Satellite Creates First Global Gravity Map of Earth
Using only two months of data, the GOCE gravity-tracking satellite has built the first-ever full map of Earth’s gravitational field....
Using only two months of data, the GOCE gravity-tracking satellite has built the first-ever full map of Earth’s gravitational field.
The map, called a geoid, reflects the bumps and valleys of Earth’s gravitational effects. The map shows what the Earth would look like if it was covered in an ocean dictated by gravity, as the European Space Agency explains. It’s not as smooth as you might think — gravity is slightly different in different parts of the globe.
The GOCE satellite, which stands for Gravity field and steady-state Ocean Circulation Explorer, makes super-precise measurements of the gravitational field. It flies in a dangerously low polar orbit, coming close to falling out of the sky, BBC reports.
It carries three pairs of platinum blocks inside a gradiometer instrument, which can sense the smallest gravitational effects — as wee as 1 part in 10,000,000,000,000 of the gravity experienced on Earth.
German researcher Reiner Rummel, chairman of the GOCE scientific consortium, explained to BBC that the satellite works much like a level.
“A geoid is nothing but a level that extends over the entire Earth,” he says. “I can take two arbitrary points on the globe and decide which one is ‘up’ and which one is ‘down.'”
The colorful map above is essentially a depiction of that effect, BBC reports. The map will help scientists better understand Earth’s internal structure, ESA says. It will also help to accurately measure key climate change factors like ocean circulation, ice dynamics and sea-level change. It could help scientists better understand how ocean currents work, because gravity would have an impact regardless of temperature, tides or winds.
The map could also be used very much like a level — it could help construction crews understand which way a fluid would naturally want to flow through a pipeline, for instance. It could even enlighten scientists about tectonic activity that causes earthquakes and volcanoes.
ESA’s mission manager, Rune Floberghagen, said the GOCE data is providing better detail than ever on the Himalayas, central Africa, the Andes and Antarctica. It’s not surprising — it’s hard to get detailed measurements in the middle of Antarctica because it’s not exactly convenient to fly in and out of an airport there.
GOCE uses ion propulsion, so it has a limited lifespan before the very subject of its study will pull it out of the sky.