NASA gives up taking the temperature of Mars

Today, NASA announced that it was abandoning its attempts to place a temperature sensor several meters below the Martian surface. As part of the agency’s InSight lander, the equipment had to be placed deep enough to avoid the influence of the weather, seasons, and daily temperature changes of Mars. But due to the unusual conditions at the landing site, the material never made it below the surface.

The InSight lander carried several instruments intended to provide a clearer picture of Martian geology. One of these instruments, the SEIS seismometer, successfully tracked the marsquakes to provide a better perspective on the structure of Mars and the local composition below the surface near the landing site. A second measures the oscillation of the axis of rotation of Mars, which will be influenced by a combination of the composition of the red planet and gravitational influences from the rest of the solar system.

The other major InSight experience is the Heat Flow and Physical Properties, or HP package.³. While previous landers did not put material deeper than about eight inches, HP³ was designed to operate several meters below the Martian surface. From there, the fluctuations at the surface would be somewhat averaged, and HP³ could measure the heat flow from the Martian interior to the surface. This would allow an estimate of the energy still left in the Martian core from a combination of its formation and its radioactivity, a key element in understanding what geological activity might still be possible there.

A 3-meter drill, however, would not fit perfectly on a lander. So HP³ was to be delivered to its operating depth by a device called “the mole”. The mole was designed to drag material below the surface by taking advantage of the friction between it and Martian soil; it would anchor itself, drive part of itself deeper using that anchor, then step forward slightly and repeat the process.

As it turned out, there was a problem with this shot: the ground didn’t allow enough friction to make it all work. Now, after nearly a year of testing and a wide variety of troubleshooting techniques, mission leaders accept that the plan just won’t work. This follows the latest attempt, which involved using a robotic shovel on InSight to pile dirt on top of the mole and attempt to squeeze it to provide more leverage.

Obviously, things didn’t work out because the soil properties at InSight’s landing site were different from expectations derived elsewhere on Mars. So in that sense, we learned something from the experience. And the rest of InSight’s instruments continue to perform as expected. But we’ll have to wait for another lander to take the temperature of Mars.