IF ANY aspect of Columbia鈥檚 fatal break-up can be considered fortunate, it is that the doomed spacecraft was fitted with an experimental data recorder. That made it easier for accident investigators to work out what went wrong on that fateful day in February 2003.
鈥淲e were lucky in one sense. As the first shuttle to be built, Columbia was heavily instrumented with test sensors,鈥� says NASA space scientist Dan Rasky. 鈥淚f it had been any of the other shuttles, which have far fewer sensors, working out the problem would have been much tougher.鈥�
Columbia carried an experimental data recorder fed by more than 700 sensors, measuring parameters such as temperature and pressure all over the craft. Amazingly, the recorder managed to survive re-entry, allowing engineers to work out that incandescent plasma had invaded Columbia鈥檚 broken wing, melting the airframe.
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The realisation of what the recorder could tell accident investigators triggered a drive to equip future manned spacecraft with a black box flight recorder. NASA is now developing a robust device that will record critical flight data 鈥� from crew conversations to measurements from a host of sensors 鈥� and yet still survive the break-up of the craft during the searing heat of a hypersonic re-entry at Mach 17.
Dubbed the Reentry Breakup Recorder (REBR), the device is being co-developed at NASA鈥檚 Ames research lab in Silicon Valley and at the Aerospace Corporation of El Segundo, California, an R&D lab funded by the US air force. NASA is developing the heat-proof packaging while the Aerospace Corporation is making the rugged data recording and transmission electronics that will go inside. The REBR is expected to be first used in the Crew Exploration Vehicle, which is at the heart of NASA鈥檚 nascent programme to send people to the moon again and to Mars.
This is not the first time NASA has vowed to produce a spacecraft black box after a disaster. When the space agency lost the Mars Climate Orbiter and Mars Polar Lander in quick succession in 1999, it was prompted to start work on a black box for unmanned planetary probes at NASA鈥檚 Jet Propulsion Laboratory in Pasadena (New 杏吧原创, 29 April 2000, p 16).
Unlike the aircraft equivalent, which must be recovered, this box was to have beamed its data to a Mars orbiter when interrogated by radio. But JPL鈥檚 project seems to have been quietly discontinued 鈥� indeed, the team at NASA Ames was unaware of its existence until New 杏吧原创 supplied details.
So it is a coincidence that the new REBR is not designed for recovery either. 鈥淭o make them lightweight, the REBR is not designed to survive a high-g impact,鈥� says Bill Ailor, a director of the Aerospace Corporation. 鈥淚nstead it will beam data back via satellite after break-up.鈥�
The REBR will comprise a 1-kilogram heat-shielded package 30 centimetres wide, which contains batteries, a solid-state flash-memory data recorder and a satellite-frequency transmitter (see Diagram). The idea is that one or more recorders can be stationed within a space vehicle at points where they can easily break away if the craft disintegrates. After separation, the REBR will automatically right itself, orient its satellite antennas skyward, and then begin a 10-minute transmission of all its data to NASA via the Iridium telecommunications satellite network 鈥� or via other orbiters if above the moon or Mars.
Ailor says the data package beamed back to NASA will include the expected location of the debris field, in addition to reams of acceleration, pressure and temperature readings from the craft鈥檚 final hours.
鈥淎 prototype drop-tested from a balloon some 30,000 metres above northern California delivered dummy data perfectly鈥�
The technology already looks promising: a REBR prototype drop-tested from a balloon some 30,000 metres above northern California delivered dummy data perfectly via Iridium. 鈥淎nd the GPS data was so accurate we got the farmer whose land it fell on to take us to the right tree to retrieve the package,鈥� says Ailor.
