<< August 2004 >>
Sun Mon Tue Wed Thu Fri Sat
01 02 03 04 05 06 07
08 09 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30 31

If you want to be updated on this weblog Enter your email here:

rss feed

Sunday, August 08, 2004
Programming in C

Occasionally the mundane is interesting, like my subject CSC1401... beginning with C, as the textbook puts it. Cool stuff - now I have all these groovy software tools for writing code... ;-)

Crimson Editor is one such tool - old hat to all you hackers, but new to me. Let's you write code like you were writing Word documents, but numbers lines and checks syntax for you too. I guess once all the pleasures of C have been explored I will have to graduate to C++, which apparently has a free compiler available. But there are other free compilers out there too for all sorts of languages.

Cool, huh?

Posted at 3:54 pm by Adam
Make a comment  

Thursday, August 05, 2004
Apollo XI plus 35...

20 July, 1969... Neil Armstrong and Buzz Aldrin touched down in the Sea of Tranquility on the Moon. And they had a reasonable expectation that their visit would not be their last. However 35 years later, Neil and Buzz and the rest of us aren't any closer to re-visiting their first Base Camp on that dusty plain.

What was once only a dream, became a reality, and yet is now a mere memory - why?

A hint can be found in how they did it - Apollo/Saturn. Cost a lot to develop and then NASA abandoned it, yet it never had a failure. In fact, aside from Apollo XIII in 1970, the system had fewer malfunctions than the Space Shuttle. But NASA had to give it away to sell a "cheaper" manned program to Nixon - or else there was going to be NO manned program, and maybe not much of an unmanned one either.

Nixon wanted to end the whole mad Moon-rush and redeploy the resources for all sorts of things. Hence no Apollo 18 or 19, though the equipment had all been built and was ready to go. Skylab survived by being too close to completion.

Another point is that the Shuttle got sold partly because of it fit in with the USAF's needs - something the purely civilian Apollo-Saturn could never do because it wasn't an aerospace plane. The USAF loved aerospace planes - the X-15 had been flying for years, the Dyna-Soar program had come close to fruition and they were actively researching lifting-bodies - and a huge manned vehicle just didn't suit. The Gemini program suited them better - it used their Titan rockets and was the basis of their Manned Orbital Laboratory. Apollo-Saturn stank too much of NASA.

So Neil and Buzz and all the rest never got to go back. A shame IMHO. A few more Apollo Moon-shots into the 1970s would have made for a greater impetus in the 1980s. But maybe Voyage is right - all the spectacular unmanned achievements of the 1970s/80s been passed-up to pay for it.

Posted at 11:56 am by Adam
Make a comment  

Skylab to Mars IV

I found since last entry that my estimates for dv around Mars are really ultra-sensitive to Mars' orbital position. Hence the propellant mass quoted is potentially off the mark. When Mars is at aphelion the dv is about ~ 1 km/s lower than if Mars was at perihelion. Early September 1986 would find Mars at aphelion, but where would Venus be for the sling-by from the novel? Working on it currently. Transfer time is ~ 384 days, meaning a launch in August 1985.

BTW The mission flight-plan from Voyage is an Opposition Class Hohmann transfer. Usually the dip past Venus is on the way back from Mars to reduce the re-entry velocity at Earth. But it works the other way too, it seems.

And I am wondering about the propellant choice - UDMH/N2O4 is very space friendly, but there are other options for fuels and oxidisers out there. Liquid oxygen is the very definition of cryogenic, but keeping it liquified doesn't take a lot of equipment or power, especially if the tank was wrapped in reflective insulation, for example. A mix of RP-1 and LOX has a decent amount of kick, an Isp ~ 353s, but LOX and UDMH can get ~ 363s, which is cool. Definitely better than the N2O4/UDMH mix of Apollo. The mix is a lot denser (0.97 vs 0.28 gm/cc) than the LH2/LOX used in the Saturn IV-B, so if we assume the tanks are lighter, but the cooling system makes up the difference, then the Interplanetary Maneuver Stage (IMS - another TLA) can mass ~ 13.5 tons like the Saturn IV-B + IU combination.

Propellants that have been tried in real rockets can all be found here...

Propellant Index

Interesting mix is LH2/LF2 - hydrogen and fluorine - which would have a highly toxic exhaust, hydrofluoric acid! Yikes! Glad the rocket makers settled on LH2/LOX for high performance - only exhaust is steam.

Posted at 11:41 am by Adam
Make a comment  

Wednesday, August 04, 2004
Price to Orbit III

John London's report on cheap access to LEO is 10 years old and I re-read with interest his conclusions. Important points...

  • Make a cheap orbital booster a national goal
  • Streamlined management of development
  • Loosening of Gov't regulation compliance - best practice NOT exacting compliance
  • Single location
  • Small team
  • Small development budget
  • Pressure-fed or simple pump-fed LOX-hydrocrabon boosters - preferably RP-1 (refined kerosine)
  • Retire the Space Shuttle's solid boosters - simple liquid propellant boosters are safer, better and tie in to the above point
  • better yet... retire the Shuttle - its multi-billion budget, even without launching a Shuttle is a terrible drain. Redeploy the resources for something cheaper, better and more frequent
  • Build a Space Station by the end of the 1990s... oh well, almost there... so manned, on-orbit operations aren't tied to the Shuttle
  • Build a simple, dedicated crew transporter - perhaps based on *gasp* Soyuz
  • So as you can see there's a lot missed by Gov't, but taken up by Musk and his kin in the private Space Access movement. And will quasi-private efforts get a Soyuz around the Moon before Big Gov't by 2008? Imagine that...

    Posted at 3:54 pm by Adam
    Make a comment  

    Tuesday, August 03, 2004
    Soyuz to the Moon II

    Here's more on the plan to send Soyuz around the Moon...

    Soyuz to the Moon

    The attached Gallery illustrates what a Block D upper-stage looks like quite well and indicates that the Russian Moon Program might have a pay-oof yet...

    Posted at 12:10 pm by Adam
    Make a comment  

    Monday, August 02, 2004
    Price to Orbit II... revision

    Lt.Col. John R. London III wrote for the USAF the book length study of space costs and space cost reduction, LEO On the Cheap, which is available for free from here:

    LEO On the Cheap

    The author released it for general distribution because his message is vitally important - Space costs too much chiefly because it is done at the extreme edge of technical ability, and the launch vehicle and satellite makers like it that way.

    Enter Elon Musk who, with the SpaceX team, has taken on board Colonel London's findings and has simplified LEO bound rockets. If SpaceX can reach their goals the price to LEO will drop to ~ $2,200/kg, instead of the ludicrous ~ $40,000 - $10,000/kg currently on offer. And the price to GTO will drop to ~ $4,400/kg or so.


    SpaceX is offering 4,200 kg payloads to LEO delivered for ~ $12 million. That's $2,860/kg, but they'll get better at it after a few launches and the price should come down. The main point about their efforts is that the rockets and avionics might not be absolute marvels of engineering perfection - instead they work well enough. Incredible amounts can be spent pushing machinery and designs to their absolute limits because of the continual review and refinement process uses large numbers of staff and resources to achieve the incremental approach to such limits.

    A common satellite design mistake is to try to fit the satellite into a specific mass - the cost of space launch means people want to use all the mass budget they're alloted. As a result in the final stages $100,000s are spent refining the design. Larger, cheaper launcher payload options would mean a cheaper design process. Bigger satellites, because of ease of design, are also cheaper satellites. A common satellite frame-work that can be adjusted for several roles - rather than needing total redesign each time - would make for cheaper satellites too.

    And rocket design? Advanced, computer controlled rockets pushed to their absolute limit, pushing propellants at high pressure into exhaust chambers with complicated and expensive turbo-pumps, and cooling jackets... well it all adds to costs. Exotic alloys for propellant tanks and refined rocket motors that push the envelope are long labours of (very expensive) engineering love - and simpler, proven designs and components could do the job for a lot less money. No commercial rocket these days needs to push the envelope when there is so much prior experience already paid for.

    Posted at 12:53 pm by Adam
    Make a comment  

    Price to Orbit I

    Back in the '70s the Space Shuttle was supposed to be the answer to revolutionise space-travel. No more expensive throwaway rockets, but routine, reuseable space-flight cheap enough for all to be involved in some way. In reality NASA over-sold the Shuttle in a valiant attempt to avoid getting the whole manned space program shut down by Richard Nixon. To achieve the hoped for price-tag of $750/kg to LEO (1980$... more like ~ $1,200/kg today) the Shuttle would need to be flying ~ 60 flights to LEO per annum with a full load of ~ 29,500 kg each time.

    So why is the Shuttle so damn expensive? For starters the whole ground support system costs $2.8 billion per annum without a single Shuttle lifting off. Developing the Shuttles cost ~ $7.5 billion and building one costs ~ $1.5 billion. Say NASA had their full complement of 5 Shuttles. If they can manage 100 flights each, they then cost ~ $90 million plus those per annum housekeeping costs ($560 million per Shuttle per year), which totals (@ 60 flights/annum) $137 million/flight before we buy fuel. Surprisingly the fuel only costs ~ $1.5 million. Go figure...

    So lets call it ~ $138 million to haul our 29,500 kg to LEO. That's still $4,700/kg - I guess NASA expected cheaper operating costs and wrote off the development costs - they expected to be making fleets of Shuttles eventually which would have driven that initial cost down dramatically.

    My old favourite from 1979, "The Space-Traveller's Handbook", is set in a fictional 2061 in which all the 1970s dreams have come true - and Shuttle costs a mere ~ $60/kg to fly. About 100,000 people fly on a Shuttle per year, plus who knows how many cargo flights launched via reusable Heavy Lift Vehicles. Hence development costs have long been paid for, mass production has cut costs per Shuttle and ground support costs are spread over LOTS of flights (~ +2,000/annum.) That's how flight costs could be cut down dramatically - LOTS of traffic to LEO and beyond.

    The reality is different, very different. In the fiction there are several Space Colonies - all Standford Torus designs - with a space population +100,000. There is a market - if not many space markets - that make Space pay-off for Earth's investment. In our current reality Earth-oriented "services" are the only pay-off. There is NO primary industry in Space, and that's what it really needs. So what can we get in Space and sell back here for $$$ ???

    Stay tuned...

    Posted at 1:43 am by Adam
    Make a comment  

    Cool Micro-lithography

    Here's a cool Optics news bite...

    Sydney Opera House repro/reduced

    ...micro-lithography - if it can be sped up - enables all sorts of amazing things to be crafted at micro-scale.

    Posted at 12:35 am by Adam
    Make a comment  

    Skylab to Mars III

    Mass break-down for our fictional Voyager to Mars...

  • CSM (fully fuelled) 30,329 kg (inc. 18,413 kg propellant)
  • Crew: 204 kg (3 @ 68 kg)
  • MEM: 24,947 kg
  • Multiple Docking Adapter: 6,260 kg
  • Airlock Module: 22,225 kg
  • Saturn Workshop: 35,380 kg
  • Instrument Unit: 2,065 kg
  • extra supplies (1,000 days @ 1.27 kg/day/person): 3,810 kg
    [the extra supplies are arranged in lockers that form a radiation storm shelter in the core of the Workshop]
  • Sum Total: 125,220 kg
  • Earth Return sub-total: 98,862 kg

    The CSM main engine puts out 9,979 kgf of thrust - 97.86 kN. As you can see the Earth Return stack masses just 98,862 kg - perhaps a couple of tons less once waste is dumped pre-orbital insertion. Hence it begins deccelerating at 1.01 m/s^2, burning its 18,413 kg of propellant which enables ~ 650 m/s dv. This is easily enough to park the Voyager in a Highly Elliptical Earth Orbit and let the CSM de-orbit. The re-entry speed is higher than an LEO return, but a bit lower than a Lunar mission return, hence it is easily handled by the CM's heat shields.

    But what will it be like for the crew? The gees can get quite high - will it be tolerable after months of zero-gee? In the novel, Voyage, NASA has already made several long duration missions to a Moon-Lab, which is Skylab in Lunar Orbit. Hence they have already tested astronauts at the expected gee-load. But I wonder, of course, if some sort of gees can't be supplied by rotating the Voyager...

    And tonight on Channel 10 News is a quite good article on the Mars Society's mission to Australia's Red Centre - not quite the Red Planet, but a very useful exercise. A real voyage to Mars will require a lot of parallel thinking to get carried off successfully - raw Space and Mars itself are alien, deadly environments that need our collective skills as a species to survive. Hence my analogy, parallel thinking by many minds to let those first pioneers have the best chance of survival.

    The elastic space-suit that got mentioned sounds really interesting - rather than gas pressure the idea is to supply counter-pressure for breathing via elastic force of the suit itself. This allows better freedom of movement and uses less air-supply to sustain. Also there can be no explosive decompression if there is a tear. Another technology they should be working on (and probably are) is rebreather oxygen supplies, which scrub expelled air of carbon dioxide and return it to the system, rather than directly venting like SCUBA systems. With such an astronaut could carry oxygen for a day easily, rather than mere hours.

    Mars also allows lighter meteroid protection. On the Moon micro-meteroids had to be dissipated by solid and padded protection in the suits, else the astronauts would be covered by bruises (or worse) fairly quickly. On Mars the atmosphere burns-up/deccelerates all those hyper-velocity pests, letting the far fewer larger meteorites through to dig those craters being explored by Spirit and Opportunity currently.

  • Posted at 12:18 am by Adam
    Make a comment  

    Sunday, August 01, 2004
    Skylab to Mars II

    While Discovery has been my main project I haven't forgotten the other fictional option - taking a Saturn Orbital Workshop - Skylab - to Mars and back. To boost inwards to Venus from LEO takes ~ 3.5 km/s, takes 0.4 years then 0.55 years back out to Mars. To save fuel a highly elliptical orbit around Mars is needed - Mars arrival takes ~ 1.5 km/s and departure [sans 25 tons of MEM] takes 0.9 km/s for an Earth return.

    The major problem in that case is choice of fuel - a Saturn IV-B uses LH2/LOX, but LH2 boils away in its tanks and needs to be vented or else the tank will rupture. Over a year plus much of the initial fuel will be gone. Passive cooling in insulated tanks needs the slow vent of cryogens to work, while active cooling takes energy and machinery, but avoids venting.

    Perhaps trusty old UDMH/N2O4 is the way to go. Certainly storable indefinitely but the ~2.5 km/s dv at Mars will need ~ 130 tons fuel. Which means more propellant to boost out of LEO.

    Yesterday I discovered happily that the Apollo CSM can easily brake the stack into a Highly Elliptical Earth Orbit (300 km x 200,000 km say) - a 100 ton cluster gets a dv ~ 650 m/s out of the 18,413 kg fuel in the CSM's tanks. Only about ~ 570 m/s is needed, the rest is to put the CSM into a re-entry orbit.

    Friday I figured out how much propellant a Saturn V could boost to LEO in the tanks of the IV-B stage, with just an aerodynamic shroud. Approximately 96 tons useable propellant will remain in the tanks after Orbital Insertion. So not much modification would be needed to launch suitable boosters for the Mars or Titan missions.

    Posted at 10:21 am by Adam
    Make a comment  

    Next Page