[ExI] Eyes on the Solar System

[spike at rainier66.com]

...> On Behalf Of BillK via extropy-chat
Subject: Re: [ExI] Eyes on the Solar System

On Sun, 4 Sept 2022 at 14:51, spike jones via extropy-chat
<extropy-chat at lists.extropy.org> wrote:
>
> Artemis is having a bit of difficulty, but note that Lockheed only built
the reentry system.  Boooeing built the rocket.
>
> spike
> _______________________________________________


>...I wouldn't dare criticize Lockheed in your presence!   :)

No worries BillK me lad, I know your heart is pure.  But mine isn't: far too
much of my retirement portfolio is still LockMart stock.  I need to finish
moving out of that stuff.  Already sold about 2/3 of it something like that.

>...Ars Technica has an article reporting that NASA should have known
better.
They copied the Shuttle's main engines powered by the combustion of liquid
hydrogen propellant and liquid oxygen and the Shuttle had exactly the same
problem with leaking hydrogen.

<https://arstechnica.com/science/2022/09/years-after-shuttle-nasa-rediscover
s-the-perils-of-liquid-hydrogen/>

BillK
_______________________________________________

Well right, that's part of it BillK, but when I started studying into what
they did there, that isn't all.  Do read on please, and if you are in a
hurry, the important part is at the end.

Thanks for the Ars Tech article.  They pointed out the reason I wouldn'ta
chosen H2 as a first stage.  It is high performance and all that, OK sure,
high performance in specific thrust, the power per unit mass, oh ya can't do
better than LOX and hydrogen.  However... hydrogen has always been crazy
hard to handle: tiny atomic radius, super cold, dangerous as all hell, and
you know the thing.

Had I been calling the shots, I woulda directed the team to give back a
little payload performance and use good old tried and true kerosene LOX
first stage.  Oh is it soooo much easier and (this is the critical point) it
is denser, waaay denser in its liquid phase which is critical in first
stages where volume matters, punching thru the atmosphere.  This is what
makes solid boosters practical: they carry way denser fuel, so they can
carry more of it for a given diameter, and they aren't going all that high,
so you can give away some performance in exchange for the advantages of
solids.

So... the STS and the Artemis are a mix of high and low tech with no medium
tech (if you want to think of it in those terms) with low tech being the
solids, high tech being the hydrogen burners.  Looks to me like a better
ride would be solids with a kerosene burner main engine, or even Space-seXey
liquid boosters which land feet first on dry ground with dignity.

Oh I just can't get enough of the sexiness of these kinds of videos:

https://twitter.com/iamtomnash/status/1566019351072968708

It's the best kind of techno-porn.  I get so turned on, oh mercy, better
than Viagra, and cheaper.

Coupla those babies, kerosene main engine, adios payload.  Carry a hydrogen
LOX third stage if you really need the extra delta V.

One more thing BillK if you read this far: the main engine design is space
shuttle derived, which means it was originally designed to be used 50 times.
When space hardware (or any machine) is designed to be used 50 times (and be
capable of restart) there are cost and weight penalties inherent in the
design compared to the throw-away after one use engine.  Turned out it was
cheaper, faster and more practical to use the existing engine designs with
all those cost, weight and complication costs already in place rather than
design a new engine (Why?  Because we don't have enough rocket engine
designers anymore, that's why.)  So NASA is left throwing away hardware
after each flight which was designed with a 10 year 50 cycle life.  Damn.

My approach woulda been different.  We don't desperately need to get back to
the moon, or even if so, there is no big hurry, and we really aren't going
to fly Artemis to Mars anyway (we really aren't (time to face up to that
reality (details cheerfully available on request.)))  

So... I woulda just bought a coupla Elon's SpaceseXey tail landers and
designed a new kerosene burning main stage (with advanced control to dial in
a bit of modern automated control system sexiness) which coincidentally, is
what LockMart proposed to start with.  I had nothing to do with that
proposal, they didn't consult me at all, didn't need to because they know me
in the propulsion group and know what I woulda said.  I didn't even learn of
the proposal until I concluded likewise for all the same reasons LockMart
proposed it to start with.

spike