ESA's life sciences activities cover every aspect of space life sciences, including biology, physiology, biotechnology, biomedical applications, biological life-support systems, exobiology, animal research and access to ground facilities. They have included exobiology research since 1992, when the Exobiology and Radiation Assembly (ERA) flew on the Eureca mission. This approach continues with the Biopan facility on the Russian Foton missions. Four missions flew in 1992, 1994, 1997 and 1999, and the next is planned for October. In addition, EXPOSE will be installed no earlier than 2007 on the external payload site of Columbus aboard the International Space Station, mounted on a device to point the experiments towards the Sun. These facilities are helping to understand the survivability and damage/repair mechanisms of organics, microorganisms and invertebrates in space conditions.
- ESA Astrobiology Science Team Study
As a logical progression from exobiology research in low Earth orbit, an Astrobiology Science Team was created to survey current research in exobiology and then formulate recommendations for a future search for life in the Solar System. (The full findings are published in ESA SP-1231.)
The main recommendation was that Mars should be ESA's prime target. Three fundamental requirements were identified for a search for life on Mars:
- the landing site must have high astrobiology potential. That has not been the case so far. Sites with sedimentary deposits and relatively free from wind-blown sand are prime targets;
- samples must be taken in several locations, free from surface oxidation. A rover is needed, with a drill to reach well into the soil and surface rocks, and a system to prepare the samples for analysis;
- integrated measurements must be performed on the site and samples. An astrobiology package should carry: a microscope for general examination of the samples at a resolution of 3 µm (plus a close-up camera with 50 µm resolution); an infrared Raman spectroscope for identifying mineral and organic molecules, with near-IR excitation for biological and geochemical studies; an alpha-proton-X-ray spectrometer for identifying chemical elements; a Mossbauer spectrometer for measuring iron composition and oxidation states; a pyrolitic gas chromatograph and mass spectrometer for isotopic, elemental, organic and inorganic molecular composition, and chirality measurements; sensors for hydrogen peroxide and other oxidants.
- Future Activity
For the longer term, the Astrobiology Science Team highlighted other areas:
- Europa and other bodies possibly having subsurface water and internal heat sources are candidates for both extant and extinct life.
- Titan has an atmosphere of nitrogen and methane, together with a great number of trace hydrocarbons, nitriles and oxygen compounds. Surface deposits of hydrocarbons have been predicted, although water ice is now considered to be dominant. Interest lies in the study of fundamental physical and chemical interactions driving planetary organic chemistry, and in the possible development of a life system in the absence of liquid water but with other liquids.
- Meteorites are samples of solar debris and of the material ejected from bodies such as Mars and the Moon. Martian meteorites are being closely studied for evidence of extinct life. A sample of martian sedimentary material would be a major breakthrough, likely to yield important information about life on Mars.
- Comets were probably an important source of organics for the primitive Earth and other planetary bodies.
- Meteorites and Micrometeorites imported major amounts of extraterrestrial organic material to the Earth - perhaps 1017 kg of carbon over the 300 million years of the late bombardment phase. Improved collection of micrometeorites by the Space Station and other vehicles is needed to allow unambiguous analysis of the organic components.
- Organic Molecules are potential building blocks of pre-biological materials, but they may suffer degradation and racemisation in space. The effects of space conditions on organics such as amino acids, sugars, lipids and nucleic acid bases must be studied. They may be protected by associating with mineral dust particles found in micro-meteorites and comets. Similar studies are also needed on polycyclic aromatic hydrocarbons (PAHs). Experiments of this type require access to the external environment of a space station or other vehicle with dedicated facilities.
- Microorganisms subjected to the space environment, especially the UV radiation and heavy-particle radiation flux, tend to be damaged progressively and die. However, certain types can survive in space for long periods, especially if they are protected inside meteorites. Continuing space experiments will improve our understanding of the underlying damage processes, the survivability of a range of organisms, and the possibility of life being spread around the Solar System by meteorites.
- Laboratory Simulations can provide valuable information on the organic chemistry processes in comets, on interstellar grains and in meteorites. Simulation of planetary environments and the study of their effects on microorganisms have both fundamental and practical value. Laboratory Studies will continue to provide the essential fundamental experiments in the search to understand the earliest steps in the emergence of life. In conjunction with field experiments, they will make important contributions to the knowledge of how life develops and survives under extreme conditions, including deep subterranean life, and its application to the search for life elsewhere in the Solar System.