Harvard-Smithsonian Center for Astrophysics | 2015 Aug 27
[img3="In this theoretical artist's conception of the Milky Way galaxy, translucent green "bubbles" mark areas where life has spread beyond its home system to create cosmic oases, a process called panspermia. New research suggests that we could detect the pattern of panspermia, if it occurs. (Credit: NASA/JPL/R. Hurt)"]https://www.cfa.harvard.edu/sites/www.c ... 1/base.jpg[/img3][hr][/hr]We only have one example of a planet with life: Earth. But within the next generation, it should become possible to detect signs of life on planets orbiting distant stars. If we find alien life, new questions will arise. For example, did that life arise spontaneously? Or could it have spread from elsewhere? If life crossed the vast gulf of interstellar space long ago, how would we tell?
New research by Harvard astrophysicists shows that if life can travel between the stars (a process called panspermia), it would spread in a characteristic pattern that we could potentially identify.
"In our theory clusters of life form, grow, and overlap like bubbles in a pot of boiling water," says lead author Henry Lin of the Harvard-Smithsonian Center for Astrophysics (CfA).
There are two basic ways for life to spread beyond its host star. The first would be via natural processes such as gravitational slingshotting of asteroids or comets. The second would be for intelligent life to deliberately travel outward. The paper does not deal with how panspermia occurs. It simply asks: if it does occur, could we detect it? In principle, the answer is yes.
The model assumes that seeds from one living planet spread outward in all directions. If a seed reaches a habitable planet orbiting a neighboring star, it can take root. Over time, the result of this process would be a series of life-bearing oases dotting the galactic landscape. ...
Statistical Signatures of Panspermia in Exoplanet Surveys - Henry W. Lin, Abraham Loeb
- arXiv.org > astro-ph > arXiv:1507.05614 > 20 Jul 2015 (v1), 06 Aug 2015 (v2)