One of the holy grails for NASA is the idea of finding life that has evolved on worlds beyond the Earth. Much of the exploration of Mars has been focused on finding signs of life, the Los Angeles Times noted on Monday. Beyond Mars, some of the outer planet moons such as Europa, orbiting Jupiter, and Titan, orbiting Saturn, have been touted as possible abodes of extraterrestrial life.
But any ETs found within the solar system are likely to be no more than microbes, interesting to scientists, but not the sort of alien beings science fiction has imagined that first contact would involve. The space agency held a panel discussion on Monday touting a new venue for the search for ET, planets orbiting other stars. Confirmation that one or more of these exoplanets contains life would be a game changer in our understanding of our place in the universe.
Current space telescopes such as the Hubble, the Spitzer Space Telescope, and especially the Kepler Space Telescope have revolutionized our knowledge of planets orbiting other suns. Some 5,000 possibilities have been detected, using a technique that involves measuring how the light of a star diminishes when a planet passes between it and Earth. In this way, scientists have been able to determine the approximate size and distance from the host star of many of these planets.
Most of the planets thus detected have been gas giants, similar to Jupiter. Some have been so-called “super-Earths” which are rocky worlds larger and more massive than Earth. Some of the latter have been found in the so-called habitable zone around their parent stars, where the temperature is enough to sustain liquid water. One of these planets is an actual Earth-sized world.
The next generation of space telescopes, the Transiting Exoplanet Surveying Satellite (TESS), the James Webb Space Telescope, and the proposed Wide Field Infrared Survey Telescope - Astrophysics Focused Telescope Assets (WFIRST-AFTA) promise to expand our understanding of exoplanets, according to the NASA panelists. More Earth-sized worlds will be discovered thanks to the greater range and precision of these telescopes. More importantly the atmospheres of some of these worlds will be measured and characterized.
There are certain markers that can be detected in another planet’s atmosphere that would suggest that it is an abode of life. These include water vapor and carbon dioxide, among other chemicals. Discovery of such worlds would be solid evidence that life exists on other planets, possibly of greater complexity than mere microbes. It is the prospect of science fiction becoming reality.