At any given moment, more than 2,000 thunderstorms producing on the order of 50 lightning flashes per second are active throughout the world. That’s a lot of lightning, and while no single space-based instrument could ever hope to capture it all, one instrument—the Lightning Imaging Sensor (LIS) on the International Space Station—has given scientists a more expansive look at global lightning than they’ve ever had.
“Even though we have the Geostationary Lighting Mapper (GLM) [aboard NOAA’s GOES-R series satellites] and Europe just launched their version of it, the Lightning Imager on their Meteosat Third Generation satellite, LIS on the space station can see parts of the world that are not observed by those geostationary instruments,” said Dr. Geoffrey Stano, chief scientist at NASA’s Global Hydrometeorology Resource Center Distributed Active Archive Center (GHRC DAAC).
LIS detects the distribution and variability of total lightning, including cloud-to-cloud, intra-cloud, and cloud-to-ground lightning, and it measures the amount, rate, and radiant energy of lightning during both day and night. Two LIS instruments were built in the 1990s, one for the Tropical Rainfall Measuring Mission (TRMM) and a spare that was kept in storage. The TRMM LIS operated successfully for more than 17 years, from launch in 1997 until April 2015. After TRMM ceased operations, the spare LIS was installed on the International Space Station in February 2017 for what was expected to be a two- to four-year mission. Now, more than six years later, NASA plans to decommission the space station's LIS by the end of 2023.
“The LIS instrument will be decommissioned sometime in [late-2023]. It just depends on when the SpaceX mission to the [International Space Station] occurs,” said Leigh Sinclair, team lead for GHRC's Data Management Group and Lightning Team. “If [the mission] gets pushed back, then the decommissioning will be pushed back.” [Editor's note: The SpaceX mission to the International Space Station launched on Thursday, November 9, and docked with the space station on Saturday, November 11.]
On whatever day the decommissioning occurs, it will mark the end of nearly 25 years of data from the two LIS sensors.
“If it had not been for the International Space Station, this instrument would never have flown, but because the space station gave it a home, we now have an additional six years of data to extend the history from the original LIS mission aboard TRMM,” Stano said. “Aside from a gap of about two years between 2015 and 2017, you pretty much have continuous observations from 1997 through 2023 between the TRMM LIS and the [space station] LIS, so you’re looking at about almost a quarter-century of data, which is really impressive for this style of observation.”