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Emily Lakdawalla • Mar 01, 2019

InSight Update, Sol 92: The Mole Did Hit a Rock

Mars could've given us a break, but it didn't. The HP3 mole started hammering itself today, and almost immediately (after just 5 minutes) appears to have encountered a rock. After four hours of hammering, it may have pushed the rock aside, but doesn't appear to have buried itself completely beneath the soil yet, because it's still measuring temperatures consistent with the Martian air temperature. No matter; they'll try again Saturday. Patience is the theme of the InSight mission.

Result's of InSight's first hammering attempt, sol 92
Result's of InSight's first hammering attempt, sol 92 InSight's mole hammered away for four hours on sol 92 (1 March 2019), but didn't penetrate very far because it encountered a rock, a complication that wasn't unexpected. The effort shifted the position of the instrument housing by 2 centimeters. More hammering is planned, and the probe should be able to continue burying itself.Image: NASA / JPL-Caltech

Here is the full text of the update, which was posted to the DLR HP3 team blog today.

The mole has hammered for its maximum 4 hours yesterday and has reached a depth of at least 18 cm and not more than 50 cm, but not the planned 70 cm. The data indicate that the mole has reached that depth within about 5 minutes but then soon encountered an obstacle (the exact depth of which is not known).

It worked against this obstacle for the remainder of the time and may have pushed it aside after 3.5 hours as indicated by a slight rotation of the mole. The thermal sensors on the mole and on the science tether indicate that the burial was not more than 50 cm (because the bottommost temperature sensor measured a temperature as expected for the air temperature).

Moreover the temperature sensors on the mole cooled at a rate that suggest that it is at least not completely in the soil. The incident with the obstacle caused the mole to incline by about 15° (to be confirmed) with respect to vertical which caused the support structure on the surface to shift by about 2 cm:

The team is busy planning another round of hammering - again a time by up to 4 hours - to be uploaded today and starting on Saturday. The results are expected to be down Sunday.

DLR just issued a press release which mentioned that it took 4,000 hammer blows over those 4 hours.

For more on how the HP3 probe's penetration is supposed to work -- and why subsurface rocks are hopefully just a delay, not a serious problem -- read my previous article.

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