make it good for solar power if we ever get round to it.

Risk tradeoffs

2007-08-17T17:04:29Z

So, Nasa has decided not to repair damage to the Thermal Protection System (TPS) tiles on the underside of Endeavour. Much of the discussion they wert through was a tradeoff between risks. How did they reach the decision - and what options were available?

I have this knack for producing sexy, exciting titles to entries here....

They machined a test segment of tiling with the same damage that the shuttle has and subjected it to extreme theremal testing. The result was (picture from Nasa status briefing slides):

The first thing about the TPS damage is that shuttles have landed with worse damage - there was never a view that the magnitude of the damage would result in catastrophic breakup - but it might result in overhaul work to the underlying (aluminium honeycomb) structure. There's quite a bit of experience with this on early shuttle missions, some of which came back with quite large singed patches. However, the possibility of catastrophic failures caused by ice or foam debris during ascent was not fully appreciated until the loss of Columbia. this has led to the intensive imaging process on the Shuttle prior to docking with the ISS.

Also post-Columbia, various repair options have been developed (and there is always scope for improvisation - as the sewing down of a loose thermal blanket on the last mission demonstrated). Having precisely imaged the hole, NASA had options for filling it but after much analysis decided against it. Why not do this one when they stitched the blanket back on the last one?

There are several reasons - firstly, the underside of the shuttle is less accessible, and (overall) more thermally critical. Because the access is difficult (involving the astronaut being perched on a boom on the end of a manipulator arm with several joints being steered by camera) there's a much greater risk of the astronaut causing further damage. The thermal testing that has been performed after replicating the gouge indicates that although the adjacent tile might be damaged, there shouldn't be any structural issues (and Endeavour is not due for another flight until 2008, giving ample time for repair).

Furthermore, if the repair is not done perfectly, the change in airflow might have unexpected effects. Finally, there is a 1 in 2000 risk on each Extra Vehicular Activity (EVA) that the astronaut would be killed by a piece of orbital debris, so there is a reason for not doing it if you don't have to.

What would be the scenario if the shuttle had been more severely damaged so that there was serious doubt about a safe re-entry?

Again, post-Columbia the requirement is that another shuttle is available to rescue the astronauts, who can camp out on the international space station (ISS) until the so-called "launch-on-need" (LON) shuttle can reach them - there are sufficient consumables on the space station to do this. This procedure is Contingency Shuttle Crew Support(CSCS).

What happens to the shuttle in this case? There are two options. Firstly, a small amount of rewiring allows them to configure the remote closing of the docking hatch and undocking of the shuttle from the space station - the shuttle computers can be controlled from the ground, so the shuttle would be deorbited into an ocean (the payload bay doors would not be closed and the shuttle would enter the atmosphere with that ide down to accelerate disintegration).

There's a more interesting option, though, that NASA are more coy about. Further rewiring would allow the few manual functions (landing gear being the big one) in re-entry and landing to be automated from the ground as well - the shuttle could then make a remote-controlled landing (probably at Vandenberg in California - if the shuttle did break up on re-entry, the debris would land in the sea). the risk trade here is very interesting - it seems an obvious route to take but there is a risk in leaving the crew on the ISS.

While there are three permanent crew on the ISS, a three-seater Soyuz is always available as a refuge or escape module for the crew (the point at which someone officially becomes ISS crew is when their moulded seat-liner, which supports them during re-entry on the Soyuz, is put in place). The assumption is that a leak or fire would firstly involve isolating parts of the ISS and ultimately might involve the crew evacuating. The shuttle crew would not have an evacuation option. Of course, the likelihood is they wouldn't stay on the ISS for long before rescue, but it requires some balancing of the extent of damage and the risk of possible delay to the rescue mission.

Finally, there's the mission next year to service the Hubble Space Telescope - there will not be a station available to camp out in for that, so the requirement there is stricter - the LON shuttle will be on the other pad when the first once launches, and the shuttles will grapple each other with their manipulator arms while the crew move from one to the other in spacesuits. There was great hesitation in doing the Hubble mission at all, but the astronaut corps mad eit very clear that they were willing to take the risk in order to keep the telescope operating until its replacement is launched.

Oribits episode 2: Shuttle ascents and aborts

2007-08-05T00:14:00Z

I started writing this post a week or so back and an unfortunate combination of circumstances caused it to go missing... the well-educated amongst you will possibly feel that you know all this stuff already, so apologies in advance. You can always go and do a complicated poll for evilmattikinz instead... Oh, and do ask questions if you want!

I promised in the last episode to offer some numbers, and this entry will be full of shuttle-related stuff so you can follow the launch (expected this week)- so to substantiate my statements about Shuttle trajectories, here is a picture (from the Ascent/Aborts Flight Procedures Handbook[1], courtesy nasaspaceflight.com):

I'll explain the blobs on the line first (a brief explanation of shuttle propulsion systems follows for those unfamiliar...). SRB staging is the point (around 2 minutes into flight) where the solid rockets start to burn out and are jettisoned, leaving the shuttle flying on main engines only - this continues until main engine cut-off (MECO on the graph). The point at which the engines are shut down at MECO is determined by the shuttle's velocity rather than time (this fact will be relevant later). In the case of missions to the space station, MECO is 25819fps (feet per second - the shuttle isn't metric).

Just to clarify the propulsion set-up - the shuttle has 3 main engines (SSME - space shuttle main engines), 2 orbital maneouvering system (OMS) engines, many small thruster jets (RCS - reaction control system) and the two solid rocket boosters (SRB). They are notable because once lit, they can't be turned off. This means that the launch sequence is careful to fire up the SSMEs first and check they are at close to full power before igniting the SRBs[2].

Returning to the graph - after MECO we have the external tank seperation[3] followed by OMS-1, the first burn of the orbital maneuvering system. In fact, this is rarely used now - most missions are flown to orbit on the main engines (sometimes using the OMS engines to assist them while they are running) and a second burn of the OMS (not shown) is used to attain the final orbit.

The interesting thing to note on the diagram is the other labels - these are an outline of the possible "abort" modes - the intention of the shuttle design is to incorporate a high degree of redundancy, and that means planning for various kinds of failures. The most common ones would be "systems" failures (cabin leeks, loss of cooling capacity for example) or engine failures (1, 2 or 3 main engines failing). The most common case is a single-engine failure, and the marks on the graph indicate (in general terms) the abort mode to be used for a single engine failure at different stages. During an actual flight the flight controllers will call out the boundaries to the crew ("Negative Return", "Single Engine Press 104" etc.) as the ground have much better tracking information and insight into performance. The crew have backup data to use if communications with the ground are lost.

During the first stage an abort can be declared, but nothing will happen until the SRB seperation. Then (and for some time after), the first abort option is RTLS (Return to Launch Site). This is comparativeky exotic. The intention is to land the shuttle back at the Kennedy Space Center - because it is be some distance away, they gradually pitch the shuttle around to fly back (as a way to get rid of some of the velocity they have been picking up. Once it has too much energy, that stops being an option.

TAL (Transatlantic Abort Landing) is the next option - they land in Spain (Zaragosa and Moron) or France (Istres) - this is a little like a normal re-entry. The lower line on the graph shows the profile up to MECO for that mode. The next option, AOA (Abort Once Around) involves landing in the USA after doing almost a whole orbit. Finally, ATO (Abort to Orbit) is the state where they can reach an orbit, even if it isn't the orbit planned. It is possible to make the nominal orbit (and thus have a successful mission) with two engine failures if they happen late enough - this is the significance of "Press to MECO" and "Single Engine Press to MECO" - because the three SSMEs share the same hydrogen and oxygen supply, a longer burn on the remaining engine(s) can be sufficient to achieve the desired orbit. The 104 is just the standard throttle setting (in percent of the nominal rating of the engine - they are normally run at 104% now) - it is possible to use 109% under some circumstances.

All these options are considered "intact aborts" - the intention is that the shuttle will land normally at a prepared landing site; there are also a large number of "contingency abort" situations - 3 engines failing in first stage would probably result in the crew bailing out over the ocean - but there are procedures to cover these cases. The "busiest" case is (I gather) an AOA for systems problems such as lack of cooling - there is a lot of equipment to turn off (to avoid generating heat and using power) and a lot of reconfiguration in a short space of time. One of the training staff described them as "sporty"!

I'll try ot get another one up here before the shuttle launch... though you may be fed up of lengthy essays by then :)

[1] The book used by the ground staff to explain the systems and the rationale behind the procedures. The crew have a much shorter checklist to work from (the whole 8 minute nominal ascent is a single page - they don't have a lot to do).
[2] The SSMEs use liquid hydrogen and liquid oxygen, stored in the large brown external tank.
[3] The flight path for the shuttle has to be designed to avoid dropping the external tank over populated areas or shipping lanes, even though it will disintegrate as it re-enters the atmosphere.

Decisions, decisions...

2007-07-22T19:56:51Z

Just before the next exciting episode of the "getting to orbit" series.

Does anyone have any recommendations for good single board ARM computers and a reasonable source. This is for a one-off, needs to be capable of running Linux, needs I2C support and a spare serial port not used for host communication. Low power consumption obviously a good thing!

Advice welcome - pointers to reviews also. I've tried googling and can't find anything conclusive (I can find lots of SBCs but how am I to know which to avoid!).

Brief remarks about orbital mechanics for the educated layperson (and for marmosets too)

2007-07-02T23:30:54Z

... as it came up in conversation at the weekend, I thought I'd offer a brief guide to getting spacecraft in and out of orbit. I must confess to being self-taught in these matters and the reader is advised to consult other sources for further detail. The JPL Primer is a good reference for the educated layperson in aspects of spacecraft operation. This entry is no subsitute for a proper tutorial, and I take no responsibility for your multi-million pound spacecraft landing in your neighbour's fishpond because I or you misunderstood ...

I assume that you are familiar with orbits as "freefall" where the orbiting body continues to fall towards the planet but keeps missing?

Getting into orbit: You need to achieve sufficient velocity in the right position for the orbit you want. The launch trajectory is therefore firstly "up" to clear the atmosphere and then "along" to pick up velocity (target velocity is around 28 000 km/hr[1]). If you kept heading directly away from the earth it would be like throwing a stone straight up. Unless you throw the stone at escape velocity, it will land on you again...

The angle you choose is intended to give you the right velocity at the right altitude i.e. once you turn your engines off you are coasting on a useful orbit. It may not be the final orbit you want (usually it is an elliptical orbit and a later engine firing is used to adjust it).

The important bit - how you adjust your orbit. Orbits are described by a set of parameters which allow you to perfectly describe the position of an orbital body. As a general description of an orbit and its viability for a spacecraft, the most important are the apogee and perigee heights[2]. Apogee - furthest point from the Earth, perigee closest[3].

The golden rules:

Increasing your energy (powering "forwards") at one of these points increases your height at the other.
Decreasing your energy (powering "backwards" / i.e. "retro" firing) at one of them decreases your height at the other.

So - the way you deorbit most efficiently is to wait until you are at the apogee[4] and then fire your thrusters against your current direction to slow you down. You will start to descend. Eventually you will intercept the atmosphere and orbital mechanics stop being so relevant!

What happens if you burn in other directions though? We've done forward and back so how about sideways or up and down? Sideways burns adjust the inclination of the orbit (the angle at which it crosses the equator) - this takes a lot of velocity vector change so the ideal is to launch into the final inclination you desire - in other words to use your launch propulsion to point in you in the right direction to start with. For example, the International Space Station (ISS) is in a 51.6 degree inclination orbit and the timing of launches to intercept with it is carefully chosen. More about launch windows in a later episode.

Up and down? These will change the orbital height but are fuel-inefficient (but faster) compared to burning forward and back. This is a very loose description but if you fancy more serious maths... - warning, equation heavy. I may put some figures in in due course as illustrations or I may be too lazy.

[1] This is inertial velocity based on a fixed point at the centre of the earth. You get some inertial velocity for free from the rotation of the earth at launch if you head eastwards.
[2] Expressed as semi-major axis and eccentricity if you are being analytical about your ellipses.
[3] For generic orbits (i.e. not the earth) terms are apoapsis and periapsis.
[4] You could do it anywhere on orbit but as your perigee is closer to the earth already, you need less velocity change to pull it into the atmosphere.

Next episode - numbers, orbits, ascents and aborts for the shuttle when on ISS missions... Oh, I hear the enthusiastic anticipation already...

Just a little rewiring...

2007-05-09T22:16:21Z

I like these sort of things - Organ Conversion (best to start at the bottom to see what he's started with) even if I don't have the patience to do anything like this myself. There is an interesting thing about the Hauptwerk software he's using, which I may come to in a future post...

(On which subject, I have a backlog of things to talk about, and I really will, honestly, sometime soon...)