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posted by martyb on Saturday July 06 2019, @05:36AM   Printer-friendly
from the non-impacting-moler dept.

Updated information on the Mars InSight Lander's Mole probe.

NASA has now announced that the plan to investigate the cause of the mole's depthless digging was implemented successfully and they have the results

As was previously reported the Mars InSight Lander's heat probe was only able to reach a depth of 13cm in its attempts to drill to a final depth of five meters. Earlier this month NASA announced their plan to move the lander's support structure out of the way so it could view the hole and determine the problem.

Initially, the InSight team thought that the mole had hit a rock and was blocked. But after analysis and experimentation with a mock-up lander at test-bed facilities, they came up with another explanation: a cavity in the soil.

They couldn't be sure without seeing into the hole, which lead to the June effort to move aside the lander support structure.

Now that the mole's support structure has been moved aside, camera's[sic] on the lander's instrument arm are able to see into the hole. And they've confirmed what the InSight team suspected. A small pit has formed around the mole, depriving it of the necessary friction to penetrate deeper.

"The images coming back from Mars confirm what we've seen in our testing here on Earth," said HP3 Project Scientist Mattias Grott of DLR. "Our calculations were correct: This cohesive soil is compacting into walls as the mole hammers."

This is important because the mole works differently from your garden variety post hole digger and

relies on friction with the [soil] surrounding it to hammer its way into the ground [...]. Without that friction, the mole will just recoil from the hammering action, and bounce around in the hole, rather than penetrate.

This was actually the hoped for result as a large blocking rock would have effectively been game over. NASA will next put into action its plan to attempt to remedy the situation

The robotic instrument arm has a small scoop on the end, and they intend to use that scoop to pat on the hole and compress the soil, hopefully eliminating the cavity.

There is a NASA Q&A page on the mole's situation available as well.


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  • (Score: 2) by c0lo on Saturday July 06 2019, @11:50PM

    by c0lo (156) Subscriber Badge on Saturday July 06 2019, @11:50PM (#863974) Journal

    This design seems to use the walls of the recently-dug hole to burrow deeper, instead of having some top-side construction to anchor itself to the surrounding soil. I wonder why they didn't use the support structure as anchor to provide the required friction.

    Mass of the payload - try digging a 15m deep hole when your support structure is a kite [wikipedia.org] (because that's all you can afford to send to Mars on the budget).

    • Lander mass: 358 kg (789 lb). Mars weight (0.376 of Earth's):[56] 1,320 N (300 lbf) [that's equiv 134 kgf on Earth]
    • About 6.0 m (19.7 ft) wide with solar panels deployed.[3]
    • The science deck is about 1.56 m (5.1 ft) wide and between 0.83 and 1.08 m (2.7 and 3.5 ft) high (depending on leg compression after landing).[3]

    You have some solar panels that need to be supported, off-axis at at a height of 1-1.5m when unfurled, but can't afford mass/volume for struts.
    If this structure is to act as an "oil digging rig" (hat tip towards Bruce Willis), can you imagine the vibrations in the structure?

    --
    https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
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