ExoMars - Schiaparelli landing Options

[Phil Stooke]

Starting a new topic here - hopefully that's OK! Clearly there will be a lot of action around this in the next weeks and months with descent images and HiRISE views of the hardware.

I thought I had posted this map earlier but apparently not. This shows the various landing ellipses in this area. The original plan was for an ellipse oriented NW-SE, but it changed with the different launch date and is now nearly E-W. Note that the ellipse shown in the recent ESA release is the envelope of all ellipses over a given launch period, but the actual landing ellipse for the given launch date is smaller. Opportunity's final landing ellipse is shown for comparison.

http://exploration.esa.int/mars/57445-exom...6-landing-site/

http://exploration.esa.int/mars/57446-exom...6-landing-site/

Phil

[nogal]

I had originally posted this information on another thread, but then Phil started this topic and I think it fits better here.

ESA has relased information [LINK] on Schiaparelli's intended landing site on Meridiani Planum, including the landing elipse which, at its eastern edge, just grazes the Endeavour crater. Perhaps Opportunity could spot Schiaparelli descending under its parachute on October 19?

The landing ellipse's size is given on the above mentioned article as 100x15 km, but this could be a simplification for in order to match the ellipse on this image, I had to make it 115.4x23.9 km. The ellipse is centered at 2.048S, 6.114W.

This is how it looks on Google Earth (Mars):


And here is the KMZ file:  Schiaparelli.kmz ( 19.26K ) Number of downloads: 2331


Fernando

[sittingduck]

Will Opportunity be able to image the Schiaparelli EDL? Maybe the re-entry plasma?

[James Sorenson]

Opportunity is heading down deeper into Endeavour, so I'd say that is becoming less likely because of lack of visibility of the surrounding plains and the part of sky where it is expected to be. I guess the only chance will be if the lander overshoots to the far end of its ellipse where Oppy could possibly capture the desent.

[Explorer1]

Even capturing one pixel would be a fantastic success of planning; does the MRO team have any imaging planned like the previous landers? (I'd like to update my avatar)...

[Deimos]

The nominal trajectory has the entry phase and parachute phase each potentially visible, but less than 15 deg above the level horizon. The crater will prove a challenge for even one pixel. It may be worth a bet on the EDM going well downrange--nothing ventured, nothing gained.

[Ron Hobbs]

The ESA site is featuring images of the landing site. It looks to me that if Schiaparelli lands really long, Oppy might have a chance.

Meridiani Planum with Landing Ellipse

I've got my fingers crossed.

Here is the main website: Spotlight on Schiaparelli Landing Site

[akuo]

I tried to look for information about coverage of the Schiapparelli landing events and communications. Only thing mentioned seems to be that MEX will record the lander's signal for later transmission. Anyone know when that transmission would come? Any chance of following Schiapparelli live, even detection of the carrier signal with radio telescopes like was done with Huygens?

I guess I've gotten too used to Nasa lander style blow-by-blow earth receive time coverage with first pictures arriving minutes after the landing.

I assume at least the orbiter will stay in constant DSN contact during the insertion.

[Paolo]

I think you can find answers to most of your questions here:
http://blogs.esa.int/rocketscience/2016/03...e-theyre-going/

[Paolo]

yesterday ESA published two short articles on Schiaparelli and the expected sequence of images

http://exploration.esa.int/mars/58425-prep...o-land-on-mars/
http://exploration.esa.int/mars/58435-what...relli-s-camera/

I am starting to see other forums getting inflamed by rants about the plans for imaging or lack of it. given the minimal exoected data output of the lander (150 Mbits, of which 100 Mbits will be engineering data) I am not surprised that no proper camera was carried.

[akuo]

Thanks Paolo, that's the info I need.

To summarise:
An Indian radio telescope in Pune might detect if Schiapparelli is transmitting at all, live.
MEX and MRO will record a subset of telemetry, which could be received at 16:30 and 16:45 UTC on the landing day.
TGO will record full telemetry and it should be available 10h later, at 1:00 UTC.

[Phil Stooke]

http://www.midnightplanets.com/web/MERB/im...4P2671L6M1.html

This is a test image taken by Opportunity and downlinked only about 20 minutes before this post. It's a test for the attempt to view Schiaparelli. Good luck - uh - break a wheel! (no, don't).

Phil

[Deimos]

And context for that test image: http://www.leonarddavid.com/europe-readies...ober-touchdown/

[akuo]

With Oppy being so close, was there any consideration on having it listen to Schiapparelli on UHF during the EDL?

[climber]

Can somebody point out Victoria crater?

[climber]

With Oppy being so close, was there any consideration on having it listen to Schiapparelli on UHF during the EDL?

Listening to Schiapparelli? On what Chanel ?

[centsworth_II]

Can somebody point out Victoria crater?

It's labeled in post 1 and is the most prominent crater south of the flag in post 2.

[climber]

Oh yes, sorry about that.
If I remembrer correctely, so far, the landers have all overshot the center of the elipse? Is that correct? I guess we still have a chance to get pictures of Oppy's landing hardware...

[akuo]

Listening to Schiapparelli? On what Chanel ?

Yeah, that could be a problem. I'm pretty sure lander to lander communications were not on top of their minds when these things were designed. Also the radiation cone from the UHF antenna would be pointing in wrong direction, but proximity should definitely help with that.

[climber]

This was just for Schiaparelli = Channels, oh well...

[katodomo]

I guess we still have a chance to get pictures of Oppy's landing hardware...

DECA should have a resolution of at best 4-5 m/pixel (at 1.5 km distance), hence not much chance of that.

[Explorer1]

Schiaparelli seperation confirmed!

[nogal]

Here is a link to a page where live updates about ExoMars are being posted: http://m.esa.int/Our_Activities/Space_Scie...val_and_landing
Excerpt from the page above:

16 October

18:43 CEST: Full telemetry link with ExoMars/TGO has been restored via ESA's 35m deep-space ground station at Malargüe, Argentina.

18:30 CEST: The Schiaparelli module was released from the Trace Gas Orbiter (TGO) at 14:42 GMT (16:42 CEST) as planned. Today, three days before gravity will ensure the arrival of ExoMars 2016 at Mars, the Schiaparelli Entry, Descent & landing demonstrator Module separated from the TGO orbiter and is now en route on a ballistic trajectory to reach the Red Planet, enter its atmosphere and land softly in an area close to the equator known as Meridiani Planum.

However, TGO unexpectedly did not return telemetry (on-board status information), and sent only its carrier signal, indicating it is operational. The anomaly that prevents TGO's telemetry from being sent is under investigation, and is expected to be resolved within the next few hours.

Fernando

[Hungry4info]

ESA's official twitter confirms TGO is now returning telemetry.

[nogal]

A few ESA links about Schiaparelli's EDL:

Schiaparelli's descent trajectory

Schiaparelli's descento to Mars in real time (the whole 5m 52s of the descent)

ExoMars: From separation to landing

Fernando

[nogal]

ExoMars TGO burning proceding ok, "with slight overperformnace" (Flight Operations Director)

Schiaparelli: at 15:19 UTC it is known it was awake and executing the pre-programmed sequence. Furher information expected within the hour

Fernando

[xflare]

Following Tweets from ESA, it seems they were able to follow much of the EDL up until the final moments, at which point did the signal disappear? - at the point of landing??

[akuo]

No exact timing mentioned but the Puna radiotelescope seeing the UHF signal lost it at some point when Schiaparelli would have been in powered flight or at landing.

[xflare]

Mars Express transmitting EDL data now.

[Art Martin]

I have a question about this lander mission for the experts. I was surprised to hear the lander has no solar panels, will operate briefly until batteries run out, and has no surface cameras at all, that this mission was primarily just to practice landing techniques in preparation for a future rover mission. It sure seems that these techniques have been fully developed by the US and we are having stunning successes at landing in difficult conditions and I would assume that there would be no reservations at all about sharing the technology with ESA. While I understand that ESA wants to show they can do it on their own, the costs to send a lander are astronomical and not reinventing the wheel seems to be a very logical step. Why is ESA not piggybacking off our experience more? Was this simply a situation where they had such limited payload weights available and this was some last minute addition to the ExoMars mission or did they truly need this step? I just can't fathom going to all that trouble to set something down like this and not include solar panels and a camera.

[climber]

Does somebody know when Oppy's images attempt will be on the ground?

[xflare]

Looks like the Orbiter burn was successful - signal acquired right on time.

[nogal]

ExoMars TGO is now confirmed to be in martian orbit.

I have a question about this lander mission for the experts....

Hello Art Martin. I think most of your questions are answered in these ESA pages: About ExoMars
Fernando

[Explorer1]

Oppy's image attempt should come this afternoon, PST. Regarding the final fate of the lander, the Mars Express data is being analyzed now, and should shed light, on what occurred.

MRO imagery would of course, give the ultimate ground truth, but I don't known when that is planned for...

[PaulM]

I have a question about this lander mission for the experts. I was surprised to hear the lander has no solar panels, will operate briefly until batteries run out, and has no surface cameras at all, that this mission was primarily just to practice landing techniques in preparation for a future rover mission. It sure seems that these techniques have been fully developed by the US and we are having stunning successes at landing in difficult conditions and I would assume that there would be no reservations at all about sharing the technology with ESA. While I understand that ESA wants to show they can do it on their own, the costs to send a lander are astronomical and not reinventing the wheel seems to be a very logical step. Why is ESA not piggybacking off our experience more? Was this simply a situation where they had such limited payload weights available and this was some last minute addition to the ExoMars mission or did they truly need this step? I just can't fathom going to all that trouble to set something down like this and not include solar panels and a camera.

Entry descent and landing technology is classified because of its relationship with ICBM technology. This is why we were lucky to see oppy's microscopic images of her heat shield. However, you will notice that jpl have never described what the images revealed. I was surprised that communications protocols between opportunity's central computer and it's instruments were also classified. I have read that this is why opportunity's European made instruments have an analogue interface and not a digital interface to the main computer.

[mcaplinger]

Entry descent and landing technology is classified because of its relationship with ICBM technology.

While there is some truth to this (for "classified" read "covered by ITAR"), there is plenty of open-literature information about US Mars EDL systems.

[xflare]

According to BBCs Jonathon Amos Mars Express saw pretty much the same thing as the radio telescope.... which doesn't sound good. Perhaps something happened at backshell separation or engine ignition.

[B Bernatchez]

When might we get HiRise coverage of the landing zone?

[Phil Stooke]

Have to figure out where it is first. Tracking might help. A CTX image might be the first thing they would try, to find it for targeting HiRISE next time.

Phil

[James Sorenson]

There are two candidates that I spot in the Oppy images that have come down. But these really do look like CR hits to me. I wouldn't rule out the lander though.
http://qt.exploratorium.edu/mars/opportuni...ARP2857L6M1.JPG

http://qt.exploratorium.edu/mars/opportuni...ARP2857L6M1.JPG

[Guest_Steve5304_*]

There are two candidates that I spot in the Oppy images that have come down. But these really do look like CR hits to me. I wouldn't rule out the lander though.
http://qt.exploratorium.edu/mars/opportuni...ARP2857L6M1.JPG

http://qt.exploratorium.edu/mars/opportuni...ARP2857L6M1.JPG

Those definately are not cosmic Ray hits...pictures were taken some time apart and the second picture hives with the trajectory of the first that's definately the lander.

[Explorer1]

Flipping between the two links James posted I see something around the 9 o'clock position in the 2nd image a lot fainter than the cosmic ray hits (near the black dust spec on the lens).
I know, I know, grasping at straws, but look at my avatar, I can't help myself!
Trouble is we can only guess what it would look like...

[tanjent]

Based on the shape of the landing ellipse relative to the rover's position, I would have expected the lander to move from left to right across Opportunity's field of view. The phrase "landing long" has been used to express the prerequisite for Schiaparelli's getting near Opportunity's position at all. That said, there are many possible ways to become disoriented when viewing pictures like this for the first time.

[TheAnt]

The second image, at top right, look a bit like a comet. Isn't that Schiaparelli?

http://qt.exploratorium.edu/mars/opportuni...ARP2857L6M1.JPG

Last news from BBC, the same, no signal so isn't it a risk the batteries run out even if the lander mission would turn out to be retrievable after all?
Regardless, this was a crucial step for the Exomars rover, so another delay seem likely.

[fredk]

Those definately are not cosmic Ray hits...

As I mentioned in the MER thread, this is daytime at Meridiani, so the exposures are very short. I wouldn't expect the lander to be streaked, especially since if anything we'd be seeing the slow end of the descent trajectory. So I think everything we see is consistent with CR's and noise.

The real clincher would be a feature appearing in simultaneous L6/R2 frames, but I don't see anything matching.

[nprev]

Had to work all day so just catching up.

Let's please remember that members of the Schiaparelli team may well be reading our posts, if they have the time to do so given the enormous amount of frantic work that must be underway trying to understand--and hopefully recover from--this anomaly.

Mars is hard. There's no denying that. There's no such thing as a 'routine' landing there, not for anyone. But the only way to truly fail is to never have tried at all.

Best wishes to them, and best of luck.

[JRehling]

I've seen a spacecraft re-enter (Stardust) from downrange, albeit at night. I'm not sure what the martian daytime version would look like, but the terrestrial nighttime version was pretty cool.

[mcaplinger]

I have read that this is why opportunity's European made instruments have an analogue interface and not a digital interface to the main computer.

This is not only OT but pretty nonsensical. As an example, the foreign instruments on MSL (RAD, part of Chemcam, and REMS) are not analog interfaces. The digital interfaces may not be publicly documented, and ITAR is often invoked, but they are certainly not secrets within the project.

IMHO the ESA EDL demonstrator is as much about politics and nationalism/regionalism as it is about technical issues, and I have been working on space missions with international participation since the mid 80's.

[JRehling]

Mars is hard. There's no denying that.

This is nothing we don't already know, but Mars is almost the worst-case scenario for landing. The atmosphere is thick enough to burn a craft up, but not thick enough for a parachute to finish off a soft landing. The Moon, Earth, Venus, Titan, asteroids, comets – all are easier to make a soft landing on than Mars. Mercury might be harder, but at least there, the entire braking would have to be via thrust with no need for a heat shield. Mars requires Rube Goldberg entry schemes, and many attempts at landing there have paid the price.

[xflare]

I followed the edl on twitter, they got so close I really thought it was going to make it, then the tweets just stopped... The sad thing also is that the successful arrival of the ExoMars Orbiter is going to be completely overshadowed like Mars Express.

[Explorer1]

Staying up late for the conference; looks like all the data from the descent was collected and is being processed (which will take a few days) and confirmation that ground radar was activated and that the rockets fired for at least a few seconds. So all key pieces of hardware did fire and they have telemetry (600 megs!). There will be attempts in the coming days to takes MRO images, but it may be a while to find something that small in the images.

Signal was lost about 50 seconds before planned touchdown. When parachute/backshell should have detached from the lander received telemetry started to deviated from expected. Multiple possibilities on what happened after, and they won't speculate yet. May try to send reset commands in a few days.
AMELIA instrument got science data though, so good news for them!

Hopefully the media will chalk this up as at least a partial success.

[xflare]

Arggh stream kept buffering so missed quite a bit, So the data from the AMELIA investigation was transmitted in real time and recorded on TGO??

hmm lots of interesteing info from Jonathon Amos , quote: Signal received for 19 secs after engines shut off...maybe in free fall.

[abalone]

"Schiaparelli Mars probe's parachute 'jettisoned too early'"

Europe's Schiaparelli lander did not behave as expected as it headed down to the surface of Mars on Wednesday.

But it is at the end of this parachute phase that the data indicates unusual behaviour. Not only is the chute jettisoned earlier than called for in the predicted timeline, but the retrorockets that were due to switch on immediately afterwards, fire for just three or four seconds. They were expected to fire for a good 30 seconds.

In the downlinked telemetry, Schiaparelli is seen to continue transmitting a radio signal for 19 seconds after the apparent thruster shutoff.

http://www.bbc.com/news/science-environment-37715202

[climber]

To me this si more than a partial succes since all EDL instruments get activated.This means they've got it mostly right and they Will learn where they'll have to put more margins. They also said they don't rule out Schiaparelli was too low when engines fired. I understood that data started to deviate from previsions at the end of parachute work. Nevertheless they've got radar' and engines fired!
Experience tells that parachute and heat shield lands prety close to the landers. This will help finding the module...and we know where it is NOT sincy Oppy didn't catch it.
Go ESA, you're pretty close.

[climber]

"Schiaparelli Mars probe's parachute 'jettisoned too early'"




http://www.bbc.com/news/science-environment-37715202

Sorry to tell that I never heard such assesments during the conference.

[alphasam]

Sorry to tell that I never heard such assesments during the conference.

Not quite in so many words, however that is what they were indicating.

https://twitter.com/BBCAmos/status/789025342283456513

The telemetry says the retro-rockets did fire. This event lasts three or four seconds. #ExoMars

https://twitter.com/BBCAmos/status/789025867712307200

....communication with Schiaparelli is maintained for 19 seconds after the rockets are seen to shut off. Is the probe in freefall? #ExoMars

https://twitter.com/BBCAmos/status/789025046727684100

The communication from Schiaparelli ends 50 seconds earlier than expected. #ExoMars

In the timeline parachute jettison/thruster firing should have occured just 30s before landing.

http://exploration.esa.int/mars/57464-exom...scent-sequence/

[tolis]

I think that it is a mistake that they tried to avoid giving any details on EDM altogether. All the questions they received afterwards
were about EDM. No-one doubts that the lion's share of the science will come from TGO and the EDM was a technology test.
However, one should also be mindful of the fact that the public, who is always footing the bill on these missions, need to be kept informed
(think of passengers in an airplane during an emergency). Coming across as evasive, which in my opinion is what happened here,
puts bees on the bonnet of public opinion, which then propagates to the elected representatives.

[PaulM]

This is not only OT but pretty nonsensical. As an example, the foreign instruments on MSL (RAD, part of Chemcam, and REMS) are not analog interfaces. The digital interfaces may not be publicly documented, and ITAR is often invoked, but they are certainly not secrets within the project.

IMHO the ESA EDL demonstrator is as much about politics and nationalism/regionalism as it is about technical issues, and I have been working on space missions with international participation since the mid 80's.

I did not like the idea of analogue interfaces when I read it 10 years ago from someone on this site so I am pleased that it is not true. The one thing that I would like to find out is how much of the ablative material was still present on opportunity's heat shield. There was speculation 10 years ago that heat shields could be made lighter in future if this information was known

[craigmcg]

Its always good to be patient in these situations, as hard as it may be. It is fun for us armchair engineers to try and piece together the clues and come up with our own guesses.

I watched the conference just now on livestream and was left wondering what the next step would be in disclosure of the analysis of the EDL. Looking forward to understanding more.

[Gerald]

There will be attempts in the coming days to takes MRO images, but it may be a while to find something that small in the images.

Either the shock wave or the thrusters should have created a darkish and less saturated patch of less surface dust on the ground, which should simplify the search in HiRISE images, if taken within the next days/sols.

[xflare]

Either the shock wave or the thrusters should have created a darkish and less saturated patch of less surface dust on the ground, which should simplify the search in HiRISE images, if taken within the next days/sols.

Here is Mars Global Surveyor's first images of the Opportunity landing site in 2004 http://www.msss.com/mars_images/moc/2004/02/09/ Merdiani is very flat and has few features, I think it might be easier to find than other missing landers with MRO.

Also , here are the impact sites of the 75kg tungsten balance weights from Curiosity, which were very clearly seen in the MRO context camera images. https://www.nasa.gov/mission_pages/MRO/mult...a/pia16456.html Schiaparelli weighs about 500kg.

[climber]

Let see if it enters the category of multiple landings as Phylae. It's possible that it had still some horizontal velocity when hiting the ground. MRO will tell

[katodomo]

Question: Schiaparelli carried INRRI, a laser retroreflector. Would any current or planned near-future orbiter actually have come with a laser that could have used this within the next decade or so?

(i assume that dust storms would have made INRRI unusable relatively fast in comparison to units placed on the moon almost five decades ago)

[Phil Stooke]

Not sure, but they would take that into account in the design. And there is talk of one being added to Insight as well. Something must be intended but I'm not sure of all the details. I have seen talk of laser reflectors before, and it's possible that a network of them would be built up over time, perhaps allowing very accurate rotation data to be collected to monitor precession (for instance).

[nprev]

MOD NOTE: Two posts set invisible for inciting (and responding to) a debate re the 'success' of this mission-- see rule 2.6.

We're not doing that.

[alan]

ESA promised to continue attempts to communicate with the lander in the coming days using available orbiters and to make an effort to locate the lander or its remnants on the surface of Mars.

Sure enough, by October 21, NASA's sharp-eyed Mars Reconnaissance Orbiter, MRO, imaged the wreckage of the Schiaparelli on the surface of Mars exactly at the center of a planned landing ellipse. In the meantime, ESA engineers suspected that the GNS software had been a likely culprit in the failure, commanding the premature cutoff of the propulsion system, which led to a catastrophic crash.

http://russianspaceweb.com/exomars2016-edm-landing.html#mro

Found this via https://twitter.com/cosmos4u/status/789484298143408128

[tedstryk]

It appears that they may recover the data from AMELIA (the descent instruments). So they might learn something about the atmosphere, and they will certainly have some info about the technology. Not a success, but not a total failure either. Seems Mars-6 (sent back atmospheric data during descent, then crashed) would be a better comparison than Mars 3 (20 seconds of useless signal).

[xflare]

http://russianspaceweb.com/exomars2016-edm-landing.html#mro

Found this via https://twitter.com/cosmos4u/status/789484298143408128

Im guessing this would be in a COntext Camera Image.... all the Curiosity EDL hardware is visible in it too.

[Explorer1]

Yes, its a CTX image; low res, but that settles it... http://www.esa.int/Our_Activities/Space_Sc...li_landing_site

HiRISE images next week.

[JRehling]

This is an extreme "cup half full" interpretation, but the chance to observe impacts of known mass and velocity helps very much to interpret the natural impacts which are regularly observed on Mars, the mass and velocity of which are unknown. So, while this outcome was not desired, there is a benefit. The operational failure is a disappointment, but scientifically, the observation of this impact partially offsets the few days' of surface operations that were lost.

[nogal]

There were repeated remarks that the landing would be attempted during the dust season, a first. So how much dusty was the atmosphere at the landing area? Is there any data from Opportunity? And how could it have influenced the EDL?
Fernando

[Explorer1]

Yes, that's a good point JHReling. I seem to recall the HiRISE images of Curiosity's tungsten counterweights and interplanetary cruise stage impacts were useful in that regard. Saving the AMELIA data is also another bit of silver lining to this cloud.

Small consolation to the rest of the team though; they must be going through something none of us laypersons can imagine. Even I'm having mixed feelings about seeing the high res images next week...

[Habukaz]

There were repeated remarks that the landing would be attempted during the dust season, a first. So how much dusty was the atmosphere at the landing area? Is there any data from Opportunity? And how could it have influenced the EDL?
Fernando

There is currently a significant amount of dust in the Martian atmosphere, at least. Apparently, weather radars are capable of picking up dust storms on Earth, and rain can reduce the performance of radar altimeters. Whether a radar altimeter with poor software or performance could get thrown off by the current amount of dust in the Martian atmosphere is to me an interesting question (and whether Mars' dryness would be relevant here).

EDIT: it's not the altimeter, apparently

[alan]

53 km's from Oppy, I bet she could reach it.

[fredk]

So how much dusty was the atmosphere at the landing area? Is there any data from Opportunity?

Lemmon posts very regular tau measurements here. Tau has climbed from its winter low, but at ~0.9 is on the low side compared with previous years.

[neo56]

I looked at Oppy's new images on Midnight Planets and spotted this pic I've not seen yesterday: http://www.midnightplanets.com/web/MERB/im...RP2857L6M1.html

Do you think the two bright spots above the horizon could be Schiaparelli and its parachute? I circled them:


Time of acquisition seems too early (2:44:13 PM UTC) but Mike specifies that acquisition times are approximate.

[Explorer1]

We know from the CTX images that it landed near the middle of the landing ellipses, way below the local horizon, so it can't be. I also withdraw my own speculation from earlier in the thread, given the ground truth.

[fredk]

On top of that, with the landing site over 50 km from Oppy, the pancam pixel scale would mean that those two specks were about 2.4 km apart! (So I guess theoretically possible if taken just after the parachute/backshell separated.)

[fredk]

I see a couple of possibly interesting features on the after CTX image. Marked with the black ellipse is some faint dark streaking that roughly aligns with the main lander splat. And circled is a small dark spot. Both weren't in the before image:


It's easiest to see them by flipping between the before and after images. Even though the image is very noisy, both features appear to rise above the noise fluctuations but still could be extreme fluctuations or other artifacts.

Perhaps the streaks, being dark and so perhaps due to removed dust, are associated with the engine firing, and the dark spot the heat shield?

[tolis]

I see a couple of possibly interesting features on the after CTX image. Marked with the black ellipse is some faint dark streaking that roughly aligns with the main lander splat. And circled is a small dark spot. Both weren't in the before image:


It's easiest to see them by flipping between the before and after images. Even though the image is very noisy, both features appear to rise above the noise fluctuations but still could be extreme fluctuations or other artifacts.

Perhaps the streaks, being dark and so perhaps due to removed dust, are associated with the engine firing, and the dark spot the heat shield?

Indeed, I pointed those two out here

They appear to be downrange of the crash site. That's what you would expect for something that continues on ahead of the decelerating EDM.

[marsophile]

...the exposures are very short. I wouldn't expect the lander to be streaked,

If the retro-rockets were firing, wouldn't they show up as a streak even in a short exposure?

[James Sorenson]

When pancam auto-exposes images through each filter, it does so until it reaches a specified DN value. If I recall, that is about a DN of 3000. So Images taken with L2 or R2 would have a lower exposure time then say images taken with L6, L7 or R1. You can even see this in the raws as you approach the blue and UV end, the images start to get more noiser from CR hits and hot pixels since it takes more time to reach the specified DN. So I'd expect L6 images would be in the few second range and If schiaparelli went through the FOV (which is now extremely unlikely if not ruled out since we know where it landed), I would think it would leave a small streak. Images taken with R2 would be a fast exposure and would likely not show a streak at all.

[mcaplinger]

These images were likely not autoexposed, but you're ignoring the fact that these are frame transfer cameras and would show artifacts with anything moving in the scene, which would probably lead to some kind of streaking for fast-moving objects regardless of exposure time. That said, the team looked at these images and said they saw nothing but cosmic-ray hits, so I'd say leave it at that.

[nogal]

A minuscule tribute to the ExoMars team. I have updated the kml file with the latest CTX images and also reviewed and extended the text of the several item's descriptions. Zoom in to see the "after" image. Enable (check) the "Hardware" to get small icons of Schiaparelli and its parachute.
Fernando
 Schiaparelli.kmz ( 408.86K ) Number of downloads: 383

[marsophile]

One way to rule out the streak in

http://qt.exploratorium.edu/mars/opportuni...ARP2857L6M1.JPG

as being from Schiaparelli is to examine the times involved. From the filename, the above image was taken at 530160694 seconds in the epoch beginning on January 1, 2000 at 11:58:55.816 UTC. Using a J2000 calculator and subtracting the 64.2 seconds until 12:00:00 would put the image acquisition at 2016-10-19 14:50:29.799 UTC. However, the loss of signal from the Schiaparelli lander reportedly occurred about a minute before the scheduled landing time of 14:48 GMT (= UTC). Thus, the lander would have already crashed before the image was taken, unless I have made some error in my calculation.

[mcaplinger]

The time in the file name is an SCLK value and drifts around in a way tabulated by the NAIF group http://naif.jpl.nasa.gov/pub/naif/MER/kernels/sclk/mer1.tsc . According to the quick Python program I just wrote (below) this time corresponds to 2016 OCT 19 14:51:27. But your conclusion is right. I'm not sure how the imaging times for the MER imaging were commanded but this seems late.

CODE

import math
import sys
from spice import *
furnsh("naif0001.tls")
furnsh("mer1.tsc")
t0 = scs2e(-253, sys.argv[1])
print "t0", t0, et2utc(t0, "c", 0), et2utc(t0, "isod", 0)

[Deimos]

The images were taken with fixed exposure times to minimize a streak. The contrast was expected to be low, even in the unlikely event the lander came to a part of the sky where Opportunity had a line of sight. So, spreading the sub-pixel feature over lots of pixels would just further reduce it.

The few red images were to mitigate against model error or tau change--the contrast was predicted to go through 0 within the Pancam bandpass. But they were few due to bits and to image timing. Pancam is slow; slower still in the rover's current operational mode. Tests ahead of time struggled to demonstrate a way to go fast--generally, when the images have gone fast, subframes were used. So, after the first 5 images (4 L, 1 R), there was no chance. I was expecting ~6 L images, and was betting the descent would be a little later and farther downrange (not having a better option--imaging from inside the crater was like looking for your keys under the streetlight, even if you thought you might have dropped them off in the dark spot off to the left).

[tolis]

Reported in Anatoly Zak's website:

"By October 24, engineers narrowed down a possible culprit to an error in the software of the Schiaparelli's Doppler radar altimeter, which misled the main computer into thinking that the spacecraft had already reached the landing altitude."

That sounds like something you should catch during testing on the ground (Earth ground, that is)

[Decepticon]

[vikingmars]

Reported in Anatoly Zak's website:

"By October 24, engineers narrowed down a possible culprit to an error in the software of the Schiaparelli's Doppler radar altimeter, which misled the main computer into thinking that the spacecraft had already reached the landing altitude."

That sounds like something you should catch during testing on the ground (Earth ground, that is)

Maybe the radar caught the heatshield flying down in its line of sight...

[tolis]

Maybe the radar caught the heatshield flying down in its line of sight...

It might be, but the way the sentence is phrased points to a coding issue instead.
A simple unit conversion problem, for instance: alt=4km -> alt=4m.
Not to suggest that this is actually the culprit, just an example.

[Art Martin]

That would be mind blowing if the sequences of landing were placed entirely within the control of the just switched on radar without some background logic going on dealing with the timing of the descent. I would think that even if the craft overshot or undershot its target a bit, the overall timing of events would still end up within a few seconds of the expected and any results coming back from the radar which were way out of those parameters should be considered suspect. I'm a computer programmer but have never been involved in code for spacecraft so I'm talking only from the standpoint of someone that has written code where mistakes could cost a lot of money. You put in what ifs and alternate paths for the logic in those critical events. Of course I have the luxury of not having the decisions come at me over a very short span of time. I'm curious how NASA would handle this in code. Radar would seem to be a critical component but what would software do if the results from it made no sense?

[nogal]

That sounds like something you should catch during testing

I've been writing code since 1970 (when the world was "young and uncomplicated" ), but I never dealt with real-time, or near-real-time handling code which, I suspect, Schiparelli must use, and imposes a lot of constraints on code, including path-length (the time available for a given algorithm to execute).

I red somewhere that it has been mathematically proved that, except for simple cases, it cannot be demonstrated that a program is 100% correct. So, given one has to live with errors, what can be done to minimize them? Software building, coding methodologies can be used. "Proven" code can be reused - as long as the context of the proof remains valid for the case at hand and people are aware of it. And, of course, testing. A lot of testing. Automated testing can catch some errors, and test cases are specifically created. Can one foresee everything? Every possible combination of inputs? Some errors are caught by sheer luck, others may remain hidden for a long time, until a rare set of conditions manifests itself. Every time an error is caught its correction is included in the next release of the software. It works for the relatively forgiving environments of every day life. Space is much, much more harsh.

I'm just offering my own experience, not excusing anyone or anything. Sometimes, getting the kinks out of a program, feels harder than landing on Mars [pun intended].
Fernando

[Habukaz]

According to this audio (transcript) from Deutschlandradio, there was a timeout in the radar altimeter that ultimately made the onboard computer think it was on the ground far too early.

[katodomo]

The transcript link above also links:

the EDM mission overview
a paper on the tests performed with the radar
(both in English)

[JRehling]

As a career software engineer, I doubt very much if either logical correctness or speed of execution are much of an issue here. The logic of the program is almost certainly a small matter compared to the complexity of the dynamic situation with multiple hardware systems operating in a complex and partly uncertain physical world. Even if a program were proven "correct," if that meant correct given that your radar behaved normally and during the actual landing, the radar experienced a glitch, then the correctness of the program could prove irrelevant.

The speed of modern microprocessors probably exceeds the requirements by more than one order of magnitude.

My take, from the outside looking in, is how to make a system that can save the spacecraft if physical events and the performance of sensor hardware go a bit beyond expected limits. If they go radically outside of expected limits, then the software might not be the problem anyway. But if they go moderately beyond normal expectations, then an ideal system might save the spacecraft whereas a good one might not.

I don't know which, if any, of those possibilities apply here. It seems, though, that telemetry took place past the point when things went wrong, so there's a good chance that we'll eventually know the root cause.

[PDP8E]

I would like to know if ESA released a test article out of an airplane at 20K feet to test the system in real-time/real-world....
I would love to see that film...

[mcaplinger]

As a career software engineer, I doubt very much if either logical correctness or speed of execution are much of an issue here.

Logical correctness is always an issue. As an unrelated example, MPL failed because of a lack of proper software debounce in the contact sensor that detected landing. I guess you can call that dynamics, but I'd call it a logical failure. At any rate, however you characterize them, software errors can be stupid and simple or extremely subtle or anywhere in between. If I had to make mistakes, I'd prefer to make subtle ones, but failure is failure and nothing much would surprise me in this case.

[Explorer1]

English language article saying main hunch is a computer glitch; it may have thought it was on the ground already, and the scientific instruments even turned on!

http://www.nature.com/news/computing-glitc...-lander-1.20861

At least it should be easier to fix than a hardware problem (all of which seemed to perform flawlessly).

[siravan]

One of the difficulties of landing on Mars (among others) is the inability to do a full EDL rehearsal on Earth. Software verification and validation is all well and good, but if you cannot test your system in its entirety, all bets are off. We just don't know what happened (yet), it could be a subtle logical error only apparent in Mars environment or a simple error like the big-endian/little-endian mix up that doomed MGS. However, the whole point of Schiaparelli EDM lander was an end-to-end testing of the EDL system, and as such, it was a very successful test.