November 18, 2011

Another attempt to make the case for Project Orion nuclear pulse propulsion

Gary Michael Church makes the case for reviving project Orion on the Lifeboat Foundation blog (H/T Centauri Dreams)

Psychological limits of human beings limit space journeys to a few years. Chemical propulsion is not capable of taking human beings to the outer solar system and back within those crew limits. The solution is a reaction one million times more powerful. Nuclear energy is to the space age as steam was to the industrial age.

The term “ISP”, expressed in seconds, is used in measuring the efficiency of a rocket engine and chemical rockets have low ISP numbers but high thrust. The most efficient rocket engines, such as the space shuttle main engines, with a listed ISP of 453 seconds are also among the most powerful. Atomic bomb propulsion, thanks to the billions of dollars poured into star wars weapons research, would have an ISP exceeding 100,000 seconds.

Space travel as not only a speed and distance problem, but also a time and distance problem, low thrust lengthens any missions to the outer solar system beyond crew limits. The thrust imparted by atomic bombs can in a short period easily accelerate thousands of tons to the comparatively extreme speeds necessary and then coast. Unlike an electric propulsion failure, a few dud bombs need not doom a mission or crew.

The first serious work on bomb propulsion was done by physicist Freeman Dyson and weapon designer Ted Taylor on the top secret project Orion. Dyson’s son, in his book Project Orion, refers to the classified star wars project Casaba Howitzer. This device focused most of the energy of a nuclear explosion in one direction. Ted Taylor’s specialty was small warheads and he designed the Orion bombs, aka “pulse units.” The “unclassified” state of the art in nuclear weapons can direct 80 percent of bomb energy into a slab of propellant, converting this mass into a jet of superheated plasma. A pusher plate would absorb the blast without melting for the fraction of a second it lasts and accelerate the spaceship in steps with each bomb. Perhaps the closest experience to riding in an atomic bomb propelled spaceship would be repeated aircraft carrier catapult launches. Instead of the ocean, space. Instead of supersonic fighters, a thousand ton spaceship.








The problems with space travel are more than just the political barriers to detonating nuclear devices. The space industry is ipso facto a nuclear industry. Not only is nuclear energy the only practical source of propulsion in deep space, nuclear radiation generated by supernova and other celestial sources permeate space outside the protection of the earth’s atmosphere. All astronauts are radiation workers. Most, but sadly not all, space radiation is relatively easy to shield against. Many will argue using atomic bombs for propulsion is unnecessary. The presence of a small percentage of highly damaging and deeply penetrating particles — the heavy nuclei component of galactic cosmic rays makes a super powerful propulsion system mandatory. The tremendous power of atomic bomb propulsion is certainly able to propel the heavily shielded capsules required to protect space travelers. The great mass of shielding makes chemical engines, inefficient nuclear thermal rockets, the low thrust forms of electrical propulsion, and solar sails essentially worthless for human deep space flight. Which is why atomic bomb propulsion is left as the only “off the shelf” viable means of propulsion. For the foreseeable future, high thrust and high ISP to propel heavy shielding to the required velocities is only possible using bombs. The most useful and available form of radiation shielding is water. While space may not be an ocean, it appears human beings will have to take some of the ocean with them to survive.

The water comes before the bombs in human space flight because of the humans. The radiation hazards of long duration human space flight beyond earth orbit are only recently being addressed after decades of space station experience. The reason for this neglect is low earth orbit space stations are shielded from much of the radiation found outside the Earth’s Van Allen belts and magnetic field. An appreciation of the heavy nuclei component of galactic cosmic radiation, as well as solar events, will put multi-year human missions beyond earth orbit on hold indefinitely until a practical shield is available. While vested interests continue to promote inferior or non-existent technology, dismissing the radiation hazards and making promises they cannot keep, radiation scientists studying deep space conditions are skeptical — to say the least.

The impracticality of a massive shield is due to first the expense of lifting hundreds of tons of shielding into space from Earth, and secondly propelling this mass around the solar system. Propelling this mass is not a problem if using atomic bombs, however, another problem arises. Even if the bombs could be politically managed, there is still the need to escape Earth’s gravitational field with all that shielding. Bomb propulsion is ideal for deep space but cannot be used in Earth orbit due to the Earth’s magnetic field trapping radioactive fallout that eventually enters the atmosphere.

NOTE- My nuclear cannon concept to use one large underground nuclear pulse could launch large amounts of water from the earth.

A correction to the launching water from the Earth. I have proposed one underground nuclear pulse to create a nuclear cannon. This would allow allow all of the radiation to be trapped underground or in the ocean if the the launch was also under water. This variant on nuclear pulse propulsion can get around the existing nuclear treaties. Underground nuclear tests of 150 kilotons or less are still permitted and the fallout can be trapped. Chemical cannons have confirmed that payloads can be launched that can withstand 2000 – 5000 Gs. Particularly g force resistant supplies like water or ice. The ice could be launched as pycrete in a shell that uses reshaped submarine hull technology.


The situation changed in March 2010 when NASA reported Mini-SAR radar aboard the Chandrayaan-1 lunar space probe had detected what appeared to be ice deposits at the lunar North Pole. An estimated 600 million tons of ice in sheets a couple meters thick. Moon water would allow a spaceship in lunar orbit to fill an outer hull with the 500+ tons of water required to completely shield a capsule from heavy nuclei. This would enable an empty spaceship to “travel light” to the Moon and then boost out of lunar orbit using atomic bomb propulsion with a full radiation shield. Parker’s guaranteed but impractical solution had suddenly become practical. Fourteen feet of water equals the protection of the Earth’s air column at an altitude of 18,000 feet above sea level. This would protect astronauts not only from all cosmic radiation but the most intense solar storms and the radiation belts found near the moons of Jupiter. With water and bombs, epic missions of exploration to the asteroid belt and outer planets are entirely possible. The main obstacles are again political, not technical. Bombs work, water works, and the Moon is in range of chemically propelled spacecraft launched from Earth.









The 5 megaton underground nuclear test video. Notice things are shaking as this is like a magnitude 7 earthquake but there was no radiation venting. 85% of the energy for the nuclear cannon would go at the projectile.

Amchitka islands today.



Dr. Volz hand catches Eider Ducks on Amchitka Island, Aleutians, for Radionuclide Internal Dose Assessment

University of Alaska study of Amchitka Island: "There were no indications of any radioactive leakage, and all that was really wonderful news."

FURTHER READING
1989 congressional analysis of underground test safety.

A person's total exposure would be equivalent to 32 extra minutes of normal background exposure (or the equivalent of 1/1000 of a single chest x-ray).

A worst-case scenario for a catastrophic accident at the test site would be the prompt, massive venting of a 150-kiloton test (the largest allowed under the 1974 Threshold Test Ban Treaty). The release would be in the range of 1 to 10 percent of the total radiation generated by the explosion (compared to 6 percent released
by the Baneberry test or an estimated 10 percent that would be released by a test conducted in a hole open to the surface). Such an accident would be comparable to a 15-kiloton above ground test, and would release approximately 150,000,000 Ci. Although such an accident would be considered a major catastrophe today, during the early years at the Nevada Test Site 25 above ground tests had individual yields equal to or greater than 15 kilotons.


Gas Storage in Salt Structures
















There are salt domes that are 6.5 kilometers thick and 10 kilometers across.

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