GOCE has now been fully reconfigured for launch in September and is currently being prepared for shipment on July 29th from the European Space Agency’s (ESA) test facilities in the Netherlands to the Plesetsk Cosmodrome in northern Russia. Originally, the Gravity field and steady-state Ocean Circulation Explorer (GOCE) mission had been scheduled to launch in May 2008. However, due to precautionary measures taken following a problem with an upper-stage section of a Russian Proton launcher, the launch date was postponed until September 10th. Consequently, the satellite had to be reconfigured into a ‘summer launch configuration’. As the GOCE gravity mission is designed to fly at a particularly low altitude of just 263 km, and at a slight inclination with respect to an exact polar orbit, the satellite goes into the shadow of the Earth during polar nights for 28 minutes 135 days each year. By going into the Earth’s shadow where no sunlight hits the satellite, GOCE experiences changes in temperature that could potentially affect measurements. Not knowing exactly when GOCE would launch, the option to determine whether it went into Earth’s shadow (referred to as an ‘eclipse period’), between October and February or between April and August, was included in its design.
The selection of the appropriate option is made by launching into a northward equator crossing at 06:00 or at 18:00. The main difference between the launch times, as seen from the Sun, is that it determines whether the satellite flies clockwise or anticlockwise around the Earth. As GOCE will launch in September, the preferred eclipse period is April to August as that allows for unaffected commissioning and science operations until April next year. Once aboard an Antonov cargo aircraft, the shipment will be flown to Arkhangelsk, Russia, where the container will be transferred to a train for the rest of the journey to the Plesetsk Cosmodrome. After the satellite is unpacked, a final check will be carried out before being mounted onto its Rockot launch vehicle 13 days prior to launch.
