Mars May Have Been Too Cold for Life |
|
Written by spacetravel.org
|
|
Monday, 15 August 2005 22:46 |
|
To find out the length of the periods when Mars surface temperature was higher than freezing, David Shuster of the California Institute of Technology in Pasadena and Ben Weiss of Massachusetts Institute of technology examined previously published data on the ratio of potassium-40 and argon-40, two isotopes in meteorites from Mars found on Earth.
Radioactive potassium-40 is a solid that decays into the gas argon-40, which then diffuses very slowly out of the rock in a way that is dependent on temperaturethe higher the temperature, the faster it diffuses out. The scientists deduced that the oldest meteorite studied could not have been warmer than 0ºC for more than a million years in total since it formed 3.5 billion years ago. Surface water could have existed in liquid form on Mars for short periods, as indicated by the presence of channels and rocks that seem to have been eroded by liquid water, but Mars may not have stayed above freezing long enough for life to evolve.
|