Science & Technology: SMART-1 is spiralling out through the Earth's radiation belts

SMART-1 is spiralling out through the Earth's radiation belts
19 Nov 2003 12:55

Summary of overall status, current activities and planned activities.
The spacecraft is now in its 102nd orbit and has been functioning very well since the last anomaly occurred on November 5. SMART-1 has now operated flawlessly for more than 12 days.

The spacecraft was operated in electric propulsion mode almost continuously, only interrupting it during the eclipses where the power available from the batteries cannot sustain the high demand of the engine. As a precaution we were also keeping the engine off until the orbit altitude was more than 10 000 km. The total cumulated thrust time is now more than 663 hours and we have consumed about 10.5 kg of Xenon fuel. Moreover, the electric propulsion engine performance, periodically monitored by means of the telemetry data transmitted by the spacecraft and by radio-tracking by the ground stations, has shown in the last period a stable slight over performance in thrust of about 1.5%. We are presently increasing the semi-major axis at a rate of about 150 km per day. Due to the electric propulsion system's excellent performance and the decreased radiation environment, we are now planning to extend the thrust to altitudes below 10 000 km.


The electric power produced by the solar arrays continues to be affected, as expected, by the radiation environment. We continue to register on average a loss of less than 2 Watts per day. This degradation should last until the trajectory crosses the radiation belts, i.e. for another month. At this rate the solar arrays will have lost about 130 W at the exit of the radiation belts. Due to the built in power margins, this will allow the spacecraft to continue thrusting at full power, hence shortening the time envisaged to reach the Moon. Of course, this is provided that we won’t get another exceptional solar storm again soon.

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