Some of the members of the ESA Astrobiology Topical Team
In the interdisciplinary field of “astrobiology” scientists search for the origins of life on Earth and for signs of extraterrestrial life. Understanding how life appears and finding its evidence elsewhere have become central questions in science. Several years ago, the European Space Agency (ESA) established an international, interdisciplinary team of researchers in this field, the “Astrobiology Topical Team”, to review and report on the latest advances and to plan more strategically for the future. This work is now published in a series of three scientific articles in the journal Space Science Reviews (volume 209).
In the article “Astrobiology and the possibility of life on Earth and elsewhere …”, the Topical Team addresses the latest advances in astrobiology. It is known now that the ingredients necessary for the appearance of life can be found in meteorites that fall to Earth, and as an even larger relative constituent of comets. From this, chemists are elaborating new reasoning based on complex chemical systems that lead us to imagine how molecules such as RNA or proteins could have formed, leading to the emergence of life.
In addition, recently developed scenarios for the formation of the planets of the Solar System have reshaped our understanding of the face of primitive Earth: our planet may have been inhabited much earlier than imagined. More and more indicators of life, in the form of microfossils or life-indicative chemical imbalances, have been found in the oldest rocks of our planet. Terrestrial life also demonstrates an astonishing ability to adapt to environments formerly considered too extreme to harbor life, broadening the perspective of finding life elsewhere in the Solar System. Much further away, around other stars, thousands of recently-discovered exoplanets will soon be sufficiently well characterized using powerful telescopes to fuel our hopes of detecting signs of life outside our Solar System. All these developments are detailed in the article "Astrobiology and the Possibility of Life on Earth and Elsewhere ..." (available online).
The article “Earth as tool for Astrobiology - A European Perspective” gives recommendations on the exploration of particular regions of our own planet. Some regions, often remote and desert, present environmental conditions—acidity, temperature, humidity, etc.—that make them relatively good analogues of other planets of the solar system, such as Mars, or even of the primitive Earth. These extraterrestrial environments are also simulated in many laboratories. The Topical Team examined the ways in which the Earth is used for astrobiology, e.g. by field trips to these analogue regions, by searching for the oldest traces of extinct life in the oldest known rocks, and learning how these signatures are preserved over time, and by exposing samples to laboratory-simulated outer-space or planetary environments to study the changes induced in minerals, molecules, and microorganisms.
Beyond the popular exploration missions (exemplified by the Mars rover Curiosity and the Rosetta probe and its lander Philae), space is a privileged tool for astrobiology studies. In the article “Space as a Tool for Astrobiology: Review and Recommendations for Experimentations in Earth Orbit and Beyond” the Topical Team focused on a comprehensive international review of the experiments conducted in Earth orbit and beyond to study the evolution of organic matter and the resistance of living organisms to the highly hostile environment of space. This environment and its unique combination of different types of radiation, solar and cosmic, are particularly difficult to simulate in the laboratory. The first experiments exposing microorganisms to these conditions date back to the Gemini and Apollo missions in the 1960s and 1970s. Supporting hardware and devices have since been significantly improved, and at present the exterior of the International Space Station is regularly used as a laboratory for conducting chemical or biological astrobiology studies in outer space. The return to Earth of space capsules is even used to simulate entries of meteorites into the atmosphere to better understand how life’s molecular building blocks could have been affected by their delivery to Earth.
The main questions addressed by these experiments are the following:
There are, however, critical limitations to existing space facilities. Passive exposure platforms utilized outside the International Space Station do not allow "real-time" measurements of the alteration of exposed samples, so researchers cannot analyze them until they are shipped back to Earth. Next-generation platforms should therefore allow in-situ, real-time measurements; they should also support experiments at low temperatures to better simulate cometary ices, the surface of Mars, or the environments of the icy satellites of the giant planets, such as Europa and Enceladus.
The Topical Team also recommended access to orbits more exposed to radiation than ISS-hosted facilities. Satellites in higher orbits, for example polar orbits, would offer samples more representative to the conditions of interplanetary space: space craft in such “high-inclination” orbits venture beyond the radiation-shielding effects of Earth’s magnetic field. Implementation of these recommendations will likely be facilitated by the development of nanosatellites (such as those based on the Cubesat architecture). This new generation of experiments will considerably increase the scientific return of space sample-exposure experiments.
This review and its perspectives are detailed in "Space as a Tool for Astrobiology: Review and Recommendations for Experiments in Earth Orbit and Beyond" (Open access here).
The three articles are:
Cottin, H., Kotler, J.M., Bartik, K., Cleaves, H.J., Cockell, C.S., de Vera, J.-P.P., Ehrenfreund, P., Leuko, S., Ten Kate, I.L., Martins, Z., Pascal, R., Quinn, R., Rettberg, P. and Westall, F. (2017) Astrobiology and the Possibility of Life on Earth and Elsewhere…. Space Science Reviews 209, 1-42. (https://link.springer.com/article/10.1007/s11214-015-0196-1)
Martins, Z., Cottin, H., Kotler, J.M., Carrasco, N., Cockell, C.S., de la Torre Noetzel, R., Demets, R., de Vera, J.-P., d’Hendecourt, L., Ehrenfreund, P., Elsaesser, A., Foing, B., Onofri, S., Quinn, R., Rabbow, E., Rettberg, P., Ricco, A.J., Slenzka, K., Stalport, F., ten Kate, I.L., van Loon, J.J.W.A. and Westall, F. (2017) Earth as a Tool for Astrobiology—A European Perspective. Space Science Reviews 209, 43-81. (https://link.springer.com/article/10.1007/s11214-017-0369-1)
Cottin, H., Kotler, J.M., Billi, D., Cockell, C., Demets, R., Ehrenfreund, P., Elsaesser, A., d’Hendecourt, L., van Loon, J.J.W.A., Martins, Z., Onofri, S., Quinn, R.C., Rabbow, E., Rettberg, P., Ricco, A.J., Slenzka, K., de la Torre, R., de Vera, J.-P., Westall, F., Carrasco, N., Fresneau, A., Kawaguchi, Y., Kebukawa, Y., Nguyen, D., Poch, O., Saiagh, K., Stalport, F., Yamagishi, A., Yano, H. and Klamm, B.A. (2017) Space as a Tool for Astrobiology: Review and Recommendations for Experimentations in Earth Orbit and Beyond. Space Science Reviews 209, 83-181. (https://link.springer.com/article/10.1007/s11214-017-0365-5)
Tag cloud based on the text of the paper « Space as a Tool for Astrobiology: Review and Recommendations for Experimentations in Earth Orbit and Beyond. »