INTRO
Earth’s frozen regions – the cryosphere – are changing rapidly in our warming climate. Our planet's frozen and icy areas, called the cryosphere, are a key focus of NASA's Earth science research. ICESat- 2 is a satellite mission for measuring ice sheet elevation and sea ice thickness, as well as land topography, vegetation characteristics, and clouds. It will provide topography measurements of cities, lakes and reservoirs, oceans and land surfaces around the globe, in addition to the polar- specific coverage and also has the ability to detect seafloor topography up to 100 feet (30m) below the surface in clear watered coastal areas. One of the main purposes of ICESat-2 is measuring the changing of the elevation of ice sheets by its laser system and lidar to quantify the influence of melting ice sheet in sea-level raising.
LAUNCH
Ice, Cloud, and land Elevation Satellite 2 or ICESat-2, is a follow-on to the ICESat mission, was launched on 15 September 2018 from Vandenberg Air Force Base in California. The ICESat-2 spacecraft was built and tested by Northrop Grumman Innovation Systems in Gilbert, Arizona, while the on-board instrument, ATLAS, was built and managed by Goddard Space Flight Center in Greenbelt, Maryland. The satellite was launched on a Delta II rocket provided by United Launch Alliance. This was the last launch of the Delta II rocket.
SPACE LASERS
ICESat-2's sole instrument, the Advanced Topographic Laser Altimeter System, or ATLAS collects elevation data using six laser beams - which gives the new mission much denser coverage of Earth's surface. ATLAS measures the travel times of laser pulses to calculate the distance between the spacecraft and Earth’s surface. ATLAS is sensitive enough to detect individual photons, and has such a rapid firing rate, the instrument will be able to detect both the forest floor and the tops of canopies in all but the densest woods and jungles. The original ICESat had a single laser beam, collecting data in a grid shown to the left. With ICESat-2's six laser beams, the satellite will be able to take measurements in a much denser grid.
ATLAS
ATLAS will feature new technologies that will allow it to collect a more detailed, precise picture of the heights of the planet’s ice, vegetation, land surface, water and clouds. As it orbits over the poles, ATLAS has three major tasks: Send pulses of laser light to the ground, collect the returning photons in a telescope, and record the photon travel time. A notable attribute of ATLAS is that engineers enabled the satellite to control how it is positioned in space, which is relevant because ATLAS records the distance from itself to the ground, and if its position is off, the measurement recorded for Earth's elevation will be off as well. Engineers also constructed the laser reference system, which confirms that the laser is adjusted in accordance to the telescope. If either the telescope or the laser is off, the satellite can make its own adjustments accordingly. The trip from ATLAS to Earth and back takes about 3.3 milliseconds, give or take a microsecond.
THE FOUR SCIENCE OBJECTIVES
1. Measure how much melting ice sheets in Greenland and Antarctica contribute to sea
level changes
2. Measure how ice sheets, glaciers and more are gaining or losing mass in different
regions, to help researchers understand the mechanisms behind
4. Measure the height of forests to calculate the amount of vegetation in a region