The International Space Station (ISS) isn't just an orbiting laboratory, spaceship testing-ground and multinational geek-fest -- it's also the world's highest (250 miles) and fastest (17,500mph) computer network. We burrow under its metal skin and siphon out its most interesting specifications, like some kind of star-hopping alien data vampires. But without the plutonium-coated fangs.
It ain't rocket science
Space travel sounds futuristic, but ironically much of the equipment used on the ISS wouldn't look out of place in Freecycle. The backbone of the network is over 100 military-spec data buses that were first designed in 1973 for use in the US Air Force's F-16 fighter jet. The 16-bit buses are capable of moving data around at a maximum of just 1Mbps, and use over 1,200 remote terminals to interface with other buses, sub-systems and a network of laptop computers.
These Windows XP PCs (that's right -- space remains Apple's final frontier) are just slightly more up to date, with the ISS housing 68 IBM ThinkPad A31 laptops from 2002, each boasting a 1.8GHz Pentium 4 processor, 512MB RAM and a 40GB hard drive. There are also 32 spangly 'new' Lenovo ThinkPad T61p laptops (2.4GHz Intel Core 2 Duo, 2GB RAM, 100GB hard drive), dating from 2007.
NASA has managed to leapfrog the ancient cabled network, installing its own Wi-Fi hotspot and a grand total of two access points -- although more are planned as the ISS nears completion in 2011. By that time, around 6 million lines of code on the ground will support 3 million lines of flight-software code.
Solar powered spaceship
The ISS draws all of its power from its arrays of solar cells. When the ISS is complete, it will have four massive Solar Array Wings made up of 262,400 cells covering an area of about 2,500 square metres. Together, they will generate about 120kW of power, fading to less than 105kW after 15 years of operation.
Even at their best, the cells are only about 14 per cent efficient at turning sunlight into electricity. This was state of the art when the ISS was designed, but sounds poor compared to 30 per cent efficient (and higher) solar cells coming out of labs today. A bank of nickel-hydrogen batteries store electrical energy for use during the night.
Ground Control to Major Tom
Houston will no longer accept excuses along the lines of, "The circuit's dead, there's something wrong," or simply, "We have a problem." Communications are a top priority aboard the ISS, which has been visited by nearly 200 astronauts from 15 countries (sadly not including the UK, thanks to our government's ban on funding human spaceflight).
A radio and satellite network allows two-way audio and video communications between crewmembers aboard the ISS, including astronauts conducting space walks. Transmissions with ground-control centres include audio, video and data, while system and experimental data flow freely.
Tracking and Data Relay Satellites (TDRS) allow constant radio communications in the S- and Ku-band, while UHF signals are used to talk with the Space Shuttle and crew members on spacewalks. There's also a single IP phone for cheap interstellar calls and 'limited' webcam video-conferencing abilities to allow astronauts to surprise their Earth-bound families on birthdays. Surprisingly, there's even room on board the ISS for an old-fashioned ham radio set. If you'd like to tune in, their call signs are RS01SS for the Russkies and NA1SS for the Yanks.
Control and navigation
Unlike most computer networks, the ISS is flying at thousands of miles an hour, orbiting the Earth about once every 90 minutes. The slightest navigational error could cause havoc with its heat regulation, microgravity, communications and solar power collection. It's slightly surprising then, to learn that the ISS relies for navigation on the same GPS technology that seems unable to locate your nearest Esso garage even when you drive right past it. (Look! It's just on the other side of the road!)
As well as America's GPS satellites, the ISS fixes its position using Russia's GLONASS (Global Navigation Satellite System), a sun and star sensor that can recognise distinctive constellations in the sky. Underneath the GPS antennas, RGAs (Rate Gyroscope Assemblies) use highly sensitive laser beams to measure the Station's tiniest change in orientation.
For movement, the ISS typically relies on electrically powered gyrodynes containing a 98kg steel wheel spinning at 6,600rpm, although it also has traditional rocket engines on the Service Module. There's a system in place for flight controllers on the ground to take full control of the ISS, if required.
Crew members aboard the ISS can request specific films and TV shows to be uploaded to a central file server, which they can then watch on any of the Station's laptops. The lucky spacemen don't even have to miss out on the latest cinema releases. In May, NASA astronaut and Trekkie (wow, there's a strange combination) Michael Barratt got to watchfilm on the day of release on his laptop inside the Unity module. Former Station astronaut Greg Chamitoff apparently viewed the entire Star Trek series as a regular weekly event.
When not donning rubber ears and ogling Uhuru, ISS astronauts are getting busy with their digital cameras. Station crews have snapped more than 200,000 images of Earth -- around a third of the total number of images taken from orbit by astronauts.
There are thousands more high-tech systems and computers on the ISS, embedded within its hundreds of sensor systems, life-support devices, scientific instruments, space suits, lab equipment and even exercise machines -- and they could soon be joined by.
The European Space Agency has been testing a head-mounted computer system called Wearable Augmented Reality (WEAR). Controlled by voice for hands-free operation, WEAR overlays 3D graphics on the astronaut's field of view to give them their onboard location, identify objects or provide step-by-step instructions for difficult technical procedures.
The only problem? Those lowly IBM ThinkPads simply haven't got the processing grunt to cope with WEAR's real-time 3D graphics. But what do you expect with IT? You spend £92bn on a fancy orbiting computer network and before you know it, they're telling you it's time to upgrade.