Question

What type of evidence would be required for an astrobiologist to accept there are biological beings from other planets?

Astrobiologists would love to find evidence of life on other planets, either within our solar system or circling distant stars. Within our solar system, we would ultimately want to see the life forms themselves — from the oceans of Europa or the subsurface aquifers of Mars, for example. Here we have the great advantage of being able to carry out investigations by spacecraft, but there is also the disadvantage that the life forms on Mars or Europa are not likely to be on the surface, so it will be a challenge to reach them. In searching for evidence of life on planets circling other stars, we will look for planets where there is a robust surface life that imposes its signature on the atmosphere. The challenge here is to get the remote sensing, using big telescopes, that would allow us to identify biomarkers such as unusual atmospheric chemistry that might be produced by life. Finally, of course, there is the possibility of intelligent life. The evidence here would be the simplest to interpret, if we succeed in locating artificial radio or optical signals from another civilization. Astrobiologist would be elated with any of these three forms of evidence: actual bugs from Mars or Europa, atmospheric biomarkers from planets around other stars, or coded transmissions from intelligent civilizations anywhere.

David Morrison
NAI Senior Scientist
March 31, 2009