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Science & Exploration

N° 24–1998: Efforts to recover SOHO spacecraft continue as inquiry board co-chairs named

30 June 1998

Engineers are continuing efforts to reestablish contact with the ESA/NASA Solar and Heliospheric Observatory (SOHO) spacecraft using NASA's Deep Space Network (DSN). Contact with SOHO was lost on 25 June (European time) during maintenance operations.

A team of experts from ESA and Matra Marconi Space, prime contractor for the SOHO spacecraft, gathered at NASA's Goddard Space Flight Center, Greenbelt, MD, to assist the NASA Flight Operations Team in assessing the situation and analysing the spacecraft status should contact be re-established.

Engineers are concentrating on gaining a full understanding of the events which led to the loss of signal, information which might help them devise procedures which may recover contact with SOHO. Commands are being sent to SOHO about once per minute through the DSN's 34-meter antennas instructing the spacecraft to activate its transmitters.

Based on the last telemetry data received from SOHO, engineers said it appears most likely that the spacecraft is slowly spinning in such a way that its solar arrays, which generate power, either do not faced the Sun at all or do not received adequate sunlight to generate power. However, based on the last data received, it appears that SOHO's solar panels may be exposed to an increasing amount of sunlight each day as it orbits the Sun. If this assumption is correct, within a few weeks enough sunlight might be hitting the solar panels to generate power to charge its batteries.

The incident will be the subject of a joint ESA/NASA inquiry board co-chaired by Prof. Massimo Trella, ESA Inspector General and Dr. Michel Greenfield, Deputy Associate Administrator for the Office of Safety and Mission Assurance, NASA Headquarters. The other members of the board will be selected from ESA and NASA as well as from the scientific community. The board is expected to convene later this week at NASA's Goddard Space Flight Center.

More information, images and status reports from SOHO can be found on the internet at : or via the new ESA science web site

For further information, please contact :
Franco Bonacina ESA Public Relations Division Paris Tel:+33(0)

Don Savage NASA Headquarters Washington DC Tel: +1.202.358.1727 Bill Steigenwald NASA GSFC, Greenbelt MD Tel: +1.301 286.5017