NASA Lunar Reconnaissance Orbiter (LRO) and LCROSS Polar Crater Impactor
The NASA Lunar Reconnaissance Orbiter (LRO) and the Lunar Crater Observation and Sensing Satellite (LCROSS) are two different satellites which were launched together and sent to the moon in 2009 on two very different trajectories.
The Lunar Reconnaissance Orbiter's mission includes mapping the Moon's surface, with detailed 3D topology, in support of future manned missions. In addition, the LRO measured the radiation environment globally, so that we can design to protect humans and other life stationed there. Surface temperatures were also measured. Instruments included detectors to help measure the quantity and distribution of water ice, and cameras to take detailed photos of the surface.
The LRO went into a polar orbit and descended to an altitude of 50 km. This mission was very successful.
Lunar Crater Observation and Sensing Satellite (LCROSS) was designed to impact a permanently shadowed crater in the south pole region in order to kick up material for inspection to measure the quantity and types of volatiles which may be frozen there. LCROSS consisted of a spent fuel tank to kick up the material (its Centaur upper stage), plus a small second satellite called The Shepherding Spacecraft to fly thru the debris four minutes later to make close up measurements and quickly report the results before it impacted itself very shortly thereafter.
LCROSS was put into a very different orbit from LRO. LCROSS was put into a high polar Earth orbit at nearly the same distance as the Moon, and oriented to come down onto the Moon's pole at a steep angle.
The Cabeus crater near the Moon's south pole was chosen for the impact experiment, and the results confirmed the presence of water (ice) in the lunar pole, confirming the findings of the Clementine and Lunar Prospector missions. Estimates of the concentrate were roughly 6% (officially 5.6% plus or minus 2.9%).
The plumes of both impacts actually consisted of much less material than expected. There had been a major public relations campaign saying that it would be visible using moderately sized telescopes from Earth, but this turned out to not be the case. Nonetheless, the plume was large enough for scientific instruments to measure the water composition.
In December, 2010, a topographic map of the Moon was released to the public, which became the most detailed map of the Moon. Resolution is 100 meters per pixel. The LRO continues to send data back.
Notably, the LRO collected more data than all other planetary missions combined to date, 192 terabytes, because the LRO has a dedicated ground station rather than needing to share time on NASA's Deep Space Network, and also because the Moon is close to us.