LIDAR Findings

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This web site will report the LIDAR findings -- new information about the clouds and atmosphere of Mars -- as soon as they become available.

Mounted on the Mars Polar Lander, the LIDAR instrument sends a laser beam with a wavelength of 0.88 microns pulsing upward. The instrument then measures the light that dust and aerosol particles (such as haze and clouds) bounce back to the craft.

In the active mode, the instrument uses a gallium-aluminum-arsenide laser diode, emitting a low-energy pulsed beam that is reflected off whatever aerosol and dust particles exist in the sky. The reflected light is measured by a single-photon avalanche diode. The amount of light registered by this diode indicates the amount of dust and aerosol particles in the sky. Such measurements might show haze or clouds on Mars and, consequently, give indications about the distribution of the frost on the martian surface.

The LIDAR will also notice fine particulates in the martian atmosphere other than the expected, ever-present dust. And the instrument should also measure the scattering layers from clouds, thereby providing an indication of cloud heights in the martian atmosphere.

In the passive mode (without the laser transmitter), the instrument will measure the sky and cloud brightness and monitor the Sun or even Phobos' scattered light in a vertical column above the lander. The Lidar is also expected to detect ice haze or cloud layers during sunrise and sunset.

* Information on this page has been adapted from "Russian Science on a U.S. Spacecraft," by Vyacheslav (Slava) Linkin, Mars Underground News, vol. 8, no. 2, second quarter, 1996.

IKI, Russia's Space Research Institute