Cold, dark, sub-ice waters of Vostok and Europa may harbor life, scientists sa

Contact:
RichardGreenberg, (520) 621-6940, greenberg@lpl.arizona.edu
Website: http://www.lpl.arizona.edu/People/Faculty/greenberg.html
 

By Lori Stiles
 
Europa is likelier to harbor life than is Mars, planetary scientist Richard Greenberg says in an article in the April 2000 issue of Wired magazine.
 
Greenberg is a University of Arizona professor and member of the Imaging Team for NASA’s Galileo Jupiter-orbiter spacecraft.
 
"I’d bet there’s life on Europa," Greenberg told writer Oliver Morton. "I wouldn’t bet there’s life on Mars. "
 
Morton’s article, "Ice Station Vostok," argues the case for scientists who propose to explore pristine Lake Vostok — one of the world’s 15 largest lakes — which sits beneath 2 and 1/2 miles of solid ice in east Antarctica.
 
Lake Vostok is Earth’s closest analog to the likely sub-surface ocean on Jupiter’s moon, Europa. Lake Vostok has been sealed over with ice for 30 million years, but many scientists believe that an indigenous ecosystem endures in the cold, dark waters. The technologies and strategies they would develop to find out would be useful in future missions to Europa, they add.
 
In Wired, Greenberg notes evidence that the ice on Europa is very thin in some places. Water may be close enough to the surface for photosynthesis to occur, if Europa does have a liquid ocean beneath its ice-shell surface.
 
Using Galileo spacecraft images and theoretical modeling, Professor Greenberg and post-doctoral researchers Greg Hoppa, Randy Tufts and Paul Geissler of the UA Lunar and Planetary Laboratory discovered the strongest evidence yet that there is a liquid ocean beneath Europa’s bizarre, tortured ice. They reported it six months ago in Science.
 
Europa’s unique cycloidal cracks and ridges that run hundreds of miles through the entire lunar surface ice result from Jupiter’s pull on Europa’s sub-surface ocean, the University of Arizona scientists said. Each arc segment in a cycloidal crack forms in 85 hours, the time it takes the jovian moon to complete an orbit around its planet, they said. The cycloids faithfully record the daily tidal stresses on Europa just as trees faithfully record each growing season in annual rings, they added.