Dr Attree explained: “HP3 will be digging down into the subsurface of Mars and recording temperatures and heat flow from the interior. The magnitude of the heat flow tells us about the Martian deep interior and helps to create formation and evolution models. If historical climate change has led to more or less excess heat stored in the subsurface, it could influence HP3’s results.”
The team considered a specific situation where cycles in Mars’s orbit causes its atmosphere to collapse – or freeze – onto the poles. In these cases, the team found that thermal conductivity of the Martian soil decreases – and, in turn, excess heat could build up.
“We found that small changes caused by climate change are unlikely to be picked up by HP3,” Dr Attree continued. “However, it may be possible to detect very large changes – and this is important because we may be able to carry out similar measurements on other planets.”
Dr Hagermann added: “We have demonstrated that it is not only historical changes in air temperature but also changes in air pressure and thermal conductivity of the soil that could be detectable, which might also be relevant for Earth, where borehole temperature measurements have played an important part in reconstructing past climate.”
Built by the German Aerospace Centre, the self-hammering HP3 probe is designed to burrow between three and five metres (10 to 16 feet) into the Martian soil – 15 times deeper than any previous hardware on Mars – to measure the heat flow from the planet’s interior. By combining the rate of heat flow with other InSight data, the team will be able to calculate how energy within the planet drives changes on the surface, such as planetary evolution and the shaping of mountains and canyons.
The latest paper, Potential effects of atmospheric collapse on Martian heat flow and application to the InSight measurements, is published in Planetary and Space Science.
Read more about the NASA InSight mission.