The Qaidam Basin in north Tibetan Plateau, a Martian analogue : applications for a landing site of Mars missions

Abstract

Mars, the fourth planet from the Sun and the second smallest rocky planet in our Solar System, is now a cold desert world. Its extreme hyper-arid environmental conditions and the fact that it lies approximately 56.4 million kilometres away from Earth are the most difficult challenges for studying it. Earths’ hospitable environment and the presence of liquid water are the most notable differences yet most intriguing factors when comparing the planets and their past. It is known that 3.9 billion years ago Mars supported liquid water on its surface and could have harboured primitive microbial life. Much of Martian history today is expressed in water-related landscapes, indicating that despite the current hyper-arid conditions, during some periods Mars was more similar to Earth than any other known planet in the outer space, and in fact, remains so to date. But where is the water? Could microbial life be present on the Martian surface today? Until a manned mission to Mars is feasible, there is a need for a Martian analogue that comprises not only similar Martian materials, evolutionary history and morphological structures, but also at a scale comparable to Mars. The Qaidam Basin, a faraway area in the northern Tibetan Plateau, is such a Martian analogue and can give us insight in the quest to answer these questions. Formed from the drying up of sulfate brines in a giant lake, the area harbours one of the most extreme hyper-arid environments on Earth. The Qaidam Basin is the highest desert on Earth and the largest sedimentary basin in the Tibetan Plateau, offering a gigantic laboratory to compare Martian climatic processes, geological landforms and potential records of Martian microbial life. The detection of Ring Structures that imply tectonism on both the Qaidam Basin and Mars or the findings of biomarkers on carbonates in the Qaidam Basin are of key importance in Astrobiology. Additionally, the Qaidam Basin is described in great detail to a realistic environment to mimic the Holden Crater Landing site of the NASA Mars 2020 mission. The numerous similarities investigated suggest that the Qaidam Basin is the best terrestrial representation of parts of the Martian surface and should be considered as an essential site to test future Mars sample return missions. On the basis of the investigations on samples from the Qaidam Basin, the potential mineralogical, geological and records of life on ancient Mars are discussed, especially during the period when the surface water on Mars disappeared. The results obtained are unique and provide critical information, advancing the knowledge of Mars history and life in extreme conditions. Whether Mars has the right conditions for habitability today is still uncertain, but if mankind decides to live beyond Earth, the knowledge of environmental conditions and the availability of water will play a critical role in the planning of such missions.