23 January 1996
On the occasion of the first presentation of scientific results derived from GOME data, the media were also briefed on the status of the ERS-2 mission, 9 months after the satellite's launch on 21 April 1995.
As reported in press release no. 22-95, activation of the payload went as planned except for an anomaly with the Active Microwave Instrument (AMI) which acquires the high resolution radar images of the Earth's surface and measures sea surface wind speed and direction as well as ocean wave parameters. This anomaly was soon restricted to the wind scatterometer mode and, since July 1995, the AMI, both in the image and wave modes, has been in continuous operation; SAR images are now routinely distributed to users.
After an extensive investigation, the wind scatterometer anomaly was resolved by an ingenious work-around solution and the instrument has been working operationally since 22 November 1995; the validation tests will continue until end April 1996, just prior to ERS-2 taking over fully from ERS-1 at the end of May.
The radar altimeter and its supporting microwave sounder are fully operational and the new GOME instrument is already producing data of exceptional interest, thus promising to be the best ozone monitoring instrument currently in orbit. The PRARE entered its operational phase on 1 January 1996 and the PRARE ground station network is being progressively completed. The instrument is fully compliant with its specified performances.
The Along Track Scanning Radiometer (ATSR-2) which was working remarkably well since launch, ceased normal operations on 22 December because of a problem with the scanning mirror. A team at the Central Laboratories of the Research Council (CLRC) in the United Kingdom, which developed and funded this UK-provided instrument, is investigating the reasons for the anomaly. CLRS has agreed to keep the media informed of progress in the investigation and of the efforts made to resume the instrument's normal operations.
Since 16 August 1995 and until mid-May 1996, ERS-1 and ERS-2 are being operated simultaneously. This is the first time ever that 2 identical SARs are operating in tandem. The orbits of the two satellites are carefully phased to provide a 1- day revisit interval; this enables collection of (interferometric SAR image pairs which will be used for the generation of a global Digital Terrain Model (DTMs) set as well as for many other novel applications such as differential interferometry. In this context, ESA has just released an Announcement of Opportunity to the scientific/-academic community to evaluate the potential of SAR interferometry (INSAR) and differential INSAR for geo-hazard risk assessment arising from earthquakes, volcanic erruptions, landslides and glacial surges.
"Were it not for the problem with the ATSR-2, I could have said that we have 2 fully operational ERS satellites in orbit. ERS-1 continues to function like clockwork 41/2 years after its launch and, in tandem with ERS-2, is producing great results every day" said Guy Duchossois, Head of ESA's Earth Observation Mission Management Office.