GOCE - the hidden life of a satellite

GOCE SpacecraftA number of years ago I worked for Astrium Space, a member of the ESA and EADS developing models and simulations of spacecraft attitude sensing and dynamics. "Attitude" meaning the orientation: roll, pitch, yaw, rates, sensors, and control algorithms.

Specifically, I worked on a revolutionary new Drag-Free and Attitude Control Subsystem, DFACS, that performs autonomous determination and control of the spacecraft's attitude pointing, angular movements and linear and angular accelerations. You can download an article describing the system that was used for HYPER .

It was at this time, living and traveling extensively through Europe on short trips, constantly connected with a mobile phone, a cheap GPS receiver, and blogging and photo sharing that you could see the convergence and emergence of Where2.0. Fortunately the Wayback machine has my old blog "An American Engineer in Germany" recorded for posterity.

In addition, I was quite frustrated with the satellite industry. The politics and budgets that inexplicably cancel projects years, and millions of dollars/euros - or even when physics gives you a swift kick and dooms your satellite to a 30-minute flight before immediately de-orbiting. Not a rewarding way to end 10 years of hard work.

At Astrium, I was a member of the GOCE satellite team. The goal of GOCE, Gravity field and steady-state Ocean Circulation Explorer, was to utilize a very high precision gradiometer in order to measure the magnetic characteristics of the Earth. The benefit is a highly detailed gravitational model of the Earth's geoide which can then inform ocean circulation and sea-level models, orbital predictions, space-time drag, and more. Since the force of gravity falls off at a cubic rate inverse square from the distance to the mass, GOCE must fly at a relatively very low altitude. It therefore uses continuous ion thrusters to compensate for atmospheric drag, and another reason the DFACS is so important.

About 6 months after leaving Astrium, I had been told that the project was shelved, and never wondered about it.

Then surprisingly, while at the UNGIWG workshop in Rome last February, a director of UNOSAT told me that GOCE was in fact completed and being boxed up for shipment to the launch site! Again I didn't track it until a couple of weeks ago, twitter showed it's power again and Astronautics pointed out that GOCE was launching!

On March 17, GOCE launched from the Plesetsk Cosmodrome in Northern Russia. GOCE is the first of ESA's Core Missions of the Earth Explorer programme - others including atmospheric dynamics, ice sheet thickness measurement, radiative balance, and ocean salinity.

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So while the space industry can be quite frustrating, it is undeniably exciting to see something you helped build hurtling around the Earth at approximately 7,700 meters per second just 170 miles above us. GOCE is even using GPS to track its own position in space.

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About the Author

Andrew Turner is an advocate of open standards and open data. He is actively involved in many organizations developing and supporting open standards, including OpenStreetMap, Open Geospatial Consortium, Open Web Foundation, OSGeo, and the World Wide Web Consortium. He co-founded CrisisCommons, a community of volunteers that, in coordination with government agencies and disaster response groups, build technology tools to help people in need during and after a crisis such as an earthquake, tsunami, tornado, hurricane, flood, or wildfire.