Plenary Session, Invited Lecture

The search for life in our Solar System

P. Ehrenfreund1,2
1Space Policy Institute, George Washington University, 2Leiden Observatory

One of the most fascinating questions in planetary science is how life originated on Earth approximately 3.5-3.7 billion years ago and whether life exists beyond Earth. Life on Earth has adapted to nearly every explored environment including the deep ocean, dry deserts and ice continents. What were the chemical raw materials available for life to develop? What role did small Solar System bodies play in the delivery of raw material for life during the heavy bombardment phase in the early history of our Solar System. Where can we find life or remnants of life in our Solar System considering the progress and data on “extreme life” on Earth that has transformed our view of habitability.

A fleet of present and future robotic space missions target planets and moons in order to assess their habitability and to seek biosignatures of simple extraterrestrial life beyond Earth. Prime future targets in the outer Solar System include moons that may harbor internal oceans such as Europa, Enceladus, and Titan. Life may have emerged during habitable periods on Mars and evidence of life may still be preserved in the subsurface, caves, or evaporite deposits. Several orbiters as well as the Insight lander and the Curiosity rover are exploring Mars. In 2021, three additional robotic missions arrived at Mars. China’s ambitious Tianwen-1 mission composed of an orbiter, lander and rover landed its rover Zhurong in May 2021 in Utopia Planitia.   The United Arab Emirates orbiter “Hope” is starting its scientific measurements of the Martian atmosphere.  NASA’s Mars2020 mission Perseverance rover landed in the Jezero crater and will collect material for a future Mars sample return mission. Mars is still the central object of interest for habitability studies and life detection beyond Earth, paving the way for returned samples and human exploration.

Extensive science activities in support of planetary exploration are performed worldwide in the laboratory, in the field and through simulation studies. Life detection strategies need to be robust to recover traces of biomarkers and are critically dependent upon the sensitivity of detection methods. This lecture will discuss the current results of Mars missions and discuss the science and technology preparation crucial for robotic and human exploration efforts investigating habitability and biosignatures in our Solar System.