On Tue, Oct 15, 2013 at 9:01 PM, Derek Clarke <derek_c@xxxxxxxxx> wrote:
Boot, don't tickle.
1) build a nuclear reactor! Use it for power for the electrolysis and
liquification plant for fuel and the rocket factory for booster cases.
Have you considered what this will cost in terms of investment and
time? I know where to get the numbers and could do it, but if you
have already done it, that would help. It's going to take an awful
lot of reactors to supply the fuel since there would be one going into
orbit all the time and the power levels of large rockets is around 50
GW.
Trying to keep the cost down, I specified hydrogen made from LNG. It
still takes $2 B of capital equipment, 1$1.3 B in steam reforming the
natural gas and 0.7 B for the plant to make they hydrogen into a
liquid.
2) develop a really big dumb booster. I'm thinking multiple Saturn V here.
You Don't Care about GTO, just be able to get tonnes into LEO.
3) since you designed the booster, you can optimise it for the end use.
Specifically, each launch delivers a chunk of antenna, some solar cells and
a big tank you can use for infrastructure. All you really need.
4) assemble in LEO. As you point out we know better how to do that,
especially if the assembly consists of undocking and docking manoeuvres!
Make the solar cell farm from interlocking discs the diameter of the
booster. Make the antenna the same way. An active antenna won't care.
5) once your powersat is assembled, use it to power the BFO ion drive you
delivered in the last couple of launches to get it to GEO. So it takes a
year or so to get there...
Back in the 70s this was Boeing's preferred approach--til someone
worked out how big power sats were and how long they would be exposed
to space junk. They gave up the idea because virtually every one of
them would be wrecked on the way out. If you fold them up so they
don't get hit as often, they take longer to get out to GEO because
they don't have as much power so they get hit just as many times.
That's not the only drawback to solar electric propulsion from LEO to
GEO
A completed power sat is worth at least $8 B. (5 GW x $1.6 B/GW)
building 20 of them a year and sending them up to GEO on a year long
mission would tie up $160 B as capital in transit. That's a lot more
than my estimate of $60 B to put the transport infrastructure in
place.
6) Rinse and repeat.
The cost of access to space is people cost, not aluminium and LH and LOX.
Minimise the people cost and the rest follows. So you leverage on mass
production of stuff that works first time every time and making your own
fuel. Use the simplest possible engines. The rest is cheap electronics.
Forget fancy schemes of reusable spaceplanes with pitiful cargo capacity and
lasers of power sufficient to carve your name in glass in the Sahara. Just
build hundreds of boosters we'd already be using if NASA hadn't got lost in
dreams of bus services to LEO.
I don't like the lasers either for that very reason. Be glad to share
the spreadsheets. If you can find a better way, I am all for it.
Unfortunately chemical rockets just suck for payload fraction, even
the best of them. A 1400 ton Falcon Heavy will put less than 20 tons
in GEO. I know of no way to do better on chemical fuels, which is why
the huge, expensive lasers.
Lasers, incidentally, don't make sense unless you are running them
24/7. Then they contribute only a few tens of dollars per kg to the
lift cost.
Keith
PS, I have given this a *lot* of thought, but am certainly glad to
have new ideas. Last April, Steve Nixon came up with the idea of
powering the initial propulsion laser from the ground with a reversed
microwave power link, like a power satellite but transmitting from a
10 km diameter antenna and receiving on a 1 km rectenna. That change
cut the peak capital investment from $140 B to $60 B--even taking into
account a $12 B transmitter.
Another few ideas like that one and we can fund it from our pocket change. :-)
On Tuesday, October 15, 2013, Keith Henson wrote:
On Mon, Oct 14, 2013 at 10:40 PM, Derek Clarke <derek_c@xxxxxxxxx> wrote:
Nice try, but no cigar. That programme is far too expensive.
So far, the technical people say it is to expensive and the finance
people say it can't be done for technical reasons.
Now, *I* have no idea of how to raise that scale of money, but as
energy project go, it is about half the size of the largest and there
are several of the same size, mostly LNG projects. If the Chinese do
it, $60 B is twice the cost of Three Gorges Dam.
Then there are
the implications of large numbers of multigigawatt lasers.
That I clearly state in the talk. Even one of them has huge
implications. Someone with experiences in military studies says the US
will attempt to destroy any Chinese propulsion laser. If the Chinese
were doing it jointly with the Indians would we still destroy it? Is
it in the interest of the US for the Chinese to get off coal? From the
viewpoint of the US, how do propulsion lasers differ in kind from
Predator drones and Hellfire missiles?
It was also not clear why you go to the expense of developing Skylon
just to
launch the first satellite.
The second generation Skylon, the one with the laser hydrogen heaters
is required to get the long term transport cost down. It's just too
much of a technological jump at one time so we need the original
version. The cargo needed for the first microwave powered propulsion
laser is in the ten thousand ton range. That will take ~1000 flights
of something to get it there. At two hundred flights per vehicle,
that will take 5-6 Skylons and about a year. I don't know any less
expensive way to get that much into space, especially when we need the
engineering experience of flying a couple of Skylons a day. Working
up to 3 flights an hour is going to be an interesting task.
Keith
On Tuesday, October 15, 2013, Keith Henson wrote:
http://youtu.be/qCiw99yRBo8
Talk I gave at Google in July.
Keith
On Mon, Oct 14, 2013 at 10:40 PM, Derek Clarke <derek_c@xxxxxxxxx> wrote:
Nice try, but no cigar. That programme is far too expensive. Then there
are
the implications of large numbers of multigigawatt lasers.
It was also not clear why you go to the expense of developing Skylon
just to
launch the first satellite.
On Tuesday, October 15, 2013, Keith Henson wrote:
http://youtu.be/qCiw99yRBo8
Talk I gave at Google in July.
Keith
On Tue, Oct 15, 2013 at 9:01 PM, Derek Clarke <derek_c@xxxxxxxxx> wrote:
Boot, don't tickle.
1) build a nuclear reactor! Use it for power for the electrolysis and
liquification plant for fuel and the rocket factory for booster cases.
2) develop a really big dumb booster. I'm thinking multiple Saturn V here.
You Don't Care about GTO, just be able to get tonnes into LEO.
3) since you designed the booster, you can optimise it for the end use.
Specifically, each launch delivers a chunk of antenna, some solar cells and
a big tank you can use for infrastructure. All you really need.
4) assemble in LEO. As you point out we know better how to do that,
especially if the assembly consists of undocking and docking manoeuvres!
Make the solar cell farm from interlocking discs the diameter of the
booster. Make the antenna the same way. An active antenna won't care.
5) once your powersat is assembled, use it to power the BFO ion drive you
delivered in the last couple of launches to get it to GEO. So it takes a
year or so to get there...
6) Rinse and repeat.
The cost of access to space is people cost, not aluminium and LH and LOX.
Minimise the people cost and the rest follows. So you leverage on mass
production of stuff that works first time every time and making your own
fuel. Use the simplest possible engines. The rest is cheap electronics.
Forget fancy schemes of reusable spaceplanes with pitiful cargo capacity and
lasers of power sufficient to carve your name in glass in the Sahara. Just
build hundreds of boosters we'd already be using if NASA hadn't got lost in
dreams of bus services to LEO.
On Tuesday, October 15, 2013, Keith Henson wrote:
On Mon, Oct 14, 2013 at 10:40 PM, Derek Clarke <derek_c@xxxxxxxxx> wrote:
Nice try, but no cigar. That programme is far too expensive.
So far, the technical people say it is to expensive and the finance
people say it can't be done for technical reasons.
Now, *I* have no idea of how to raise that scale of money, but as
energy project go, it is about half the size of the largest and there
are several of the same size, mostly LNG projects. If the Chinese do
it, $60 B is twice the cost of Three Gorges Dam.
Then there are
the implications of large numbers of multigigawatt lasers.
That I clearly state in the talk. Even one of them has huge
implications. Someone with experiences in military studies says the US
will attempt to destroy any Chinese propulsion laser. If the Chinese
were doing it jointly with the Indians would we still destroy it? Is
it in the interest of the US for the Chinese to get off coal? From the
viewpoint of the US, how do propulsion lasers differ in kind from
Predator drones and Hellfire missiles?
It was also not clear why you go to the expense of developing Skylon
just to
launch the first satellite.
The second generation Skylon, the one with the laser hydrogen heaters
is required to get the long term transport cost down. It's just too
much of a technological jump at one time so we need the original
version. The cargo needed for the first microwave powered propulsion
laser is in the ten thousand ton range. That will take ~1000 flights
of something to get it there. At two hundred flights per vehicle,
that will take 5-6 Skylons and about a year. I don't know any less
expensive way to get that much into space, especially when we need the
engineering experience of flying a couple of Skylons a day. Working
up to 3 flights an hour is going to be an interesting task.
Keith
On Tuesday, October 15, 2013, Keith Henson wrote:
http://youtu.be/qCiw99yRBo8
Talk I gave at Google in July.
Keith
On Mon, Oct 14, 2013 at 10:40 PM, Derek Clarke <derek_c@xxxxxxxxx> wrote:
Nice try, but no cigar. That programme is far too expensive. Then there
are
the implications of large numbers of multigigawatt lasers.
It was also not clear why you go to the expense of developing Skylon
just to
launch the first satellite.
On Tuesday, October 15, 2013, Keith Henson wrote:
http://youtu.be/qCiw99yRBo8
Talk I gave at Google in July.
Keith
