PROSPECTIVE LAVA TUBES AT HELLAS PLANITIA
LEVERAGING VOLCANIC FEATURES ON MARS TO PROVIDE CREWED MISSIONS PROTECTION FROM RADIATION
ANTONIO J. PARIS, EVAN T. DAVIES, LAURENCE TOGNETTI, & CARLY ZAHNISER
CENTER FOR PLANETARY SCIENCE
ABSTRACT
Mars is currently at the center of intense scientific study aimed at potential human colonization. Consequently, there has been increased curiosity in the identification and study of lava tubes for information on the paleohydrological, geomorphological, geological, and potential biological history of Mars, including the prospect of present microbial life on the planet. Lava tubes, furthermore, could serve as in–situ habitats for upcoming crewed missions to Mars by providing protection from solar energetic particles, unpredictable high-energy cosmic radiation (i.e., gamma-ray bursts), bombardment of micrometeorites, exposure to dangerous perchlorates due to long-term dust storms, and extreme temperature fluctuations. The purpose of this investigation is to identify and study prospective lava tubes at Hellas Planitia, a plain located inside the large impact basin Hellas in the southern hemisphere of Mars, through the use of Earth analogue structures. The search for lava tubes at Hellas Planitia is primarily due to the low radiation environment at this particular location. Several studies by NASA spacecraft have measured radiation levels in this region at ~342 μSv/day, which is considerably less than other regions on the surface of Mars (~547 μSv/day). Notwithstanding, a radiation exposure of ~342 μSv/day is still sizably higher than what human beings in developed nations are annually exposed to on Earth. By analyzing orbital imagery from two cameras onboard NASA’s Mars Reconnaissance Orbiter (MRO) – the High-Resolution Imaging Science Experiment (HiRISE) and the Context Camera (CTX) – the search for lava tubes was refined by identifying pit crater chains in the vicinity of Hadriacus Mons, an ancient low-relief volcanic mountain along the northeastern edge of Hellas Planitia. After surveying 1,500 images from MRO, this investigation has identified three candidate lava tubes in the vicinity of Hadriacus Mons as prospective sites for manned exploration. To complement this investigation, moreover, 30 in-situ radiation monitoring experiments have been conducted at analog lava tubes located at Mojave, CA, El Malpais, NM, and Flagstaff, AZ. On average, the total amount of solar radiation detected outside the analog lava tubes was approximately ~0.470 μSv/hr, while the average inside the analog lava tubes decreased by 82% to ~0.083 μSv/hr. We infer, therefore, that the candidate lava tubes identified southwest of Hadriacus Mons could be leveraged to decrease the radiation and to reduce the crew’s exposure from ~342 μSv/day to ~61.64 μSv/day (a decrease of ~82%). This investigation, therefore, concluded that terrestrial lava tubes can be leveraged for radiation shielding and, accordingly, that the candidate lava tubes on Mars (as well as known lava tubes on the lunar surface) can serve as natural radiation shelters and habitats for a prospective crewed mission to the planet.
Approved by the Washington Academy of Sciences: Prospected Lava Tubes at Hellas Planitia (Paris, et al)