MOLA, the Mars Orbiter Laser Altimeter, mapped Mars’s global topography aboard Mars Global Surveyor.
MOLA measured elevation by timing laser pulses sent from orbit to the Martian surface and reflected back to the spacecraft. These measurements produced a highly detailed global topographic map, revealing the planet’s dramatic elevation contrast between the northern lowlands and southern highlands.
The instrument also helped scientists study volcanoes, valleys, impact basins, and the shape of the polar ice caps. Mars Global Surveyor entered orbit in 1997 and operated for many years, making its topographic data a foundation for later geological and climate research.
MOLA is easy to confuse with other Mars instruments. HiRISE is a high-resolution camera on Mars Reconnaissance Orbiter, MARSIS is a subsurface radar on Mars Express, and THEMIS is an imaging instrument on Mars Odyssey. Only MOLA is the laser altimeter associated with this global elevation map.