Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Keeping a Close Eye on Ice Loss

18.05.2018

AWI contributes two million euros towards the cost of a new satellite mission

GRACE-FO mission launch on 22 May 2018 at 12:47 p.m. PST


GRACE-FO

Illustration: NASA/JPL-Caltech

A few months ago, the GRACE mission’s two Earth observation satellites burnt up in the atmosphere. Although this loss was planned, for the experts at the Alfred Wegener Institute it left a considerable gap in monitoring ice loss in the Antarctic and Greenland. Now the follow-up mission will finally be launched, and will play a vital role in predicting future sea level rise.

Without a doubt, one of the greatest threats in connection with climate change is the continuing rise in sea level – and the more intensively the enormous ice sheets in Greenland and the Antarctic melt, the worse it will become.

To more accurately gauge the loss in mass of these large ice sheets, scientists at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) permanently evaluate Earth observation data gleaned from satellites.

For them, the GRACE satellites were an extremely important pair of spacecraft. They had been in orbit since 2002, but in 2017, at the ripe old age of 15 they were decommissioned, and early this year they made a controlled re-entry into the Earth’s atmosphere, where they burnt up as planned. Ever since then, the AWI experts and the international research community have had to do without an important source of information on the condition of the large ice sheets.

And now, to fill that gap, at 12:47 p.m. PST on 22 May 2018, the successor, GRACE Follow-On (GRACE-FO) will be launched into orbit from Vandenberg Air Force Base in California (USA). “We’re delighted,” says AWI geophysicist Ingo Sasgen.

“For 15 years, the GRACE mission provided us with unique and fascinating time sequences on the ice sheets’ mass losses. Since June 2017, this time sequence has been interrupted, which means that we don’t have any data on the last melt season in Greenland. It’s very good news that the measurements are now going to be continued.”

GRACE stands for “Gravity Recovery And Climate Experiment”. As the name suggests, the satellites' task is to measure the Earth’s gravitational field on a monthly basis. This gravity data can then be used by various experts for different purposes. It is particularly important for the AWI’s researchers, because the changes in ice mass in Greenland and the Antarctic can be clearly seen in the Earth’s gravitational field.

If more ice is lost as a result of melting or calving than can be recovered through snowfall, the mass of the ice sheet decreases, and so does the gravitational field in that area. Accordingly, the GRACE measurements can tell us whether or not, where, and by how much the ice sheets shrink or grow.

The two GRACE satellites employ a microwave radar system to permanently measure the distance between them, and normally fly approximately 220 kilometres apart. If the first satellite flies over an area with higher gravity, it is slightly attracted and thereby accelerated.

This increases its distance from the second satellite, and the discrepancy shows how great the change in gravity is within a radius of circa 400 km. The accuracy of this approach is extraordinary – it can measure the distance between the twin satellites to within a few micrometres.

The new GRACE mission will also rely on microwave radar. “To allow the second mission to launch quickly and not to lose too much time and risk gaps in the data, the choice was made to use tried and trusted technologies,” explains Ingo Sasgen. “However, there is also a laser measuring device on board, which will be tested during the mission. Roughly 25 times more accurate than the microwave radar, we believe it can further improve the gravitational field analysis.”

As with the previous mission, the German Research Centre for Geosciences (GFZ) and NASA are providing the scientific support for the GRACE-FO mission. The German Aerospace Center will carry out the mission on behalf of the GFZ. In turn, the AWI will contribute not only its ice expertise, but also two million euros to help cover the cost of the Falcon 9 booster rocket from SpaceX.

The data provided by GRACE-FO will be essential, as it will not only allow Ingo Sasgen and his colleagues to help determine how major ice sheets are responding to the on-going global warming; they will also feed the data into mathematical models known as numerical climate models to predict how ice losses will evolve over time.

Further, GRACE-FO will conduct high-precision gravity-field measurements, which experts at the AWI will combine with readings from other satellites, e.g. CryoSat-2, which uses radar to accurately measure the thickness of sea-ice cover. CryoSat-2 can be used e.g. to identify which parts of an ice sheet had the most snowfall. In addition, GRACE-FO will scan 400-kilometre grid sections, which is comparatively coarse. Measuring five-kilometre sections on average, CryoSat-2 offers significantly higher resolution. But CryoSat-2 has limitations of its own: its radar sweep also penetrates into the upper layers of snow and ice, making it difficult to precisely measure their thickness, especially since the exact conditions on-site are unknown.

To compensate for this aspect, the AWI also takes calibration readings with its research aircraft. A further source of uncertainty: over time, snow collapses under its own weight, which can skew measurements of its thickness. According to Ingo Sasgen, “With the CryoSat-2 data alone, it’s impossible to say whether a change in the thickness of ice and snow was produced by the snow compacting, or by melting. That’s why we need GRACE Follow-On; the respective change in the gravitational field shows us whether or not ice and snow are actually being lost.” In essence, the satellites constitute a perfect match, as they offer complementary strengths.

With the start of the GRACE-FO mission, after roughly a year an important gap in satellite monitoring will become a thing of the past. As with its predecessor, the planned mission duration is five years. But Ingo Sasgen hopes that the second generation, just like the first, might continue to provide data for as long as 15 years. “We would then have a time series covering roughly 30 years, which would mean a truly representative timespan for climate models. The data gained will be a valuable resource for climate research, today and for decades to come.”

Notes for Editors:

Printable images and graphics are available in the online version of this press release at: https://www.awi.de/nc/en/about-us/service/press.html

Your scientific contact person at the Alfred Wegener Institute is Dr Ingo Sasgen (tel.: +49 (0)471 4831 2468; e-mail: ingo.sasgen(at)awi.de).

Your contact person in the Communications Dept. of the AWI is Sebastian Grote (tel.: +49(0)471 4831-2006; e-mail: media(at)awi.de).

Follow the Alfred Wegener Institute on Twitter (https://twitter.com/AWI_Media) and Facebook (www.facebook.com/AlfredWegenerInstitute).

The Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) conducts research in the Arctic, Antarctic and oceans of the high and mid-latitudes. It coordinates polar research in Germany and provides major infrastructure to the international scientific community, such as the research icebreaker Polarstern and stations in the Arctic and Antarctica. The Alfred Wegener Institute is one of the 18 research centres of the Helmholtz Association, the largest scientific organisation in Germany.

Ralf Röchert | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

More articles from Information Technology:

nachricht Your Smartphone is Watching You: Dangerous Security Holes in Tracker Apps
13.08.2018 | Fraunhofer-Institut für Sichere Informationstechnologie SIT

nachricht Another step forward on universal quantum computer
13.08.2018 | Yokohama National University

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

Im Focus: World record: Fastest 3-D tomographic images at BESSY II

The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.

Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...

Im Focus: A molecular switch may serve as new target point for cancer and diabetes therapies

If certain signaling cascades are misregulated, diseases like cancer, obesity and diabetes may occur. A mechanism recently discovered by scientists at the Leibniz- Forschungsinstitut für Molekulare Pharmakologie (FMP) in Berlin and at the University of Geneva has a crucial influence on such signaling cascades and may be an important key for the future development of therapies against these diseases. The results of the study have just been published in the prestigious scientific journal 'Molecular Cell'.

Cell growth and cell differentiation as well as the release and efficacy of hormones such as insulin depend on the presence of lipids. Lipids are small...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

Can radar replace stethoscopes?

14.08.2018 | Medical Engineering

The end-Cretaceous extinction unleashed modern shark diversity

14.08.2018 | Life Sciences

Light-controlled molecules: Scientists develop new recycling strategy

14.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>