On Aug 22, 2019, at 10:09 PM, Henry Vanderbilt <hvanderbilt@xxxxxxxxxxxxxx>
wrote:
I think there does exist some scope to do significant things in space over
the next generation based on known-reaction chemical rockets. Within the
obvious practical chemical rocket limits: Days to the Moon, months to inner
planets and asteroids (marginal), years to anywhere else (prohibitive). And
only if the current government space morass can be bypassed, because they
both foot-drag on the obvious need for depots, routine reusability and
eventually local propellant sources, and they multiply already-high costs by
a prohibitive factor of ten-to-twenty.
But, that would still be just an initial industrial toehold off-planet, with
at best iffy long-term economic sustainability. Yes, agreed, in the long run
we must get past conventional rockets to something orders of magnitude more
energetic.
Of course the common problem with higher-energy propulsion is that generating
and handling that higher energy without melting takes too much mass,
resulting in what I am inclined to call "the mousefart thrust problem." The
power supply masses far too much so it takes too long to get up to speed.
And intermediate cases, like nuke thermal rockets, just don't gain enough Isp
to make up for the reactor mass. Yeah, you can get to Mars in four or five
months - but you can do that with chemical rockets also, given depots and
local propellant spent profligately - which would likely be cheaper overall
than developing and fielding the thermal-rocket reactors.
NSWR is an interesting attempt to combine high energy and high
thrust-to-weight in an onboard nuclear powerplant. Practical? Who knows.
I'll happily watch the tests - via video, from a LONG way off.
I tend to think that the most promising near-term approaches to
usefully-better-than-chemrocks space transport involve offloading as much of
the high-energy machinery as possible to fixed power-beaming stations at
either end of high-traffic routes. That way you can just throw mass at
gaining the efficiencies needed so your power generating and beaming
machinery doesn't melt. The two power transmission methods I currently like
are laser array, and neutral particle beam. Lasers you can convert to
electricity then use in electric thrusters, with useful fast-transport
performance at ship-end power-handling-to-mass ratios only (only!) a half
order-of-magnitude better than current SOTA. (It may also be possible to use
laser beams to directly energize reaction mass in other-than-material
containment, but that has a whole lot lower TRL.)
Neutral particle beams I only last spring became aware of as an option - I
gather the ship needs to apply a charge to the approaching beam, then magsail
on it - others can no doubt shed much more light on the concept (so to speak).
My bottom line though is that self-contained ships that can zoom around like
the Millenium Falcon require several (human) generations more advanced
low-mass power-handling than an external beam-powered transport net. Subway
cars in space, if you will - far less sexy. But we can build them a whole
lot sooner, within this generation, and we should, IMHO.
(RE your opening question, FWIW, I've never heard of any NSWR-specific
nuclear experiments. As you say, this isn't the fifties, there is no known
funded program, and I would think it'd be really hard to do a
proof-of-concept on that on any likely discretionary budget.)
Henry
On 8/22/2019 8:01 PM, anthony@xxxxxxxxxxx wrote:
Have any experiments been conducted using Zubrin’s nuclear salt-water rocket
(NSWR) concept to verify the design or has it fallen into the ”anything
that’s nuclear” black hole?
The cost to even get to the experimental stage wouldn’t be trivial seeing
this isn’t the 50s. I subscribe to the model that if we are going to
accomplish anything *really* significant in space flight in the next
generation, we have to get the known chemical reaction approach monkey off
our back. That’s just my opinion. The Zubrin citation is only an example BTW.
I’d like to hear some thoughts about this.
Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto
