NASA Completes Thermal Testing on Satellite’s ATLAS

Engineers at NASA’s Goddard Space Flight Center in Greenbelt Maryland have completed thermal testing on NASA’s Ice, Cloud and land Elevation Satellite-2, the ICESat-2, to assure it will perform at its best and take precise measurements both day and night in any temperature in the harsh environment of space.

“When we do these tests, we want to confirm that in the worst-case conditions on orbit, both hot and cold, with no air, you can still expect the performance that you want from the instrument. It’s an extreme test,” Melody Djam, system engineer at Goddard, said.

The team tested an instrument on the ICESat-2 called the Advanced Topographic Laser Altimeter System (ATLAS). The ATLAS, which is comprised of more than 20 different components, has three main functions. It sends light to the ground, ensures items are aligned to catch returning photons, records photon returns.

“Laser altimeters like ATLAS measure the distance between the instrument and the ground by timing how long it takes the light to travel to Earth, bounce off the surface, and return to the instrument. Using this distance, the satellite’s location in space, and the speed of light, the ICESat-2 mission will be able to precisely determine the height of Earth’s surface below,” according to Space Daily.

Vacuum testing was completed on the ATLAS and the engineers calculated how hot the ATLAS will get in orbit both in full sun and the Earth’s shadow. “With liquid nitrogen and heaters, the thermal vacuum then cycled four times between 55C and -25C,” according to the research group.

“The science team had designed different scenarios that reflect light in different ways – a glacier in summer, for example, results in different photon returns than a forest in fall or an ocean under cloudy skies. And the instrument also has to tell the difference between laser photons that it needs to count, and the static of background photons from natural sunlight. Plus, it has to do this under the different temperatures that could cause materials to expand or contract.”

The ATLAS performed well during testing. The computer systems were slow at points in collecting data but the research team plans to improve this within the next few months. The entire instrument is expected to be fully assembled and tested in 2016 and the completed ICESat-2 satellite is expected to go into orbit in 2017.


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