Odyssey: Double the Science for 1/8 the Price

NASA scientists have chosen to renew the mission of the Mars Odyssey orbiter, by all accounts a resounding success, for at least one more year (through Sept. 2006.)
Each day twin rovers Spirit and Opportunity transmit data to Odyssey which relays that information to Earth. It will also provide critical mission data for NASA's Phoenix mission to Mars, scheduled to land in 2008 and the Mars Reconnaissance Orbiter, scheduled to reach orbit in 2006. (Current MRO mission status.)
Although its original approximately three year-mission cost was a whopping $297 million, NASA is getting a bargain with its mission renewal: just $35 million for almost two more years.
In addition to discovering vast quantities of water ice, determining higher than expected radiation levels were present and providing the most detailed surface maps to date, Odyssey has shown some surface features continue to defy explanation. Like these olivine-rich layers of rock.

Keep in mind, everyone is racing to find water on Mars. Water means a future permanent human colony. How soon that would happen (if there's even enough water-ice present to support one) is unknown, especially given what they have recently discovered about higher than expected radiation levels (about three times Earth normal) but it's a start.
And no matter what else happens from this point forward, NASA scientists have shown the dangers of Mars exploration can be overcome through old-fashioned hard work and human perseverance.