NASA eyes dark energy, outer solar system missions

By Will Dunham Wed Feb 6, 11:48 AM ET

WASHINGTON (Reuters) - The U.S. space agency is planning a mission to better understand a mysterious form of energy in the cosmos and an ambitious unmanned journey to the outer solar system, NASA officials said.

NASA would initiate seven new science missions in fiscal year 2009 that starts October 1 under the budget President George W. Bush proposed to Congress this week. NASA's proposed $17.6 billion budget includes $4.4 billion for science missions.

"In fact, we have more new starts in this budget for science than in the last three years combined," Alan Stern, who leads NASA's science missions, said in an interview.

NASA is planning to begin work on a mission to send a spacecraft to either Jupiter or Saturn -- the two biggest planets in the solar system -- with the idea of orbiting one of three moons of these two outer solar system giants. Launch is seen by 2017, with the mission cost pegged at $2.1 billion.

Two of the three moons under consideration orbit Jupiter: Europa, which boasts an ice-covered ocean that some scientists think is a candidate for harboring some form of life; and Ganymede, the largest moon in our solar system.

The third option is Saturn's moon Titan, the second-biggest moon in the solar system. "By the end of this year, we will have it down to our final choice," Stern said.

NASA also is planning a mission involving the launch by 2015 of an Earth-orbiting satellite to study dark energy, a mysterious force thought to cause the universe to expand at an accelerated pace. Scientists think dark energy makes up roughly 70 percent of the universe but do not understand its nature.

Another science mission being planned envisions a spacecraft being launched in 2015 to study the Solar Corona, a region around the sun where the solar wind originates.

"The latter half of the next decade is going to revolutionize our knowledge of how the solar wind is accelerated, the corona is heated, and the inner workings of the star that makes life possible on Earth," Stern said.

"This will be the first mission to ever dive down into the solar corona -- much, much closer than Mercury orbits, and to places where the thermal emissions are just hellacious."

NASA also is planning new robotic missions to the moon and Earth science missions.

(Editing by Philip Barbara)