JPL Drops Energy Measuring Device on Mars

Published : Friday, March 1, 2019 | 5:50 AM

HP3 on the Martian Surface: NASA's InSight lander set its heat probe, called the Heat and Physical Properties Package (HP3), on the Martian surface on Feb. 12. Image Credit: NASA/JPL-Caltech/DLR

Pasadena-based Jet Propulsion Laboratory has placed a device on the surface of Mars that can assist scientists in divining how much energy is needed to build a rocky planet.

National Aeronautics and Space Administration’s InSight Lander is managed by JPL, specifically for the Science Mission Directorate.

It is second such instrument to access the Martian surface – a device that measures heat moving through Mars’ subsurface.

JPL said the Lander’s heat flow and physical properties package, or HP3, was successfully deployed in February about three feet from InSight’s seismometer, which the lander recently covered with a protective shield.

New images beamed down to Mission Control confirmed HP3’s deployment.

“Our probe is designed to measure heat coming from the inside of Mars,” said JPL’s Sue Smrekar, InSight Deputy Principal Investigator. “That’s why we want to get it below ground. Temperature changes on the surface, both from the seasons and the day-night cycle, could add ‘noise’ to our data.”

Equipped with a self-hammering spike, called mole, HP3 will burrow up to 16 feet below the surface, deeper than any previous mission to the Red Planet.

NASA’s Viking 1 lander, which arrived on Mars in July 1976, scooped 8-plus inches into the planet’s subsurface. The agency’s Phoenix Lander, which touched down on Mars in May 2008, scooped seven inches down.

HP3 looks like an automobile jack but with a vertical metal tube up front to hold the 16-inch-long mole.

A tether connects HP3′s support structure to the lander, while a second, attached to the top of the mole, features heat sensors for gauging the Martian subsurface. Meanwhile, heat sensors in the mole itself will measure the soil’s thermal conductivity, or how easily heat moves through the subsurface.

The mole will stop every 19 inches, wait a good two days, and then take a thermal conductivity measurement of the soil. The two-day wait allows the mole to cool. It will then be heated up by about 50 degrees Fahrenheit over 24 hours. Temperature sensors within the mole measure how rapidly this happens, which tells scientists the conductivity of the soil.

Between the careful burrowing action, the pauses and the time required for the science team to send commands to the instrument, more than a month will go by before the mole reaches its maximum depth. If the mole extends as far as it can go, the team will need only a few months of data to figure out Mars’ internal temperature.

“That thing weighs less than a pair of shoes, uses less power than a Wi-Fi router and has to dig at least 10 feet on another planet,” Hudson said. “It took so much work to get a version that could make tens of thousands of hammer strokes without tearing itself apart; some early versions failed before making it to 16 feet, but the version we sent to Mars has proven its robustness time and again.”

For more information about InSight, visit

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