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Enabling & Support

N° 22–1995: ERS-2 In-Orbit Status

22 May 1995

After a perfect launch on Ariane flight V72, at 01.44 hours Universal Time on 21 April 1995, ERS-2 performed its early- orbit phase manoeuvres under autonomous control, exactly to plan and without anomaly.

The satellite then entered its nominal operational mode, ready for the payload to be switched on. All parameters from the platform and payload support electronics were fully nominal. Over the next 9 days, the Instrument Data Handling Sub- system, Radar Altimeter, PRARE, ATSR, and GOME were successfully activated.

On 30 April, the first attempt to acquire a SAR image proved unsuccessful due to activation of the receiver overload protection circuit. Investigations started immediately to establish the cause of the anomaly and a second attempt to enter image mode proved successful after the transmitter output power had been reduced. This, and the subsequent image modes showed nominal performance, and the first ERS-2 images were acquired over the Gulf of Gaeta on 2 May (cf. ESA Press Release No 16-95).

Entry into wave mode, with reduced transmitter power, also proved successful. However, attempts to achieve wind mode have so far proved unsuccessful, even with reduced transmitter power. An extensive anomaly investigation is under way but not yet complete. Further planned steps in the investigation include ground simulations of the anomaly, with satellite support equipment and flight spares now being shipped back from Kourou.

In the meantime it is intended to operate the Active Microwave Instrument in image mode.

During the investigation, the wind mission will be taken care of by ERS-1, as was in any case planned for this period.

Despite this as yet unsolved anomaly, the commissioning activities for the remaining instruments have started.

Initial evaluation of data from the (new) Global Ozone Monitoring Experiment (GOME) shows that the instrument is working well with spectra of atmospheric constituents being clearly identified.

Data from the new visible channels on the Along Track Scanning Radiometer are in line with expectations, and the infra-red channels are functioning nominally.

The re-designed Precise Range and Range Rate Experiment is functioning well.

The Radar Altimeter appears to be performing very like the ERS-1 instrument and it is expected that equivalent performance will be achieved after in-orbit calibration.