|status reports||20-March-2019 09:54:04|
No. 19 - Entering Eclipse Period
04 March 2004The spacecraft is now in its 233rd orbit, in good status and with all functions performing nominally. Starting on 24 February 2004 operation of the electric propulsion drive was resumed. The engine is turned on every orbit around perigee for about 1.5 hours.
We are now approaching a season of long eclipses. This is due to the present alignment of the Sun, Earth and the line of apsides (line joining the apogee and the perigee). At launch the apogee point of the spacecraft's orbit was on the Sun side. Now, around six months on, the perigee point is on the Sun side and the apogee point is in the Earth shadow cone (umbra).
This is not necessarily a problem except for three further factors that come into effect at this time:
The combination of these three factors means the spacecraft will travel at its slowest through a relatively large umbra region. When the spacecraft is in the umbra it cannot receive power to its solar panels.
The orbital period is now about 25 hours, therefore the eclipses will repeat every day with a one hour shift per day. A total of 20 eclipses will occur starting on 1 March. The longest eclipse will start at 17:34 UTC on 13 March and will last for 2 hours and 8 minutes (2 hr 15 min considering also the penumbra). This will stress the power system and in particular the batteries to the maximum limit. The flight control team and the power specialists will be watching the spacecraft behaviour carefully during this period.
Update on Commissioning Activities
As covered in earlier status reports the previous few weeks have seen the commissioning of the spacecraft scientific payload. The last few days of commissioning were dedicated to the camera AMIE, the transponder KaTE, to the imaging X-ray spectrometer DCIXS and the solar X-rays monitor XSM.
DCIXS and XSM
EPDP and SPEDE
Planned Spacecraft Activities
The ESOC specialists periodically compute the osculating orbital elements. These elements define the so-called "osculating orbit" which would be travelled by the spacecraft if at that instant all perturbations, including EP thrust, would cease. Therefore, it is an image of the situation at that epoch. In reality, the path travelled by the spacecraft is a continuous spiral leading from one orbit to another. The most recent osculating elements are as follows:
Displayed in the plot are the osculating orbits at launch (GTO) and at different times throughout the mission. Since the start of the mission the electric propulsion engine has changed the orbital parameters as follows:
Bernard H. Foing
Last Update: 28 August 2006For further information please contact: SciTech.email@example.com
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