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The Mars Orbiter Laser Altimeter (MOLA) was one of five instruments on board the Mars Global Surveyor (MGS) spacecraft, which operated in Mars orbit from September 1997 to November 2006. However, the MOLA instrument transmitted altimetry data only until June, 2001. The MOLA instrument transmitted infrared laser pulses towards Mars at a rate of 10 times per second, and measured the time of flight to determine the range (distance) of the MGS spacecraft to the Martian surface. The range measurements resulted in precise topographic maps of Mars. The precision maps are applicable to studies in geophysics, geology and atmospheric circulation. MOLA also functioned as a passive radiometer, and measured the radiance of the surface of Mars at 1064 nanometers.〔 This article contains public domain material from NASA Goddard Flight Center web site. 〕 ==Planetary laser altimetry== A laser altimeter is an instrument that measures the distance from an orbiting spacecraft to the surface of the planet or asteroid that the spacecraft is orbiting. The distance is determined by measuring the complete round trip time of a laser pulse from the instrument to the surface of the planet or asteroid and back to the instrument. The distance to the object can be determined by multiplying the round-trip pulse time by the speed of light and dividing by two. With a well-known attitude and position of the instrument or spacecraft, the location on the surface, which is illuminated by the laser pulse can be determined. The series of the laser spot, or footprint, locations provides a profile of the surface.〔 This article contains public domain material from NASA Goddard Flight Center web site. 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mars Orbiter Laser Altimeter」の詳細全文を読む スポンサード リンク
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