NASA is targeting Jupiter's moon Europa, considered by many scientists as the solar system's best bet for harboring life beyond Earth, for "habitability" mission.

For launch in 2020, researchers at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., are developing a concept mission that would investigate whether life could have existed on the huge moon.

The mission would involve the dropping of two identical robotic landers, the redundancy being a hedge in case something goes wrong, on the surface of Jupiter's moon, which scientists believe have water underneath its icy shell.

The robots will be equipped with mass spectrometer, seismometers and several cameras to detect various organic chemicals, if they exist in the moon's surface, and to capture images that will shed light on the moon's geology.

According to Hand, the landers can last for at least seven days to do its work before radiation coming from Jupiter takes its toll. Instead of heavy protective shield against radiation, mission planners want to devote as much weight as possible to the robots' scientific gear.

So the landers' prime mission is being designed to last for just seven days, to make sure they get their work done before the radiation takes its toll. But it's possible the robots could last longer than that, Hand said.

"Europa, I think, is the premier place to go for extant life," said JPL's Kevin Hand. "Europa really does give us this opportunity to look for living life in the ocean that is there today, and has been there for much of the history of the solar system."

While the lander mission is still a concept, Hand said the results of the study are encouraging. "This is a habitability mission," he said, adding that the mission is not about detecting life in Europa but rather to assess the moon's ability to support past and present life.

If the mission pushes through it could be ready to launch by 2020, with arrival on the moon's surface by 2026 or so.

According to NASA, a different mission that would send a spacecraft to study Europa, from orbit is also being considered. The Jupiter Europa Orbiter mission would launch in 2020 and cost about $4.7 billion, NASA said.