No. 17 - Successful Trajectory Correction Manoeuvre
06 March 2006 10:21Report for Period 24 February to 02 March 2006
On 24 February a Trajectory Correction Manoeuvre was executed in order to trim the spacecraft trajectory after the Main Engine calibration manoeuvre. The manoeuvre executed flawlessly but the current knowledge of the orbit indicates that it is very likely that another fine tuning will be required once the orbital knowledge has increased.
MAG and ASPERA science acquisitions continue as planned.
As from this week the spacecraft will be closer to the Sun than when at Venus, therefore, it is already facing the maximum solar constant it will have to face during its mission.
The table below shows a chronology of the main activities in the reporting period:
At the end of the last Cebreros pass in the reporting period (DOY 061, 13:00) Venus Express was 63.2 million km from the Earth, 107.8 million km from the Sun, and 14.3 million km from Venus. The one-way signal travel time was 211 seconds.
The knowledge of the spacecraft trajectory improved significantly after the execution of the TCM, due to ranging measurements, and calculations suggest an additional TCM at around VOI – 13 days is needed to clean-up all the deviations introduced by WOL operations, limitations of Sun pressure model, and eventual out gassing.
With the next reporting period all preparation activities will be concluded such that the rest of the cruise phase will be dedicated to the navigation task in order to achieve the most accurate orbit insertion.
Between DoY 061 and 063 the –X face of the spacecraft will be exposed to the Sun with an angle of 5 deg in order to characterise and possibly get rid of the outgassing effects seen in January during the thermal characterisation. This activity is required since this is the attitude the spacecraft will have in the last 10 days before arrival at Venus.
On DOY064 the last science operations with MAG and ASPERA will be performed.
On DOY 065 a test with the DSN station in Madrid will take place in order to rehearse the operations that will be done with the same station during the orbit insertion burn. This test will include acquisition of 2-ways and 1-way S-band signal with the simulation of an occultation inbetween. The spacecraft attitude will also be such that the orientation of the LGA-1 with respect to the Earth will be the same as the one for the orbit insertion.