The International Space Station and Solar Power

by john hare

There is a coding contest now for programmers to find the best algorithm for pointing the International Space Station’s solar arrays to avoid shadowing the masts during parts of the orbit which causes them to shrink from the cold and possibly buckle. Given that the station is in its’ second decade now, I would think that this should have been a problem solved quite some time ago. Since there is a contest to solve that problem, it would seem that I’m wrong.

It seems to me that the basic problem is that the ISS is large and unwieldy enough to have inflicted this problem on itself. Since eventually there will be even larger and more convoluted orbital platforms depending on solar energy, it might be worth taking a look at different options for power.

One option is a co-orbiting solar power satellite (SPS) dedicated to ISS power. If maximum distance can be kept under a hundred miles, the ISS side rectenna would be a fairly small piece of hardware that should have far less effect on the ISS microgravity environment. An ISS dedicated SPS could be upgraded at will (or ability) without affecting the ISS at all. Even though some power would be lost to efficiency issues, a solar array ten or a hundred times as large could make up the difference and then some.

The co-orbiting SPS could also serve as an embryonic transport node for ISS and points beyond. An SPS based tug could capture ISS bound payloads for sorting and repackaging before drifting them over to the station at the time of need or convenience. This would considerably relax the requirements on ISS bound supply transports. The ISS visiting vehicle requirements apparently cut the effective payloads by a considerable amount with the last Falcon IX delivering a small fraction of its’ advertised payload.

The tug meeting all the visitor requirements on a permanent basis would also be a safer option for ISS delivery than a constant mix of American, Japanese, Russian, and ESA ships arriving at various intervals.

The transport node would make an effective storehouse for items not yet needed or no longer required on the ISS. By relaxing the timing of deliveries via available storage, all the supplying entities could launch at earliest convenience rather than somewhat arbitrary schedules based on the latest delay by the other guy. By using the tug to remove unwanted stuff from the station, more room would be available for the researchers doing the real work.

The co-orbiting SPS would make a useful safe haven for ISS crew that needed to evacuate. With available tugs and taxis, the ISS staff should be able to increase to a dozen or so if escape requirements are still the bottleneck for crew size.

For points beyond, the SPS could provide considerable early power to electric propulsion vehicles during the gravity well climb out. The assembly and check out portions would allow on board techs to add used ISS gear to outbound missions that could use it.

All these suggestions are old. It just seems that a NASA contest to solve a power problem is a good time to rehash them.

You can find more posts by John Hare on the blog Selenian Boondocks.

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