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

[PDP8E]

The Italian news agencies are running several stories today about the Schiaparelli EDM Lander.
I counted six articles -- all roughly the same
The craft was built in Italy for ESA. Thales Alenia Space is the spacecraft builder in coordination with Russia’s Roscosmos. The official ESA (interim?) crash report is due on November 24, 2016

Enrico Flamini, 'scientific coordinator' at the Italian Space Agency (ASI) relates what went wrong with the Schiaparelli EDM lander.
• He reports that the lander was ‘in wild oscillation’ on the parachute
• When the altimeter read 2000 meters, the gyros reported -10m (below the surface)
• He said the computer believed the gyros and eventually the lander crashed
• He also said that the stratospheric balloon drop tests of the whole system were never done, to save a million euros
• ASI wanted the Swedish Space Corporation to do the ‘stratospheric throws’, but ESA gave the work to a Romanian company that eventually didn’t do the job
• ESA then 'made itself content' with computer simulations of the landing provided by a British company

Here is one (of many links available)

Sciaparelli Crash http://www.quotidiano.net/tech/marte-schiaparelli-sonda-1.2690005

[JRehling]

As noted, this isn't a complete/consistent account. It seems to remain open as to whether software caused the crash or if the software simply responded futilely to an already hopeless situation.

Fluid dynamics are not trivial to model computationally, so using computer simulations to validate parachute descent seems like a bad option, but saying that now benefits, of course, from hindsight.

[mcaplinger]

using computer simulations to validate parachute descent seems like a bad option...

The last time the US did actual flight-like testing of supersonic parachutes was for Viking (not counting the LDSD flights, which both failed.)

[JRehling]

How to test systems that operate in the uncertain realm of fluid dynamics is an interesting proposition.

The Wright brothers tried to use an analytical approach to design propellers for an airplane, and realized that they couldn't do it. So, they started off with the design of ship propellers, which were a proven technology, and adjusted as best they could for the different parameters of air vs. water. It worked.

I see that the Schiaparelli parachute system evolved from the Huygens system. That also involves very different parameters, though certainly not as different as the Wright brothers' case.

Parachutes have worked for entry on Venus, Earth, Mars, Jupiter, and Titan. It would seem like there's not much left to prove there.