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InSight scientists give up on heat sensor mole

After another failed attempt earlier this month to dig with the German-made mole on the InSight Mars lander, the science team has decided to abandon all further efforts.

After getting the top of the mole about 2 or 3 centimetres under the surface, the team tried one last time to use a scoop on InSight’s robotic arm to scrape soil onto the probe and tamp it down to provide added friction. After the probe conducted 500 additional hammer strokes on 9 January, with no progress, the team called an end to their efforts.

This means the heat sensor, one of the two instruments carried by InSight, is also a failure, and will not be able to provide any data about the planet’s interior temperature.

From the beginning InSight appears to have been a poorly run and badly chosen project. Other than a weather station, it carried only two instruments, a seismometer and a heat sensor. Its launch was delayed two years when the French attempt to build the seismometer failed and JPL had to take over, fortunately with success. Now the failure of the German-made mole has made the heat sensor a failure.

To send a lander to Mars at a cost of a billion dollars with so little payoff seems in hindsight to have been bad use of money. Plenty of other NASA planetary missions have done far better for far less.

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  • Col Beausabre

    “At least I learned what not to do, and that is always a valuable lesson”. – The Duke of Wellington on his first wartime campaign in Flanders as Colonel of the 33rd Foot.

    So, with the limited results from Insight, what have we learned not to do in the future…..I’ll kick things off by stating, don’t assume alien environments are like Earth (basic failure of the heat probe – that Martian soil would be like Earth’s). Assume it will be, well, alien, Question , and if possible, test your assumptions

  • pzatchok

    Don’t trust someone that doesn’t make hammers to make you a specialty one for extreme environments.

    Find a pro. or at least someone with experience.

  • Ray Van Dune

    When I first heard that Insight was going to bore into Mars with a hammer, my reaction was to wonder if there is no German for “drill”… but there is, “substantivbohrer”. But they built a fizzlebohrer!

  • Ken Lundermann

    I’d say InSight has failed ultimately for much the same reason the Viking landers’ three life-detection experiments failed: unwarranted assumptions about the nature of the martian soil. In InSight’s case the assumptions pertain to the soil’s physical properties; in the Vikings’, to its chemical properties.

  • LocalFluff

    They should simply put a shaped charge explosive on one of the rovers to drop off on the surface. And then drive back to the fresh crater and learn something about what’s under the uppermost inch.

  • Localfluff: Sure that would work if one simply wanted to learn something about the makeup of the material below ground. It isn’t really necessary, as the rovers Curiosity and Perseverance have drills to accomplish the same thing.

    What InSight was supposed to do was insert a temperature sensor underground. Blowing up the ground wouldn’t work. However, a simple drill would have. Why they went with this cockamamie mole baffles me, especially as Curiosity had already proven that a drill would work.

  • Col Beausabre

    Local Fluff & Bob – From my knowledge using explosives in the military, shaped charges (HEAT rounds) bore holes in earth and rock while if you want a crater, you use a cratering charge (ammonium nitrate pushes stuff, while high explosives like TNT shatter it)

    This video shows new lieutenants at the Engineer School first blowing a shaped charge to dig the pilot hole for the main charge and then blowing the cratering charge. You use a crater like that to stop movement on something not easily by-passed like the approach to a bridge.

  • I still don’t think this works for inserting a temperature gauge. That sensor must be in touch with the ground at all points, and have no contact with the surface in order to get a reliable and trustworthy reading of the internal ground temperature.

    Think of inserting the temperature sensor into a roast. You want tje point of the sensor as close to the center of the roast as possible to get an accurate reading. And you don’t want it exposed to the outside at all.

    It is possible that weight considerations (and cost) made a drill on InSight impossible. If so the German approach might have been the best alternative they could think of at the time. It didn’t work.

  • Max

    Every job, depending on the substance, requires a different tool for optimum results.
    An assumption was made about mars surface, the compaction of soil in low gravity.
    The drill worked, but not well for rocky ground. It would take heavy equipment, or explosive.
    A drill in compacted soil, ice, lome, volcanic ash would’ve been perfect.
    A drill in sand/dirt will fill back in as fast as the drill can remove it. In this situation, which I believe the hammer was made for, would have worked if the soil (if I can call it that) is loose and soft like powder or sand.
    In this situation in which the ground they selected to sample, the device was under powered for the task resulting in minimal penetration due to action reaction mass (available force) in low gravity. The rock that deflected the bit was unfortunate but should’ve been expected for the soil that they “chose to penetrate”. This is a case of scientist overriding engineers using the improper tool for the job.
    Sure, they were worried about getting the unit stuck in the sand if they chose a better location in which the hammer was designed for. The digger arm would have been helpful for extraction in that case. They should’ve taken the chance so the experiment would succeed.

    I would suggest next time that they walk the rover to the edge of a skylight/collapsed tunnel/void, drop the temperature probe and wire as deeply into the shaft as possible with the other end of the wire connected to a detachable weather station, seismograph with solar panel so the rover can continue to explore.
    This would actually result in useful information about the vent as well as seasonal temperatures and the difference between underground and surface. Especially if the vet is active. That would be exciting.

  • Marcus

    They definitely didn’t assume the soil was the same as here on earth. When you try something new, sometimes you fail – it doesn’t mean you did anything wrong. I’m certainly glad they didn’t send a precursor mission for an extra billion to dig into the soil and study first. I’ve seen no evidence that a drill or explosives would have worked better – the rover drills were designed to drill a centimeter or two into rock, not several meters through loose soil. Also i dont know anyway to directly simulate martian gravity on soil, except maybe centrifuge on space station (or for very short periods in vomit comet or suborbital rockets). Seems like a difficult problem and they just got it wrong. Hopefully they do publish interesting results about the soil.

    Inpersonally wish they wouldn’t give up, but I guess they’ve pushed it as far as they think they can

  • mrsizer

    Max, I have no idea if the probe is detachable, but you raise a good planning point: Have a backup plan for all the equipment so if it fails in its primary mission, it can still be used for _something_. Making the probe detachable would (probably) have not added much cost or weight, compared to what was already spent getting it there.

    The entire experiment seems a bit useless. I just looked up Earth’s geothermal gradient: “It is about 25-30 °C/km of depth near the surface in most of the world” (Wikipedia). So, about 1 degree per 40 meters. How sensitive is this probe and how deep did they intend to sink it? 40 meters seems awfully deep and less than 1 degree seems awfully small to show anything useful.

  • Marcus

    Seems like a great student science fair project to build a similar mole and test in different soils here on earth.

    Not sure why I like the mole so much – maybe because when I first read about it it seemed like no way it would work… sad my first impression was correct

  • Lee Stevenson

    It’s sad that the mad little probe didn’t achieve its objective, and hindsight is always 20-20, but don’t blame the Germans Bob… Focusing ( IE pointing out it’s German built twice in a short post ), NASA approved it, launched it, and it’s hardly the first failed experiment on Mars. I personally agree that anything planned to land on Mars should have a better science payload given the launch costs… Bang a “decent” camera on the thing… A microphone, there are many cheap and easy additional instruments that could and should be incorporated in far reaching missions. Regardless, I feel a very “anti European” tone to this post. The French messed up, their mission was refused, the German mission has failed, but NASA has failed itself on Mars missions…. Don’t pour all the blame on any one agency. And by failing in its mission, the mole has given valuable information regarding the Martian regolith.

  • LocalFluff

    I mean that after multiple landers and rovers, they should’ve done more to examine at least the physical properties of the Martian “soil” (compacted dust) below the surface. The very short drill of Curiosity has only drilled in bedrock AFAIK. ESA’s ExoMars rover, delayed until the next conjunction because of problems with parachute tests, intends to drill up core samples from 2 meters deep. It will use a proper drill that surely won’t get stuck like this, but I think they would like to know more about the properties of the non-bedrock ground of Mars.

  • Lee Stevenson

    @Local, I remember watching a program MANY years ago when Steve Squires ( at the time head scientist for Spirit and Opportunity ) visited ESA to check out the European rovers progress.. When asked if he had any words of wisdom to impart, ( and this was VERY early in the rovers development ), he couldn’t stress enough the importance of having all 3 sets of wheels steerable, indeed he said that without that capability both the NASA rovers would have gotten in trouble. ExoMars has only 2 out of its 3 sets of wheels steerable! I believe this mission is very much a case of “hope for the best, but prepare for the worst” ( and should the mission be a failure, then our host has every right to blame Europe! The thing has been designed and built by committee… Never a great idea!)
    On a more cheerful note, should traveling ever be a good idea again, and should I head down your end of the country, or you head up to the bright Stockholm lights, we should meet up and discuss space stuff, and perhaps even politics over a Norrands Guld or 2… A “Behind the Black” Swedish meetup!?

  • APL

    It is not a pile driver. Living moles actually dig the dirt away in order to burrow. I just don’t really understand how the self contained hammer was supposed to hammer itself down 3 meters into the soil. Is this not the reverse of “pulling yourself up by your bootstraps”. Can anyone point to a similar tool being used on earth as an example?

  • Mike borden

    Panda probe hammering column

    In the mole the “hammer” is automated and coiled by a spring untill tension pops it back down. Miniscule in comparison. But the same basic principle.

  • john hare

    A radical concept comes to mind. Contract out to people that do whatever for a living. Drilling by well drilling companies that don’t get paid unless they reach water/oil/gas/leprechauns…..That the purchase order calls for. “My drill broke so pay anyway” gets a “get off my site while I find a competent company”.

  • Max

    Pile drivers are quite common. Used in driving supports for buildings and bridges.
    YouTube has many types and examples. (Including highrise buildings in China with inadequate support, toppling over like dominoes.)
    Usually it takes days to reach bedrock, china has been experimenting with pre-made walls/floors to set up a high-rise in less than a week. At the beginning of the video, the pile drivers uses hundreds of tons to push the support into the ground in minutes.

    I believe the failure of the insight probe may have been to “light weight of the platform” as reaction mass. Mars dirt placed on top of the driver unit in a bag or compartment would have given the hammer more mass/down pressure to work against.

    LocalFluff and Col Beausabre maybe on the right track using explosives, but not in the conventional way. Think “nail gun”.
    An explosive charge in a tube, to drive a probe underground. A magazine of charges like a Roman candle would have been perfect.

    A over view of insight hammer problems from an article 2 years ago. (Nice colored picture)

    Detailed pictures of hammer design.

    The expectation of the hammer drill which did not come close to reality.

    “the HP3 is powerful enough to drive through rock,”
    “Here’s how an ideal mole mission will go. “There’s a penetration cycle that takes about four days,” Hudson explains. The hammering will go down 50 centimeters. There will be a time limit on this drilling of four hours, but the NASA team hopes it will take less, possibly even just half an hour.”

    mrsizer said;
    “The entire experiment seems a bit useless. I just looked up Earth’s geothermal gradient: “It is about 25-30 °C/km of depth near the surface in most of the world” (Wikipedia). So, about 1 degree per 40 meters.”

    You are right, the temperature measurement would be in the 1 hundredths of 1°. The soil is lighter than earth’s and the gravity is 1/3 creating less internal temperature. (by theory)
    It would be useful to determine how far seasonal temperatures penetrate from the surface.

    I still believe the most cost effective and usable remote sensing device would be a helium filled steerable balloon (s) with solar panels on top and a weather package with fisheye cameras as visual documentation / range finding.
    The technology exists so small and lite now, that it fits in a wristwatch and uses very little power.
    With only seven milbars of air pressure, (The equivalent of 110,000 feet high on earth) helicopters or flying drones would be energy prohibitive.
    Hydrogen would work better, but would not last very long as hydrogen atoms pass right through materials.

    Resolution mine Az., deepest shaft in the United States nearly 7000 feet. 20 minutes by elevator to reach the bottom. 175°F.
    (The deepest mine in the world in South Africa is 150°F in bottom)

    This internal heat on Earth comes near the surface in California, Utah, Idaho, southern Colorado.
    I firmly believe that Elon Musk tunnel technology and his “Boring machine Co.” could drill down at a 45° angle to where the temperature is hot enough to destroy equipment. (like what you would expect on Venus)
    $1 billion will lay the infrastructure to boil water to drive steam turbine efficiently (with off the shelf parts) for thousands of years creating free energy from continental drift.
    Mine offices in caverns can be expanded for an underground self sustaining community, (where the temperature is 70°) with farming and livestock, could be a prototype for what can be done on Mars. (didn’t people of the future live underground in the old book “Time machine”?)

  • pzatchok

    The mole did not work because it relied not on gravity but on spring tension to fire or drive it into the ground.

    The spring though it imparts speed to the hammer it also counter pushes the mole in the opposite direction at the same time.

    It would have required a larger mass mole vs, hammer/driver to reduce the counter movement but having a large mass to drive requires a large mass to be the hammer.

    They could have used the slide hammer idea but it would have required a far longer shaft to get the lesser gravity to work for you.

    Or an armored ‘rod from God’ idea. A sensor filled penetrater dropped from orbit.

  • Richard M

    “What InSight was supposed to do was insert a temperature sensor underground. Blowing up the ground wouldn’t work. However, a simple drill would have. Why they went with this cockamamie mole baffles me, especially as Curiosity had already proven that a drill would work.”

    A 5 meter deep hole requires a pretty sizable drill, though, and apparently that was seen right out of the gate by mission designers as something which would blow out InSight’s budget, mass, and volume limits. (Recall that as a Discovery program mission, it was originally cost capped at $425 million, which is pretty slim money for a planetary lander. The failure of and need to rectify the SEIS nearly doubled mission cost.)

    Maybe they should have just given up on the whole idea right from the start if that was the case?

    I still think JPL does good work. The real problem may have been the constraints they were forced to design this mission under. And maybe the Discovery selection team ought to have considered that risk more deeply in 2012.

  • Richard M

    Taking a closer look at the Heat Flow and Physical Properties Package (HP3) – the “mole” instrument that failed – I see that its total mass was only….3kg. Wow.

    I’m not a drilling expert by any means. but I do think it would be a tough row to hoe to come up with a conventional drill (that could meet all the necessary specs for interplanetary flight and Martian surface conditions) that could drill down 5 meters for under 3kg.

    If that was the mass budget they had to work with for the entire heat flow experiment, that seems like a tough hill to climb. Granted that the soil was not what was expected, maybe they should not have tried to do it on the cheap, mass or volume wise. It does appear that Bruce Banerdt and his program team settled on the HP3 approach very early, going back to at least 2010 (when it was still called GEMS), from what I can make out.

  • Max

    I picked up my phone to comment on a simple cost effective way to bury the probe(s) from orbit all over the surface of the planet by using length of rod and a sensor package in It’s hollow center. Attached with a properly long flexible solar panel/data antenna about 6 inches wide that unfurls itself like a measuring tape once it’s dropped from orbit. The flexible solar tape will keep the rod in a vertical impact position and drop to the ground after impact. If the speed is too fast they can use a parachute to slow the descent until it reaches the proper safety height.

    But “pzatchok” also thought of the idea.

    ” Or an armored ‘rod from God’ idea. A sensor filled penetrater dropped from orbit.”

    Well done, I wish you were on the project.
    A armored rod from God is reminiscent of the “Chronicles of Riddick”

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