Presently the thrust arcs last for about 27 hours out of an orbital period of 81 hours. The thrust duration will progressively increase to a longest thrust arc of 41.5 hours starting on 10 August at 12:52, when the orbit period will be about 120 hours (5 days).

The Electric Propulsion power is operating at 1358 W, as the power margins on the spacecraft are rather comfortable and operating at a higher power level saves fuel.

The Earth has now passed the aphelion point of its orbit around the Sun. As indicated in the graph below there has been a steady decline in the power output of the solar array since perihelion in January.

The electric propulsion thruster still exhibits some variation in thrust, caused by the varying amplitude of the anode current oscillation. No Optocoupler Single Event Transients, causing the flame-out, have been observed during this period.

Up to 3 July, and the 248th engine pulse, the ion-engine had cumulated a total ON time of about 2643 hr, consumed about 41.6 kg of Xenon and imparted to the spacecraft a velocity increment of about 1930 ms-1.

In status report #24, 11 June 2004, a slight degradation in performance of Transmitter A, as measured by on-board telemetry parameters, was indicated. In an initial attempt to understand the problem an experiment to measure the electromagnetic power radiated to ground by Transmitter A, compared to Transmitter B has now taken place.

This required a special orbital configuration and careful procedures to be in place. The test confirmed that the Transmitter A is about 1 dB (1 W) weaker than Transmitter B. Experts are making further investigations.

Related Links
Smart 1 at ESA
SpaceDaily
Search SpaceDaily
Subscribe To SpaceDaily Express