XPost: sci.space.policy, sci.astro, sci.physics
From: jfindley@cinci.nospam.rr.com
In article , droleary@
2017usenet1.subsume.com says...
>
> 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.
>
> > >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.
Falcon 9 is the "first generation" reuse for SpaceX. For "zero waste",
you'll have to wait for their "second generation" which will be BFR/BFS.
> > >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. Nor a mag-lev cannon. I?m not
> sure how viable a high-altitude balloon launch would be, but it may
> also be cheaper than traditional first-stage rockets.
High altitude balloon launch is a tad risky and only gains you a bit of
altitude and zero velocity. Not worth the complexity and cost, IMHO.
> > >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. 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.
Sure, but SpaceX has proven that you can reduce costs dramatically by
using existing technology and introducing reuse of as many components as
possible. They're getting close to catching fairings and they have some
ideas for second stage reuse too. That would be very close to "zero
waste" with Falcon, if they can get to that point.
BFR/BFS is planned to be "zero waste" from the very beginning. Fully
reusable TSTO with "gas and go" like operations.
Also don't count out Blue Origin. They're off to a slow start, but have
a very reliable funding source in Jeff Bezos ($1 billion a year).
Besides, how you going to get those space elevator bits into orbit?
That's right, conventional (hopefully reusable) launch vehicles.
Jeff
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