As NASA scientists continue to search for signs of past life on Mars, they're also casting a hopeful eye toward finding life on one of Jupiter's moons.
NASA researchers have been putting some thought into what a mission to the moon Europa would consist of. What would they hope to find and how would they go about it?
Europa is one of Jupiter's four largest moons, which are known as the Galilean satellites -- so named after astronomer Galileo Galilei, who observed them in 1610.
Europa's surface is believed to be composed mainly of water ice, and NASA reports that there is evidence that the icy surface may be covering an ocean of water or slushy ice. Europa could have twice as much water as there is on Earth.
The moon intrigues astronomers and scientists because it sits in what is known as the habitable zone, a relatively small area around a star in which water may be present in liquid form if conditions are right.
Jupiter, the fifth planet from the sun and the largest planet in the solar system, has more than 60 known moons.
"If one day humans send a robotic lander to the surface of Europa, we need to know what to look for and what tools it should carry," said Robert Pappalardo, a senior research scientist with NASA's Jet Propulsion Laboratory. "There is still a lot of preparation that is needed before we could land on Europa, but studies like these will help us focus on the technologies required to get us there, and on the data needed to help us scout out possible landing locations."
Pappalardo noted that Europa is the most likely place in our solar system, beyond Earth, to sustain life.
"A landed mission would be the best way to search for signs of life," he said.
Scientists from NASA, Johns Hopkins University, the University of Colorado, Boulder, and the University of Texas, Austin, have been working on issues related to one day launching an exploration mission to Europa.
For instance, they were focused on finding out more about Europa's composition. What makes up the reddish spots and reddish cracks that stain the moon's icy surface? Are there organic molecules, which are part of the building blocks of life?
NASA has not announced any specific plans to launch a mission to Europa. However, NASA is putting a lot of muscle behind finding out if Mars was ever able to support life, even in microbial form.
On Tuesday, the space agency celebrated the Mars rover Curiosity's one-year anniversary on the Red Planet. With data coming back from the robotic rover, as well as other rovers and orbiters working on Mars, NASA scientists have concluded that Mars had a sustained ancient water flow and its soil contains chemicals needed to support life as we know it.
It suggests that millions or billions of years ago, Mars may have been a blue planet, just like Earth is today.
"We've not found any smoking gun for life yet, but it's exciting to find a place that could have supported it," said Bethany Ehlmann, an assistant professor of planetary science at CalTech and a participating scientist on NASA's Curiosity team, in a previous interview. "One of the biggest questions is how unique is our planet? Is Earth rare or common? Is there life elsewhere? If there's life on a neighboring planet, maybe it tells us something about the distribution of life in the rest of the universe."
Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at @sgaudin, on Google+ or subscribe to Sharon's RSS feed . Her email address is email@example.com.