This post was authored by Stephanie Marcus, Science Reference Librarian in the Science, Technology, and Business Division.
On November 8 the Library will welcome cryospheric scientist Tom Neumann, who will speak on “GRACE-FO and ICESat-2: NASA’s Leadership in Monitoring the Polar Regions from Space.” Dr. Neumann is deputy project scientist on ICESat-2 (Ice, Cloud, and land Elevation Satellite), which launched from Vandenberg AFB September 15, 2018 on the final flight of a Delta II rocket. ICESat-2 is on a three-year mission to study the Earth’s cryosphere–its frozen and icy areas. It carries the Advanced Topographical Laser Altimeter System (ATLAS), which sends out 10,000 laser pulses per second. ATLAS has a single laser split into six beams and arranged in three pairs to better gauge the slope of Earth’s surface. Mechanisms on board precisely time the round-trip of laser photons as they leave ATLAS, reflect off the ground and return to the receiver telescope. By matching those times with the satellite’s precise location in space, mission scientists will be able to determine the heights of Earth’s surface. If you love data, you will find it on the website of the National Snow and Ice Data Center: https://nsidc.org/ .
The first ICESat was operative from 2003-2009, after which Operation IceBridge continued the measurements with annual airborne flights over the Arctic and Antarctic. Our originally scheduled speaker, Thorsten Markus, was unable to present his talk, as he will be with IceBridge at the time of the lecture. Scientists are excited about this first time that IceBridge will be able to compare some of its measurements with ICESat-2.
Another mission, GRACE (Gravity Recovery and Climate Experiment), which launched in 2002 and ended in October 2017, consisted of twin spacecraft that flew about 137 miles apart in a polar orbit 310 miles above Earth. GRACE mapped Earth’s gravity field by making accurate measurements of the distance between the two satellites, using GPS and a microwave ranging system. It has revealed how water, ice and solid Earth mass move on or near Earth’s surface due to Earth’s changing seasons, weather and climate processes, earthquakes and even human activities, such as from the depletion of large aquifers. It did this by sensing minute changes in the gravitational pull caused by local changes in Earth’s mass, which are due mostly to how water is constantly being redistributed around our planet. The project’s Principal Investigator, Byron Tapley, remarked that “It has advanced our understanding of the contribution of polar ice melt to global sea level rise and the amount of atmospheric heat absorbed by the ocean. Recent applications include monitoring and managing global water resources used for consumption, agriculture and industry; and assessing flood and earthquake hazards.”
GRACE-FO (Follow on) launched on May 22, 2018 with new twin spacecraft. Both GRACE missions are a joint project with the German Research Centre for Geosciences. GRACE-FO uses the same microwave technology, however, they will also test an experimental instrument using lasers instead of microwaves, which promises to improve the precision of separation distance measurements on future generations of GRACE satellites by a factor of up to 20, due to the laser’s higher frequencies.
Dr. Neumann has been involved extensively in field work on the Greenland and Antarctic ice sheets, leading four expeditions and participating in five others between the two poles.
Date: Thursday, November 8, 2018
Time: 11:30 a.m.-12:30 p.m.
Place: The Pickford Theater, 3rd floor Madison building
For inquiries about this program, contact Stephanie Marcus in the Science, Technology & Business Division at [email protected] or the division office at: (202) 707-1212. Individuals requiring accommodations for this event are requested to submit a request at least five business days in advance by contacting (202) 707-6362 or [email protected].