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No. 143 - Deep-space telecommand testing

No. 143 - Deep-space telecommand testing

Report for the period 31 July to 27 August 2010.This report covers 28 days of Rosetta operations. During the reporting period the spacecraft remained configured in active cruise mode in preparation for the new test and validation campaign required for the deep space phase of the mission. The main activities were the high-gain antenna (HGA) strobing test and the low-gain antenna (LGA) telecommand link test performed on 20 August.

During the reporting period mission operations were conducted using the ESA New Norcia (NNO) ground station and DSS-43 (Canberra, 70 m) NASA Deep Space Network (DSN) antenna.

Main activities during reporting period

DoY Date Pass Activity
214 02-Aug-2010 NNO 2350 Monitor
215 03-Aug-2010 NNO 2351 Monitor
218 06-Aug-2010 NNO 2354 Monitor
221 09-Aug-2010 NNO 2357 Monitor
223 11-Aug-2010 NNO 2359 Monitor
225 13-Aug-2010 NNO 2361 Monitor
228 16-Aug-2010 NNO 2364 Monitor
230 18-Aug-2010 NNO 2366 Monitor
232 20-Aug-2010 DS-43 2368
NNO 2368
HGA strobing test and LGA TC link test
235 23-Aug-2010 NNO 2371 Monitor
237 25-Aug-2010 NNO 2373 Monitor
239 27-Aug-2010 NNO 2375 Monitor

DoY = Day of year

At the end of the reporting period on 27 August, Rosetta was 576 million km from Earth (3.85 AU); the one-way signal travel time was 32 min 02 sec (1922 sec). The spacecraft's distance from the Sun was 456.5 million km (3.05 AU).

High-gain antenna strobing test; low-gain antenna telecommand test

During the hibernation entry window next year, Rosetta will be between 3.7 and 4.4 AU from Earth. At those distances and once Rosetta is spinning, it will be necessary to be able to command Rosetta using the LGA and to detect the strobing signal coming from the HGA.

On 20 August, a test was conducted to characterise the telecommand link to the LGA and detection of the HGA strobing signal at 3.75 AU from Earth. It was possible to command the spacecraft using the LGA at 7.8 bps from the New Norcia and DSS-43 ground stations. Both stations detected the HGA strobing signal; this signal was obtained by commanding the HGA to sweep the Earth several times, simulating a strobing signal.

Spacecraft

Payload Status
ALICE The instrument is currently OFF
CONSERT The instrument is currently OFF
COSIMA The instrument is currently OFF
GIADA The instrument is currently OFF
MIDAS The instrument is currently OFF
MIRO The instrument is currently OFF
OSIRIS The instrument is currently OFF
ROSINA The instrument is currently OFF
RPC The instrument is currently OFF
RSI The USO is ON/muted since 3 February 2010 (DoY 032/2010) 
VIRTIS The instrument is currently OFF
Lander (Philae) The instrument is currently OFF
SREM The instrument is ON with standard settings since 3 February 2010 (DoY 032/2010)

Future milestones

The reporting period was a bridging phase between the last science phase of the mission before hibernation and the real deep-space mission. The spacecraft has now crossed the boundary of 3 AU heliocentric distance and is entering the real deep-space phase. Activities are now focused on hibernation entry and a successful comet rendezvous; as part of this, a first solar array performance test is planned before the conjunction phase.

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Legal disclaimer
This report is based on the ESOC mission operations report, WOR #143. Please see the copyright section of the legal disclaimer (linked from the home page http://sci.esa.int) for terms of use.

Last Update: 1 September 2019
28-Mar-2020 18:39 UT

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