posted 08-11-2010 12:16 PM               

Although NASA knows of 44 Near Earth Objects (NEOs) in orbits that could be accessible given a heavy-lift rocket roughly equivalent to the canceled Ares V, only three meet the necessary requirements for a future visit by astronauts, according to NASA officials speaking at a NEO event in Washington Aug. 10.

The list of asteroids was winnowed down according to mission constraints, including that any visit by astronauts be no longer than 180 days round trip, and any object visited be larger than 50 meters (164 ft.) across.

Out of the 44 reachable asteroids, 27 were too small, and only 15 have orbits that allow for exploration between 2020 and 2050 -- the timeframe NASA wants to pursue for NEO missions. The 180-day mission constraint further cuts the list to three. The specifics of those objects -- such as composition, spin state and possible moons -- are yet to be determined.

posted 09-01-2010 03:46 PM               

While NASA admits more knowledge about objects that pass within 28 million miles (45 million km) of Earth could increase the number of possible destinations, only two currently meet the guidelines set out by the space agency in its attempt to send a manned mission to an asteroid by 2025, a goal set by President Barack Obama. One of the asteroids could be reached in 2020 and the other in 2025.

A third candidate would not be within range until 2045.

One other problem I see - The objects are so small it will only take one trip to see the whole thing!