Pages

August 29, 2007

Update using Mini-mag orion to get to 10% of lightspeed

News from Centauri Dreams of progress on the mini-mag Orion concept Take what would be a rocket design that is 70-80 times more efficient than existing chemical rockets and beam particles at it so that it can go at 15% of the speed of light at a cost of $3 billion per flight in Uranium.

UPDATE: I have made progress on my analysis of enhancing mini-mag Orion. I have a new article about pre-deploying the pellets and using charged carbon nanotubes to provide Lorentz force propulsion to the pellets This could be used to remove the need for the massive laser array and power sources 2500 times larger than the current electrical power of the United States. The nanoscale components would seem to become both achievable and affordable over the next ten years. System integration and the key nuclear rocket will still require a committed effort to achieve.

Use of Mini-Mag Orion and superconducting coils for near-term interstellar transportation

1000 T crewed spacecraft and propulsion system dry mass at 10% of lightspeed contains 9 X 10**21 J. The author has generated technology requirements elsewhere for use of fission power reactors and conventional Brayton cycle machinery to propel a spacecraft using electric propulsion. Here we replace the electric power conversion, radiators, power generators and electric thrusters with a Mini-Mag Orion fission–fusion hybrid. Only a small fraction of fission fuel is actually carried with the spacecraft, the remainder of the propellant (macro-particles of fissionable material with a D-T core) is beamed to the spacecraft, and the total beam energy requirement for an interstellar probe mission is roughly 10**20 J , which would require the complete fissioning of 1000 ton of Uranium assuming 35% power plant efficiency. This is roughly equivalent to a recurring cost per flight of 3.0 billion dollars in reactor grade enriched uranium using today's prices. Therefore, interstellar flight is an expensive proposition, but not unaffordable, if the nonrecurring costs of building the power plant can be minimized.


UPDATE: Powering the beam ?

In the abstract that I see they talk about 10**20 joules for 10% of lightspeed for a 1000 ton ship. Going 1% of lightspeed would take 100 times less energy 10**18 joules.

In the paper, they talk about the power required based on 40% efficiency.
They indicate 2.5 TW when they should be saying 2.5 PW.
They had 1000 TW (1PW) as the acceleration power needed for the sheath/pellets. So 40% efficiency means 2.5 PW.

It seems we can make this more efficient by lightening the sheath.
The pellet is only 80 grams. The sheath is 2kg of conducting mylar.

If we put some engineering into the sheath (say using carbon nanotubes for strength, conduction and lower weight) maybe we can get the sheath down to 128 grams. A total reduction in weight of the sheath pellet to 208 grams instead of 2080 grams.

Then the acceleration power for the sheath pellets would go down to 100TW, efficiency could be increased slightly with higher acceleration tolerance and less laser losses. But keeping it at 40%. 250TW.

We can drop in speed to 1% of lightspeed instead of 10% this means 100 times less power. Drop in weight of the vehicle would still save 10 times to go 100 tons and 100 times to go 10 tons.

So 10 ton vehicle at 1% of light speed would need 25GW of laser array power to accelerate the lighter sheath/pellets.

A 100 ton vehicle at 1% of light speed would need 250GW of laser array power to accelerate the lighter sheath/pellets.

A typical 1200 MW nuclear power plant produces 32 PJ per annum.
3.2 * 10**16 joules.

10 twin reactors would get us up to 6.4*10**17 joules. About the power levels needed for the 1% of lightspeed. (which is plenty fast for all the plans that I can think of for doing whatever we want in the solar system). Plus it is over 100 times faster than what we have been able to achieve. 10.8 million kph (6.5 million mph vs 50,000 mph - without a lot of gravity slingshots)

FURTHER READING
My past coverage on minimag Orion

2 comments:

EEtimes2 said...

There's still the problem of the 25/250GW lasers as none have been created that large or powerful. Add on the engineering feet to send so called "pellet's" of fuel to a space capsule several to thousands of AU's away would be incredible. We may have some knowledge how to create a pre-interstellar spacecraft, but alot of research would have to be done. Making it several decades before anything could be launched.

bw said...

Please look at my next post where I discuss means of pre-deploying the pellets. Also, the lasers can be laser arrays. X thousand 100kw lasers. By next year we will have 100kw solid state lasers.

http://advancednano.blogspot.com/2007/08/fuel-scooping-variable-minimag-orion.html

Pre-deployment of pellets can be done with any vehicle or system. I believe that nanotechnology will happen and that by 2012 we will have fairly cheap carbon nanotubes with ten thousand ton/year production. We can use that capability to make high performance Lorentz propulsion for the pellets. Most of the capabilities could be in hand by 2015-2020. then another ten years to build and deploy.