The National Aeronautics and Space Administration said every 10 years U.S. astronomers and physicists take part in the Astronomy and Astrophysics Decadal Survey in cooperation with the National Academy of Sciences. They produce directions that guide federal agencies such as NASA and the National Science Foundation in planning astronomy and astrophysics programs for the coming decade. "The exciting new astrophysics mission concept studies we are funding will seed preparations for astronomical space missions and paradigm-shifting discoveries across the early 21st century," said Alan Stern, associate administrator for NASA's Science Mission Directorate.

The concept studies total approximately $12 million in fiscal years 2008 and 2009.

Some of the proposals explore a powerful new combination of telescopes and instruments optimized for observing the tenuous filaments of intergalactic hydrogen gas known as the cosmic web gas.

Another mission would place two laser beacons on Mars. Precise measurements of the distance to these beacons would provide the most stringent test yet of Einstein's theory of general relativity.

The studies' results are expected in March 2009.