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Old June 13th 18, 12:05 AM posted to sci.space.policy,sci.astro,sci.physics,rec.arts.sf.science
Fred J. McCall[_3_]
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Default Towards routine, reusable space launch.

Doc O'Leary wrote on Sat, 9 Jun
2018 17:19:39 -0000 (UTC):

For your reference, records indicate that
Fred J. McCall wrote:

Doc O'Leary wrote on Fri, 8 Jun
2018 13:10:48 -0000 (UTC):

What are the actual numbers when it comes to savings from a reusable
rocket?


That depends on a lot of things.


Well, sure, but it always helps to have some data to work with before
beginning an optimization process. Best/worst cases or averages or
whatever. What the savings is related to the total cost of the launch
is going to be guiding factor on how much effort it makes sense to
expend to re-use different parts of the system.


When I say it depends on a lot of things, I meant exactly that. You
can't 'invent' data. Space Shuttle was supposedly 'partly reusable',
but it was MORE expensive than throwing away hardware with similar
capabilities. SpaceX seems to think that they can reduce the cost of
a launch by a third by reusing first stages (and that was before they
were optimized for reuse). They think that BFR/BFR Spaceship will
cost less than 1% of the hardware price per flight (a fully reusable
system good for 100 launches before servicing). Pick your poison.

It?d also be interesting to know how new technologies might
impact the economics of launching items into space (including just making
disposable launch vehicles much cheaper).


Real reuse will always be cheaper. If you can make disposable launch
vehicles much cheaper, the same technologies allow making reusable
launch vehicles much cheaper.


That is non-obvious. Ideally, I would think a “zero waste” system
would be cheapest; every kg of mass that gets sent up either stays up
(doing something useful) or was the fuel. All this booster landing
(and subsequent refurbishing for relaunch) we’re seeing, while cool,
is definitely *not* the most efficient use of resources.


Yes, magic would be more efficient, but we don't have magic.

Once you start to contemplate
the need for multiple daily launches, even recovering boosters to reuse
them seems like a slow and labor-intensive process.


But orders of magnitude faster than throwing them away and building a
new one.


But that’s still assuming old technologies rather than new ones. You
don’t “throw away” a space elevator.


You also can't build one without 'magic' because it is impossible for
materials to be strong enough.


Nor a mag-lev cannon.


Now the payload needs to be 'magic' to withstand the launch.


I’m not
sure how viable a high-altitude balloon launch would be, but it may
also be cheaper than traditional first-stage rockets.


I'm sure. It doesn't accomplish what a first stage accomplishes, so
it doesn't really matter if it's cheaper or not. What it's not is
'effective'.

On the path to a
space elevator, it seems like there should be many more ways to reach
escape velocity that do a better job than what Musk is doing today.


You've discovered a good supply of unobtainium, have you? Otherwise,
rockets are your man for getting stuff to orbit for the foreseeable
future.


It’s always a good idea to noodle around with other technologies, no
matter how impossible they appear to be today.


Building a tether on Earth requires materials that are stronger than
materials can theoretically be. Noodle all you like. Basic laws of
physics aren't going to change no matter how hard you wish.


Because, yes, rockets
are the way to get to orbit, but I’m most interested in the
*unforeseeable* future that has humans on other planets around other
stars. Just being satisfied with rockets is not going to make that
happen.


When you're in entirely the wrong newsgroup. You need something that
starts with 'alt' or 'rec'.


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn