Kate Ramsayer – ICESat-2

ICESat-2’s Laser Fires 2 Trillionth Shot, Spots Clouds

Happy 2,000,000,000,000th, ICESat-2! NASA’s Earth-observing laser in orbit passed a milestone on March 9 at 12:51 p.m. EDT — 16:51:00.268 UTC, to be precise — as its laser instrument fired for the 2 trillionth time and measured clouds off the coast of East Antarctica.

A data visualization with a bright blue background and dots, representing height measurements taken by ICESat-2. A vertical green line marks the satellite's 2 trillionth laser pulse. An inset map of Antarctica shows a green line from the interior of the continent, through a spot labeled Vanderford Glacier, and out into the southern ocean, locating data shown on the larger plot. — ICESat-2’s height-measuring laser instrument, ATLAS, fired its 2 trillionth shot on March 9, detecting clouds off the coast of East Antarctica. This data plot of surface heights marks that milestone with a vertical green line. In the few minutes before and after the shot, ICESat-2 measured the surface of the ice sheet and high clouds over the coast (in the left of the image), followed by clouds and a couple breaks where the ocean surface is detected. (Credit: NASA/A. Martino)

ICESat-2’s instrument, the Advanced Topographic Laser Altimeter System (ATLAS), uses rapid pulses of green laser light and an incredibly precise clock system to track the height of Earth’s surface from space. Its first measurements from orbit profiled the Antarctic ice sheet in September 2018.

Since then, it’s fired 10,000 times a second to provide height profiles of the planet’s changing glaciers, sea ice, water reservoirs, forests and more — even detecting the coastal seafloor in places.

The laser is in excellent shape, even after six years and a couple trillion shots, said Anthony Martino, ATLAS instrument scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. At this rate, it could last well into the 2030s, he said — and there’s a second laser aboard that the mission could switch to, if needed.

On a dark background, six rows of dots arranged in pairs go from the top left of the image toward the bottom right in a bumpy, uneven slope - data measurements of a glacier surface. — ICESat-2’s six beams measured height profiles of Vanderford Glacier less than two minutes before the 2 trillionth shot, capturing the glacier’s topography and the surrounding ice. (Credit: NASA/ A. Martino)

While the primary mission of ICESat-2 is to measure ice, ATLAS operates around the clock and the 2 trillionth shot captured a common sight: clouds. About 79 seconds earlier, it passed over the clear skies of the Antarctic ice sheet as it flows down Vanderford Glacier and into the Southern Ocean.

Vanderford Glacier is East Antarctica’s fastest retreating glacier, as warmer ocean water seeps in to melt it from below, according to a recent study. And it’s a prime example of what scientists can use ICESat-2 data for, said Denis Felikson, ICESat-2 deputy project scientist at NASA Goddard.

to the left, a map of a section of East Antarctica with ice height gains, in blue, and losses, in red, from ICESat-2 data between 2019 and 2024. Vanderford Glacier is labelled and red. To the right, a line graph showing the drop, then slight rebound, then drop in elevation of a site on Vanderford. — An ICESat-2 data visualization shows the gain (blue) and loss (red) of ice in Vanderford Glacier (black circle) and the nearby regions of East Antarctica between 2019 and 2024. Taking data from a single site within that black circle, scientists can also get a continuous picture of the ice throughout the years. (Credit: D. Felikson/NASA)

Tracking a specific site on Vanderford throughout ICESat-2’s record, for example, shows how the ice surface dropped about six feet between 2019 and 2022, rose a few feet the next year, but then dropped back down in 2024. Zoom out, and researchers can track elevation across the glacier and its surroundings.

“With data from 2 trillion laser shots, and more to come, we have this consistent global record of all of Earth’s ice from space, at glacier scales but also in really fine detail,” Felikson said. “Both of these scales are critical for us to understand how Earth is changing over time.”

Against a black background, a line of bright blue dots go in a wavy horizontal line. These are height measurements of ocean waves from ICESat-2. — Through a break in the clouds a few seconds after the 2 trillionth shot, ICESat-2 captured waves of the Southern Ocean. (Credit: A. Martino/NASA)

By Kate Ramsayer, NASA’s Goddard Space Flight Center

NASA’s ICESat-2 Resumes Data Collection After Solar Storms

An artist's rendering of Earth, shown in natural colors against black space. Superimposed on the globe are green lines, representing the orbital paths of ICESat-2. The satellite is labeled as a dot along one of the orbits — An artist’s rendering of the orbital paths of ICESat-2, seen in green. ICESat-2 is now back in its normal orbit, after solar storms in May created unexpected drag on the spacecraft. (Credit: NASA’s Goddard Space Flight Center)

NASA’s ICESat-2 satellite returned to science mode on June 21 UTC, after solar storms in May caused its height-measuring instrument to go into a safe hold. The ICESat-2 team restarted the mission’s instrument, a lidar called the Advanced Topographic Laser Altimeter System (ATLAS), which is once again collecting precise data on the height of Earth’s ice, water, forests and land cover. No damage to the spacecraft or instrument has been detected.

The ICESat-2 instrument had been in a safe hold since May 10, when solar storms created unexpected drag on the spacecraft. This triggered an automated response to turn ATLAS off to protect the instrument. The storm also pulled the spacecraft out of its regular orbit and it drifted down 3.7 miles (6 kilometers) vertically.

The ICESat-2 operations team conducted a series of thruster burns to return the satellite to its desired orbit and completed a sequence of commands to turn ATLAS back on. The team also conducted routine fine-tuning of the laser temperatures.

Data from the instrument are now being collected as before the solar storm, and the ICESat-2 team will continue to monitor the spacecraft and instrument, said project scientist Tom Neumann of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Observations from ICESat-2 are available free to the public at www.nsidc.org, which includes 5 ½ years of the satellite’s critical measurements of Earth’s changing ice sheets, glaciers, sea ice, forested areas, inland water bodies, and more.

After Solar Storms, ICESat-2 Expected to Resume Operations in Mid-June

An artist's rendering of the ICESat-2 satellite over Earth. The background is black, and the bottom third of the image is filled with a curving horizon of Earth, with white clouds and ice, blue ocean and green land. The ICESat-2 satellite orbits above Earth. It's a slivery box-like structure with blue solar panels off to the right. Bright green lines come down from the satellite, representing its laser. — An artist’s rendering of ICESat-2. The satellite went into a safe hold following solar storms in May 2024, and is expected to return to science mode in mid-June. (Credit: NASA’s Goddard Space Flight Center)

After going into a safe hold on May 10 due to impacts from the strongest solar storm to hit Earth in two decades, the lidar instrument on NASA’s ICESat-2 satellite is scheduled to resume collecting data around June 17. The storm did not cause any detectable damage to the satellite or its instrument.

Between May 7 and May 11, strong solar flares and coronal mass ejections were released from the Sun and sparked a geomagnetic storm at Earth that caused our planet’s atmosphere to expand in places. This created unexpected drag on ICESat-2, rotating the satellite, and triggering the satellite to enter safe hold, which turned off ICESat-2’s science instrument.

The ICESat-2 team has conducted two thruster burns to raise the spacecraft’s altitude, allowing it to now drift back to its normal orbit around 310 miles (500 kilometers) above Earth. Once there, the team will return the Advanced Topographic Laser Altimeter System instrument to science mode, to continue measuring the height of Earth’s ice, water, forests, and land cover.