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Project Status
Martin Kessler
The overall status of the project is very good. The satellite has been shipped to Kourou, the launch campaign is underway and the ground segment is close to launch readiness.
As reported in the last ISO INFO, a few functions - including a column of pixels in ISOCAM and a C200 detector element in ISOPHOT - showed intermittent behaviour at the end of 1994. Investigations into these anomalies concluded that five out of the six were due to breaks in the very thin (0.1 mm diameter) wires making up the electrical harness connecting the external electronics boxes to the outside of the cryostat. All connections affected have been have been re-made using techniques that permit easier inspection of their quality and successfully re-tested.
The remaining anomaly concerns column # 24 of the long-wavelength detector of ISOCAM. During the thermal vacuum test when the outer skin of the cryostat was at a temperature of below about 200K, this column went open-circuit. Extensive investigations did not reveal conclusively the cause of this problem, but it could be a faulty connection inside the cryostat. Correction of any such fault, would entail warming up and opening the cryostat, leading to a launch delay of at least 18 months - a process with risks and without guarantees of improving the situation. Thus, having taken into account the views of the ISO Principal Investigators, ESA decided that the cryostat would not be opened and that it would be launched ``as is''. The Science Operations Centre, in close co-operation with the ISOCAM Principal Investigator, is preparing contingency plans to be used should this column fail in orbit. Observers will be kept informed of any developments.
The end-to-end tests of the ISO satellite with its ground segment were successfully completed in April. During the period from April to July, there was a series of reviews of the status of the satellite and its ground segment. These concluded that the satellite was ready for shipping to the launch site and that, pending closure of some actions, the ground segment would be ready to support launch and operations by 15 October.
ISO , and its associated support equipment, was packed into containers, loaded into 15 lorries and left ESTEC on 1 June - a grand total of 95 tons. It went by road to Rotterdam and from there by sea to Kourou. The launch campaign then started on 19 June. On 19 August a one-month planned hold will begin, with operations resuming on 27 September, leading to the scheduled 3 November 1995 launch.
Next: Helpdesk Up: Cover Page Previous: Introduction
K. Leech
ISO Resident Astronomer
August 1995
Tue Oct 3 19:21:38 MET 1995