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Re: Beyond P3D



Hello,

Looking back through my mail archive I came across (the attached)
post from Lyle Johnson of about a year ago. I remember at the time
eagerly awaiting replies/comments on this extraordinary idea - and
have yet to see any!

Since no one has knocked this one down I take it that is still up there
(or could be...). There must be someone on this list; at GSFC or
somewhere who could comment?

Anyway Lyle - Thanks and you get my nomination for
'Most Original Post' of 1997...

- Richard      ON9BCS / G7JMG



From Lyle Johnson's original post of 7 August 1997:
>
> Hi!
> 
> Since lots of folks are expressing their views on possible post-P3D
> missions, I thought I'd toss in one for consideration... well, two :-)
>
> The first is for a small number of small spacecraft in low earth
> orbit...
>
> "Oh no, I've heard this one before, I hoped this would at least be
> ORIGINAL!"
>
> Ah, but I mean LOW earth orbit, say 300-350 km altitude, linear
> transponder, L band up , S band down, plus a high-rate digital link (say
> a megabit or two data rate) that can be "time shared" for multiple
> simultaneous users who don't want to track doppler.
>
> "But the orbit will decay in a couple months or so, won't it?"
>
> Well, no.  You see, I suggest we place a small 3-stage linear
> accelerator (a tube with magnets and coils) down the center of this
> thing, use an antenna on the tail of it with a rudder for stability (we
> do have SOME gas up there to work against) and accelerate the positive
> (more massive) ions for thrust.  ASU did a study on something like this
> for one of the variants of ASUSat-1.  They concluded they would need a
> 40% to 60% duty cycle on the accelerator (6-10 watts solar power, 5 kg
> mass, rather high-drag cross section because of particles they wanted to
> detect off the blunt-nosed forward surface of the satellite)  to
> maintain orbit at these altitudes. I have a summary of the design
> proposal somewhere around here.  Put a small number of these in a sun
> synchronous 6AM-6PM orbit.  You ALWAYS have power then, local time is
> convenient for us earth-bound folks (near sunrise and sunset), fuel is
> plentiful, it is non-polluting, and we can do some research into this
> part of the ionosphere on a long-term basis that hasn't been done
> before.
>
> If we are in such an orbit, we might be able to minimize solar panel
> area by always facing the sun with one "side" of the spacecraft and only
> have enough cells on other sides to allow us to get to the right
> "rotation" about our long axis (presumed to be along the velocity
> vector).
>
> Such a spacecraft would have to be aerodynamic, probably a tube-like
> structure with the accelrator tube down the center to get thrust along
> the center of mass, etc.
>
> If the drag isn't too much and we can get anough thrust, we MIGHT be
> able to boost to this type of orbit from a hand-launch from the shuttle
> or MIR or FREEDOM or ???   We'd have to change our orbit inclination
> over time, as well as our altitude, but with unlimited fuel and some
> excess delta-vee, we should be able to do it.  And we can easily
> maintain orbit separation between individual spacecraft for the same
> reason.  I'm not a physicist, so I don't pretend to know, but hey, we're
> sharing ideas, right?
>
> "Ok, Lyle, that sounds weird but at least you're looking at turning the
> disadvantage of really-low altitudes into an advantage and exploiting
> it.  What about the second idea?"
> ... snip ... (second idea is good too)

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