A malfunction in one of the TESIS telescopes has been fixed

Specialists from the TESIS Control Centre, at the FIAN Laboratory of Solar X-ray Astronomy, have succeeded in fixing a malfunction in one of the observatory's central telescopes, which occurred in the second half of May. The first malfunctions in the operation of the Gershel x-ray telescope were logged on 10 May, 2009. The Gershel telescope was observing the corona and the transition layer of the Sun at a wavelength of 171 and 304A.

Analysis of service data transmitted to Earth has shown that the telescope's entry shutter drive mechanism was functioning incorrectly: the indicators which show the furthest positions of the drive motor failed to display the "open" position. While searching for the causes of the malfunction, specialists reduced the load on the channel, and the telescope was switched to a minimal observation regime. Nevertheless, on 18 May at 09:20 Moscow time, there was a complete failure in the shutter, which closed, physically blocking the telescope's field of vision.

Analysis of the drive mechanism's behaviour prior to the malfunction and simulating the course of events back on Earth helped to narrow down the range of possible causes of the failure. The main version of events pointed to a malfunction in the drive mechanism's reducer, which is responsible for the rotational power from the main shaft of the motor to its output shaft, which is connected to the shutter. On Wednesday 26 May, the software package onboard the observatory was updated by specialists from the Laboratory. As a result, the drive motor was switched to a discontinuous operational regime with the option of rotating both in a forwards and reverse direction (telescopes fitted with petal-type shutters, freely rotating clockwise and anti-clockwise). The function responsible for the forced shutdown of the drive motor at end position indicators was also switched off.

On 1 July, 2009, the observatory returned to its scheduled programme of solar observation.