[ExI] "NASA's 1st Deep-Space Capsule in 40 Years Ready for Launch Debut"

[spike]

-----Original Message-----
From: extropy-chat [mailto:extropy-chat-bounces at lists.extropy.org] On Behalf
Of BillK
Subject: Re: [ExI] "NASA's 1st Deep-Space Capsule in 40 Years Ready for
Launch Debut"

On Wed, Dec 3, 2014 at 6:33 PM, Ben <bbenzai at yahoo.com> wrote:
...
> I remember reading about this 'orion' spaceship a little while ago, 
> and getting all excited, until I realised that it's a far cry from the 
> original Orion concept!

http://www.islandone.org/Propulsion/ProjectOrion.html

> Ben Zaiboc

Ulam wrote about Orion in his book.  From the article: ...water would have
been injected to serve as propellant. This design produced the relatively
small Isp of 1150 seconds...  

The best chemical propulsion we have is about 460 seconds ISP, but also
consider, that 460 number is for LOX and H2, which isn't long term storable.
You need to use all that within a few days of launch.  So if you are going
out somewhere (anywhere other than the moon) you need something other than
LOX/H2, such as hydrazine, which gives a specific thrust in the 210-220
second range, if you insist on using seconds as an Isp measure (eeeewwww,
yuk.  (You know they aren't really seconds, ja?))  I wouldn't consider 1150
relatively low, but if you figure in the weight penalty of the blast shield
and the weight benefit of not needing enormous H2 tanks, you still fall
behind chemical propellants.

As I recall, they never did work out the neutron problem fully without an
enormous heavy blast shield.  But in any case, I think the real show-stopper
was launching all that plutonium on rockets known to explode.  We would need
to launch from some tiny dot of land somewhere in the south Pacific, such as
Gilligan's Island as a launch site, and even then there would be a risk of
dropping several tons of weapons grade plutonium on some hapless native in
the Brazilian rain forest.

Just the mention of Orion causes me to think back on the 1950s and 1960s.
All the really good fun military insanity happened in those decades, where
they were so terrified of the commies nuking us, all caution was thrown to
the wind.  They would think of stuff like Orion and make pitches on it
around tables where no one was laughing at the absurdity of it all.  Global
sanity gradually returned, which is good, but boring in a way.  {8^D

spike