Space is dangerous: CoRoT is the latest casualty

Space is dangerous.  With launch hazards, the impossibility of repair, the concern of design errors undetected until the spacecraft a thousand miles away and forever unreachable, draining batteries and degrading solar arrays, growing tin whiskers and diminishing fuel reserves, micrometeoroids and an increasing abundance of space debris, it’s amazing that mission-ending accidents don’t happen more often.

And there’s one more hazard I didn’t mention: radiation.

Computers don’t get cancer or develop radiation sickness, but charged particles can flip bits in a circuit or even saturate a circuit so severely that it melts through in one spot and causes a short.  It’s a serious problem that contributes heavily to the cost of a spacecraft in shielding, careful circuit protection (especially around solar arrays, which are exceptionally good at grabbing charged particles and feeding them right into the circuitry), and massive error correction in both hardware and software — since corrupted data can be a very big deal, if the corruption is in a computer instruction.  Even the signals received from the ground can become corrupted in this way, so it’s a huge focus of spacecraft design.

And sometimes all that engineering effort is not enough.  There is no way to complete protect all of the computer circuits, all of the instructions, all of the data storage, all of the communications, so instead you protect as best as is practical and then you cross your fingers.  The current solar maximum has been cooperative as far as that goes, with space weather much more benign than it normally is during the solar peak.  But “more benign” is not the same as “mostly harmless”.  And now the French Convection, Rotation and Planetary Transits (CoRoT) space telescope has been hit.

CoRoT is not completely dead, but no data has been received from its main instrument, a 27 cm telescope and camera designed to patiently scan the sky in hopes of capturing a planetary transit around a distant star.  It’s been functioning great since its launch in 2006 (not bad for a three year primary mission), discovering dozens of planets and a great many basic science contributions to astrophysics, but now its mission is over.  Controllers on the ground will perform a series of engineering experiments with it, and then will safe it, which will mostly consist of safely discharging its batteries and feathering the solar arrays so it is less likely to explode when uncontrolled.  It will eventually fall out of orbit.

Good work, CoRoT.  Sad to see you go, but you’ve done well.  Bonne nuit.

CNES: CoRoT mission page


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