ExoMars and Schiaparelli

ExoMars and Schiaparelli

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Discussion

MartG

Original Poster:

20,620 posts

203 months

Thursday 24th November 2016
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Eric Mc said:
More like insufficient funds allocated for testing and running extensive simulations.
Or a case of "we never thought it would do THAT, so never tested it"

Eric Mc

121,775 posts

264 months

Thursday 24th November 2016
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I wonder if they operate the "Simsup" regime as practised by NASA?

Simpo Two

85,147 posts

264 months

Thursday 24th November 2016
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So if the craft thought it was below the surface perhaps it fired its braking thrusters to get back up nuts

What is a 'saturation-maximum period' and how does that relate to rotation?

annodomini2

6,860 posts

250 months

Thursday 24th November 2016
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Simpo Two said:
So if the craft thought it was below the surface perhaps it fired its braking thrusters to get back up nuts

What is a 'saturation-maximum period' and how does that relate to rotation?
Sensor failed.

MartG

Original Poster:

20,620 posts

203 months

Thursday 24th November 2016
quotequote all
Simpo Two said:
What is a 'saturation-maximum period' and how does that relate to rotation?
I'd guess that after the 'chute deployed the probe was spinning faster than the spin-rate sensor could measure, so the sensor was giving its max output reading for longer than expected and the software saw this and marked the sensor as 'failed' ?

Simpo Two

85,147 posts

264 months

Thursday 24th November 2016
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Ha, the wonder of sensors + software making 2+2=3.

I had a Jaguar XJ40, and one day was alarmed to see 'FUEL FAIL' flash up in the binnacle. The fuel hadn't failed, the speedo sensor had. So the computer thought 'The car is doing 0mph but there is fuel going somewhere, must be leaking'.

Eric Mc

121,775 posts

264 months

Thursday 24th November 2016
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I wonder if ESA are using chips made by Leyland?

Simpo Two

85,147 posts

264 months

Thursday 24th November 2016
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I guess software is only as good as the blokes wot wrote it.

What was the purpose of the spin sensor? Obviously the parachutes and rockets must fire regardless, or you'll get pretty much what happened. So is there a system of little sideways rockets to stop/reduce spin before deploying chute? If you can't control spin you may as well not bother knowing about it!

Eric Mc

121,775 posts

264 months

Thursday 24th November 2016
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They could have used aerodynamic devices, such as small finlets, to steady it using airflow.

Simpo Two

85,147 posts

264 months

Thursday 24th November 2016
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That would (have been) good. Idiot-proof too, they just have to go 'kapoing' out of the sides smile

scubadude

2,618 posts

196 months

Friday 25th November 2016
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Sounds a bit like they didn't have enough voting logic, doing something based on one sensor isn't smart. Cross checking an altimeter, speed sensor, spin sensor etc before ditching the chutes rather than reacting to one sensor going to 100% suddenly (highly suggestive of sensor failure) is bad programming IMO.

I have wondered if the pending arrival of multiple landers at Mars (especially if manned) would make it worthwhile sending a swarm of orbiters and mini landers to give Mars its own GPS and ILS capability? Surely this is something SpaceX will want/need as they'll want their landers arriving within close proximity.

Simpo Two

85,147 posts

264 months

Friday 25th November 2016
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Pondering this incident last night, I realised it's another reason to have manned missions. An astronaut on the spot would have realised immediately what was happening and what to do - rather than rely on made-up software flowcharts devised by (albeit wellmeaning) geeks in an office.

Eric Mc

121,775 posts

264 months

Friday 25th November 2016
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Although it was along time ago, don't forget it was a backroom geek who saved Apollo 11's bacon when they started getting the 1201 alarms.

annodomini2

6,860 posts

250 months

Friday 25th November 2016
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Simpo Two said:
I guess software is only as good as the blokes wot wrote it.

What was the purpose of the spin sensor? Obviously the parachutes and rockets must fire regardless, or you'll get pretty much what happened. So is there a system of little sideways rockets to stop/reduce spin before deploying chute? If you can't control spin you may as well not bother knowing about it!
Generally SW is only as good as the person who specified it.

Why do you think so many government IT projects fail.

This sounds like an FMEA failure. That or there was no redundancy in the system so there was nothing they could do to mitigate the failure.

Simpo Two

85,147 posts

264 months

Friday 25th November 2016
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annodomini2 said:
This sounds like an FMEA failure. That or there was no redundancy in the system so there was nothing they could do to mitigate the failure.
Aha, 'Failure Mode Effect Analysis'. Or just have a bloke there to fly it smile

CrutyRammers

13,735 posts

197 months

Saturday 26th November 2016
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Eric Mc said:
Although it was along time ago, don't forget it was a backroom geek who saved Apollo 11's bacon when they started getting the 1201 alarms.
True, but it's the difference between assessing something on the spot, and having to think of every eventuality in advance. Humans are good at the former, bad at the latter.

Toaster

2,938 posts

192 months

Tuesday 29th November 2016
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CrutyRammers said:
Eric Mc said:
Although it was along time ago, don't forget it was a backroom geek who saved Apollo 11's bacon when they started getting the 1201 alarms.
True, but it's the difference between assessing something on the spot, and having to think of every eventuality in advance. Humans are good at the former, bad at the latter.


Those alarms were by design, not only did they act as a warning as the software identified it was running more tasks than the CPU could cope with, but also re-assined lower level tasks. I am not sure Geek is the word to use for Margret Hamilton, but maybe recognition of a top Scientist who did anticipate of such a possibility and wrote the software that would cope with such an event happening, so maybe Humans are good at both.

Eric Mc

121,775 posts

264 months

Thursday 1st December 2016
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Some nice early footage coming in from the orbiter. They are able to turn the images into mini-movies - which is something new, I think, for Mars.

https://spaceflightnow.com/2016/11/30/europes-new-...

MartG

Original Poster:

20,620 posts

203 months

Thursday 12th March 2020
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Press Release N° 6–2020

The European Space Agency (ESA) and the Roscosmos Space Corporation have decided to postpone the launch of the second ExoMars mission to study the Red Planet to 2022.

http://www.esa.int/Newsroom/Press_Releases/ExoMars...