A Frustrating Situation

Sept. 22, 2015
Ec Jk

Attempts to repair a faulty satellite finally came to a conclusion late last month—unsuccessfully.

NASA’s SMAP satellite, launched in January, was designed to measure moisture in the soil worldwide. Using both radar and microwave radiometer systems sharing a single reflector, the satellite was intended to provide a new soil moisture map every few days. (SMAP stands for Soil Moisture Active and Passive.) Using the two different components—the passive microwave radiometer is more sensitive to soil moisture, but the active radar provides higher resolution data—would be, one NASA scientist said, like “looking through both lenses on a pair of bifocals at the same time.”

Attempts to repair a faulty satellite finally came to a conclusion late last month—unsuccessfully. NASA’s SMAP satellite, launched in January, was designed to measure moisture in the soil worldwide. Using both radar and microwave radiometer systems sharing a single reflector, the satellite was intended to provide a new soil moisture map every few days. (SMAP stands for Soil Moisture Active and Passive.) Using the two different components—the passive microwave radiometer is more sensitive to soil moisture, but the active radar provides higher resolution data—would be, one NASA scientist said, like “looking through both lenses on a pair of bifocals at the same time.” [text_ad] Data from the satellite would have both immediate and long-term uses. Knowing where soils were already saturated could help predict the likelihood of flooding and landslides, and even help predict the weather, because areas with very moist soils tend to support larger storms. Farmers in drought-stricken regions could time their planting based on soil moisture to increase crop yields. Long-term mapping of the variations in soil moisture would ultimately help scientists understand the water, energy, and carbon cycles. It took a few months after launch for the reflector to fully deploy and for SMAP to start transmitting data; the first soil moisture maps were released on April 21. Operations went smoothly for a few more months. But things began to go wrong in July, when the radar stopped transmitting data. A special team was formed at the Jet Propulsion Laboratory to troubleshoot the problem. Their efforts are documented on a NASA website, although the last entry there is dated August 5, at which time the team was still working on the problem. On August 24, according to a NASA statement, a last—and unsuccessful—attempt was made to power up the radar, and the agency now believes there are no further options and the radar is not recoverable. Some data will still be available from the microwave radiometer, and the mission to map global soil moisture will continue, but without the high resolution the radar would have provided.

Data from the satellite would have both immediate and long-term uses. Knowing where soils were already saturated could help predict the likelihood of flooding and landslides, and even help predict the weather, because areas with very moist soils tend to support larger storms. Farmers in drought-stricken regions could time their planting based on soil moisture to increase crop yields. Long-term mapping of the variations in soil moisture would ultimately help scientists understand the water, energy, and carbon cycles.

It took a few months after launch for the reflector to fully deploy and for SMAP to start transmitting data; the first soil moisture maps were released on April 21. Operations went smoothly for a few more months. But things began to go wrong in July, when the radar stopped transmitting data. A special team was formed at the Jet Propulsion Laboratory to troubleshoot the problem. Their efforts are documented on a NASA website, although the last entry there is dated August 5, at which time the team was still working on the problem. On August 24, according to a NASA statement, a last—and unsuccessful—attempt was made to power up the radar, and the agency now believes there are no further options and the radar is not recoverable.

Some data will still be available from the microwave radiometer, and the mission to map global soil moisture will continue, but without the high resolution the radar would have provided.
About the Author

Janice Kaspersen

Janice Kaspersen is the former editor of Erosion Control and Stormwater magazines.