[AR] Re: OT laser propulsion and power satellites
- From: Keith Henson <hkeithhenson@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Mon, 21 Oct 2013 21:50:37 -0700
The idea is to build power satellites, initially at a rated of 100
GW/year. That's less than 5% of the needed construction rate, but it
still takes lifting 500,000 tons per year to GEO, and for the power
satellites to make economic sense, the cost has to get below $100/kg.
I don't know how to do that with chemical rockets, which is why the
honking big propulsion laser.
But that generates other problems, like a 3 GW output laser takes
about 6 GW of power in and generated 3 GW of waste heat. Doing it the
hard way with chemical rockets to build a power sat, laser, optics and
heat sink came in at around $140 B. Steve Nixon suggested powering
the propulsion laser initially from the ground using a reversed
microwave link, 10 km diameter phased array transmitter on the ground
and a 1 km rectenna in space. That saves at least 14,000 tons and
better yet, you don't have to take it to GEO, you can build it in LEO
and using the same power source take it out to GEO on electric
thrusters. With that much power, it can scoot out to GEO in something
like ten days.
40,000 km isn't a problem for lasers. Mirrors already exist that will
do the job. The big advantage of GEO for the propulsion laser is that
the launch window is always open, critical when we need to fly three
times an hour.
BTW, I don't have any current use for your "pull" type of laser
propulsion, but will keep it in mind. I didn't have any use for
electric propulsion for LEO to GEO (to slow) either until Steve's idea
came along.
On Mon, Oct 21, 2013 at 9:21 PM, Jake Anderson <jake@xxxxxxxxxxxxxxx> wrote:
> On 22/10/13 14:44, Keith Henson wrote:
>>
>> On Mon, Oct 21, 2013 at 2:02 PM, John Stoffel <john@xxxxxxxxxxx> wrote:
>> snip
>>>
>>> Laser sounds neat, but I always wonder what happens when it loses lock
>>> and illuminates something else by accident...
>>
>> That's why the acceleration path is over water.
>>
>> Keith
>>
> I got to thinking, If your goal is to loft power sats, rather than actually
> generate power there is no need for your first sat to be in GEO.
> Put it in a middlish LEO orbit, as you cruise over the launch site (during
> the day) fire the laser (so total distance is now more like 400Km rather
> than 40K, so your laser is going to be easier) and "pull" the payload into
> orbit behind you, worst case it'll be ~8 minutes or 4000km behind you at
> burnout and your inital rocket launched payloads are now twice as easy to
> loft.
>
>
>
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