While other nations are planning migration to planet Mars, the National Aeronautics and Space Administration (NASA) of the United States is planning to fly to the moon - that is Jupiter's moon which is covered in large oceans of water under a thick ice later.

NASA plans to reach the planet's moon by 2021 using the $2-billion Europa Clipper rocket. Robert Pappalardo, senior research scientist at NASA's jet propulsion laboratory in California, explained that Jupiter's moon was selected because of the presence of water which is a sign of life on Earth.

He said that Jupiter has 67 confirmed moons and the largest are Europa, Io, Ganymede and Callisto. Although these moons are very far from the sun to benefit from solar heat, the oceans underneath its layers of ice are warmed up during their orbit around the planet.

"The search for life in our solar system somewhat equates to the search for liquid water. When we ask the question where are the water worlds, we have to look to the outer solar system because there are oceans beneath the icy shells of the moon," BBC quoted Mr Pappalardo.

Among Jupiter's many moons, NASA picked Europa because its oceans are in contact with rock below that are probably geologically active, he said on Friday at the yearly gathering of the American Association for the Advancement of Science in Boston, Massachusetts.

He added that Europe is subject to extreme levels of radiation which means it would likely be covered in oxidants at its surface, created by the ripping apart of water by energetic radiation and could be used by lifeforms as a fuel type.

However, the ambitious plan is subject to NASA's final approval, which currently is still focused on sending another rover to Mars after the agency's Curiosity rover drilled last week its first hole in Mar's surface in its attempt to start an examination of Martian soil.

The $2 billion bill excludes cost of the launch vehicles and rockets.