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ExoMars landing today!


JB80

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1 hour ago, symesie04 said:

I would imagine the difficulties of landing on a comet are vastly different to landing on Mars hence why those probes were different. Regarding Beagle 2 and Schiaparelli if you look at them they are not actually that different in landing technologies. Probably the biggest difference is the last stage of the landing which in Beagles case used airbags and in Schiaparelli case thrusters. The thing is Beagles solar panels failed to deploy possibly because of the deflated airbags causing problem so they it would seem that this time the plan was to do away with the potential and very uncontrollable element and use thrusters instead. But it seems to me that there are some calling for using the same technology but fixing the problems and yet when ESA do this they are accused of not sticking with tried and trusted technology. Im a little confused i must say.

I'm thinking that ESA could swallow its pride and consider approaches proved by NASA.

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According to ESA (the info they've released so far) things went pear-shaped a few seconds after the parachute was deployed - it was jettisoned (i.e., released rather than torn away) far too soon. Nothing could save the lander after that, the malfunction of the retro thrusters is irrelevant as it would have been impossible to slow the craft using those alone because it was travelling way too fast as it approached the surface, the retros would have been operating outside of their envelope (very high speed) so no wonder they just cut off quickly. Presumably there were sensors which measured height (there was an on-board radar), velocity, and of course the time intervals would have already been accurately calculated and included in the code for reference. ESA would have been checking the trajectory was correct prior to re-entry and although there was no facility to make course corrections any irregularities would have been obvious. So the guilty finger must point at the source of the command which jettisoned the parachute too early, whether a faulty sensor which told it that phase of the descent was complete (how? - doesn't sound likely - and velocity and radar measurements should have prevented it), or perhaps there was a simple coding error.

ChrisH

 

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"Esa director-general, Jan Woerner, said the fact that Schiaparelli returned 80% of its anticipated descent telemetry makes it a success, irrespective of what happened in its last seconds. "

Strange definition of success LOL :)  It's not the jump off a cliff that hurts, it's the landing...

ChrisH

 

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1 hour ago, Stub Mandrel said:

I'm thinking that ESA could swallow its pride and consider approaches proved by NASA.

Ah yes but i think your find now that the commercial sector are involved in the space exploration that NASA dont give away their technologies cheaply. So any attempt by ESA to copy NASA techniques would of been a first time learning curve anyway. I sometimes wonder if in this high tech age if we just presume everything will work as the computer plans and when it doesnt its a colossal failure of mans design rather than a setback on the learning curve.

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Looks like it dug its own grave. Impact at up to 300km/h

I suppose it's yet further vindication of Colin Pillinger, who took a bit of stick over Beagle 2's failure. 

Not so easy putting a lander on Mars as some might think.

 

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Ah yes but i think your find now that the commercial sector are involved in the space exploration that NASA dont give away their technologies cheaply. So any attempt by ESA to copy NASA techniques would of been a first time learning curve anyway. I sometimes wonder if in this high tech age if we just presume everything will work as the computer plans and when it doesnt its a colossal failure of mans design rather than a setback on the learning curve. 

They do communicate with NASA, a bit, but the 2 have slightly different approaches. NASA seem to be more cautious. It may be that being a single body NASA can take say 2 years more. ESA seem to operate to have a defined time and so get on with things, maybe a bit too fast. Their project selection was a bit odd. One or two get the go-ahead based on the idea that by the time the satellite/rocket goes up then technology will have progressed and produced something they can use, because there is nothing they can use at the inception date. Then if the something is not produced it is fall back on something likely inadaquate, or cancel. Both of which can be very costly and/or embarrasing.

Also the ESA approach of geographical return means that if one aspect is given to say a new company in Italy to do when previously a Swedish company did it successfully then the Swedish company does not pass on the experience etc they gained. So the wheel has to be reinvented.

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