Chapter 12
Searching for Life on Mars:
A Brief Summary
Roberto Orosei
Abstract Mars is today a cold, dry and sterile world with a thin atmosphere made
of CO 2 . The geologic and compositional record of the surface reveals however that
in the past Mars had a thicker atmosphere and liquid water flowing on its surface.
For this reason, it has been postulated that life could have developed and that some
primitive life forms may be existing even today. This paper will summarize the
main discoveries that have led to the current understanding of the geologic, climatic
and potentially biologic evolution of Mars, and will provide an overview of current
developments and near-future plans for the search for life on the red planet.
12.1 Introduction
Mars is the fourth planet of the Solar System and the second smallest, preceeded
only by Mercury. Differentiated in a metallic core and a silicate mantle, Mars has
a mass of about one-tenth that of our planet, a diameter slightly less than half the
Earth’s, and a surface area approximating that of terrestrial landmass. The Martian
day is only slightly longer than Earth’s, and its rotation axis has a similar inclination.
The Martian surface can be subdivided into three main morphological provinces:
the Southern hemisphere consisting of a cratered highland reminiscent of the Moon,
the topographically depressed and smooth Borealis basin, covering most of the Northern hemisphere, and the Tharsis plateau, a highland of volcanic origin 5000 km across
centered on the equator and encompassing some of the largest volcanoes in the Solar
System.
Other major features of the Martian surface are Valles Marineris, the largest
canyon in the Solar System with a length of 4000 km and a depth of up to 7 km,
and the two impact basins of Hellas Planitia and Argyre Planitia, with a diameter
of 2300 km and 1800 km respectively. Mars also possesses two permanent polar ice
R. Orosei (B)
Istituto Nazionale di Astrofisica, Istituto di Radioastronomia, 40129 Bologna, Italy
e-mail: roberto.orosei@inaf.it
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
S. Montebugnoli and A. Melis (eds.), The Search for ExtraTerrestrial Intelligence,
Springer Proceedings in Physics 260, https://doi.org/10.1007/978-3-030-63806-1_12
115
Searching for Life on Mars:
A Brief Summary
Roberto Orosei
Abstract Mars is today a cold, dry and sterile world with a thin atmosphere made
of CO 2 . The geologic and compositional record of the surface reveals however that
in the past Mars had a thicker atmosphere and liquid water flowing on its surface.
For this reason, it has been postulated that life could have developed and that some
primitive life forms may be existing even today. This paper will summarize the
main discoveries that have led to the current understanding of the geologic, climatic
and potentially biologic evolution of Mars, and will provide an overview of current
developments and near-future plans for the search for life on the red planet.
12.1 Introduction
Mars is the fourth planet of the Solar System and the second smallest, preceeded
only by Mercury. Differentiated in a metallic core and a silicate mantle, Mars has
a mass of about one-tenth that of our planet, a diameter slightly less than half the
Earth’s, and a surface area approximating that of terrestrial landmass. The Martian
day is only slightly longer than Earth’s, and its rotation axis has a similar inclination.
The Martian surface can be subdivided into three main morphological provinces:
the Southern hemisphere consisting of a cratered highland reminiscent of the Moon,
the topographically depressed and smooth Borealis basin, covering most of the Northern hemisphere, and the Tharsis plateau, a highland of volcanic origin 5000 km across
centered on the equator and encompassing some of the largest volcanoes in the Solar
System.
Other major features of the Martian surface are Valles Marineris, the largest
canyon in the Solar System with a length of 4000 km and a depth of up to 7 km,
and the two impact basins of Hellas Planitia and Argyre Planitia, with a diameter
of 2300 km and 1800 km respectively. Mars also possesses two permanent polar ice
R. Orosei (B)
Istituto Nazionale di Astrofisica, Istituto di Radioastronomia, 40129 Bologna, Italy
e-mail: roberto.orosei@inaf.it
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
S. Montebugnoli and A. Melis (eds.), The Search for ExtraTerrestrial Intelligence,
Springer Proceedings in Physics 260, https://doi.org/10.1007/978-3-030-63806-1_12
115