DSCOVR camera captures mysterious light flashes: NASA

DSCOVR camera captures mysterious light flashes

The powerful camera on board NASA’s Deep Space Climate Observatory (DSCOVR) has captured hundreds of flashes of light coming from above our planet’s surface that scientists say are caused by sunlight reflecting off minute ice particles.

Launched in 2015, DSCOVR is an Earth and space weather satellite. Its camera captured the flashes of light that occurred hundreds of times over the extent of a year.

The eagle-eyed instrument captures images of Earth almost hourly from a location between the plant and its host star.

After analyzing the images captured by the DSCOVR camera, the scientists determined that the flashes were the result of light reflecting off ice particles floating nearly horizontally in the air.

NASA researcher Alexander Marshak said in a statement, “The source of the flashes is definitely not on the ground. It's definitely ice, and most likely solar reflection off of horizontally oriented particles.”

Scientists are now trying to determine how common the floating ice particles are, and how they affect light and heat coming from the Sun.

The NASA release further informed...

NASA’s Earth Polychromatic Imaging Camera (EPIC) instrument aboard DSCOVR is taking almost-hourly images of the sunlit planet from its spot between Earth and the sun. Alexander Marshak, DSCOVR deputy project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, first noticed light flashes occasionally appearing over oceans as he looked through that day’s EPIC images.

Investigating the flashes, Marshak and his colleagues found that similar reflections from our pale blue dot caught the attention of astronomer Carl Sagan in 1993. Sagan was looking at images taken by the Galileo spacecraft, which launched in 1989 to study Jupiter and its moons. During one if its gravitational-assist swings around Earth, Galileo turned its instruments on this planet and collected data. Sagan and his colleagues used that to test a key question: Whether spacecraft could detect signatures of life from afar.

Flashes of light reflected off oceans – like those referenced by Sagan – could have a simple explanation, Marshak said: Sunlight hits a smooth part of an ocean or lake, and reflects directly back to the sensor, like taking a flash-picture in a mirror.

But when the scientists took another took a look at the Galileo images, they saw something Sagan and his colleagues apparently missed -- bright flashes of light over land as well. And those flashes appeared in the EPIC images as well. As the contact listed on the website that posts all EPIC images, Marshak started getting emails from people curious about what the flashes were.

“We found quite a few very bright flashes over land as well,” he said. “When I first saw it I thought maybe there was some water there, or a lake the sun reflects off of. But the glint is pretty big, so it wasn’t that.”

The scientists reasoned that if these 866 flashes were caused by reflected sunlight, they would be limited to certain spots on the globe – spots where the angle between the sun and Earth is the same as the angle between the spacecraft and Earth, allowing for the spacecraft to pick up the reflected light. When they plotted the locations of the glints with where those angles would match, given Earth’s tilt and the spacecraft’s location, the two matched.

This helped confirm that it wasn’t something like lightning causing the flashes, Marshak said: “Lightning doesn’t care about the sun and EPIC’s location.” The researchers also plotted angles to determine that the light was reflecting off of ice particles floating in the air nearly horizontally.

Another feature of the EPIC data helped confirm that the flashes were from a high altitude, not simply water on the ground. Two channels on the instrument are designed to measure the height of clouds, and when the scientists went to the data they found high cirrus clouds, 3 to 5 miles (5 to 8 kilometers) where the glints were located.

“The source of the flashes is definitely not on the ground. It’s definitely ice, and most likely solar reflection off of horizontally oriented particles,” Marshak said.

Detecting glints like this from much farther away than in this case could be used by other spacecraft to study exoplanets, he said. As an Earth scientist, however, Marshak is now investigating how common these horizontal ice particles are, and whether they’re common enough to have a measurable impact on how much sunlight passes through the atmosphere. If so, it’s a feature that could be incorporated into computer models of how much heat is reaching and leaving Earth.

The DSCOVR mission is a partnership between NASA, the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Air Force, with the primary objective to maintain the nation’s real-time solar wind monitoring capabilities, which are critical to the accuracy and lead time of space weather alerts and forecasts from NOAA.

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