Last month, NASA's ICESat-2 laser tool was launched into orbit for the first time on September 30. With each of 10,000 pulses per second, the device sends 300 trillion. green photons of light on Earth, noting the time of their return. This method allows the satellite to observe changes in the Earth’s ice. On the morning of October 3, the satellite sent the first measurements of altitude throughout the entire Antarctic glacier.
ICESat-2 was launched on September 15 to determine how the heights change over time. The device accommodates an important ATLAS device that detects time photons with an accuracy of less than a billionth of a second, which allows the mission to detect even small changes on the planet’s ice sheets, glaciers and sea ice. As soon as ICESat-2 was in space, the team was waiting for the moment to turn on ATLAS. It was necessary to eliminate the presence of contamination, otherwise there is a risk of damaging the optics.
The ICESat-2 (photon cloud) data visualization shows the first set of altitude measurements from a satellite taken from orbit around the Antarctic ice sheet. Each blue dot is a photon detected by the ATLAS instrument. A photon cloud displays the height measured by photons in the middle of an ice sheet. Spotted points are background photons from sunlight, and the dense blue line is the concentration of laser photon points returned to the satellite. Within two weeks after launch, the ICESat-2 operational group switched on and tested various systems and subsystems of the spacecraft and instruments in order to bring the satellite into its polar orbit (at an altitude of 500 km above the Earth). Until the laser was turned on, it was important to open the airlock protecting the telescope and detector elements. This was successfully completed on September 29th. The next day, we rotated and tested the laser.
Optical-mechanical engineer Tyler Evans explains how ATLAS captures and filters returning photons from Earth
After 3 days, the ICESat-2 team received the first segment of altitude data obtained during the flight over Antarctica. Computer programs all night analyzed the latitude, longitude and elevation presented by each photon returned to ATLAS, and by 6 o'clock in the morning the height data for the others were compiled.
A bright green photon of light should travel from the NASA spacecraft to Earth and back to help complete an important scientific mission When studying preliminary ICESat-2 data, the researchers analyze a “photon cloud” —a graph of each photon returning to the ATLAS instrument. Many points in the cloud are background photons represented by natural sunlight reflected from the earth at the same wavelength as the laser photons.
The first photon cloud shows the length of the height measurements from East Antarctica, passing close to the South Pole at a latitude of 88 degrees south and stretching to West Antarctica. Next, ICESat-2 will work on a set of procedures to optimize the instrument, including tests, so that the laser points to exactly the right angle and generates at the correct wavelength. Full work will begin in a few weeks.