Author Topic: Solar Electric Tugs  (Read 1838 times)

Offline DLR

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Solar Electric Tugs
« on: 08/12/2010 01:55 PM »
Solar Electric Tugs seem to be a good idea to support the manned exploration and exploitation of the Moon and more accessible Near-Earth Objects. There is one drawback however. If Low Earth Orbit serves as the transportation node where cargo delivered by chemical launchers is picked up, SEP tugs would have to travel through the Van Allen radiation belts. What are the effects of radiation on solar cells? How great is the lifespan of a hypothetical SEP tug powered by solar cells affected by the belts? Would the use of solar thermal power generators instead of photovoltaic arrays be less problematic?

Offline alexterrell

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Re: Solar Electric Tugs
« Reply #1 on: 08/12/2010 09:26 PM »
That depends on the type of cell used.

Traditional silicon cells (and I believe amorphous silicon) suffer from radiation effects. However, craft have travelled through the Van Allen belts before.

Some of the thin film cells (e.g CIGS) appear to be more radiation proof. I recall somewhere they might lose 20% of their effectiveness on one pass, but are stable from there on.

Solar thermal would bypass this problem and have been advocated in advanced concepts. I would have my concerns about the reliability of the moving parts over a multi-year mission.

Offline Robotbeat

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Re: Solar Electric Tugs
« Reply #2 on: 08/12/2010 09:38 PM »
Also, if solar cells are heated temporarily, they can anneal away the vast majority of the damage.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline alexterrell

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Re: Solar Electric Tugs
« Reply #3 on: 08/22/2010 02:20 PM »
So what next?

There is meant to be a 200KW VASIMR demonstrator on ISS in 2012/13. Is this confirmed?

Next stage should be a 1MW VASIMR Earth Departure Stage, to take SDHLV payloads to L1 or beyond.

Offline pathfinder_01

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Re: Solar Electric Tugs
« Reply #4 on: 08/22/2010 08:15 PM »
The ISS test has been delayed till 2014. As for using it as an earth departure stage, I would prefer it to be lofted by something other than shuttle derived. It would likely be cheaper and could be built NOW instead of needing the rocket to be made first.  I think we should go for building an tug. I suspect that as an earth departure stage it could be costly, but if the system is reusable it could be worth it.

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