July 1998: Feasibility
studies begin for GOCE
May 2002: Satellite
construction begins
October 2005: Planned
launch date
March 2007: Gradiometer integrated into
satellite
August 2007: GOCE
arrives at the ESA
facility in the Netherlands for final testing
17 March 2009: GOCE
launches
November 2010: ESA
grants the project an
18-month extension
March 2011: Geoid
completed
November 2012:
Completion of
planned mission
October 2013: GOCE
runs out of fuel
11 November 2013:
GOCE re-enters Earth’s
atmosphere
Space-Time
Continuum
GOCE in the Large Space
Simulator at ESA’s Test
Centre in Noordwijk, the
Netherlands
any moving parts—no motors, no switches—since any disturbance would be
picked up, thus contaminating the data.
To accomplish this achievement—what Mr. Muzi describes as being “on
the border of feasibility”—the team had to develop the accelerometers without
fully knowing how they would work in space. Because of gravity on the ground,
the team couldn’t replicate operational conditions and therefore couldn’t test
the accelerometers to final performance.
“We had to base our design on a combination of tests, simulation and
analysis. We built a high-fidelity end-to-end simulator to prove that we would
achieve performances overall,” Mr. Muzi says. “That was a challenge because,
at the end, the satellite was a measurement device.”
The complexity didn’t end there. To calibrate the accelerometers during the
mission, Mr. Muzi’s team had to develop yet another pioneer technology: a micro-
propulsion system that could provide miniscule thrusts to minutely maneuver the
satellite in space. When Mr. Muzi asked two subcontractors to provide a proof-of-
concept test for their proposed implementation, the test failed.
“The technology was not there yet,” Mr. Muzi says. “I told my team that we had
to come up with a bright idea. We were more than two years into the project.”
A member of Mr. Muzi’s team devised an alternative calibration method
using a simple cold gas system, and the team then found a new subcontractor
to build it.
MISSION TRANSITION
Originally, the launch was supposed to take place in October 2005. Look-
