With a manned Mars voyage suggested for next decade and space probes going ever farther from Earth, conventional propulsion systems are proving way too inefficient and NASA has gone looking for more exotic ways to fly.
NASA developing more efficient power for space flights Cosmiverse.com
Mars Global Surveyor Aging Gracefully Cosmiverse.com
Intricate “fixes” from Earth have kept the Mars Global Surveyor working well beyond its original mission. The spacecraft is now in its second extension following a very successful primary mission and is providing scientists with valuable information about how the red planet changes over time. Since there are no service garages in space, mission planners have to perform any needed repairs from the ground, including finding ways to save fuel.