GOCE giving new insights into Earth's gravity (w/ Video)

June 29, 2010
The first global gravity model based on GOCE satellite data has been presented at ESA’s Living Planet Symposium. Based on only two months of data, from November and December 2009, it illustrates the excellent capability of GOCE to map tiny variations in Earth’s gravity field. Credits: GOCE High Level Processing Facility

(PhysOrg.com) -- The first global gravity model based on GOCE satellite data has been presented at ESA's Living Planet Symposium. ESA launched GOCE in March 2009 to map Earth's gravity with unprecedented accuracy and resolution.

The model, based on only two months of data, from November and December 2009, shows the excellent capability of the satellite to map tiny variations in Earth’s gravity.

"GOCE is delivering where it promised: in the fine spatial scales," GOCE Mission Manager Rune Floberghagen said.

"We have already been able to identify significant improvements in the high-resolution 'geoid', and the gravity model will improve as more data become available."

The geoid is the shape of an imaginary global ocean dictated by gravity in the absence of tides and currents. It is a crucial reference for accurately measuring , sea-level change and ice dynamics - all affected by .

Chairman of the GOCE Mission Advisory Group and Head of the Institute for Astronomical and Physical Geodesy at the Technische Universität München, Prof. Reiner Rummel, said: "The computed global looks very promising. We can already see that important new information will be obtained for large areas of South America, Africa, Himalaya, South-East Asia and Antarctica."

"Over continents, and in particular in regions poorly mapped with terrestrial or airborne techniques, we can already conclude that GOCE is changing our understanding of the gravity field," Dr Floberghagen added.

"Over major parts of the oceans, the situation is even clearer, as the marine gravity field at high spatial resolution is for the first time independently determined by an instrument of such quality."

New GOCE models are already yielding a wealth of new information that is useful for many domains of geosciences. GOCE’s final gravity map and geoid will be instrumental in advancing science and applications in a broad range of disciplines, ranging from geodesy, geophysics and surveying to oceanography and sea-level research.

"With each two-month cycle of data, the gravity model will become more detailed and accurate. I am convinced that the data will be of great interest to various disciplines of Earth sciences," Prof. Rummel said.

Excellent technical achievement

In order to achieve its very challenging mission objectives, the satellite was designed to orbit at a very low altitude, where the gravitational variations are stronger closer to Earth.

Since mid-September 2009, GOCE has been in its gravity-mapping orbit at a mere 254.9 km mean altitude - the lowest orbit sustained over a long period by any Earth observation satellite.

The video will load shortly
The need for GOCE to fly in a low orbit means it has to compensate for the atmospheric drag it experiences at this exceptionally low altitude. The animation shows a close-up of the ion-propulsion assembly, which keeps the satellite in a smooth trajectory - free from all effects except those of gravity itself. Two winglets provide additional aerodynamic stability. Credits: ESA - AOES Medialab

The residual air at this low altitude causes the orbit of a standard satellite to decay very rapidly. GOCE, however, continuously nullifies the drag in real time by firing an ion thruster using xenon gas.

It ensures the gravity sensors are flying as though they are in pure freefall, so they pick up only gravity readings and not the disturbing effects from other forces.

To obtain clean gravity readings, there can be no disturbances from moving parts, so the entire satellite is a single extremely sensitive measuring device.

"The gravity measuring system is functioning extremely well. The system is actively compensating for the effects of atmospheric drag and delivering a continuous set of clean gravity readings," Dr Floberghagen said.

"This in itself is an excellent technical achievement. GOCE has proven to be a nearly perfect satellite for measuring gravity from space."

In May, ESA made available the first set of gradients and 'high-low satellite-to-satellite tracking'. These data are available to scientific and non-commercial users - and much more will come in the following months.

Explore further: ESA makes first GOCE dataset available

Related Stories

ESA makes first GOCE dataset available

June 9, 2010

The first products based on GOCE satellite data are now available online through ESA's Earth observation user services tools. ESA launched the satellite in March 2009 on a mission to map Earth's gravity with unprecedented ...

GOCE delivering data for best gravity map ever (w/ Video)

September 30, 2009

(PhysOrg.com) -- Following the launch and in-orbit testing of the most sophisticated gravity mission ever built, ESA’s GOCE satellite is now in ‘measurement mode’, mapping tiny variations in Earth’s gravity in unprecedented ...

GOCE's 'heart' starts beating

April 8, 2009

GOCE's highly sensitive gradiometer instrument has been switched on and is producing data. Forming the heart of GOCE, the gradiometer is specifically designed to measure Earth's gravity field with unprecedented accuracy.

GOCE satellite achieves drag-free perfection (w/Videos)

May 26, 2009

(PhysOrg.com) -- ESA's gravity mission GOCE has achieved a first in the history of satellite technology. The sophisticated electric propulsion system has shown that it is able to keep the satellite completely free from drag ...

March launch planned for GOCE gravity mission (Video)

February 4, 2009

(PhysOrg.com) -- ESA is now gearing up to return to Russia to oversee preparations for the launch of its GOCE satellite - now envisaged for launch on 16 March 2009. This follows implementation of the corrective measures after ...

GOCE gravity satellite moves to launch pad

March 11, 2009

(PhysOrg.com) -- With liftoff just five days away, ESA's GOCE spacecraft - encased in the protective half-shells of the launcher fairing - has been transported from the cleanroom and installed in the launch tower at the Plesetsk ...

Recommended for you

Hints of extra dimensions in gravitational waves?

June 28, 2017

Researchers from the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI) in Potsdam found that hidden dimensions – as predicted by string theory – could influence gravitational waves. In a recently ...

New 'hot Jupiter' exoplanet detected by K2 mission

June 28, 2017

(Phys.org)—An international team of astronomers has identified a new extrasolar planet from the data provided by Kepler spacecraft's prolonged mission known as K2. The newly found exoworld, designated EPIC 228735255b, is ...

Galaxy NGC 1132 has a disturbed hot halo, study finds

June 27, 2017

(Phys.org)—A new study recently published on arXiv.org reveals that the fossil group galaxy NGC 1132 (also known as UGC 2359) has a disturbed and asymmetrical hot halo. The findings provide new insights into the formation ...


Adjust slider to filter visible comments by rank

Display comments: newest first

1.9 / 5 (8) Jun 29, 2010
Thanks for the very interesting report.

Similar maps of gravity variations for the Sun might be able to elucidate the depth and mass of the object(s) responsible for cycles of magnetic activity and sunspots at the solar surface.

With kind regards,
Oliver K. Manuel
3.7 / 5 (3) Jun 29, 2010
Why bother waiting for solar gravity variations when helioseismology has become such an advanced science? Oh, that's right, you're ignoring it because it doesn't support your preconceived notions.
3 / 5 (6) Jun 29, 2010
Thanks for the very interesting report.

Similar maps of gravity variations for the Sun might be able to elucidate the depth and mass of the object(s) responsible for cycles of magnetic activity and sunspots at the solar surface.

With kind regards,
Oliver K. Manuel

Between ionized gas and plasma, what qualifies as an object? Solid, tangible . . . ?
not rated yet Jun 30, 2010
Am I reading this right? The blue end of the spectrum indicates lower gravity and the red indicates higher gravity?
not rated yet Jun 30, 2010
I wish there was a scale on the chart. How much lower is the gravity south of India? Anyone?
1 / 5 (1) Jun 30, 2010
There is a color scale at the bottom of the chart. Its units are probably milligals, although it doesn't explicitly state that.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.