The MOLA instrument is functioning as a passive radiometer and is routinely sampling the 1064-nm radiance of the Martian surface. Measurements are collected once a second and have a resolution of approximately 300 m x 3 km.
MOLA has not collected altimetry data since June 30, 2001, when the instrument oscillator stopped. Without the oscillator the laser does not receive fire commands. At the time of the oscillator anomaly, MOLA had been in space for 1696 days, and had undergone 216 power-on/off cycles. The MOLA laser had fired 671 million times in space and MOLA had made about 640 million measurements of the Martian surface and atmosphere. Until the anomaly, the laser energy had been nominal and steady at about 20 mJ/pulse. The June 30 event was the first anomaly in MOLA's operation since the MGS launch in November 1996 .
To measure the radiance of the Martian surface, the MOLA receiver is used to measure optical power at 1064 nm scattered by Mars within its receiver field-of-view. MOLA's passive radiometer mode was built into the instrument, but was previously used only to automatically adjust the settings of the ranging receiver thresholds. Passive radiances were collected throughout the MGS Mapping and Extended Mission, and these observations are only now being processed for scientific use. In the passive mapping mode, the instrument has been optimized for measuring radiance, and the instrument now has greater sensitivity than it did when used for ranging. Radiance measurements are being relayed back to Earth in the same manner as the altimetry data. The first data collected by MOLA in radiometer mode has been processed, calibrated and documented, and is undergoing review by the NASA Planetary Data System. The data will be released immediately after review.