Hello? Anybody out there?
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No one thinks microscopic critters could live on Europa's surface. It's too cold (about minus 260 degrees F.) and gets too much radiation from Jupiter. But slushy or watery bubbles even three or four feet below the surface could be safe places for microbes to live.Skip to next paragraph
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If the ice is fairly thin, Lloyd French has a good idea about what to do next: Send some of his "cryobots" to Europa.
The JPL engineer has designed small, torpedo-shaped cryobots ("cryo" for cold, "bots" for robots) that would use nuclear power to melt through the ice. The "bots" would carry scientific instruments to analyze the ice and would leave small radio-relay devices behind as they descended. The radios would get stuck in the ice as it refroze behind the bot. The radios would relay data from the bot to a lander on the surface, which would send it to Earth.
Mr. French tested a prototype bot on an ice-covered lake in Norway in January 2002. The tests "told us it was working," he says. And if he doesn't have a chance to use them at Europa anytime soon, he adds that they also would be useful in studying the polar ice caps on Mars.
With all these tantalizing puzzles to solve, Greeley says, "it's a really exciting time in human history. We're seeing new worlds for the first time."
Could intelligent, technologically advanced life exist beyond our solar system? Scientists are trying to find out. Some are using optical telescopes to look for laser-beam signals. Others use radio telescopes to listen for radio signals. And one of these radio teams needs your help.
Using a home computer and a free computer program from the University of California at Berkeley (go to: http://setiathome.ssl.berkeley.edu), you can take part in the hunt for E.T.
SETI@home scientists at the university are sifting through radio signals from space (a big source of naturally generated radio signals), looking for ones that might indicate a high-tech civilization. The signals are received at the world's largest radio telescope, located in Arecibo, Puerto Rico.
The raw signals from the telescope are broken into small chunks that a modern home PC or Mac can analyze while you're running other programs or when your screen saver activates. When your computer is done, it sends in the finished chunk and downloads a new one. In March, the team used the Arecibo radio telescope to revisit 166 promising signals out of billions they'd noted since the program began in 1999. A more detailed survey is planned.
But what are the chances we could "swap howdies" with another civilization if we found one? It's tough to say, but one thing is for sure: The conversation would be slow! In April, astronomers reported discovering the 106th planet outside our solar system. It's 119 light-years away. That means that if intelligent aliens lived in that system, we'd have to wait 238 years for an answer to our signal saying "Hello"!
Discovered: Jan. 7, 1610, by Italian astronomer Galileo.
Diameter: 1,949 miles, slightly smaller than Earth's moon (2,160 miles). It's five times as reflective as the moon, though, because it's covered with ice and is the smoothest object in the solar system.
Gravity: About 1/8th that of Earth. If you weigh 60 pounds, you'd weigh just 8 pounds on Europa.
Distance from Jupiter: 417,000 miles, almost twice as far away as our moon is from Earth. It takes Europa a little more than 3-1/4 Earth days to zip around Jupiter (versus 28 days for our moon). Jupiter is a little more than five times as far from the Sun as the Earth is.
Composition: Europa appears to have a core of rock and iron covered by an ocean of water or slush 60 to 125 miles deep. The ocean is capped by a sheet of ice perhaps four miles thick. The gravitational tug of war among Jupiter and its moons creates the heat that keeps the water from freezing.
Atmosphere: There's a very thin atmosphere of oxygen.