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Schiaparelli EDL Demonstration Module Mars Landing - 19 Oct 2016

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Winston

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[video=youtube;D4xecq7P-Pk]https://www.youtube.com/watch?v=D4xecq7P-Pk[/video]
 

Winston

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ESA really needs to learn some major lessons on how to do live coverage of missions. I had to go to a UK newspaper to get an up-to-date summary:

Schiaparelli lander: what we know so far

The Schiaparelli lander has fallen silent during the last moments of its decent to Mars.

It was being tracked from Earth by the Giant Metrewave Radio Telescope (GMRT), located in Pune, India.

During its descent through the atmosphere, the GMRT saw several ‘jumps’ in the signal that correspond to key events taking place correctly on the lander, such as the parachute being deployed.

Flight controllers at ESA are refusing to ‘jump to conclusions’, preferring to wait until they can analyse the data recorded by the Mars Express spacecraft, which was in detailed communication with Schiaparelli all the way to the surface.
 

NAR29996

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So they know that it is on the surface of Mars, and are attempting to determine in how many pieces.

Meanwhile, we wait for confirmation that the orbiter (TGO) successfully completed MOI.
 

Winston

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From the live blog linked to above:

13m ago - While it’s a tense wait to discover the fate of the Schiaparelli lander, ESA are reporting that everything is working well on the Trace Gas Orbiter. This is good because the orbiter is where 99% of the science from this mission is going to come from.

33m ago - Clearly something did not go according to plan with the landing. If Schiaparelli does not communicate with Nasa’s MRO spacecraft during the upcoming pass that must be a strong indication of failure.

That sucks. Even though the lander was battery powered with very limited life, it could have still returned some nice data. Also, this might delay their 2020 rover.
 

Winston

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1m ago - And with that, ESA brings the press conference to a end.

2m ago - ESA’s Director General Jan Woerner is saying that regardless what happened to Schiaparelli, this test was a success. He says that they did this to get data about how to land on Mars with European technology - and that is what is downloading from Mars Express right now. Although he refuses to give up hope (He says, “Cross your fingers still.”) no one is talking now about the hope of signals being received by NASA’s MRO spacecraft.


ESA is pretty much real-time-coverage inept. I've noticed this on previous missions.

Well, if they need it, this 1 foot resolution camera on the MRO can be put to use since at least they'll eventually have some accurate landing coordinates.

 

cvanc

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Sounds like software/control errors doomed it

Parachute deployed as expected but jettisoned much too early

Landing thrusters fired for much less than expected duration

Sorry to say those two things taken together makes it sound like... splat :sad:

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

Winston

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Sounds like software/control errors doomed it

Parachute deployed as expected but jettisoned much too early

Landing thrusters fired for much less than expected duration

Sorry to say those two things taken together makes it sound like... splat :sad:

http://www.bbc.com/news/science-environment-37715202
Thanks for that link. The "live" blog I've been following had nothing about that when I checked it earlier this morning.

Looks like it time to use the MRO camera to look for pieces parts...

"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 are seen to fire for just three or four seconds. They were expected to fire for a good 30 seconds."

Sounds like the landing radar may have been fooled somehow into thinking in was lower than it was or just a software glitch.
 
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georgegassaway

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I]"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 are seen to fire for just three or four seconds. They were expected to fire for a good 30 seconds."[/I]

Sounds like the landing radar may have been fooled somehow into thinking in was lower than it was or just a software glitch.
I wonder if the way the chute got jettisoned early, if it wasn't a totally clean separation that would have made the lander tumble. Or, if the retrorockets were supposed to activate at a specific time, or specific altitude, so that an early cute release, high up, would mean the retros were not going to fire until later and/or lower, so it may have had time to tumble and cause other resulting issues with the retros (even "ullage" problems), if the retros were designed to work with the lander upright and not free-falling with a possible tumble.

But in any case, once the chute released early, that was probably an inevitable crash. By releasing early, it let the lander fall faster and faster down to the altitude for the retros to fire, but it would not have had enough fuel to handle the higher descent velocity, nor enough altitude left unless the retros had a lot of throttle capability. Or if the retros would have fired right after a very early chute release (and kept firing for the full 30 seconds), then it would have been way higher than planned when the retros ignited, so it would have slowed down but then run out of fuel at some significant altitude (hundreds or thousands of feet?) above the ground, free-falling to a crash.

So, it may have been a chain of events. But the first link seems to be the chute releasing early, ruining the rest of the landing sequence from that point on, anything else going wrong after that likely was a consequence of the early release. Unless they really had two totally independently bad things happen, where the retros might have stopped firing anyway even if the chute had not separated early. In which case........ really bad for two critical failures. But since they are going with the "it was just a test flight" excuse, then "great", they would learn of two problems out of one disaster.

UPDATE - Well, after Googling for some other info, it may not be as "simple" as just a chute releasing early. Some theorizing on whether the rear heat shield separated or not. If it did not, that not only would have affected the performance of the parachute descent, but literally would really have screwed with / blocked the thrust performance of the retros. Or perhaps various other things not related downstream from just an early chute release. So, a lot of stuff for them to figure out what may have happened. Good thing is that they did apparently have a LOT of live realtime data coming from it, up until they no longer had anything (but by then, it was already in deep trouble).
 
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Winston

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I wonder if the way the chute got jettisoned early, if it wasn't a totally clean separation that would have made the lander tumble. Or, if the retrorockets were supposed to activate at a specific time, or specific altitude, so that an early cute release, high up, would mean the retros were not going to fire until later and/or lower, so it may have had time to tumble and cause other resulting issues with the retros (even "ullage" problems), if the retros were designed to work with the lander upright and not free-falling with a possible tumble.

But in any case, once the chute released early, that was probably an inevitable crash. By releasing early, it let the lander fall faster and faster down to the altitude for the retros to fire, but it would not have had enough fuel to handle the higher descent velocity, nor enough altitude left unless the retros had a lot of throttle capability. Or if the retros would have fired right after a very early chute release (and kept firing for the full 30 seconds), then it would have been way higher than planned when the retros ignited, so it would have slowed down but then run out of fuel at some significant altitude (hundreds or thousands of feet?) above the ground, free-falling to a crash.

So, it may have been a chain of events. But the first link seems to be the chute releasing early, ruining the rest of the landing sequence from that point on, anything else going wrong after that likely was a consequence of the early release. Unless they really had two totally independently bad things happen, where the retros might have stopped firing anyway even if the chute had not separated early. In which case........ really bad for two critical failures. But since they are going with the "it was just a test flight" excuse, then "great", they would learn of two problems out of one disaster.

UPDATE - Well, after Googling for some other info, it may not be as "simple" as just a chute releasing early. Some theorizing on whether the rear heat shield separated or not. If it did not, that not only would have affected the performance of the parachute descent, but literally would really have screwed with / blocked the thrust performance of the retros. Or perhaps various other things not related downstream from just an early chute release. So, a lot of stuff for them to figure out what may have happened. Good thing is that they did apparently have a LOT of live realtime data coming from it, up until they no longer had anything (but by then, it was already in deep trouble).
I FINALLY found something approaching a decent technical overview of the lander:

http://exploration.esa.int/mars/58425-preparing-to-land-on-mars/

"the inertial measurement unit, which includes accelerometers and gyroscopes, and the radar doppler altimeter"

I can't find a labelled image of the lander that shows its underside, but I recall seeing in a landing animation what looked liked, because of their superficial similarity to Curiosity's doppler radar antennas, radar antennas on its underside, so that's why I suspected it must have a doppler radar altimeter. One of the major challenges with Curiosity was the development of a doppler radar that couldn't be easily fooled.
 

Winston

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Curiosity's relevant sequence:

http://spaceflight101.com/msl/msl-landing-special/

Heatshield separation has to fulfill two objectives, the first being a clean separation without re-contacting the descending Entry Vehicle and second being a separation without obscuring more than one beam of the Terminal Descent Sensor – MSL’s Landing Radar and primary Navigation Sensor from that point onwards.

The first objective is met by jettisoning the Heatshield at a point at which there is a sufficient difference in the ballistic coefficients of the Heatshield and the Entry Vehicle ensuring that a positive separation velocity is achieved. For that, an accurate Velocity Trigger is used to initiate Heat Shield Separation at a max speed of Mach 0.7. (Using IMU Navigation makes it hard to measure exact velocities and Flight Computers rely on Navigated Velocities until the moment of TDS [Terminal Descent Sensor] acquisition.) At the point of Heatshield Jettison, the MARDI Instrument becomes active (refer to the section below). With the Heat Shield out of the way, the TDS could begin to collect data immediately after release, but it could receive false data by acquiring the heat shield instead of the ground with more than one of its beams.

The minimum distance of the Heatshield for TDS activation is 17 meters and the shield is expected to cover that distance relative to the Entry Vehicle in about 8 Seconds. An 8-second delay has therefore been implemented into the TDS Activation Sequence making sure at least 5 beams will acquire the ground. The Vehicle will take data for about 30 seconds measuring its speed with a 3-axis Doppler Velocimeter and calculating its altitude with a Slant Range Altimeter. At that point, a velocity trigger will initiate Backshell Separation. Just before Backshell Separation, the 8 Mars Landing Engines are primed by opening fuel valves with 8 pyrotechnic devices to allow fuel to flow to the engines which will start up at 1% Thrust prior to Backshell Separation.
 

Winston

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A pair of before-and-after images taken by the Context Camera (CTX) on NASA's Mars Reconnaissance Orbiter on 29 May 2016 and 20 October 2016 show two new features appearing following the arrival of the Schiaparelli test lander module on 19 October.

One of the features is bright and can be associated with the 12-m diameter parachute used in the second stage of Schiaparelli’s descent, after the initial heat shield entry. The parachute and the associated back shield were released from Schiaparelli prior to the final phase, during which its nine thrusters should have slowed it to a standstill just above the surface.

The other new feature is a fuzzy dark patch roughly 15 x 40 metres in size and about 1 km north of the parachute. This is interpreted as arising from the impact of the Schiaparelli module itself following a much longer free fall than planned, after the thrusters were switched off prematurely.

The main image covers an area about 4 kilometres wide, at about 2 degrees south latitude, 354 degrees east longitude, in the Meridiani Planum region of Mars. The scale bars are in metres. North is up.


 

Winston

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"Estimates are that Schiaparelli dropped from a height of between 2 and 4 kilometers (1.4-2.4 miles), therefore impacting at a considerable speed, greater than 300 kilometers per hour (186 mph)," the agency said.

MRO took the photos with its relatively low-resolution CTX camera. The orbiter will image the crash site with its sharper High Resolution Imaging Science Experiment (HiRISE) camera next week.
 

Winston

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Translated from German:

https://translate.google.com/transl...log-zu-exomars-dps-und-mehr-kosmischem/#Okt24

Software bug of the Radar Height Meter crashed Schiaparelli

As soon suspected protested a software problem led to the crash of the ExoMars Landedemonstrators Schiaparelli - and should report the height above the Martian soil, although in communicating the computer in Radar Doppler Altimeter, the four flat antennas (Fig.), With the Central computer. This has ESA's Director of Mission Operations and ESOC boss told the Germany radio today : "As far as we can reconstruct so far, the software has not spoken correctly from a radar altimeter with the general navigation software. There has been a timeout that caused the parachute to be blown too early, which led to the device believing it was already on the surface, so it turned off the brake boosters. And now we assume that the probe has crashed in about 2 to 4 km in free fall. We would have liked to see that the brakes that ignited the 60 seconds had actually ignited them but only three seconds. So the image actually fits seamlessly together; It is still a bit speculative, but we expect very accurate information and clarity about what happened in the next two weeks. "The findings will also flow into the 2020 landing and a full success of the EDM would have been pleasing - "But I believe that we have everything together to lead the mission to a success in 2020." There is no written information about the new findings from the ESA in the evening, not even a beep descriptions of the normal operation of the radar altimeter in this paper and this article (in the chapter "Guidance, navigation & Control") and of its tests in this paper and the ESA-note . As well as products with no enlightenment here , here , here , here , here and here , together with an 8-minute TV report - and another cartoon that's not quite met ... [23:15 CEST - end]

 

georgegassaway

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"This glitch is the most likely reason the European Mars lander failed"

http://qz.com/819601/software-glitc...nder-schiaparelli-to-crash-on-the-red-planet/

What could be worse for a programmer than being told that a software glitch ruined an important project? Well, how about if that software glitch happened on Mars, when a new robot was about to make a do-or-die landing.

Over the past week, scientists at the European Space Agency (ESA) have been deconstructing the data sent by the Schiaparelli craft, which on Oct. 19 failed to make a safe landing on the red planet. The most likely culprit, they believe, is a software glitch that either triggered commands too early or misinterpreted data coming from the various sensors on the lander.

Here’s what was supposed to happen:

At 121 km above the surface of Mars, Schiaparelli enters the Martian atmosphere.

For 1 minute and 12 seconds, its heat shield protects Schiaparelli from burning up on re-entry.

At 45 km above the surface of Mars, the parachute is released to slow down the descent.

At 4 minutes and 1 second since the start, the heat shield separates. Then at 5 minutes and 21 seconds, the parachute separates.

Immediately after, the thrusters fire, which burn for 30 seconds and bring Schiaparelli down with a soft thud.

The data Schiaparelli sent back reveals that the parachute separated a minute too early. As that happened, the thrusters should’ve fired for 30 seconds. Instead they fired only for 3 seconds before they were turned off, because the lander’s computer thought they were close to the ground.

The result? The lander went down crashing from a height of more than 2 km above the surface. The evidence of the resulting, probably explosive, landing can be seen in the before and after picture captured by a Mars satellite.

See full article at the link above.
 

Winston

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"This glitch is the most likely reason the European Mars lander failed"

http://qz.com/819601/software-glitc...nder-schiaparelli-to-crash-on-the-red-planet/

See full article at the link above.
Actually, the translated German forum post I posted earlier explained it in better detail, direct from ESA, "As far as we can reconstruct so far, the software has not spoken correctly from a radar altimeter with the general navigation software. There has been a timeout that caused the parachute to be blown too early, which led to the device believing it was already on the surface, so it turned off the brake boosters."

Even though that's not very clear due to the translation, it looks like it was a radar altimeter related issue as I'd originally conjectured. The Quartz article states about the landing thrusters, "Instead they fired only for 3 seconds before they were turned off, because the lander’s computer thought they were close to the ground."

The heat shield is jettisoned prior to the jettison of the parachute/backshell to allow the doppler radar on the bottom of the lander to determine altitude for the preferred parachute/backshell jettison. In this case, there was possibly a false doppler radar return caused by excessive oscillation of the lander under parachute (a remaining concern during the Curiousity EDL) or a false radar return from the heatshield (believed to be adequately dealt with prior to the Curiousity EDL and not a concern). There either wasn't an adequately long interval for ignoring radar return transients (which, I believe is that "timeout" they refer to, a debounce routine) or the transient false radar returns were too long to be ignored (due to false heatshield ranging or lander oscillation).
 

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"Further Clues to Fate of Mars Lander, Seen From Orbit" - By JPL


The most powerful telescope orbiting Mars is providing new details of the scene near the Martian equator where Europe's Schiaparelli test lander hit the surface last week.

An Oct. 25 observation using the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter shows three impact locations within about 0.9 mile (1.5 kilometers) of each other. An annotated view is available online at

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA21131

The scene shown by HiRISE includes three locations where hardware reached the ground. A dark, roughly circular feature is interpreted as where the lander itself struck. A pattern of rays extending from the circle suggests that a shallow crater was excavated by the impact, as expected given the premature engine shutdown. About 0.8 mile (1.4 kilometers) eastward, an object with several bright spots surrounded by darkened ground is likely the heat shield. About 0.6 mile (0.9 kilometer) south of the lander impact site, two features side-by-side are interpreted as the spacecraft's parachute and the back shell to which the parachute was attached. Additional images to be taken from different angles are planned and will aid interpretation of these early results.

For more, see the rest of the article at the link below.

http://www.jpl.nasa.gov/news/news.php?feature=6663
 

georgegassaway

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For those who don't see many movies, or recall, Wilson is a nod to the volleyball that the stranded all alone Tom Hanks character talked to in "Cast Away"
 
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Winston

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For those who don't see many movies, or recall, Wilson is a nod to the volleyball that the stranded all alone Tom Hanks character talked to in "Cast Away"
:) Amazon sells "him" for a very reasonable price:

https://www.amazon.com/dp/B00005LL1K/?tag=skimlinks_replacement-20

MRO's Closer Look at Schiaparelli Impact Site on Mars

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA21131

At lower left is the parachute, adjacent to the back shell, which was its attachment point on the spacecraft. The parachute is much brighter than the Martian surface in this region. The smaller circular feature just south of the bright parachute is about the same size and shape as the back shell, (diameter of 7.9 feet or 2.4 meters).

At upper right are several bright features surrounded by dark radial impact patterns, located about where the heat shield was expected to impact. The bright spots may be part of the heat shield, such as insulation material, or gleaming reflections of the afternoon sunlight.

At mid-upper left are markings left by the lander's impact. The dark, approximately circular feature is about 7.9 feet (2.4 meters) in diameter, about the size of a shallow crater expected from impact into dry soil of an object with the lander's mass -- about 660 pounds (300 kilograms) -- and calculated velocity. The resulting crater is estimated to be about a foot and a half (half a meter) deep. Surrounding the dark spot are dark radial patterns expected from an impact event.

The dark curving line to the northeast of the dark spot is unusual for a typical impact event and not yet explained. Surrounding the dark spot are several relatively bright pixels or clusters of pixels. They could be image noise or real features, perhaps fragments of the lander. A later image is expected to confirm whether these spots are image noise or actual surface features.

 
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Peartree

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I think the curved line suggests something was spinning rapidly on impact.
 
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