ESA's Earth Explorer Mission

Getting the low down on gravity

The Gravity field and steady-state Ocean Circulation Explorer GOCE mission, due to be launched in spring 2008, is ESA's first satellite dedicated to measuring the Earth’s gravity – a fundamental force of nature that influences many dynamic processes within the Earth’s interior, and on and above its surface.

By measuring the Earth's gravity field and modelling the geoid, or hypothetical surface of the Earth, with extremely high accuracy and spatial resolution, GOCE will significantly advance our knowledge of how the Earth works in several domains – oceanography, geophysics and geodesy – as well as providing insight into the physics and dynamics of the Earth's interior, such as volcanism and earthquakes.

Because the gravitational signal is stronger closer to the Earth, GOCE has been designed to fly in a particularly low orbit - at an altitude of just 250 km. However, the remaining atmosphere at low altitudes creates a demanding environment for the satellite and presented a challenge for its design.

Unlike other missions where various independent instruments are carried aboard the spacecraft, GOCE is unique in that the instrumentation actually forms part of the structure of the satellite. A completely stable, rigid and unchanging local environment is required to acquire extremely high fidelity ‘true’ gravity readings, so the spacecraft intentionally has no mechanical moving parts.

Animation & more @ ESA’s Earth Explorer gravity satellite on show
Image Credits: ESA – AOES Medialab
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Phenomenological Quantum Gravity by Bee @ Backreaction
Phenomenology of Quantum Gravity by Lubos @ The Reference Frame
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