ESA Science & Technology - No. 45 - Rosetta Observations of Deep Impact at Comet Temple-1

The spacecraft was slewed to point its remote sensing payload instruments towards comet Tempel-1 on 28 June. The comet was constantly tracked until 14 July, following a complex profile designed to satisfy the observation requirements of the four active instruments, ALICE, MIRO, OSIRIS and VIRTIS. Three of the remote sensing instruments were active continuously from 29 June to 14 July. VIRTIS was operated only for a few hours around the predicted time of encounter of Deep Impact with the comet, on 4 July. Daily passes were taken with the New Norcia station throughout the reporting period, to downlink the scientific data collected during the observations. An average of 60 Mbytes of data were produced and downlinked every day.

The observation campaign was very successful. All instruments operated very well and their science data were collected as planned and are undergoing the first analyses. A few problems occurred with the commanding timing of OSIRIS and with the MIRO instrument but could be recovered in both cases within about 24 hours, with minor impact on the overall instrument operations and data return. The exercise was the first scientific planning and operations scenario over large scale and an extended period of time for the Rosetta mission. It provided an important experience and a wealth of lessons learned which will be very useful to design the spacecraft operations around Rosetta's target comet 67 P/Churyumov-Gerasimenko.

Taking advantage of the long period of daily contact with the spacecraft, software maintenance activities were carried out for two instruments, Rosina on 6 and 7 July, and ALICE on 14 July. Rosina completed the software modifications required for the DFMS instrument and the related commissioning activities. Also a small maintenance activity was carried out on COSIMA on 28 June.

SREM was always active in the background for the entire period.

A total of 18 New Norcia passes of a max duration of about 9 hours commanding were taken over the reporting period. A DSN proficiency pass was taken on 14 July with the DSS-25 station.

At the end of the reporting period (DOY 196) Rosetta was at 87.1 million kilometres from the Earth. The one-way signal travel time was 4 minutes 50.5 seconds.