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."

2010

[bob_jordan]

Didn't anyone watch 2010. All you need is a non-conductive blade and a little red calculator.

Bob.

Re:2010

[gl4ss]

i didnt find it in the article by quick glance.. but i assume that even with non-conductive blade the wires could still short-circuit against each other.

Re:2010

[EccentricAnomaly]

if two wires accidentally touch there could be a short even with a non-conductive blade

Re:2010

[stj]

You forgot one thing: you must ensure that the constructor of the circuit to be disconnected must not be around the device after the blade has been installed.

why?

[bobba22]

Forgive my ignorance, but what does this umbilical system do? Surely it can't be to keep the batteries charged on the flight to Mars, especially as they'll be doing very little, comms with the rovers *I assume* will be via RF. I can't believe that a rigid docking system would be less practicable than a severing system. Won't a severing system be fraught with possible problems - dust getting in the mechanism could stop the guillotine action altogether rendering the whole thing useless. What point am I missin

Re:why?

[freuddot]

Your tone imply that you know better than the guys out there at Nasa.

You say : I can't believe that a rigid docking system would be less practicable than a severing system.

Guess what, I can't believe that some random slashdotter just happens to know better what is more practicable for a Mars Rover.

As a greater thinker once said, "There's a point in life where you've got to stop taking everyone else for morons".

Re:why?

[ralico]

Well, its NASA's baby. If they want to have an umbilical cord, then let them...

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.

Re:why?

[hubie]

I'm sure there are all sorts of data that you'd want from the rover while in flight, and you'd want to operate any heaters if needed, etc, so you'll want connectivity between the rover and the spacecraft. However, the more connections you have to handle this data, the more connections you'd need to undo when you want to release it. If you plugged the rover into a rigid socket for launch, it would have to be very very secure so as not to shake loose on launch, but as you make the docking connection more an

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.

Gravity and the Guillotine

[a5cii]

Umm correct me if im wrong but wouldnt gravity stop the guillotine blade falling???

i can just see the blade floating away like a big red baloon

Re:Gravity and the Guillotine

[Paladin_Krone]

do you think nasa would make a device big enough for a true guillotine blade to fall? come on its mechanicly drivin

fiber

[The AtomicPunk]

Why not just use fiber optics for the connections? Eliminates the problem of shorts ...

Shorting wires?

[Paladin_Krone]

why not just use a little plastic bracket to hold the wires just pas where the severing will take place? This would prevent the wired from touching. And as far as the blade, use ceramic.