Grace FO satellite structures. Photo: Airbus Defence and Space

[Via Satellite 05-26-2015] Airbus Defence and Space has completed the development and design phase for the Gravity Recovery and Climate Experiment follow-on (Grace-FO) satellites. The company delivered satellite structures for the two spacecraft to the NASA Jet Propulsion Laboratory (JPL) where the building phase has commenced.

The two Grace-FO satellites continue the mission of the original two Grace satellites launched in 2002. They are designed to provide an updated model of the Earth’s gravitational field every 30 days for a five-year mission. The spacecraft will also create up to 200 daily profiles of temperature distribution and water vapor content in Earth’s atmosphere.

Each Grace-FO satellite weighs approximately 600 kilograms, and will circle the Earth in the same polar orbit at an altitude of about 500 kilometers. Spaced 220 kilometers apart, the satellites will continuously measure the distance between each other, using Global Positioning Satellite (GPS) receivers for positioning and a satellite-to-satellite microwave connection for distance measurements. Because distance changes under the influence of the Earth’s gravity, this enables the gravitational field to be continuously measured.

The Grace-FO mission is based on a cooperative agreement between NASA JPL and the German Research Centre for Geosciences (GFZ-Potsdam). The satellites are planned for launch in mid-2017.