Since 2009 the European Space Agency’s Gravity field and steady-state Ocean Circulation Explorer (GOCE) has been mapping the Earth’s gravitational field. More potato-shaped than spherical, the latest images shows just how different gravity can be at different points on our planet.
The geoid is a model of the earth that doesn’t follow the surface of the crust but rather the average ocean surface if the oceans were at equilibrium and extended through the continents–in other words, the shape the earth would take based on its existing gravitational field if it wasn’t distorted by tides, currents, and crust features.
In the above image, yellow indicates the strongest gravitational pull while blue indicates the lowest. And while we experience these differences in gravity as negligible, they have a big impact on ocean dynamics and the movement of heat around the planet–key to understanding atmospheric conditions and climate change. (ESA/HPF/DLR)
A new US–German gravity-mapping mission that launched in May reports Nature, has not gathered science data since mid-July because of a problem with a key instrument. The twin satellites of the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission measure minute differences in the distance between them to chart changes in Earth’s gravity. Doing so can reveal the distribution and flow of water and ice across the planet.
But part of a microwave instrument aboard one of the satellites shut itself down on 19 July following signs of an electrical problem. Mission managers are investigating the cause and plan to switch to a back-up system later this month, NASA’s Jet Propulsion Laboratory in Pasadena, California, announced on 14 September.
The Gravity Recovery and Climate Experiment Follow-On mission uses twin probes to monitor Earth’s gravity field.
The Daily Galaxy via Nature and The ESA
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