Lunar Reconnaissance Orbiter and LCROSS
A Moon mapper that watches new craters form, and a rocket stage crashed to find polar ice.
Key facts
- Agency
- NASA (United States)
- Type of mission
- Lunar orbiter and impactor
- Target
- The Moon
- Launched
- 18 June 2009
- Status
- Orbiter operating; LCROSS completed 2009
The Lunar Reconnaissance Orbiter, LRO, has circled the Moon since 2009, mapping it in more detail than any other world except Earth. Its narrow-angle camera can see objects about half a metre across, enough to photograph the Apollo landing sites, with the descent stages, rover tracks and even the paths the astronauts walked.
New craters
By comparing pictures of the same places taken years apart, scientists have found more than 200 fresh craters made since LRO arrived, and many thousands of smaller marks around them. One of them, about 18 metres wide, was made on 17 March 2013 by an impact bright enough to be seen as a flash by telescopes on Earth. These new craters measure how often the Moon, and so the Earth, is struck by small bodies today, and they show that the lunar soil is churned faster than once thought.
LCROSS
LRO was launched with a companion, LCROSS, the Lunar Crater Observation and Sensing Satellite. On 9 October 2009 the spent upper stage of the rocket was steered into Cabeus crater, near the south pole, a place never lit by the Sun. LCROSS flew through the plume and then crashed itself four minutes later. Its instruments detected water in the plume, about 5% of the material by mass, proving that ice lies in the permanently shadowed craters.
Why it matters to meteorites
LRO's maps of minerals, temperatures and young craters help trace where lunar meteorites could have come from and when they were launched.
Key dates
| Date | What happened |
|---|---|
| 18 June 2009 | LRO and LCROSS launched together on an Atlas V rocket. |
| 9 October 2009 | The rocket stage and then LCROSS struck Cabeus crater; water was found in the plume. |
| 17 March 2013 | A small impact on the Moon was seen as a flash from Earth; LRO later imaged the new crater. |
See where this mission fits among all the others in the mission timeline.
Did you know?
LRO's thermometer found the coldest places then measured in the Solar System, in polar craters at about −240 °C.
LRO has photographed the descent stages left at all six Apollo landing sites.