NASA rafts monitor Tahoe’s temperature
They may not look like they are part of NASA, but they are.
Four small, yellow rafts out near the middle of Lake Tahoe are quietly taking the lake’s temperature for comparison with NASA’s recently launched Terra satellite.
The Terra, a $1.3 billion satellite, was launched on Dec. 18 at Vandenberg Air Force Base, Calif. The satellite is the first to be launched as part of a 15-year mission to map the earth and review environmental and physical changes.
“We know the planet’s changing, what the Terra will do is give the planet a physical,” said Dr. Simon Hook, a research scientist at the Jet Propulsion Laboratory in Pasadena, Calif.
Working in collaboration with the University of California, Davis, Tahoe Research Group, Hook spent 12 hours in Tahoe City last Thursday preparing the rafts so that they would be ready when Terra sends its first temperature readings at the end of February.
The temperature readings are only one of Terra’s many different features.
“The Terra is taking the pulse of the planet,” Hook said.
“One of the problems we always face is how accurate are the satellite temperature measurements,” Hook said. By placing the rafts on Lake Tahoe, Hook hopes to resolve some of those problems.
“There are lots of reasons we choose Tahoe,” Hook said. “Tahoe is high, big and because it is water, the temperature is much more consistent.”
Lake Tahoe also has a few added bonuses: great water clarity keeps the equipment in good condition and the lake doesn’t freeze.
The rafts take continuous measurements of the lake’s surface temperature which can be downloaded by Hook in Pasadena. He can then calculate what the satellite sees by using atmospheric disturbance and wind speed equipment located on the U.S. Coast Guard’s dock in Tahoe City.
“It is important that the rafts make continuous measurements because the satellite will only be over Lake Tahoe for a few seconds and will not make it back over the lake for two weeks,” Hook said.
The rafts are nicknamed “doghouses” by Hook and raft designer Ali Abtahi because the solar panels form a roof over the 6-by-9 foot rafts. The rafts are painted bright yellow with reflective tape and hazard lights. Behind the rafts trails a small contraption nicknamed “the insect” because it looks like to a praying mantis, Hook said. The “insect” takes all of the measurements.
Hook also operates three other validation sites, all in Australia. The sites are set up on different types of terrain.
“We need to know how the satellite works over different terrain,” Hook said.
According to Hook, the rafts in Tahoe are operational and all they need to do now is wait for the satellite.
“It’s all maintenance from now on,” he said.
Eventually Hook wants to put weather stations on the rafts to help him calculate what the satellite sees.
“My hope is that we can do multiple satellite validations because Tahoe is so ideal,” Hook said.
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