NASA launching laser satellite to study Earth's changing ice

NASA is preparing to launch a laser-equipped satellite next month that will measure changes in the height of Earth's polar ice with unprecedented precision, helping scientists better understand how rapidly the ice sheets of Greenland and Antarctica are melting.

The Ice, Cloud and Land Elevation Satellite-2 (ICESat-2) is scheduled to launch from Vandenberg Air Force Base in California on September 15, NASA said.

The mission comes as scientists continue to monitor the growing contribution of melting polar ice to global sea-level rise. Melting from the Greenland and Antarctic ice sheets alone has contributed more than a millimetre per year to the rise in global sea levels in recent years, accounting for roughly one-third of the observed increase. The rate of ice loss has also been accelerating.

ICESat-2 is designed to measure annual changes in the elevation of land ice across Greenland and Antarctica to a precision roughly equivalent to the width of a pencil. It will collect about 60,000 elevation measurements every second, giving researchers a much more detailed picture of how the polar ice is changing.

"The new observational technologies of ICESat-2 will advance our knowledge of how the ice sheets of Greenland and Antarctica contribute to sea level rise," said Michael Freilich, Director of the Earth Science Division at NASA's Science Mission Directorate.

At the heart of the spacecraft is the Advanced Topographic Laser Altimeter System, or ATLAS. The instrument determines surface elevation by measuring the time taken by individual photons of laser light to travel from the satellite to Earth's surface and back.

ATLAS will fire its laser 10,000 times every second and send hundreds of trillions of photons towards Earth through six beams of green light. By analysing the returning photons, scientists will be able to determine changes in the height of ice surfaces with exceptional accuracy.

"That meant we had to engineer a satellite instrument that not only will collect incredibly precise data, but also will collect more than 250 times as many height measurements as its predecessor," said Doug McLennan, ICESat-2 Project Manager.

The satellite builds on a 15-year effort by NASA to monitor changes in polar ice. The programme began with the first ICESat mission in 2003 and continued with Operation IceBridge, an airborne research campaign launched in 2009 to track rapidly changing polar regions.

ICESat-2 will provide more frequent and detailed observations. As it travels from pole to pole, the satellite will pass over the same polar regions four times a year, allowing researchers to compare seasonal and annual changes in ice elevation.

The data could help scientists determine where ice is thinning or gaining height and improve understanding of the processes driving ice loss. Such information is critical for improving projections of future sea-level rise and assessing the potential impact on coastal communities around the world.

The satellite's mission will not be limited to the polar regions. ICESat-2 will also measure the height of Earth's ocean and land surfaces, including forests, providing data that could support a range of research into changes across the planet.