InSight mission Options

[Paolo]

the GEMS Discovery finalist has been renamed InSight and now has its own website: http://insight.jpl.nasa.gov/

[djellison]

We already know from the fresh craters found by CTX et.al. that we don't have to wait long for mother nature to do exactly that anyway.

[JRehling]

There are a lot of issues on the deliberate-thump and impact sounding of Mars.

Impacts are part of the plan (not like we could do anything to stop them!) and one mission objective is to determine the impactor flux at Mars. Of course, many impacts are filtered out by the atmosphere. Perhaps nearby impacts that don't reach the ground will be detected (that kinetic energy goes somewhere).

Deliberate-thump is not part of the plan. One issue is that the landed hardware has to be set up in time for the thump, and previous landers' moving parts usually haven't gotten moving in the minutes after landing. So there'd be a bit of complexity in getting the thumper to arrive where you want it but after a delay, OR force the seismometer to be deployed very rapidly (which is subject to error; Spirit and Phoenix both had hiccoughs).

Note that Phobos tides will be another form of known stress. These will be much weaker than lunar tides on Earth, but they expect to detect them. Tidal stress is generally reckoned to follow the inverse cube of distance, and Phobos is very close to Mars. However, the equations I've seen may have been derived assuming distance >> planetary radius, which is not the case for Phobos and Mars. In any event, the tides are non-negligible.

[JRehling]

Here's a piece about the seismometer which will fly on InSight. Given the >4 decade interval, it may not be surprising that it is more sensitive than the lunar seismometers in the ALSEPs. The Viking seismometer was less sensitive than the ALSEPs, as Viking had much more severe mass limits than Apollo.

http://www.kit.edu/visit/pi_2012_11447.php

I suppose that any metrics of the equipment also depend on the planet. How well the local regolith allows the seismometer to couple, and how well the planet propagates waves are factors beyond our control. Also, winds will blow against InSight, which was no concern on the Moon.