Lunar Reconnaissance Orbiter (LRO)

About Lunar Reconnaissance Orbiter (LRO):

• It is a NASA spacecraft that was launched on June 18, 2009.
• Primary Objective: To make a 3D map of the Moon's surface from lunar polar orbit.
• It has also been used to study the Moon's geology, mineralogy, and environment.
• It orbits the Moon in an eccentric polar mapping orbit.
• LRO is equipped with 7 science instruments, the most well-known of which is a 195-millimeter (7.7-inch) telescope and camera system that can see details up to 2.5 meters across. 
• LRO is equipped with a laser altimeter that produces 3D maps by shooting lasers at the surface and measuring reflection times.
• The spacecraft also carries two instruments suited to peering into dark craters to search for signs of water ice, and a temperature instrument that led to the discovery of the coldest place in the solar system.

Q1) What is an Altimeter?

An altimeter is a device used to measure altitude, which is the height or elevation above a specific reference point, usually the Earth's surface or sea level. Altimeters are commonly used in aviation, mountaineering, and various other applications where knowing one's vertical position is essential.

Source: India's Chandrayaan-3 moon lander spotted from lunar orbit (photo)