NASA engineers try to fix probe blocked on Mars: NPR

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A mole is stuck in the ground on Mars – not the furry animal but a probe on NASA Mars InSight lander, called the Mole. It's a probe that was supposed to go to a depth of 15 feet under the Martian surface, but it got stuck after being one.

Joe Palca of NPR has more.

JOE PALCA, BYLINE: The mole is basically a tube with a kind of internal pile driving mechanism that allows it to sink into the ground. His job is to measure heat flow from inside Mars. At the end of February, InSight's mission leaders ordered the mole to begin its descent.

TROY LEE HUDSON: It was after this first attempt that we found that we had not achieved our original goal.

PALCA: Troy Lee Hudson is a scientist and engineer at NASA's Jet Propulsion Laboratory in Pasadena. He says that a support structure was used to start the mole in his journey down. But now…

HUDSON: The support structure is on our way. This prevents us from getting a clearer visual image of the mole and the soil that surrounds it.

PALCA: So Hudson says they're going to use the robotic arm of the InSight lander to retrieve the structure.

HUDSON: Very slowly and carefully and place it on the ground somewhere else so that we can then see and interact directly with the mole and the soil that surrounds it.

PALCA: Hopefully, the arm will start moving the support structure later this week. Scientists chose the InSight landing site as they thought they could penetrate the ground. But they still had to make assumptions about what the conditions would be. Jose Andrade is a soil engineer at Caltech.

JOSE ANDRADE: The amount of information and understanding we have of these materials is very limited in Martian conditions.

PALCA: Martian conditions include lower gravity and lower atmospheric pressure than those here on Earth. And even here on Earth, Andrade says predicting how the sand will behave when you try to break a stake is surprisingly difficult.

ANDRADE: When you look at a grain of sand, it looks simple, innocent. But when they meet, they gang up. And they become extremely complex.

PALCA: The ground conditions on Mars may be even more complex than the designers of the mole had thought.

Joe Palca, NPR News.

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