Journey to an Asteroid
The Orion CEV will create capabilites that have not existed since the time of Apollo. We have a Vision to reach the Moon, which humans first visited in 1969, and Mars someday after that. A huge number of strange new worlds are surprisingly close. NASA has been studying a mission to go where no one has gone before, to an asteroid.
In many ways an asteroid mission is even easier than reaching the Moon. Many asteroids pass nearly as close. Unlike the Moon or Mars, an asteroid does not have a big gravity well to descend into. Without even using a landing vehicle, an Orion could approach very close to an asteroid. The practical payoff could be enormous, because one of these Earth-crossers will someday hit the Earth!
Surprisingly little is known about the makeup of asteroids. The only "sample return" so far is from meteorites. Researchers are not sure whether they are solid objects or big rubble piles. That complicates any attempt to land on an asteroid or deflect it from Earth. Many asteroids are peanut-shaped, indicating that they are formed from two objects bumping into one another. Some asteroids may in fact be two objects orbiting closely around their common center of gravity.
The image of asteroids as big rocks may not be completely correct. The largest asteroid is Ceres, 580 kilometres in diameter. Observations recently published in NATURE suggest that Ceres may be largely made of water! It may contain even more water than the Earth. Water-asteroids striking the Earth may explain how we acquired water in the first place.
The best views of Ceres are from the Hubble Space Telescope. Though the view is fuzzy, Ceres has a mysterious bright spot. This looks a lot like the hot spot of Enceladus, a moon which contains water and is about the same size. Models of Ceres point to a differentiated interior, indicating an internal source of heat. Ceres may be considered a minor planet, with the same processes we have seen on other bodies. As with Enceladus, the interior of Ceres may be modelled with an internal singularity.