Featured Research

from universities, journals, and other organizations

New Gravity Mission On Track To Map Earth's Shifty Mass

Date:
September 13, 2002
Source:
NASA/Jet Propulsion Laboratory
Summary:
Six months into its mission to precisely measure Earth's shifting water masses and map their effects on Earth's gravity field, the joint NASA-German Aerospace Center Gravity Recovery and Climate Experiment, or Grace, is already producing results of considerable interest.

Six months into its mission to precisely measure Earth's shifting water masses and map their effects on Earth's gravity field, the joint NASA-German Aerospace Center Gravity Recovery and Climate Experiment, or Grace, is already producing results of considerable interest.

Using just 14 days of data, a preliminary Grace gravity field map has already been produced and is proving to be substantially more accurate than the combined results of more than three decades of satellite and surface instrument gravity measurements collected before Grace.

Grace Principal Investigator Dr. Byron Tapley of the University of Texas Center for Space Research in Austin said preliminary data analyses provide strong validation for the Grace mission concept and its on-orbit sensor and satellite performance. "The quality of these preliminary Grace gravity fields tells us that the mission is on track to achieve its performance objectives," Tapley said. "In addition to improving our knowledge of Earth's mean gravity field, the ability to measure time variations in gravity will be a new and important Grace contribution."

"This first Grace gravity field data is about 10 times more accurate for large-scale features than any pre-Grace gravity model of Earth," said Dr. Michael Watkins, Grace project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "While these first fields are already extremely promising, we expect to do up to 10 times better after we perform additional calibrations of the instruments."

"The Grace mission will soon demonstrate its mission goal to help us better understand how variations in Earth's gravity field reflect changes in climate," said Dr. Christoph Reigber, Grace co-principal investigator at the German Geo-Research Center and principal investigator for the German Challenging Minisatellite Payload, or Champ, mission. Champ was launched two years ago as the first in a series of dedicated Earth gravity field missions planned for this decade and is operating in parallel with Grace.

"Our joint U.S.-German science team continues to process and evaluate Grace's diverse geophysical data in preparation for the release of our first science products in the near future," Reigber added.

Launched March 17, 2002, Grace senses minute variations in Earth's surface mass and corresponding variations in Earth's gravitational pull. The monthly gravity maps generated by Grace will be up to 1,000 times more accurate than current maps, substantially improving the accuracy of many techniques used by oceanographers, hydrologists, glaciologists, geologists and other scientists to study phenomena that influence climate.

Among the first and most important applications for Grace's data will be to improve our understanding of global ocean circulation. The hills and valleys in the ocean's surface are due to currents and variations in Earth's gravity field. Grace enables separation of those two effects to better measure ocean currents and their effect on climate.

"These first results from Grace look very promising from an oceanographic point of view," said Dr. Lee-Lueng Fu, Topex/Poseidon and Jason-1 project scientist at JPL. "Even with this preliminary gravity field, Grace has enabled us to use Topex/Poseidon and Jason-1 data to determine ocean circulation features more accurately."

Grace measures Earth's gravity field by measuring the separation between the twin satellites with an accuracy of one millionth of a meter (less than 1/10th the width of a human hair). Grace's instruments must all work together and be very accurately calibrated and aligned, a process the Grace project is just now completing during the mission's commissioning phase, which began in early April. Science instruments and supporting systems such as ground data processing have been activated, evaluated and calibrated.

Watkins says the twin satellites and the mission's science data system are generally performing well. "We're basically observing the smallest details of how these satellites behave on orbit, 'fine tuning' them, and adjusting our analyses to take those details into account," he said.

Grace is a joint partnership between NASA and the German Aerospace Center (Deutsches Zentrum fuer Luft und Raumfahrt, or DLR). The University of Texas' Center for Space Research has overall mission responsibility. GeoForschungsZentrum Potsdam is responsible for the German mission elements. JPL manages the U.S. portion of the project for NASA's Office of Earth Science, Washington, D.C. Science data processing, distribution, archiving and product verification are managed under a cooperative arrangement between JPL, the University of Texas' Center for Space Research and the Geo-Research Center in Germany. For more information on Grace, see http://www.csr.utexas.edu/grace, or http://www.gfz-potsdam.de/grace.

JPL is a division of the California Institute of Technology in Pasadena.


Story Source:

The above story is based on materials provided by NASA/Jet Propulsion Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

NASA/Jet Propulsion Laboratory. "New Gravity Mission On Track To Map Earth's Shifty Mass." ScienceDaily. ScienceDaily, 13 September 2002. <www.sciencedaily.com/releases/2002/09/020913065631.htm>.
NASA/Jet Propulsion Laboratory. (2002, September 13). New Gravity Mission On Track To Map Earth's Shifty Mass. ScienceDaily. Retrieved August 20, 2014 from www.sciencedaily.com/releases/2002/09/020913065631.htm
NASA/Jet Propulsion Laboratory. "New Gravity Mission On Track To Map Earth's Shifty Mass." ScienceDaily. www.sciencedaily.com/releases/2002/09/020913065631.htm (accessed August 20, 2014).

Share This




More Earth & Climate News

Wednesday, August 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Green Power Blooms as Japan Unveils 'hydrangea Solar Cell'

Green Power Blooms as Japan Unveils 'hydrangea Solar Cell'

AFP (Aug. 19, 2014) — A solar cell that resembles a flower is offering a new take on green energy in Japan, where one scientist is searching for renewables that look good. Duration: 01:29 Video provided by AFP
Powered by NewsLook.com
Disquieting Times for Malaysia's 'fish Listeners'

Disquieting Times for Malaysia's 'fish Listeners'

AFP (Aug. 19, 2014) — Malaysia's last "fish listeners" -- practitioners of a dying local art of listening underwater to locate their quarry -- try to keep the ancient technique alive in the face of industrial trawling and the depletion of stocks. Duration: 02:29 Video provided by AFP
Powered by NewsLook.com
Wildfire Hits California's Angeles National Forest

Wildfire Hits California's Angeles National Forest

Reuters - US Online Video (Aug. 17, 2014) — A wildfire sweeps across the Angeles National Forest prompting campers to quickly leave as officials began evacuating the area -- local media. Gavino Garay reports. Video provided by Reuters
Powered by NewsLook.com
Symphony Performs at Southern Utah's Red Rocks

Symphony Performs at Southern Utah's Red Rocks

AP (Aug. 16, 2014) — The Utah Symphony hopes to complement the beauty of Utah's soaring red rocks and canyons with free desert performances near Utah's national parks this weekend. (Aug. 16) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins