It’s been a long way to Insight Mall. Insight landed on Mars almost two years ago, in November 2018. While the lender’s other devices are working fine and returning scientific data, the mall is struggling to gain access to the planet’s surface.
After much hard work and a lot of patience, Maul finally managed to bury himself in Marion Regolith all the way.
But the play is not over yet.
The mole is a 16-inch long heat probe that encloses itself deep inside the surface. Its maximum depth is 5 meters (16 feet) below the surface, and that is its ideal operating operating depth. But it can also collect useful scientific data at a depth of about 3 meters (10 feet). As it is now, the mole is nowhere deep enough to do any science.
But two years later, it’s still the nod.
The mole’s real name is Heat Flow and Physical Properties Package or HP3. It is designed to measure the heat coming from the interior of Mars. Teether has a heat sensor along its length connecting it to the Insight Lander. Insight means internal research using seismic investigations, geodesy and heat transport. The heat transport part of the mission is the work of the mole.
Since deploying the tool, it has faced problems. The mole slowly penetrates the ground. But that hammering speed depends on the friction between the mole and the sides of its hole. Without that friction, the tool simply bounces out of the hole.
The problem is called duricrust. It is a hard surface layer that forms in dry areas. And Mars is definitely dry. The duricrust around the mole prevents the ground from falling into the mole, as it is a hammer, and deprives the instrument of the necessary friction to get to Mars.
While Insight is primarily a NASA mission, the mall was designed and built by DLR (German Aerospace Center). They are working with NASA’s JPL, which has an engineering version of the mall in bed in testing. It is there that they have tried to overcome these challenges.
They tried to use a scoop at the end of Insight’s tool arm to apply side pressure to the mole, hoping to provide the necessary friction. They, too, have tried to push the mall, while carefully avoiding sensitive teethers. And they have tried to scoop up the loose material and deposit it in the hole of the mall.
Today NASA announced that the mall was finally completely buried in the dirt. It’s a kind of victory, but there’s still a long way to go. Now that it is buried, the Insight team will turn more clay on the top of the instrument and start cutting it before starting the hammer operation.
But all this has taken time.
Troy Hudson, a scientist and engineer at NASA’s Jet Propulsion Laboratory, said: “But we’re not quite done. We want to make sure there’s enough soil on top of the mole to be able to dig it out on its own without any help,” Hudson said in a press release.
It will take months to scoop up the clay and apply it. NASA says hammering operations are not likely to resume until January 2021. Part of the obstacle to operation is the accumulation of dust on Insight’s solar panels. This will reduce the power available for the entire mission.
Tilman Spohan is the Scientific Director for Mall in DLR. He is writing a blog about trying to get the mole working. In today’s October 16, 2020 entry, Spoh talks about the next steps and how they are working towards another “free mall test”. Free mole testing is when they allow the mole to hammer its surface into the surface without the help of the mole.
“After a bit of discussion about the next steps, we decided that two parallel scoop activities should be carried out on Saturday, October 17 (Sol 659).”
“Then, thermal conductivity will be measured, which will give us indirect signals about backfilling.” “After that, to compress the sand and press it on the mole, the filling will be pressed. Depending on the result of the backfilling, further filling of the pit will be done before hammering and the second free mall test will be conducted later. “
On Earth, it would be easier to use the drill to go below the surface. But drills are heavy, require a lot of power, and require stability to prevent spinning instead of drilling. That is not possible on Mars. A drill weighs a lot more and will require more power than a mole. The mole is only 1 inch (2.7 cm) in diameter and about 16 inches (40 cm) long. It should be both enough and less to fit the limits of the mission.
Hopefully, the mole will eventually reach its working depth. In the meantime, Insight’s other devices are working and returning data. Thanks to Sais (seismic experiment for internal formation) we know that Mars is an earthquake active planet.
But without a reading of the mole and its heat transport, the Insight Lander will never be able to live up to its goal.