NASA Fiddles With Mars Rover

binaryDigit writes "The San Jose Mercury News has an article detailing the delay in launching the next Mars rover. Apparently 'a guillotine like device designed to sever the cables could produce a short circuit'. I assume some sort of standard connector was ruled out in this case? Yet another setback for NASA, though they at least caught the problem before launching it and then not being able to do anything about it."

Comments

I believe that is the standard way

[hubie]

I assume some sort of standard connector was ruled out in this case?

Those devices are very common to sever cables and bolts. They are reliable and effective. Essentially they are pyrotechnic devices that fire an explosive charge that drives a knife edge through whatever you want severed---basically a little cannon that shoots out the knife blade. Judging from the short news blurb, it sounds like a problem with the design of the back-end electronics that were supposed to handle the expected severing.

Re:why?

[EccentricAnomaly]

All of the avionics, the computer, etc. are on board the rover. The umbilical cables connect the rovers to sensors, solar panels, antennas, thrusters, etc on the cruise stage and on the descent stage.

As far as a rigid docking system... that sounds very unreliable to me. A cable will very reliable be connected when you need it to be connected and you can reliably cut the cable when you need to. Designing a rigid docking system seems like a very difficult problem if you want it to be reliable... and it seems like a waste of effort if you aren't reusing the system....

The problem isn't with the sytem to cut the umbilical anyway, the problem is with circuits that aren't supposed to be sending a signal through a severed wire... you don't know if two severed wires could touch each other or some other piece of metal. The solution is to not send a signal through the wire after its cut.