Cameras on the ground capture the elusive laser of a NASA satellite

   MADRID, 18 Abr. (EUROPA PRESS) -

Cameras for the observation of meteorites installed near Mount Fuji, in Japan, accidentally captured laser beams from NASA's ICESat-2 satellite as it passed over the Japanese country.

The glowing green lines that appeared in a video taken on September 16, 2022 were initially a mystery, until Hiratsuka City Museum curator Daichi Fujii, who operates the cameras, traced their provenance to the satellite of the POT.

It's the first time the ICESat-2 team has seen images of the satellite's green laser beams being transmitted from orbit to Earth, Tony Martino, ICESat-2 instrument scientist at the Goddard Space Flight Center in New York, said in a statement. NASA in Greenbelt, Maryland.

"ICESat-2 appeared to be almost directly overhead, with the beam hitting the low clouds at an angle," Martino said. "To see the laser, you have to be in exactly the right place, at the right time, and you have to have the right conditions."

ICESat-2 launched in September 2018 with a mission to use laser light to measure the height of Earth's ice, water, and land surfaces from space. The laser instrument, called lidar, fires 10,000 times per second, sending six beams of light to Earth. Precisely calculate the time it takes for individual photons to bounce off the surface and return to the satellite. Computer programs use these measurements to calculate ice losses from Greenland and Antarctica, look at how many polar oceans are frozen, determine the heights of freshwater reservoirs, map shallow coastal regions, and more.

Fired from hundreds of kilometers into space, laser light is not harmful. In fact, it is difficult to detect. If someone stood directly under the satellite and looked up, the laser would have the force of a camera flash 100 meters away, Martino said.

Amateurs have tried to photograph the satellite as it passed, and in a couple of cases they were able to capture photos, one from southern Chile and one from Oklahoma.

The beam is even more difficult to capture, Martino noted, since cameras and eyes need laser light to reflect off something to see the beam from the side. That's where weather conditions come in.

However, on the night that ICESat-2 passed over the city of Fuji, there were enough clouds to scatter the laser light, making it visible to cameras, but not enough to block the light completely. There were actually two thin layers of clouds over Japan that night — information Martino found by analyzing ICESat-2 data, which shows clouds and the ground below.

With the precise location of the satellite in space, the location of the lightning strike, the coordinates of where Fujii's cameras were installed, and the addition of cloud conditions, Martino was able to definitively confirm that the light rays were coming from of Laser of ICESat-2.