As we are only in LEO, and rotation of astronauts prevents excessive exposure to radiation, and the price for propulsion is the limiting factor for development of space, why is radiation first over propulsion?
Brooks
--- In spacesettlers@yahoogroups.com, Gary Church wrote:
The first focus should be colonization of the Moon. Starships with pulsed
nuclear propulsion can subsequently be made to provide fast and regular
transit to Mars. ( Can nuclear propulsion be used for small space ships?
There could be problems in limiting the g forces. Why not experiment with
regular explosives also? Make balls of explosives like grenades and shoot
them in the front of reaction plates)
Selvaraj
On 19 June 2010 20:44, Gary Church wrote:
Right, but, using a nuclear pulse in or around Earth/Luna space is not necessary and is not likely to endear one to the security minded powers that be in our solar system. Nor is it either amenable to variable output, ease of fine control in navigating short or medium range targets, suitable for a small/medium size craft since it requires a massive blast shield or towing/ pushing recovered asteroids. Whereas, the NERVA motor, as designed, was to be the propulsion unit behind an apollo-style capsule enlarged to provide more space for the larger crew on a martian mission. It was deliberately designed to provide variable thrusts, including a kind of neutral gear that would allow for shunting some of the power to the environmental unit for use in maintaining the man-rated space. The N-P manner of propulsion will come into its' own (if it does) for longer range missions, and AFTER we've begun full scale harvesting of the resources available in space- the megatons of steel required for the blast-plate alone would, if it was necessary to lift it from Earth, render the craft non-cost effective not to mention the arsenal of bombs itself. And, as I stated, I think you'd play hell trying to get such a flying arsenal approved in the first place. Below, find links to videos of the NERVA engine being bench tested (it was a fully functional system that would have then, as it would today, provide a motor for a ship that could easily achieve all the objectives needed for building a space based Human civilization throughout Earth/Moon space and easily capable of chasing down and capturing asteroids):
http://www.youtube.com/watch?v=N15KmQthbKE
http://www.youtube.com/watch?v=ZRTrTRXOaTM&feature=related
Project Orion [(Nuclear Pulse Rocket project by US)2000 bomb arsenal, 10,000-8,000,000 tons mass]
http://www.youtube.com/watch?v=3l2QopJbDBs&feature=related
http://www.youtube.com/watch?v=neLA_IuRLI8&feature=related
Sent: Saturday, June 19, 2010 10:14 AM
To: spacesettlers@yahoogroups.com
Subject: Re: [spacesettlers] Re: New here, asteroids prefered
NERVA has an ISP of 850- from a reaction one million times more powerful than chemical fuel. Like using a napalm airstrike to light a cigarette. The problem with any nuclear rocket is containment- it is hard enough to keep a chemical rocket from melting. Stan Ulam correctly deduced that a fast fission device- a bomb- would be the most effective propulsion system for spacecraft. That was in 1945 shortly after the first one was lit off. It is still the only system that does not waste almost the entire amount of energy being produced. ISP for a Nuclear Pulse Propulsion system would be in the thousands and most probably in the tens of thousands.
--- On Fri, 6/18/10, Victor Smith wrote:
From: Victor Smith
Subject: Re: [spacesettlers] Re: New here, asteroids prefered
To: spacesettlers@yahoogroups.com
Date: Friday, June 18, 2010, 9:53 PM
1. NOT aerobraking- you're right...no atmosphere on the moon- instead, the reverse of a gravity slingshot, utilizing a swing by the moon (or Venus, the sun or both plus Luna for far out or very fast rocks) to reduce or augment delta v so as to modify an asteroids orbit so that it makes rendezvous with either a L-point or a position in Earth orbit at a nice safe speed to be met and towed to processing facilities. BTW, lunar orbit would suffice for processing facilities as well. I don't know that I would promote aerobraking anything past meteoric size in the Earths atmosphere due to safety considerations...luckily, though, it's not necessary.
2. Nuclear Pulse is NOT the only viable nuke propulsion system:
Begun in 1955, by the USAF, and then taken over in 1958 by NASA at that agencys' creation, NERVA (Nuclear Engine for Rocket Vehicle Application) was the expected rocket motor under development for the planned manned Mars mission then scheduled for launch in November 1981 with a manned landing in August 1982. In the late 1960s and early 1970s the Nixon administration drastically cut funding for NASA and NERVA. Eventually the NERVA/Rover program lost its altogether, and was terminated on January 5, 1973. Between 1959 and 1972, the Space Nuclear Propulsion Office oversaw 23 reactor tests at the Nuclear Rocket Development Station at the AEC's Nevada test site in Jackass Flats. These included the KIWI, PHOEBUS, PEEWEE-1 AND NUCLEAR FURNACE 1 test series on the rover reactor systems and the NRX-A2, A3, EST, A5, A6 and XE-PRIME series on the NERVA engine.
The NERVA program started out with the following objectives:
multi-mission capability
man-rated
based on full-flow topping
minimum chamber temperature of 2360 K and a minimum chamber pressure of 450 psia
minimum 75,000 lbf thrust
endurance of 600 minutes and up to 60 cycles
capable of 85,000 lbf and 500 psia transients
incorporating adequate shielding for manned operations
storable for 5 years on the ground, 6 months on pad, and 3 years in space
transportable by land, sea, and air
To meet these objectives, NERVA consisted of two reactor projects: the Nuclear Reactor eXperiment (NRX) and the eXperimental flight Engine Prototype (XE-Prime).
During its lifetime the NERVA/Rover programs accomplished the following records:
highest power: 4500 megawatts thermal power
5,500F exhaust temperature
250,000 pounds thrust
850 sec. of specific impulse
90 min. of burn time
thrust to weight ratios of 3 to 4
By the time the NERVA program was terminated, the NERVA-2 had been designed that would have met all of the program's objectives. Two of these engines would have been fitted to a NERVA stage capable of powering a manned interplanetary spacecraft. The final NERVA Alpha Flight Engine reference configuration, as documented at the end of its development, was an engine that could be launched together with its stage and a payload in a single shuttle launch. The final engine planned for the Mars mission would have been a scaled up version of this design and the Mars ship would have incorporated a pair of them.
http://www.astronautix.com/engines/nerva.htm
http://www.daviddarling.info/encyclopedia/N/NERVA.html
http://en.wikipedia.org/wiki/NERVA
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19910017902_1991017902.pdf
http://www.scribd.com/doc/29472345/How-the-NERVA-Rocket-Engine-Works
From: Gary Church
Sent: Friday, June 18, 2010 8:01 PM
To: spacesettlers@yahoogroups.com
Subject: Re: [spacesettlers] Re: New here, asteroids prefered
I am pretty much all about dealing with radiation first of all, then propulsion. NASA is making some plastic hull material that mitigates GCR. I think this is pretty important stuff. If you have an out plastic hull and an inner and fill the void up with moon water then for the first time there may be a way to actually go out there and not die of cancer. Of course to push all those hundreds of tons of water (minimum) you will need nuclear propulsion and the only viable nuclear propulsion system is Nuclear Pulse Propulsion (bombs).
--- On Fri, 6/18/10, brooksn wrote:
From: brooksn
Subject: [spacesettlers] Re: New here, asteroids prefered
To: spacesettlers@yahoogroups.com
Date: Friday, June 18, 2010, 9:23 AM
There will be countless candidates of meteroids/asteroids 5 - 10 meters across that come very close to Earth now. Adjusting their trajectories with the mass of a small spacecraft by meeting and 'parking' over and in the direction you want the object to go should take very little energy.
p = MV = Ft
p momentum
M mass
V velocity
F force
t time
Since we are picking from a very small class of asteroid, 10 meter, 2900 tons, we have kept M very low. Since we pick the asteroid with a favorable orbital path (just hitting or just missing Earth) we can keep the V very low. Since we are picking the asteroid we can also have more t time on our hands to adjust its orbit. Without doing the math it would seem to be a very cheap option, energetically, to grab an asteroid of our choice and put it into an aerobraking trajectory. And then bring it to ISS and begin study and processing of its material.
I can't see how the same mass leaving the moon to ISS would be lower in energy costs, delta v, then minor adjustments to the same mass already on course for Earth.
Brooks
--- In spacesettlers@yahoogroups.com, sraj wrote:
--- In spacesettlers, Gary Church wrote:
> times more powerful than chemical fuel. Like using a
> napalm airstrike to light a cigarette. The problem with
> any nuclear rocket is containment- it is hard enough to
> keep a chemical rocket from melting. Stan Ulam
> correctly deduced that a fast fission device- a bomb-
> would be the most effective propulsion system for
> spacecraft. That was in 1945 shortly after the first
> one was lit off. It is still the only system that does
> not waste almost the entire amount of energy being
> produced. ISP for a Nuclear Pulse Propulsion system
> would be in the thousands and most probably in the tens
> of thousands.
Nuclear salt water rocket?
Sailor, I forwarded a lot of factual data about NERVA in an earlier post that shows the below post as fantasy. The NERVA rocket is a nuclear thermal system where the energy is pulled off a pile to heat water for use (as vapor) for propulsive reaction mass and (via turbine) as power for an interplanetary spaceships life4 support module. It was in the NASA works as the motor of choice until it lost funding (along with countless other worthwhile programs) during the Reagan years. If nuclear pulse was considered as most effective in '45, it didn't maintain that status for long.
http://en.wikipedia.org/wiki/NERVA
Sent: Wednesday, June 30, 2010 11:43 PM
To: spacesettlers@yahoogroups.com
Subject: [spacesettlers] Re: New here, asteroids prefered
--- In spacesettlers, Gary Church wrote:
> NERVA has an ISP of 850- from a reaction one million
> times more powerful than chemical fuel. Like using a
> napalm airstrike to light a cigarette. The problem with
> any nuclear rocket is containment- it is hard enough to
> keep a chemical rocket from melting. Stan Ulam
> correctly deduced that a fast fission device- a bomb-
> would be the most effective propulsion system for
> spacecraft. That was in 1945 shortly after the first
> one was lit off. It is still the only system that does
> not waste almost the entire amount of energy being
> produced. ISP for a Nuclear Pulse Propulsion system
> would be in the thousands and most probably in the tens
> of thousands.
Nuclear salt water rocket?
> > Stan Ulam
> > correctly deduced that a fast fission device- a bomb-
> > would be the most effective propulsion system for
> > spacecraft. That was in 1945 shortly after the first
> > one was lit off. It is still the only system that does
> > not waste almost the entire amount of energy being
> > produced. ISP for a Nuclear Pulse Propulsion system
> > would be in the thousands and most probably in the tens
> > of thousands.
Brooks
--- In spacesettlers@yahoogroups.com, "brooksn" wrote:
>
> > > Stan Ulam
> > > correctly deduced that a fast fission device- a bomb-
> > > would be the most effective propulsion system for
> > > spacecraft. That was in 1945 shortly after the first
> > > one was lit off. It is still the only system that does
> > > not waste almost the entire amount of energy being
> > > produced. ISP for a Nuclear Pulse Propulsion system
> > > would be in the thousands and most probably in the tens
> > > of thousands.
>
> This idea is a political non starter, no one is going to allow the setting of nuclear bombs in the atmosphere for a launch vehicle or allow the launch of vehicle with its fuel tank filled with nuclear weapons to (hopefully) go off in space.
>
> Brooks
>
I am very familiar with this theory, and it has nothing to do with atmospheric launch, BUT instead deep space use, ie like Mars missions. conventional launch systems would still be used to get craft, and equipment to space, and only after said space craft is beyond the moon would such a propulsion be used...
--- In spacesettlers@yahoogroups.com, "the_gunfighter_45acp" wrote:
>
> --- In spacesettlers@yahoogroups.com, "brooksn" wrote:
> >
> > > > Stan Ulam
> > > > correctly deduced that a fast fission device- a bomb-
> > > > would be the most effective propulsion system for
> > > > spacecraft. That was in 1945 shortly after the first
> > > > one was lit off. It is still the only system that does
> > > > not waste almost the entire amount of energy being
> > > > produced. ISP for a Nuclear Pulse Propulsion system
> > > > would be in the thousands and most probably in the tens
> > > > of thousands.
> >
> > This idea is a political non starter, no one is going to allow the setting of nuclear bombs in the atmosphere for a launch vehicle or allow the launch of vehicle with its fuel tank filled with nuclear weapons to (hopefully) go off in space.
> >
> > Brooks
> >
> I am very familiar with this theory, and it has nothing to do with atmospheric launch, BUT instead deep space use, ie like Mars missions. conventional launch systems would still be used to get craft, and equipment to space, and only after said space craft is beyond the moon would such a propulsion be used...
> Second note, given that nuclear bombs have proven themselves very reliable, and that we launch them into space on ICBMs with no issues the risk is very low, but the public does act like a bunch of scared little kids assuming the worst possible out come whenever the word nuclear is used, no matter how improbably low the risk is. This irrational thinking would first have to be put at ease before such a system would be allowed.
How many ICBMs have we launched into space? How improbable is the risk of launching a space craft with several dozen nuclear bombs in the payload having a catastrophic accident? This isn't a nuclear powered spacecraft with some contamination being the risk, these are dozens of nuclear bombs designed to explode. I will put 1000 dollars down and give you 10 to 1 odds, the public will never be put at ease, including myself, to allow such a system to be allowed.
Brooks
Once we have industry in Space, the spacecraft, including
bombs, could be manufactured out in Lagrange points or
even farther away. That would help to mollify skittish
Earthlings.
http://en.wikipedia.org/wiki/Nuclear_salt_water_rocket
brooksn wrote:
>
> --- In spacesettlers@yahoogroups.com
> , "the_gunfighter_45acp"
> wrote:
> >
> > --- In spacesettlers@yahoogroups.com
> , "brooksn" wrote:
> > >
> > > > > Stan Ulam
> > > > > correctly deduced that a fast fission device- a bomb-
> > > > > would be the most effective propulsion system for
> > > > > spacecraft. That was in 1945 shortly after the first
> > > > > one was lit off. It is still the only system that does
> > > > > not waste almost the entire amount of energy being
> > > > > produced. ISP for a Nuclear Pulse Propulsion system
> > > > > would be in the thousands and most probably in the tens
> > > > > of thousands.
> > >
> > > This idea is a political non starter, no one is going to allow the
> setting of nuclear bombs in the atmosphere for a launch vehicle or
> allow the launch of vehicle with its fuel tank filled with nuclear
> weapons to (hopefully) go off in space.
> > >
> > > Brooks
> > >
> > I am very familiar with this theory, and it has nothing to do with
> atmospheric launch, BUT instead deep space use, ie like Mars missions.
> conventional launch systems would still be used to get craft, and
> equipment to space, and only after said space craft is beyond the moon
> would such a propulsion be used...
>
> Um, looking here,
> http://www.islandone.org/Propulsion/ProjectOrion.html and here
> http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) it was
> proposed as an atmospheric launch. If you are proposing only outside
> the atmosphere, that is fine.
>
> > Second note, given that nuclear bombs have proven themselves very
> reliable, and that we launch them into space on ICBMs with no issues
> the risk is very low, but the public does act like a bunch of scared
> little kids assuming the worst possible out come whenever the word
> nuclear is used, no matter how improbably low the risk is. This
> irrational thinking would first have to be put at ease before such a
> system would be allowed.
>
> How many ICBMs have we launched into space? How improbable is the risk
> of launching a space craft with several dozen nuclear bombs in the
> payload having a catastrophic accident? This isn't a nuclear powered
> spacecraft with some contamination being the risk, these are dozens of
> nuclear bombs designed to explode. I will put 1000 dollars down and
> give you 10 to 1 odds, the public will never be put at ease, including
> myself, to allow such a system to be allowed.
>
> Brooks
>
/Footfall/? Only constructed and launched outside of terrestrial
atmosphere? [My copy is put away because I read my first edition to the
point of spine damage (its, not mine).]
If anyone knows the research behind that concept, I would appreciate the
links.
ERandall