The Lunar Reconnaissance Orbiter (LRO) is scheduled for launch October 28, 2008.
The craft will map the moon's surface from some 30 miles (50 kilometers) aloft, searching for safe landing and outpost sites as well as valuable resources, such as water ice and a variety of minerals.
LRO will also study how radiation in space might impact astronauts who will spend far more time on the moon than previous visitors.
In addition, the Lunar Crater Observation and Sensing Satellite (LCROSS)—which launches with LRO—will slam into the moon, creating two large plumes that will aid the search for lunar water ice.
LCROSS's impact will likely occur in early 2009, and the resulting sprays should be visible from Earth via telescopes and other instruments.
The event should produce what Walz called "some pyrotechnics for the inauguration" of the new U.S. president—who may influence funding for the sometimes-controversial Constellation Program.
Right now the full mission is slated to cost $104 billion (U.S.).
Included in the cost is development of a new spacecraft dubbed Orion that is meant to carry people to the lunar surface.
The reusable craft will look more like an Apollo capsule than a space shuttle, but scientists still haven't determined how it will land back on Earth.
Orion's first few returns are expected to be Apollo-like ocean splashdowns, which will enable the mission team to fully test navigation while keeping the crew safe.
"The consequences of landing short, in the western United States, [would be] pretty grim," said Constellation program manager Jeff Hanley.
But Orion must also have the ability to make a safe ground landing.
In designing this safety backup, Hanley suggested that his team might develop a vehicle for which ground landings would become the preferred way to return to Earth.
Overall, Constellation scientists hope to match and even exceed the great triumphs of the Apollo program, which included the Apollo 11 voyage that first put a human on the moon.
But they are also planning to avoid some of the program's great tragedies—such as the Apollo 1 launchpad fire that claimed the lives of three astronauts.
A New Mexico launch pad, currently under construction, will be used to test abort systems that can blast a crew to a height of a mile (1.6 kilometers) and return them safely to Earth with three large parachutes.
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