Wednesday, December 21, 2011

Power requirements in space

Speculation alert:

This is about the LOXLEO concept and how it might be made to work.  The main problem seems to be getting power to it.  Previously, I thought of beamed power.  There was a project that proposed to do this from the ground into space, but was deemed to be too expensive.

There may be another way to do this by way of fuel cells.  The idea is to generate enough electricity to provide thrust and to collect the oxygen from the edge of space.  The fuel cell would power a VASIMR, which would provide the thrust.

From the video in the fuel cell link above, it may well be that the size and mass of the fuel cell device will be too big.  So another thought came to me.  Put the fuel cell in a higher orbit, but synchronized with the LOXLEO satellite.  Then beam the power down to it from a relatively short distance in space.  That would allow a larger satellite in a relatively higher and stable orbit which would power the smaller satellite down below.  The smaller satellite would collect the oxygen and be powered by the VASIMR, which would be powered in turn from a higher orbit.

The fuel cell mentioned in the link is 1 MW.  The need is for up to 6 MW, so a much bigger device is needed.  I couldn't get the mass of the 1 MW plant, nor do I know if such would be feasible in space.  But if it were to be feasible, an array of six of these would be enough.  Then the power could be beamed down, possibly.

Perhaps you could break up the functions.  The collection of the oxygen seems to be the most intense use of energy.  You could put a smaller fuel cell on the lower orbiting satellite in order to power the VASIMR, and beam the higher power from above from the bigger satellite, in order to collect the oxygen.  That would enable you to make the lower satellite smaller and have less drag to overcome.


This is the second in a series of posts which are titled LOXLEO.  Another name for it is PROFAC.  There could be other names, but the one that sticks with me is LOXLEO.

By the way LOXLEO means Liquid Oxygen from Low Earth Orbit.  Profac is a similar acronym, but it eludes me for the moment.

I'm going to link the rest of the series from this post as follows:

Part 3
Part 4
Part 5

Note Part 6 and 7 are also on Kardashevian Aspirations blog.  You can reference them there.

There's another post that revisits the series.  I suppose that could be part 8.

Yet another revisit occurs a little later.  Call that Part 9.

Part 10 discusses how a reusable rocket can set up the refueling stations for extended trips to space.

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