Tune in to a live Webcast on Thursday at 9 a.m. Eastern time for a day-long event sponsored by NASA and Lockheed Martin on the search for life beyond Earth. (Anybody who's in the Arlington, Virginia, area can go in person).
The occasion is the 50th anniversary of NASA's exobiology program, which was first funded in 1959 to search for life on Mars during NASA's Viking missions in the 1970s.
Those experiments produced no signs of life at the time, although scientists now say that chlorine compounds found in the Martian soil collected by the Viking may have been misinterpreted as contaminants, and that the soil may have organic compounds -- the building blocks of life -- after all.
In September, evidence from another spacecraft, the Phoenix Mars Lander -- which landed on Mars on May 25, 2008 -- suggested that Mars has had active volcanoes and liquid water on its surface.
NASA's exobiology program, meanwhile, expanded through the 1980s and 1990s to cover evolutionary biology and then "astrobiology," which studies the formation and evolution of planets, chemical evolution in interstellar space and the natural history of Earth. It's now focused on the beginnings and evolution of life in the universe and how we can detect it if we run across it.
A list of the scientists who will be speaking is here.
NASA's next mission to Mars is scheduled for 2013. Lockheed Martin is building the spacecraft, which is called MAVEN.
(The picture, from NASA/JPL-Calech/University of Arizona, is an artist's conception from 2007 of the Phoenix Mars Lander "(shutting) down operations as winter sets in. The far-northern latitudes on Mars experience no sunight during winter. This will mark the end of the mission because the solar panels can no longer charge the batteries on the lander. Frost covering the region as the atmosphere cools will bury the lander in ice.")