[X] My Assistant

[Chmee]

Are there any working theories why the 2 impactor probes (Deep Space 2) that piggybacked on the Mars Polar Lander did not work? Their failure should have nothing to do with the problem with the MPL lander since they were released far above the surface.

I beleive they were designed to withstand 100 gravities of deceleration and still function. Anyone?

[edstrick]

I never read or saw that a report on the DS-2 penetrators was available. But they held a failure review investigation that was mostly ignored by the media. The conclusions was similar to Beagle: No "Smoking gun", unlike polar lander, but the vehicles had major deficiencies in design and testing and project management and were way not ready to fly.

Penetrators are useful and valuable, even if not "sexy". They're by far the best way to get seismometers where they're well coupled to the ground. The Viking 2 seismometer turned out to be an excellent wind guage, for example.

Note that the Mars 96 Soviet/international mission carried 2 hard landers and 2 penetrators on the main spacecraft. All <sigh> lost.

[The Messenger]

I never read or saw that a report on the DS-2 penetrators was available.  But they held a failure review investigation that was mostly ignored by the media. The conclusions was similar to Beagle:  No "Smoking gun", unlike polar lander, but the vehicles had major deficiencies in design and testing and project management and were way not ready to fly.

Penetrators are useful and valuable, even if not "sexy".  They're by far the best way to get seismometers where they're well coupled to the ground.  The Viking 2 seismometer turned out to be an excellent wind guage, for example.

Note that the Mars 96 Soviet/international mission carried 2 hard landers and 2 penetrators on the main spacecraft.  All <sigh> lost.

I can't find the reports, but here is a reference to them:

http://www.space.com/scienceastronomy/sola...bes_000407.html

Neither of the two reports found a smoking-gun reason for the probes’ failure, leaving it a mystery that probably will go unsolved forever.

A major criticism was that there was no complete system test - they should have built a couple of extras and crashed one into Southern Utah or something.

As I recall, during post-failure testing, one of the batteries cracked at the highest impact level, but this was from a different battery lot, and there were no battery failures during prior testing.

Every single Mars landing has either come down harder, or used more fuel than expected during the descent and landing. I was unaware of the two hard landers on Mars 96, I will add them to my list, (thanks). This includes both Spirit and Opportunity. The unexpected force of these landings - Spirit very nearly exceeded the burst strength of the air bags - was attributed to a lateral vector. However, both of these landers contained rockets that were designed to null wind velocities.

There is a much more obvious answer, but the world is too myoptic to see it:

There is a non-Newtonian vector in the gravitational force that can be modeled as a texture in space: The closer a probe is to a massive object, like a sun, the slower an object with a given momentum will travel a defined distance. Using Newtonian mechanics, we underestimate the mass of planets and moons further from the sun than the Earth, and over-estimate the mass of planets closer to the sun. This is why impact missions to Mars fail, while a Pioneer probe, that was not designed to survive landing on Venus, did not. This is also why we are seeing rocks on Titan and Enceladus. Rocks, not water-ice rocks.

[djellison]

This is why impact missions to Mars fail

Surely this would also have killed Viking, Pathfinder, and the rovers. Anything big enough to have killed DS2 would have killed previous succesfull spacecraft as well.

The Mars 96 probes never left earth orbit incidentally.

Doug