Engineers to use InSight’s scoop to help digging process


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Insight’s engineers, having failed to get its mole pile driver to dig down as planned, now plan to use the lander’s scoop to push on the mole in the hope this will prevent it from popping up with each hammer drive.

[T]he mole is a 16-inch-long (40-centimeter-long) spike equipped with an internal hammering mechanism. While burrowing into the soil, it is designed to drag with it a ribbonlike tether that extends from the spacecraft. Temperature sensors are embedded along the tether to measure heat coming deep from within the planet’s interior.

…The team has avoided pushing on the back cap [at the top of the mole] until now to avoid any potential damage to the tether.

It appears to me that they are running out of options. This new attempt carries risks. It could damage the tether required to obtain underground temperature readings, the prime purpose of the experiment. However, if they don’t get the tether into the ground, this will also prevent the experiment from functioning. Thus, this attempt could essentially be a Hail Mary pass, gambling all on one last all-or-nothing gambit.

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14 comments

  • pzatchok

    I have never understood why they thought this type of probe would actually work.

  • Edward

    pzatchok,
    Since pile driving is an old technology, I’m not sure why you would think it wouldn’t actually work.

  • wayne

    Edward–
    While I remain a fan of your comments, I must agree with pzatchok on this one.
    It works great…. on Earth.
    And I’m sure it worked great when they tested it on the back-lot, but they didn’t even bother to formulate Plan B, or Plan C.

    Armageddon–
    “You guys are NASA scene”
    https://youtu.be/_B7MzBmjaJ8
    0:32

  • sippin_bourbon

    Seems to me they probably found a rock. Try somewhere else,.maybe?

  • sippin_bourbon: No, a rock is not the problem. Do a search on BtB for the words “InSight” and “mole” and read the past posts.

    I really wish more of my readers would use this website as a resource. I do it all the time, in order to try to get my facts right before I write them.

  • pzatchok

    Edward

    This is not pile driving.

    Pile driving involves a machine that drives a pile or spike into the ground. Like a hammer drives a nail.

    Where is the hammer in this set up? They took it from a separate machine and placed it inside the spike. What happens to the force that drives the hammer down? It in part pushes the spike back up. Like a bounce.

    Not enough gravity to keep the spike going down more that bouncing back up.

    They could have instead use a different method and either dropped it in like a Rod From God or fired it into the ground with a recoilless rifle.
    Or just used a real drilling machine.

  • Andi

    Wouldn’t a real drilling machine have to contend with a pipe long enough to go down as far as they were planning (I think they were trying for 16 feet or so). Don’t think that would be practical.

  • Edward

    pzatchok,
    You have me a bit confused. First you said that it is not pile driving, then you described it as a pile driver. It did a decent job of pile driving for the first few inches, then something went awry.

    This is a classic example of exploring the unknown. Tests on Earth gave good results, using a Martian-like soil, but the actual soil at this location had unexpected properties, as was described in an earlier news report:
    https://behindtheblack.com/behind-the-black/points-of-information/insights-mole-has-popped-out-of-its-hole/

    They could have done it several other ways, many of which would add weight to the lander. 20-20 hindsight is easy, but 20-20 foresight is difficult when exploring the unknown. As an analogy for some of us, the unknown looks black (e.g. when graduation from school approached, the future looked black until I secured a job), and one has to make some assumptions and take some risks when exploring behind that black.

  • pzatchok

    Its a 2 foot long linear vibrator hanging by its power cord.

    Do you really think that would drill its own hole into the ground?

    And so far I do not remember reading about successful tests on Earth.
    They might not have tested it fully and might not have used a correct Mars soil composition.
    As the many pictures posted here show it looks like the subsoil all over the planet it more of less compacted into something denser than a pile of play sand.
    As it goes deeper the sand is more compacted and harder to vibrate through.

    Millions of years for the sand to settle and get harder with no chance of anything geological or biological to loosen it up. Nothing but the wind to push the top few inches around.

  • pzatchok

    Has anyone tested a “Rod From God” impact vehicle of any kind on any body yet?

    Could one be used to insert sensors into the surface of a planet? A drogue chute could be used to slow it down enough to save the sensors if need be.

  • Richard M

    Wayne,

    And I’m sure it worked great when they tested it on the back-lot, but they didn’t even bother to formulate Plan B, or Plan C.

    Well, Insight is only a Discovery class planetary science mission – it was cost capped at $425 million. This is a pretty small mission and a small vehicle. With four main instruments already on board, there may simply not have been the budget (by dollars or mass) for a Plan B or a Plan C.

    Otherwise, Edward’s comment above makes the difficulty plain. May just have been bad luck in the soil properties where the probe landed. While I won’t say JPL is perfect, their record on missions like this is awfully good and typically quite thoughtful, so I’m reluctant to question the design without a lot more insight into the planning process in designing Insight. These days, JPL rarely swings and misses.

    Anyway: Even if the mole is a total bust, I have to say that the data we’ve been getting back from the Seismic Experiment for Interior Structure (SEIS), RISE and TWINS instruments has already more than justified the cost of the mission.

  • Richard M: JPL had very little to do with the design of the mole. It was designed and built by the Germans.

  • Edward

    pzatchok,
    You asked: “Do you really think that would drill its own hole into the ground?

    It went a few inches into the ground, so … yes.

    might not have used a correct Mars soil composition.

    As I recall, I am the one who told you that: “this location had unexpected properties, as was described in an earlier news report

    Has anyone tested a ‘Rod From God’ impact vehicle of any kind on any body yet?

    Yes. It is called a bunker buster.

  • pzatchok

    When did bunker busters and MOAB’s start to be launched from orbit?

    Are you actually under the assumption that they designed this vibrator fully expecting to find someplace, by purely random chance, that would have 16 feet of loose fluffy sand?

    I guess I will put those engineers into the same group that thought the Apollo Moon lander would sink and disappear into the surface rigolith on the moon.

    I have yet to see any evidence that this device was even tested to a full 16 foot depth.
    This would not be the first time paperwork was ‘massaged’ to look good so the payment would come in.

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