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Icy bodies: Europa and elsewhere
The new discipline of astrobiology – that is, the science of searching for...
The new discipline of astrobiology – that is, the science of searching for extraterrestrial life – is not only rapdly growing, but has also captured the public imagination. This unit examines the emergence of icy satellites of distant planets as potential sites of extraterrestrial life. Focussing on the case study of Jupiter's moon Europa, the unit looks at the potential for life there, and speculates on the ethics of searching for life elsewhere in the solar system.
By the end of this unit you should be able to:
- discuss processes upon and within, and internal structure of, differentiated icy bodies (primarily large satellites) in comparison with the terrestrial planets;
- describe the conditions that may be required to originate and foster life in an icy body and discuss the likelihood of their having occurred;
- recognise the moral and ethical issues of landing spacecraft on potential life-bearing worlds and appreciate the need for appropriate professional codes of conduct in this respect.
- Current section: Introduction
- Learning outcomes
- 1 Icy satellites: introduction
- 2 Europa
- 3 Other icy bodies as abodes of life?
- 4 Unit summary
Icy bodies: Europa and elsewhere
Until the 1980s, the icy satellites of the outer planets were scarcely thought of as places where life could ever have existed. Few could have imagined that one of them, Europa, would within twenty years have become the rival of Mars as a priority for astrobiological study. This unit recounts the history of our changing perceptions of the icy satellites, examines the available evidence for their internal structures, and considers the niches offered for life to begin and to be sustained. In this context, the ‘habitable zone’ embraces settings devoid of both sunlight and an atmosphere. These are areas where life could survive on the energy from chemical reactions made possible by the discharge of hot chemically enriched fluids through vents on the floor of an ocean capped by a thick layer of ice. Note that ‘ice’ does not necessarily mean just frozen water. In the outer Solar System, although H2O is usually the dominant component, ice can incorporate other frozen volatiles such as NH3, CO2, CO, CH4 and N2.
This unit is an adapted extract from the Open university course