New mission proposal would send probe into Martian cave systems
MACIE probe would assess Martian caves for habitability
A recently published paper has put forward the case for sending a probe to explore Martian cave systems.
The Mars Astrobiological Cave and Internal habitability Explorer (MACIE) mission concept is designed to send a probe to one of the several caves imaged by orbiters in the last 20 years. These caves, which are all found on the slopes of dormant or extinct Martian volcanoes, are believed to be the result of subsurface lava flows. The lava tubes that remain are accessible through holes in the ceilings caused by structural collapse.
Although recent papers have made the argument that microbial life may continue to exist in briny water at or very near the Martian surface, it is nevertheless clear that the surface environment is inhospitable to life. Rover and landers equipped to drill below the surface are in development; however, as the recent chastening experience of NASA’s InSight lander shows, drilling into the surface is far from easy without human hands to deal with the unexpected. InSight’s drill - which was included as part of the lander’s design to allow the emplacement of a seismometer below the surface - was unable to penetrate the Martian regolith more than half a metre, and all attempts at troubleshooting were abandoned earlier this year.
The MACIE concept is still in an early stage of development, and methods for gaining access to a target cave are still under discussion. In light of the runaway success of the Ingenuity helicopter earlier this spring, an obvious possibility is a rotorcraft optimized for precision flight in and out of a confined space. Such a vehicle would have to be a second-generation version of Ingenuity, one with greater endurance and manoeuvring capability, as well as sufficient lifting power to enable the carrying of a suite of scientific instruments, rather than the simple camera Ingenuity carries.
Other possibilities include a four- or six-legged rover; a series of droppable mini-probes; or a rover with a tether that can negotiate steep slopes. One final option is a rugged rover, for use in environments where access to a cave can be gained over relatively flat terrain. Such an option may seem counterintuitive when confronted with the photographic coverage of Martian caves, all of which features skylights or steep-sided pits as openings. However, the authors point out that the available orbital imagery is taken from steep angles, and so such openings naturally proliferate in the data set. In fact, as the authors state, ‘some horizontal entrances have been identified, which would allow lateral entrance to a cave’.
The paper, ‘Mars Astrobiological Cave and Internal habitability Explorer (MACIE): A New Frontiers Mission Concept’, is available on arxiv.org.