ESA-Roscosmos: ExoMars 2016 updates and discussion

[Galactic Penguin SST]

I guess that there should be at least one of the orbiters (probably TGO?) that should have provided good Doppler tracking data for the EDM way down to narrow down the area it eventually ended up, allowing for faster searching by MRO's cameras.

Alas, the photos taken by the descent camera wasn't planned to be transferred until after the landing....

[Kosmos2001]

There is this post-presser 1-1 interview with Accamazzo, he explains a bit more about the early telemetry data. Unfortunately in Italian ( watching with english auto-translation, corrections please )



What i gathered
- atmospheric entry phase nominal in every way
- temperatures during descent were nominal, heat shield worked exactly as expected
- heat shield release nominal
- early parachute release and short rocket burn is conflicting and not easily explained
- the time to get further insights depends if the failure is clearly seen in input sensor data stream and it easily explain the control actions, or if we need further testing and study of possible control logic failure

My Italian is not perfect but this is the interview:

Q: What do we know about Schiaparelli?
A: Let’s start with TGO first. We can confirm that the TGO is in the nominal orbit. It made the insertion to Mars in a perfect way, it is in a perfect health and during night we also knew another thing and that’s it recorded all the transmitted from Schiaparelli during the descent in terms of telemetry, so this is not simply a radio signal but a radio signal with engineering and scientific data. With all this, we started to process data.

Q: I guess there is a lot of data. Some of it has already been treated but the other not yet. For now, what has this data shown us?
A: Ok, the data set that we have recorded from Schiaparelli has already told us several things. Schiaparelli made a nominal atmospheric entry, it made all the atmospheric flight protected only by the thermic shield in an absolute nominal way. The thermic shield worked perfectly well, it has protected the capsule, the probe, perfectly and has been released under the conditions we expected. At this point the braking parachute has been released at an altitude of 10 km also in a nominal way. All along the phase with the parachute went perfectly nominal according to data. At the end of this stage, it starts the stage where Schiaparelli behaved differently from what we expected.

Q: So, all of this happened when the parachute has detached which was all planned, it has not been an accident. So it was expected the parachute to be detached and then what was planned to happen?
A: Yes, the parachute was planned to be attached to Schiaparelli until certain conditions were verified. This conditions were verified in an altitude about 1 km over the Martian surface. What we can observe from telemetry is that the parachute detachment took place in a time, not necessary at that altitude, before what we calculated in our simulations. This are 50 seconds before what we expected. This could show, but not necessarily, that the parachute was detached in a higher altitude from what was planned. We don’t know yet. After the parachute detachment, Schiaparelli had to ignite the rocket engines during 30 seconds to slow down during the last kilometer of descending and then to land. The retrorockets have been ignited only during 3 seconds and then the probe switched to the landing mode. These two facts, the early parachute detachment and the short retrorockets burning are contradictory. We must understand why the logic onboard took this decision. We cannot do it now but the important thing is that we have all the engineering data to understand why this happened this sequence of decisions which doesn’t match with what we expected.

Q: When we speak about nominal running, what are we talking about?
A: Basically it means the the events are coming at the time we expected them. For example, the thermal shield release came approximately at the time we expected and under the dynamic conditions Schiaparelli was sampling and we programmed it for it. We can say that the temperature inside the probe during the very high atmospheric velocity phase was absolutely nominal which means that the shield has protected the probe as we planned. This is what we understand by nominal.

Q: Perfect. So, at this point, how much time we must wait until we can reconstruct what really happened to the probe?
A: It is impossible to tell it accurately but, what I think, to understand which has been the logic of actions in the lasts minutes will only take us a couple of days. Then, why it has took that decisions? Why the hardware has been provided with misleading data? This could take much longer. Weeks maybe.

[woods170]

Problem is it makes them look evasive.

Only in the eye of the beholder. Not an ESA problem.

Doesn't matter how you spin it the press have their story and that for better or worse is how the greater public will perceive it.

Yes, and contrary to the situation in the USA, ESA is not affected at all by public opinion. Courtesy of being a multi-national space agency.
No matter how you spin it, ESA is not like NASA. So please stop the felgercarb about ESA being put in a bad light because that really is only happening in the eye of the beholder. Which in this case is not ESA but a silly thing called "the public".

Maybe you should try paying more attention to public opinion being as it is the public that ultimately pays ESA's bills. Something that NASA seems more aware of when it comes to their public engagement.

The public does not pay ESA's bills. The national governments of the member states do. It may be done with tax money and it may be done diffentley. Each member state decides for itself how to cough up the funding.
Also, the amount they pay generally does not rely on how the public perceives ESA but on how much the member states will spare for ESA. For example: in the 2009 - 2014 financial crisis the ESA budget was cut for financial reasons, despite the fact that the public view of ESA actually improved during the same period.
Once again: how it works for NASA is not the way it works for ESA. ESA has no direct link to the public's opinion on a national level. Courtesy of being a multi-national space agency. It is for the very same reason that despite ESA's increased efforts at public PR it's budget has not increased accordingly.

[Kaputnik]

It would inform our speculation a great deal if we knew what the inputs and triggers were for the software.
E.g. is parachute release commanded by altitude? In which case a tangled chute would lead to apparently early release because the altitude would actually be correct, just not the velocity.
Likewise, what are the commands feeding into the retro burn start and end?

The thing that I find hard to construct a reason for is: why the retros would have shut off and the probe continue falling for around nineteen seconds (IIRC), still able to transmit.

[Nigeluna]

The interview translation posted by Kosmos 2001 makes a very important point that it may be worth emphasising.

"The retrorockets have been ignited only during 3 seconds and then the probe switched to the landing mode."

This strongly implies that the telemetry indicates as a hard fact that the system decided it was only a few feet above the surface and therefore the motors should be switched off. The fact that the signal continued for a surprisingly long time clearly shows this decision was erroneous - but why?

More shades of MPL? Similar probable effect but cause would be different if equally wierd.

[Svetoslav]

The thing that I find hard to construct a reason for is: why the retros would have shut off and the probe continue falling for around nineteen seconds (IIRC), still able to transmit.

I also find it hard to understand the onboard logic. Schiaparelli is of a different design than, let's say, Phoenix. Phoenix had three legs with a sensor on each leg. When a sensor indicated the Phoenix landing, there was engine cutoff and landing.

But Schiaparelli has no landing legs, it has crushable structure. Apparently it was the radar who had to measure the distance Schiaparelli-ground and to determine the 2 meters at which the engines should switchoff.

So the lander entered so called "landing mode" .. i.e. freefall, which would mean that it has somehow detected that it was already at a 2 meter distance, while in reality it was possibly still at hundreds of meters above the ground. It was a freefall and an impact that apparently damaged the lander badly. The crushable structure wouldn't save the lander from hundreds of meters freefall.

The question is: what would confuse the computer so much it would shut off the engines so high above the ground?

[baldusi]

Both eeergo and Kosmos2001 translations are correct. He did add in the end that this was a test, that even though they didn't got the result that they expected, it was a good experiment done exactly to validate their models. The fact that they didn't got the expected result did not diminish the success of the experiment itself.

[b0objunior]

Both eeergo and Kosmos2001 translations are correct. He did add in the end that this was a test, that even though they didn't got the result that they expected, it was a good experiment done exactly to validate their models. The fact that they didn't got the expected result did not diminish the success of the experiment itself.

I'm tired of earing this, if their model was correct, why did it crash? There must me a mistake.

[b0objunior]

Problem is it makes them look evasive.

Only in the eye of the beholder. Not an ESA problem.

Doesn't matter how you spin it the press have their story and that for better or worse is how the greater public will perceive it.

Yes, and contrary to the situation in the USA, ESA is not affected at all by public opinion. Courtesy of being a multi-national space agency.
No matter how you spin it, ESA is not like NASA. So please stop the felgercarb about ESA being put in a bad light because that really is only happening in the eye of the beholder. Which in this case is not ESA but a silly thing called "the public".

Maybe you should try paying more attention to public opinion being as it is the public that ultimately pays ESA's bills. Something that NASA seems more aware of when it comes to their public engagement.

The public does not pay ESA's bills. The national governments of the member states do. It may be done with tax money and it may be done diffentley. Each member state decides for itself how to cough up the funding.
Also, the amount they pay generally does not rely on how the public perceives ESA but on how much the member states will spare for ESA. For example: in the 2009 - 2014 financial crisis the ESA budget was cut for financial reasons, despite the fact that the public view of ESA actually improved during the same period.
Once again: how it works for NASA is not the way it works for ESA. ESA has no direct link to the public's opinion on a national level. Courtesy of being a multi-national space agency. It is for the very same reason that despite ESA's increased efforts at public PR it's budget has not increased accordingly.

So what you're saying that PR annot help their cause in any way? I think we can agree to disagree.

[Svetoslav]

I'm tired of earing this, if their model was correct, why did it crash? There must me a mistake.

And I'm tired of hearing of such kind of arguments. Models are actually computer simulations. You put as much information you know, and simulate what would happen. The problem is: you NEVER know if you really know every scenario in order to simulate it. Mars is still largely unexplored planet. We still don't know many things about the tricky atmosphere. The atmosphere is thin and nasty. So if you have found something that invalidates your model, it means that your model is wrong, however your experiment is SUCCESS in showing WHY it is wrong.

[eeergo]

Both eeergo and Kosmos2001 translations are correct. He did add in the end that this was a test, that even though they didn't got the result that they expected, it was a good experiment done exactly to validate their models. The fact that they didn't got the expected result did not diminish the success of the experiment itself.

I'm tired of earing this, if their model was correct, why did it crash? There must me a mistake.

Sorry you are tired. Real engineering and science are like this, pity you tire so rapidly.

Who said the model was correct? The test was successful because the model was not up to par with reality, and this test gave them information (600 MB of it), until well after the final EDL event (engine initiation), to hopefully correct it.

[tolis]

The thing that I find hard to construct a reason for is: why the retros would have shut off and the probe continue falling for around nineteen seconds (IIRC), still able to transmit.

I also find it hard to understand the onboard logic. Schiaparelli is of a different design than, let's say, Phoenix. Phoenix had three legs with a sensor on each leg. When a sensor indicated the Phoenix landing, there was engine cutoff and landing.

But Schiaparelli has no landing legs, it has crushable structure. Apparently it was the radar who had to measure the distance Schiaparelli-ground and to determine the 2 meters at which the engines should switchoff.

So the lander entered so called "landing mode" .. i.e. freefall, which would mean that it has somehow detected that it was already at a 2 meter distance, while in reality it was possibly still at hundreds of meters above the ground. It was a freefall and an impact that apparently damaged the lander badly. The crushable structure wouldn't save the lander from hundreds of meters freefall.

The question is: what would confuse the computer so much it would shut off the engines so high above the ground?

According to this paper http://solarsystem.nasa.gov/docs/Bayle_ExoMars_EDM_Overview-Paper.pdf, there are two sources of data used by the Guidance Navigation and Control (GNC) system: The Inertial Measurement Unit (IMU) and the Radar Doppler Altimeter (RDA). Assuming that there is no inherent flaw with the guidance logic itself, either one or both of these systems must have produced erroneous data. I note, for instance, that the IMU is recalibrated just before atmospheric entry using a sun sensor on the backshell. If that somehow caused it to go awry (but the RDA was generating valid information), the GNC system would have to choose whether to believe the IMU or the RDA. Personally, I would have gone for the RDA! But perhaps the RDA is the culprit. For instance, what if the heat shield did not separate properly from the EDM and was being dragged along? the radar pulses would bounce back from it, GNC might interpret that as "the ground" and..adios amigos. Just speculation of course.

 

[Nick]

The public does not pay ESA's bills. The national governments of the member states do. It may be done with tax money and it may be done diffentley. Each member state decides for itself how to cough up the funding.
Also, the amount they pay generally does not rely on how the public perceives ESA but on how much the member states will spare for ESA.

While I understand the point you are trying to make, there two points that are worth making:

a) the public absolutely does pay ESA's bills - ultimately the only place governments obtain money is through taxes on the public. If the public were to become actively hostile to ESA, the politicians' interest in funding it would evaporate faster than a summer rain puddle. Fortunately, that doesn't seem likely to happen. Even here in the UK, ESA receives very benign media coverage, and so far has escaped the anti-European sentiment sadly running through much of our press at the moment.

b) if the public and press perception of ESA were unimportant to it, ESA's Director-General would not have crammed personally introducing the post-landing presser into what was clearly his tight schedule that morning, and neither he nor David Parker would have been at such great pains to emphasise TGO's success, and to downplay the failure of the landing attempt.  With an upcoming Ministerial, they clearly didn't want an impression to gain traction that the result of spending €1.3bn on ExoMars will simply be to scatter bits of expensive hardware across the Martian landscape!

In that context, personally I think it was a shame that Jan Woerner tried to brush that first question off, claiming he didn't understand it. I would be amazed if, given his CV, and his position as ESA's DG, his grasp of English is not excellent. And, in any case, if he really didn't understand it, he had his British-born Director of HRE, David Parker, sitting at his shoulder to help. And he understood the question perfectly, I'm sure!

There were much better ways of answering that question, that's all. And it was an entirely foreseeable question that should have been planned for. Fortunately, no-one except us nerds is ever likely to watch the presser... 

[Khadgars]

But it's still a failure because, although they have data, the primary goal was not met. It's a partial failure at best.

Schiaparelli was a technical demonstrator sent as a secondary payload for Exomars, whose main mission is to monitor the composition of Mars' atmosphere.

The whole point of a technical demonstrator is to test something. Whether that thing works or not is not the point. The point is to get the data back to help you determine why it worked or didn't.

You have a hypothesis and you want to test it through experimentation. If the experimentation does not prove the hypothesis, then you can't say that the experiment failed. It succeeded in disproving your hypothesis, which allows you to move forward by reformulating a new one.

So Schiaparelli succeeded in disproving that at least one of the assumptions made for the EDL sequence was wrong. Schiaparelli succeeded in sending back telemetry that will allow ESA to move forward with better assumptions, and hopefully a better design. This isn't failure, it's validation, and it's a normal part of engineering and knowledge building.

Schiaparelli was an engineering test, not a test to confirm a theory.  The point of the test was to demonstrate that ESA could land any payload to the surface of Mars ahead of their 2020 rover, which will be much more complex.  In this regard, it failed.  Yes, they will get some useful data, but no need to spin this than what it is, a failure.

This is Mars, its ok to fail.  But no need to pretend it didn't happen.

[Davp99]

Expensive Test.....

[Svetoslav]

It would have been a expensive test with bad PR regardless of the outcome. Let's imagine that everything was successful. So what? The lander has no camera. Where are the photos? You went to the surface of Mars just to test technologies, and there are not even photos from the surface?

People felt underwhelmed well before Schiaparelli was launched.

The most interesting part of the mission is currently in orbit around Mars. At least TGO has a very good camera. Plus, it's trying to answer biological questions.

Schiaparelli served its purpose. Not in a way many people expect, but still ...

[notsorandom]

Both eeergo and Kosmos2001 translations are correct. He did add in the end that this was a test, that even though they didn't got the result that they expected, it was a good experiment done exactly to validate their models. The fact that they didn't got the expected result did not diminish the success of the experiment itself.

I'm tired of earing this, if their model was correct, why did it crash? There must me a mistake.

Sorry you are tired. Real engineering and science are like this, pity you tire so rapidly.

Who said the model was correct? The test was successful because the model was not up to par with reality, and this test gave them information (600 MB of it), until well after the final EDL event (engine initiation), to hopefully correct it.

Clearly Schiaparelli didn't successfully land. Though it did return data through the majority of EDL up till the last 50 seconds, validating most of the engineering. Furthermore the telemetry they got should be good enough to eliminate whatever cause this failure in future designs. No it didn't land, but it also didn't go totally dark like Beagle 2 and Polar Lander. The next time ESA tries a Mars landing they will be much more likely to be successful because of was learned from this mission. In that way I can understand them calling this a successful test.

[Kosmos2001]

Mr Woerners entry about the mission: http://blogs.esa.int/janwoerner/2016/10/21/spacecraft-are-tricky-and-engineering-is-an-art-form/

This part:

The importance of TGO and EDM can be described as 80% vs. 20%, respectively. Since we obtained at least 80% of the data during the descent, the overall success rate can be calculated as follows: 80+20*0.8 = 96%. All in all, a very positive result.

Some maths here, some there and voilà, close to 100 % of success.

[Thorny]

Some maths here, some there and voilà, close to 100 % of success.

That's like saying the Titanic was 75% successful because it made it 3/4 of the way to New York.

[Svetoslav]

That's like saying the Titanic was 75% successful because it made it 3/4 of the way to New York.

This is a straw man argument