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  • NASA’s InSight spacecraft touched down on Mars on November 26th, 2018, with the goal

  • of studying the interior of our rocky red neighbor.

  • But one year into its two-year mission, one of its major scientific instruments, a heat

  • probe attached to a self-burrowing mechanical mole, isn’t where it’s supposed to be.

  • The probe is designed to go as deep as five meters down in the martian soil, but it’s barely

  • scratched the surface, getting stuck about 0.3 meters down before recently popping out.

  • So, like I said to my dermatologist, what’s up with this mole?

  • Now the mole isn’t popping out because little green people living just under the surface

  • gave it the old-heave-ho.

  • Probably, I mean it’s hard to see into the hole it’s made with the cameras onboard InSight.

  • Really, it’s more an issue with how the mole was designed and the type of soil it's

  • digging through.

  • You might be picturing a device with a drill, but for a number of reasons a drill just wasn’t

  • possible on the mole.

  • A drill would require a powerful motor to work, which would make the instrument bigger

  • than what the lander could accommodate.

  • A powerful motor would also use more energy than InSight’s solar panels could provide.

  • And the designers would have to take the torque of the motor into account, as it would spin

  • the mole the opposite direction of the drill.

  • To eliminate that, the drill would need rigging anchoring it in place.

  • So instead, the engineers who designed the instrument at the German Aerospace Center

  • took a different approach to burying their thermometer.

  • They realized that the soil that the Mars rovers Spirit and Opportunity encountered

  • were loose and sandy.

  • So they decided to make the digging action function something like a pile driver.

  • It works by slowly compressing a spring and quickly releasing it, driving a tungsten hammer

  • into the interior of the mole’s tip. It’s literally Whack-a-mole.

  • The hammer tappa-tappa-taps away at a rate of one tap every 3.7 seconds.

  • As it burrows millimeter by millimeter, the idea was for that loose soil to flow around

  • it, providing enough friction to keep it from bouncing backwards after each strike.

  • And clearly, things aren’t going according to plan.

  • The good news is it doesn’t seem like the mole is damaged.

  • InSight’s other scientific instrument is a very sensitive seismometer.

  • Using that, the scientists can look for millisecond level variations in the hammer strokes.

  • So far the data indicate that the hammer is working fine.

  • Is it possible then the mole hit a rock?

  • The team doesn’t think so.

  • The mole is designed to knock small rocks aside and can go around medium-sized rocks

  • once it’s fully buried. The landing site they chose, Elysium Planitia, is flat with

  • as few surface rocks as possible, which minimizes the odds theyll hit an impassable rock at this

  • shallow depth to a few percent.

  • But in a cruel ironic twist, it seems like the landing site that was chosen for its lack

  • of rocks also has soil that the mole’s designers just weren’t anticipating.

  • They think it’s just not providing the friction needed to keep the digger in place.

  • In October, they tested the solution of pinning the mole against the side of its burrow with

  • the lander’s robotic arm, and for a while it seemed to work.

  • But it was short lived, and recently the mole popped halfway out of its burrow.

  • Now the team is going to try and safely move the robotic arm away and reassess the situation.

  • They can’t pick the mole up and try a different spot because there’s no way to grab onto

  • it directly.

  • If they have no other options, theyll try and press down on top of the digger directly

  • using the lander’s robotic arm, but that’s very risky considering they could damage the

  • ribbon that provides power to and collects data from the device.

  • Whatever plan they come up with will have to be rigorously tested to make sure it works

  • as anticipated.

  • So were just going to have to be patient and see if we can bury this heat probe underground

  • to see how heat flows inside Mars.

  • Even if it doesn’t happen, NASA says that overall the InSight Mission is going very

  • well, and burying the sensor is not critical to mission success.

  • And the scientists remain upbeat, saying that the behavior of the soil is still teaching

  • them something new.

  • So when it comes to the mole, like my dermatologist said, it’s nothing to worry about yet, but

  • well keep an eye on it.

  • To take an even deeper dive into NASA’s InSight mission, check out this episode of

  • Focal Point here.

  • So what do you think?

  • Will InSight succeed?

  • Let us know in the comments below.

  • And make sure to subscribe to Seeker for all your space news.

  • Thanks for watching and I will see you next time.

NASA’s InSight spacecraft touched down on Mars on November 26th, 2018, with the goal

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    林宜悉 posted on 2020/03/25
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