Flying at the Edge - Extremely Low Altitude Operations for the GOCE Mission
Tran, Viet Duc¹; Passone, Federica²; Steiger, Christoph¹; Romanazzo, Massimo³; Emanuelli, Pier Paolo¹; Floberghagen, Rune⁴; Fehringer, Michael^5
1ESA/ESOC, GERMANY; ²LSE Space, GERMANY; ³ESA, GERMANY; ⁴ESA/ESRIN, ITALY; ⁵ESA/ESTEC, NETHERLANDS

ESA's Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) is operated in an extremely low Earth orbit. The spacecraft design features a unique aerodynamic shape and employs drag-free control with an ion propulsion system to counteract the atmospheric drag. While the routine mission of GOCE at 260 km altitude has been very successful, it is inevitably coming to an end once all consumables are exhausted. To maximize the scientific return of the mission prior to its end of life, ESA has started a campaign to lower the orbit of GOCE even further, down to 240 km. This is a challenging endeavour, requiring major re-evaluations and changes on both space and ground segment. This paper presents the planning and execution of the low orbit operations campaign, focussing on the changes needed in the flight operations segment, and the in-flight operations experience at the lowered orbit.