It was five years ago this month that ESA's GOCE gravity mapping satellite finally gave way to gravity, but the…
It was five years ago this month that ESA’s GOCE gravity mapping satellite finally gave way to gravity, but the results still yield a buried treasure – giving a new picture of remains of lost continents hidden deep under the Antarctica ice .
A research group from Germany’s Kiel University and the British Antarctic Survey published its latest GOCE-based findings this week in the journal Scientific Reports.
Dubbing “Formula 1 in Space”, the GOCE (Gravity Field and Ocean Circulation Explorer) invited the Earth for more than four years, from March 2009 to November 2013. This stylish, non-moving, motionless satellite was designed around a single target : to measure the drawing of the earth’s gravity more precisely than any task previously. 1
9659002] GOCE flew at an altitude of just 255 km, more than 500 km closer than a typical Earth observation satellite, to maximize its sensitivity to gravity.
In its last year in circulation with its range of xenon fuels, GOCE operated even lower, only 225km high, for even more accurate gravity measurements. The propellant that is resistant to air drag was ultimately spent in October 2013, and it resumed the atmosphere three weeks later.
GOCE’s main production was a high-grade global gravity map or “geoid”, but the mission also charted localized gravity gradients – measurements of how fast acceleration of gravity changes – across all directions of motion, down to a resolution of 80 km.
The team from Kiel University and BAS has transformed this patchwork of 3D gravity into curvature form indices “across the different regions of our planet, analogous to the contours of a map.
The study’s leading author Prof Jorg Ebbing from Kiel University comments on” The satellite’s gravity data can be combined with seismological data to produce more consistent images of crust and upper sheath in 3D, which is crucial for understanding how flat tonics and deep sheath dynamics interact. “
In combination with existing seismological data, dients show high sensitivity to known properties in the earth’s” litosphere “, the solid crust and the part of the molten sheath below it.
These features include dense rocky zones called cratons – remains of ancient continents found in the heart of modern continental plates – high-weight “orogen” regions associated with mountain ranges and thinner crust of cribs.
The new window in the deep underground offered by these data gives new knowledge of the structure of all the earth’s continents, but above all the Antarctica. With more than 98% of its surface covered with ice with an average thickness of 2 km, the southern continent is largely an empty space on current geological maps.
“These gravitational images revolutionize our ability to study the least understood continent on Earth, Antarctica, “said co-author Fausto Ferraccioli, Geology Scientist and geophysics at BAS.
“In eastern Antarctica we see an exciting mosaic of geological features revealing basic similarities and differences between the crust of Antarctica and other continents it was associated with until 160 million years ago. “
Gravity gradient findings show the West Antarctica has a thinner crust and lithosphere compared to the East Antarctica, which consists of a mosaic of ancient cratons separated by younger orogenes, revealing a family entity to Australia and India.
These results are more than purely historical geological interest. They give clues to how the continental structure of Antarctica affects the behavior of the icebox and how fast the Antarctic regions will recur because of melting ice.
ESA missionary Roger Haagmans, GOCE, adds: “It’s exciting to see the direct use of gravity gradients , which was measured for the first time ever with GOCE, leads to a freely independent look inside the earth – even under a thick ice sheet.
“It also provides a context of how the continents might have been linked before before they shifted due to plate movement.”