Twin Craft To Study Space Weather From Within Earth's Radiation Belts 15
Early Friday morning (just a few hours from now), if the Florida weather holds, two satellites are set to launch (here's the live-blogged play-by-play) from NASA's launch facility on Cape Canaveral on a mission to study the radiation belts that surround earth and (among other things) help make this planet friendly for life. The Radiation Belt Storm Probes mission features twin craft engineered by Johns Hopkins' Applied Physics Lab which "will operate entirely within the radiation belts throughout their mission. When intense space weather occurs and the density and energy of particles within the belts increases, the probes will not have the luxury of going into a safe mode, as many other spacecraft must do during storms. The spacecraft engineers must therefore design probes and instruments that are 'hardened' to continue working even in the harshest conditions." Update: 08/24 14:53 GMT by T : Launch was a no-go, but there'll be another try early Saturday morning.
Re:why 2, not 4 ? (Score:4, Informative)
Well the two cost about $435 million. I can assume there's a limit on money, plus adding another spacecraft (the two are stacked on the top), might be beyond a weight threshold that would require bigger and even more expensive launch platform.
The probes are in different elliptical orbits and one will lap the other as they fly in and out of the inner and outer belts, so they can see the particle effects on one vs. the other. There are several labs on it for measuring this, including probes that extend far away from the craft which will give three dimensional senses of what's happening.
CPU (Score:2, Informative)
If anyone else is wondering what commputer hardware they are using that can "continue working even in the harshest conditions", according to the Launch Press Kit [nasa.gov], it's the same kind of RAD-750 [wikipedia.org] PowerPC compatible CPU that's in a number of other "recent" probes, including the Curiosity rover.
Avionics computer: RBSP’s on-board avionics computer is based on a BAE RAD-750 radiation hardened processor with
16 MB of RAM plus a 16 GB SDRAM data recorder. The spacecraft interfaces are controlled by a customized radiation-
tolerant RTAX2000 FPGA (field-programmable gate array) microprocessor.