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from the diggy-diggy-hole,-diggy-diggy-hole dept.
NASA engineers are preparing another tactic to get the troubled "mole" instrument on the Mars InSight lander burrowing into the regolith as intended.
Engineers plan to use the robotic arm on its InSight Mars lander to push a heat flow probe into the surface, acknowledging that they have "few alternatives" if that effort fails.
The Heat Flow and Physical Properties Package instrument team has spent nearly a year trying to get the instrument's probe, or "mole," to burrow into the surface. The mole has an internal hammering mechanism that is designed to drive the probe as deep as five meters into the surface in order to measure the heat flow from the planet's interior.
The mole, though, stopped only about 30 centimeters below the surface. The mission has tried a number of ways to get the mole moving again, including removing the instrument housing on the surface to allow the lander's robotic arm to try and fill in the hole created by the mole, as well as pin the mole to one side of that hole, increasing the friction needed for the mole to work its way into the surface.
In October, that use of the arm to pin the mole worked briefly, allowing the mole to burrow into the surface, only for it to rebound partially out of the hole. A second attempt led to the mole again rebounding partially out of the hole in January.
The mole is a 16-inch-long (40-centimeter) spike equipped with an internal hammering mechanism that relies on friction from the soil to help it dig down. The probe is designed to drag a ribbon-cable like tether behind it as it digs.
While pushing down on the top (back cap) of the probe seems an obvious approach, according to NASA "The team has avoided pushing on the back cap until now to avoid any potential damage to the tether."
Previous Coverage
More Mars Mole Mission Misfortune
Mars Mole Mission Rues Resistanceless Regolith
NASA to Jack up Insight Lander to Assess Non-Penetrating Probe
InSight Impinges Insufficiently in Site
Also at NASA-JPL
(Score: 0) by Anonymous Coward on Monday February 24 2020, @03:02AM (2 children)
This is not how it is done. When you are here on Earth and you pay money to have somebody make a hole, they NEVER do this. There could be a reason!
The main option for small things, like water wells 50 feet down, is like a pile driver. The pounding comes from above, not from within.
The main option for deep holes, like oil well that go down 2 miles, is the mud motor. This is probably severe overkill. Fluid would need to be acquired on Mars, which isn't easy, but liquid CO2 might work. Brine also might work, but that is harder to get. Either way, you'd need a lot of power and you'd waste a lot of power.
A gas-driven version of the mud motor might also work.
(Score: 0) by Anonymous Coward on Monday February 24 2020, @03:14AM
You gotta keep in mind your on Mars, not on Earth. The *entire* mass of the lander was about 350kg - structure, power, motors, everything. And you're running on solar power with a yield of about 4.5kwh under ideal circumstances. And, of course, vibrations are a really good way to break things in unpredictable ways. And you also have no real idea about what you're drilling into. I'd imagine these are all contributing reasons to why they went for the internal hammering system. Deploy and go. Or not. But, such is the nature of lander missions. You can only accomplish so much without having a human on site to keep things moving or to setup a more sophisticated design from the start.
(Score: 2) by barbara hudson on Monday February 24 2020, @03:17AM
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