INSIGHT’S MOLE MAY NOT DELIVER ON HEAT FLOW, BUT REVEAL MYSTERIES OF MARTIAN SOIL INSTEAD
One of the instruments on NASA’s Insight Mars lander, called a mole, is behaving unexpectedly. Scientists are still trying to understand why, but even if it ultimately cannot deliver on providing measurements of the planet’s heat flow, all is not lost. In an interview, Principal Investigator Bruce Banerdt pointed out that new data about the properties of Martian soil could be an unexpected bonus that will inform future exploration by robots and humans.
NASA’s Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) spacecraft landed on Mars almost exactly a year ago. It carries two scientific instruments, one built by the French space agency CNES and the other by Germany’s space agency DLR, plus radio equipment that also is being used for science investigations.
DLR’s Heat Flow and Physical Properties Package, or HP3, is designed to take Mars’s temperature to determine how much heat is flowing out of the planet’s interior. That will tell scientists whether Earth and Mars formed from the same “stuff” and how active Mars is today.
To collect the data, a probe affectionately called the “mole” needs to be inserted deep into the soil — as much as 5 meters (16 feet). It uses a self-hammering device that relies on friction with the Martian soil to burrow downwards instead of bouncing in place due to recoil from the hammer.
When mission controllers first tried it, however, the mole only descended about 35 centimeters (14 inches). Theorizing that the soil was not providing enough friction, they used a scoop at the end of Insight’s robotic arm to pin the mole against the side of its hole and get that necessary friction. In this NASA video, the black scoop is in the center, with the cylindrical mole and its trailing tether of wires to the left.
Instead, the opposite occurred. The mole started backing out of the hole.
No one know why. DLR and NASA scientists and engineers are assessing the situation before deciding on what to try next. They do not want to make anything worse.
Determining Mars’s heat flow is very important scientifically, but typically would be obtained using a drill, which is quite expensive. Insight is a cost-capped Discovery-class mission and this probe method was chosen because it was affordable even though it meant a higher risk of failure.
In an interview on Friday, JPL’s Banerdt told SpacePolicyOnline.com that when he proposed the project to NASA as part of the Discovery selection process, he listed 10 Level 1 science requirements it would achieve. Because of the cost cap and the possibility that some experiments might have to be descoped or even eliminated to stay under it, those were separated into six “threshold” requirements that must be met to claim overall mission success and four “baseline” requirements that were highly desired but not as critical.
The HP3 data is one of the baseline, not threshold, Level 1 requirements. The threshold requirements will be met by the Seismic Experiment for Interior Structure (SEIS) that is listening for Marsquakes or the radio science Rotation and Interior Structure Experiment (RISE).
Banerdt said the design of the HP3 mole was based on scientific understanding of the Martian soil from previous NASA landers and rovers dating back to the 1970s. The soil at the sites explored by Viking, Spirit, Opportunity and Curiosity had differences, but were sufficiently consistent to inform the design of HP3.
Or so they thought.
What is causing the mole to behave so unexpectedly remains to be determined, but Banerdt sounded intrigued. Scientists discovered a thin layer of duricrust, a type of cemented soil, in the area explored by Spirit (which is part of the reason it got stuck), but the duricrust is much thicker at Insight’s location. That may suggest a different formation process on that part of Mars.
“We’re getting some really fascinating data” about the mechanical properties of the soil and near subsurface that are likely to yield many scientific papers, he enthused.
As NASA develops its plans to send humans to Mars as early as the 2030s, understanding soil characteristics will be critical for everything from habitation to resource extraction and utilization. “We have limited experience with digging on Mars,” so whatever happens with HP3’s efforts to measure heat flow, we “definitely will get some good science.”
As for measuring the temperature of Mars, if the problem cannot be resolved, it may require the more expensive drilling approach. That would have to be prioritized against other Mars science questions in the next planetary science Decadal Survey.
But it also would inform what needs to be done to establish self-sufficient habitation on Mars. Heat flow is a “key measurement for understanding the equivalent of geothermal power” or the depth of possible aquifers where temperatures are conducive to liquid water. “Doing it on a Discovery budget” was a known risk, Banerdt emphasized, but HP3 will result in important scientific knowledge even if that goal is not achieved.
Happy Mars-iversary, InSight! NASA Lander Marks 1 Year on Red Planet
InSight touched down near the Martian equator on Nov. 26, 2018.
How time does fly: NASA's InSight Mars lander has now been on the Red Planet for a full (Earth) year.
InSight aced its "6 minutes of terror" entry, descent and landing on Nov. 26, 2018, setting off some wild and delightfully nerdy celebrations at NASA's Jet Propulsion Laboratory in Pasadena, California, which runs the mission.
The past year has been a very eventful one for the stationary InSight, which is probing the Martian interior like never before. The lander's supersensitive seismometer suite has detected more than 150 vibration events to date, about two dozen of which are confirmed marsquakes. But InSight's other primary science instrument, a burrowing heat probe called the Heat Flow and Physical Properties Package (HP3), has had tougher sledding.
HP3's self-hammering tool, dubbed "the mole," has been able to dig the instrument just a foot (0.3 meters) or so underground to date, instead of the desired 10 to 16 feet (3 to 5 m). The mole has also popped out of its burrow unexpectedly. InSight team members are troubleshooting these issues, which may be caused by the weirdness of Mars' soil, and they've made some progress recently.
The solar-powered InSight is scheduled to operate for at least two Earth years on the Martian surface. The data gathered by the mission, whose name is short for "Interior Exploration using Seismic Investigations, Geodesy and Heat Transport," should help scientists better understand how rocky planets form and evolve, NASA officials have said.
Yesterday wasn't the only anniversary for a NASA Mars robot. The agency's Curiosity rover launched from Florida on Nov. 26, 2011, kicking off an eight-month cruise to the Red Planet. The nuclear-powered Curiosity has determined that its landing site, the floor of the 96-mile-wide (154 kilometers) Gale Crater, could have supported Earth-like life in the ancient past. And the car-size rover is still going strong today, climbing up the slopes of the 3.4-mile-high (5.5 km) mountain that rises from Gale's center.
Mars InSight's 'Mole' Team Peers Into the Pit
UPDATED at 12 p.m. EST (9 a.m. PST) on Nov. 6, 2019
The InSight team continues to assess the heat probe this week. Having determined the lander's robotic arm wasn't holding the mole in place, they retracted the arm and took new images to see how the pit that formed around the mole has changed. What the team sees will help determine next steps. The intention is to press the robotic arm's scoop against the mole again — a technique referred to as "pinning" — but further lab testing on Earth will be needed before any steps are taken on Mars.
For common questions and answers about the mole, visit this page.
UPDATED 4:22 pm EDT (1:22 pm PDT), Oct. 27, 2019
Mars InSight's Mole Has Partially Backed Out of Its Hole
After making progress over the past several weeks digging into the surface of Mars, InSight's mole has backed about halfway out of its hole this past weekend. Preliminary assessments point to unusual soil conditions on the Red Planet. The international mission team is developing the next steps to get it buried again.
A scoop on the end of the arm has been used in recent weeks to "pin" the mole against the wall of its hole, providing friction it needs to dig. The next step is determining how safe it is to move InSight's robotic arm away from the mole to better assess the situation. The team continues to look at the data and will formulate a plan in the next few days.
Meantime, the lander's seismometer — the Seismic Experiment for Interior Structure, or, SEIS — continues to collect data on marsquakes in order to provide a better understanding of the Mars interior and why Earth and the Red Planet are so different today after sharing similarities billions of years ago. The French space agency, Centre National d’Études Spatiales (CNES) and its partners provided the SEIS instrument to NASA.
Original story posted October 17, 2019
Mars InSight's 'Mole' Is Moving Again
NASA's InSight spacecraft has used its robotic arm to help its heat probe, known as "the mole," dig nearly 2 centimeters (3/4 of an inch) over the past week. While modest, the movement is significant: Designed to dig as much as 16 feet (5 meters) underground to gauge the heat escaping from the planet's interior, the mole has only managed to partially bury itself since it started hammering in February 2019.
The recent movement is the result of a new strategy, arrived at after extensive testing on Earth, which found that unexpectedly strong soil is holding up the mole's progress. The mole needs friction from surrounding soil in order to move: Without it, recoil from its self-hammering action will cause it to simply bounce in place. Pressing the scoop on InSight's robotic arm against the mole, a new technique called "pinning," appears to provide the probe with the friction it needs to continue digging.
Since Oct. 8, 2019, the mole has hammered 220 times over three separate occasions. Images sent down from the spacecraft's cameras have shown the mole gradually progressing into the ground. It will take more time — and hammering — for the team to see how far the mole can go.
The mole is part of an instrument called the Heat Flow and Physical Properties Package, or HP3, which was provided by the German Aerospace Center (DLR).
"Seeing the mole's progress seems to indicate that there's no rock blocking our path," said HP3 Principal Investigator Tilman Spohn of DLR. "That's great news! We're rooting for our mole to keep going."
NASA's Jet Propulsion Laboratory in Pasadena, California, leads the InSight mission. JPL has tested the robotic arm's movement using full-scale replicas of InSight and the mole. Engineers continue to test what would happen if the mole were to sink beneath the reach of the robotic arm. If it stops making progress, they might scrape soil on top of the mole, adding mass to resist the mole's recoil.
If no other options exist, they would consider pressing the scoop down directly on the top of the mole while trying to avoid the sensitive tether there; the tether provides power to and relays data from the instrument.
"The mole still has a way to go, but we're all thrilled to see it digging again," said Troy Hudson of JPL, an engineer and scientist who has led the mole recovery effort. "When we first encountered this problem, it was crushing. But I thought, 'Maybe there's a chance; let's keep pressing on.' And right now, I'm feeling giddy."
JPL manages InSight for NASA's Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by the agency's Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the InSight spacecraft, including its cruise stage and lander, and supports spacecraft operations for the mission.
A number of European partners, including France's Centre National d'Études Spatiales (CNES) and the German Aerospace Center (DLR), are supporting the InSight mission. CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument to NASA, with the principal investigator at IPGP (Institut de Physique du Globe de Paris). Significant contributions for SEIS came from IPGP; the Max Planck Institute for Solar System Research (MPS) in Germany; the Swiss Federal Institute of Technology (ETH Zurich) in Switzerland; Imperial College London and Oxford University in the United Kingdom; and JPL. DLR provided the Heat Flow and Physical Properties Package (HP3) instrument, with significant contributions from the Space Research Center (CBK) of the Polish Academy of Sciences and Astronika in Poland. Spain's Centro de Astrobiología (CAB) supplied the temperature and wind sensors.
NASA's Mars Lander 'Mole' Is Digging Again as Marsquake Mystery Baffles Scientists
The troubled "mole" on NASA's InSight Mars lander is moving again, even as scientists working on the robot's seismometer ponder new marsquake mysteries.
InSight touched down in November 2018 on a quest to understand the interior of the Red Planet. Two of its crucial tools for that task were a burrowing heat probe nicknamed the mole and a super-sensitive seismometer to study motion within the planet.
But soon after spacecraft personnel told the mole to get digging, something went wrong, and scientists and engineers affiliated with the mission have been strategizing ways to get the instrument moving ever since.
The team photographed the situation from every angle possible, pondered the likelihood of hidden rocks, evaluated soil characteristics and mimicked the situation with a replica instrument here on Earth. At one point in October, the mole popped out of Mars, as if it had simply had enough of the whole situation.
Most recently, the InSight team tried maneuvering the lander's arm to gently press sideways on the mole. On Nov. 21, NASA announced that the technique had successfully let the probe dig itself down about 1.25 inches (32 millimeters). And on Dec. 16, the agency said that the mole was continuing to burrow properly.
The update did not include details on how far the probe has moved, but a gif accompanying the tweet suggests that the probe, which measures 15.7 inches (400 mm) in length, dug about 2.5 inches (65 mm) between and Dec. 7 and Dec. 14. "More digging to come," the update concluded.
A Martian seismic mystery
Meanwhile, the team working on InSight's seismometer is also keeping busy. On Dec. 16, the group posted that "significant" marsquakes detected on May 22 and July 25 originated in a tectonic structure called Cerberus Fossae, making the area "the first active seismic zone ever discovered on Mars," according to a statementposted to the instrument's Twitter feed.
However, the scientists working with the instruments are waiting to share more information about the discovery until research papers on the topic are published.
The same instrument team announced today (Dec. 18) in a similarly brief updatethat the seismometer seems to have detected a new phenomenon as well.
"The @NASAInSight seismometer has discovered a strange, continuous signal at 2.4 Hz, apparently not related to the lander or weather activity, but excited by a lot of #MarsQuake," the statement read. "This puzzling resonance acts as a natural seismic amplifier!" What that means for the planet remains unclear.
"Mars is full of mysteries," the team wrote.