Wednesday, February 5, 2014

Mission to Mars: Orion Nuclear Propulsion

Project Orion represents one of the grandest and most audacious “might have beens” ever conceived in the fifty year history of space exploration. With the aid of the Orbiter Spaceflight Simulator designed by Dr. Martin Schweiger of UCL and its associated Project Orion add on, today’s video feature illustrates one possible mission profile that would take a crew to the planet Mars.

According to science fiction author Jerry Pournelle, who is acquainted with the project and its ex-team leader Freeman Dyson, a single mission could have provided us with a large permanent moon base. Alternatively, an Orion could reach Pluto and return to Earth in a year.

Project Orion could have potentially given us the means to explore and colonize the entire solar system in the second half of the twentieth century. But, the nature of its propulsion system was it major draw back.

The idea was to use thousands of miniature nuclear bombs to lift a space craft the size of an aircraft carrier from the Earth’s surface and send it on an orbital trajectory that would take it to Mars and beyond.

The environmental hazard of the nuclear fallout generated by its propulsion system was one major undoing of the entire project.

Orion near the Martian moon Phobos 

According to George Dyson (the son of Freeman Dyson), the author of “Project Orion: The Atomic Spaceship 1957-1965”, President Kennedy initiated the Apollo program to buy off the technical enthusiasts backing the Orion program. One design proposal presented to Kennedy was a space-going nuclear battleship, which so offended him that he decided to end the program.

Project Orion was the first serious attempt to design a nuclear pulse rocket. The design effort was carried out at General Atomics in the late 1950s and early 1960s. The idea of Orion was to react 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. 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 eight million 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 and pusher-plate lifetime. The system appeared to be entirely workable when the project was shut down in 1965, the main reason being given that the Partial Test Ban Treaty 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.

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

In this mission profile Orion is launch by Nova rocket MM S010E-1 using 8 UA1207 120 inch solid motors as first stage, 24 high pressure LH2/Lox engines in the second stage in a plug nozzle arrangement. Total Mass 10,328,000 kg without UA1207, with UA1207 12,882,640 kg.

1 x Nova MMS010E-1 10,328,000 kg

8 x UA1207 319,330 kg

Payload: Orion Spaceship 992,721 kg

Mission to Mars: Orion nuclear propulsion - Orbiter Space Flight Simulator

Author’s Note: For a more in-depth history behind Project Orion, please refer to an earlier posting of mine entitled “To Mars and Beyond by A-Bomb”.

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