Re: Lunacy from Brussels

Pooh Bear wrote:


Dirk Bruere at Neopax wrote:


Pooh Bear wrote:


Rich Grise wrote:



On Sun, 16 Oct 2005 03:12:42 +0100, Pooh Bear wrote:



How much food and water would be required to sustain life for the
duration of an interplanetary trip ? I'll bet it would make such a
venture prohibitive.

Ever heard of "plants"? 


Ever seen Silent Running ?

When we can make spacecraft the size of ocean liners you may have a
point. I'd like to know how many ppl they could support though. Probably
not a lot.

We could do it quite rapidly if the need arose.


No we couldn't. 

It is quite a simple idea and a lot of work has already been done on it.
http://en.wikipedia.org/wiki/Nuclear_pulse_propulsion

Project Orion.
In the early 1960s Kennedy rejected the plan put before him by the US military
for a spacegoing battleship weighing thousands of tonnes with a crew of 200.


Battleships were already seen as a waste of space by the middle of WW2.

Well, a spaceship that could loft thousandsa of tonnes into orbit and carry crews of hundreds around the solar system is not quite the same thing as a sea going battleship.

"The first serious attempt to design a nuclear pulse rocket was Project Orion (See the article for details, including the vehicle sizes, problems, propulsion cycle and shielding). The design effort was carried out at General Atomics in the late 1950s and early 1960s. Orion reacted small directional nuclear explosives against a large steel pusher plate attached to the spacecraft with shock absorbers. Efficient directional explosives maximized the momentum transfer, leading to specific impulses in the range of 6,000 seconds (about twelve times that of the SSME). With refinements a theoretical maximum of 100,000 seconds (1 MN·s/kg) might be possible. Thrusts were in the millions of short tonnes, allowing spacecraft larger than 8×106 short tonnes to be built with 1958 materials.

The reference design was to be constructed of steel using submarine-style construction with a crew of more than 200 and a vehicle takeoff weight of several thousand tonnes. This low-tech single-stage reference design would reach Mars and back in four weeks from the Earth's surface (compare to 12 months for NASA's current chemically-powered reference mission). The same craft could visit Saturn's moons in a seven-month mission (compare to chemically-powered missions of about nine years).

A number of engineering problems were found and solved over the course of the project, notably related to crew shielding (good) and pusher-plate lifetime (which was unlimited). The system appeared to be entirely workable when the project was shut down in 1965, the main reason being given that the Treaty Banning Nuclear Weapon Tests in the Atmosphere, in Outer Space, and Under Water made it illegal. There were also ethical issues with launching such a vehicle within the Earth's magnetosphere. Calculations showed that the fallout from each takeoff would kill between 1 and 10 people. Enthusiasts want to launch outside the magnetosphere, or use clean fusion explosives, which are technically, but not politically feasible.

One useful mission for this near-term technology would be to deflect an asteroid that could collide with the earth. The extremely high performance would permit even a late launch to succeed, and the vehicle could effectively transfer a large amount of kinetic energy to the asteroid by simple impact. Also, an automated mission would eliminate the most problematic issues of the design: the shock absorbers.

Orion's technology is also one of very few known interstellar space drives that could be constructed with known technology.

Some authorities say that President Kennedy initiated the Apollo program to buy off the technical enthusiasts backing the Orion program. The recent book by George Dyson says that one design proposal presented to Kennedy was a space-going nuclear battleship, which so offended him that he decided to end the program. "

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org
.

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