Delfi-C3... a Batteryless Satellite? August 2006 Allan Copland GM1SXX
Further to my ramblings re the merits of satellites without batteries, it seems that the forthcoming Delfi-C3 bird, a Triple CUBESAT may be launched without batteries on board.
The official website says the following..
Since the TFSC payload cannot be body-mounted primarily for thermal reasons, it is equipped with four deployable solar panels, each carrying a TFSC payload and triple-junction solar cells (InGaP/GaAs/Ge) for power generation. The four solar panels are being deployed to an angle of 35º with respect to the body, which is the optimum angle to guarantee the required minimum power provision in any orientation to the sun. Power of about 3 W (min) is being generated by the EPS (Electrical Power Subsystem) under worst lighting conditions. No batteries have been foreseen for Delfi-C3; this implies that the spacecraft will be powerless during eclipse periods of its orbit.
I can only see two things of concern with this scenario. Unless some means is provided onboard to store the settings for which items will be switched on or off in some sort of non-volatile manner, the satellites would have to be commanded each time it entered daylight. Of course, such non-volatile RAM is now common, so lets hope the designers have made use of something like this NV RAM, perhaps as part of their embedded microcontroller, to store the preferred settings for when the CPU 'wakes up' on each trip into daylight.
The other problem as is always the case with CUBESAT's, even triple CUBESATs is simply the puny power budget.
Using a triple CUBESAT I feel is 'cheating' since has far greater surface area and far greater mass than a standard CUBESAT but at least it offers many advantages over a typical University 'me-too' clone in that it should carry some genuine amateur radio content in the form of a transponder. As I've said before, the standard CUBESAT is a lousy platform carrying even a low power transponder. Perhaps it's time the Universities reconsidered the whole CUBESAT concept. They are just too small to be useful for radio amateurs.
I'll follow this one with interest.
Allan Copland
GM1SXX