November 20, 2007

Fusion propulsion if Bussard IEC fusion works

Work is continuing towards Robert Bussard's vision of inertial electrostatic fusion.

UPDATE: Tom Ligon wrote the slides and gave the speech which presented this material.

Fusion R&D
Phase 1 - Validate and Review WB-6 Results
The proposed WB-7 and WB-8 devices will be constructed and tested during 2008.
1.5 - 2 years (by the end of 2008), $3-5M

Fusion R&D
Phase 2 - Design, Build and Test
Full Scale 100 MW Fusion System
5 years (2009-2013), $200M

If the full commercial system is successful then from 2014-2029+ there would the development of nuclear fusion enabled space vehicles.

bussard fusion space plane
Two 8 gigawatt Thermal fusion engines power this vehicle. The cost estimate is 100 times less than the best system available now.

bussard fusion lunar lander
20 hours to go from the low earth orbit to lunar orbit. 24 hours to go from the earth surface to the lunar surface using these systems.

These vehicles would have three main types of fusion engines. The DFP, CSR (controlled space radiator) and ARC which are shown with different ISP and thrust levels. CSR and ARC are Quiet Electric Discharge (QED) engines with ISP in the 1500 to 70000 range. They use arcjet heating of reaction mass.

DFP are diluted fusion product engines. They have high ISP 50,000 to 1.2 million. Reaction mass added to fusion product directly from the reactor.

QED fusion space engines types
Here are block diagrams of the QED engine types

long range space vehicle sizing with the different engine types
Here are long range space vehicle sizing with the different engine types. The Bussard rockets are about 1 to 2 football fields long.

description of Mars Bussard fusion vehicle
Description of Mars Bussard fusion vehicle. 33-38 days to Mars one way.

Description of a vehicle to go to Saturn's moon Titan
Description of a vehicle to go to Saturn's moon Titan.

diluted fusion product engine schematic
Diluted fusion product (DFP) engine schematic

fusion rocket schematic for Titan mission
Fusion rocket schematic for Titan mission. Each way would take 75-90 days.

The vehicles will enable large and inexpensive space colonies.

Lunar colony
4000 people, 25 tons each, $12.5 billion (1997 estimate)

Mars colony
1200 people, 50 tons each, $15.6 billion

Titan colony
400 people, 60 tons each, $16.2 billion

Why the colonies and vehicles are relatively cheap

If we have the relatively lightweight working fusion reactors with power ranges up to 10 gigawatts or more each, then all sorts of space propulsion becomes possible.

The fusion reactors could power massive laser arrays or high powered minimag Orion style propulsion systems.

If the Bussard inertial electrostatic fusion reactors work out we would redesign everything. All of the navy and military vehicles and our entire civilization. Even these first designs would give flights to the moon and orbit equal to about the price of old Concorde airplane tickets.

2006 space conference notes on Bussard fusion rockets

The 2007 power point presentation with most of the slides for this article

A paper describing inertial electrostatic fusion propulsion

Robert Bussard on inertial electrostatic fusion.

This project had been funded again by the US Navy

Askmar has links to the scientific papers on the Fusion concept

M Simon has put together a great site with a lot of technical information on IEC reactors including the Bussard project


M. Simon said...

Shouldn't you be crediting Tom Ligon who gave the speech and made the slides?

bw said...

Yes, I will add the credit

qraal said...

Hi Brian

Excellent summary of a fusion-enabled space program. Makes current efforts look downright feeble.

But it was not inevitable that space became so anemic - look at von Braun and his Mars Base architecture from 1968-1969. He would have used NERVA-derived NTRs to propel reusable Mars vehicles to the red planet and back, enabling a temporary base by 1986 and a orbital+surface base with 72 people by 1989. All using reusable NTRs not much different from the inter-orbital Moon freighters planned at the same time.

I can see eerie parallels between the current Constellation program and post-Apollo...

bw said...


I have some coverage of NERVA ships and its descendent designs.

The liberty nuclear ship is something that could be built now.

Likewise the mini-mag orion and Orion nuclear pulse propulsion ships could be built

Tom Craver said...

Looks like your numbers assume lunar ice for water reaction mass supply? Else the LEO to Luna ship would have at least 4x the cost/kg, due to bringing all reaction mass up from Earth.

Is the same true for the Mars mission scenarios?

Luna-made aluminum rods for reaction mass, mechanically pulled into an electric smelter (or directly heated by the arc ) would seem less wasteful, and more sustainable for the long term.

bw said...

the cost estimates were from the papers and slides which I link. They were written by the emc2fusion people (including Robert Bussard before his death).

The paper describes the assumptions that were made.

Tom Craver said...

In the "System Technical and Economic Features..." paper, Bussard does note that the water for reaction mass from LEO to Luna must be delivered to orbit, and that this will increase the cost beyond the $24.2/kg quoted. He rolls in a factor of 5.14x for payload delivered to LEO to account for this.

While not broken out in the paper, reaction mass water plus payload to LEO would cost 5.14x$27/kg-payload = $139/kg-payload, plus the cost to Luna of $24.2/kg-payload, or a net of $163/kg-payload Earth to Luna. Not bad! Still, the figures on the slides give the inaccurate impression that it'll only cost about $51/kg to Luna.

The reliance on lunar water looks like a big potential hole. Just sending all 4000 colonists home each year would take about 8250T of water.

Even if water is available on the moon, it's likely to be scarce - and to make up the 8250T/year for trips home, the colonists would have to mine ~23T/day (23000 liters, or about 23 cubic meters) beyond whatever they need for their own use.

If water has to be delivered to the moon for return trips, at $163*145T for 35T of return payload, that boosts the Luna-LEO cost to about $700/kg payload returned to Earth, or about $350000 per person instead of just $12000 - 29x higher.

bw said...

The colonists can and should do a lot of recycling of water on the Moon. Mars has a lot of water and some atmosphere.

The shortage of water supplies on the moon could indicate the need for:

1) getting near earth objects with water or asteroids with water moved to the moon.
2) Using more robotics and fewer people on the moon
3) Look at more colonization of places with a lot more water. Mars, Titan, Europa, Ceres

bw said...

For reaction mass use, they probably should look at some other material if water is scarce at a particular location. If they bring hydrogen then they can react with oxygen in the regolith. Only need to haul one ninth of the weight.

Tom Craver said...

Water was probably chosen because it's cheap on Earth and easy to store for extended periods in space.

Carrying H2 to the moon in liquid form would certainly cut costs. More of the payload would go to cryo tanks and H2 losses or recovery equipment, so the overall benefit is probably more like 6x rather than 9x. At that ratio, it'd cost about the same in both directions.

But LOX is pretty cheap on Earth, and could be produced in volume on the moon and Mars - so it probably makes sense to just use LOX for reaction mass. Cost from Earth to LEO would be a bit higher, but Moon to LEO would be much lower.

And LOX could be hauled from the moon to LEO cheaper than from Earth - if the cost of building the colony isn't included.

Tom Craver said...

The most effective way to transport LOX from the moon to LEO would be to roughly triple the reaction mass capacity, to enable a full LEO/LLO round trip.

Ferry tanks up from lunar surface to a tank depot in several trips, so that the rest of the design can stay about the same - i.e. one fusion engine.

The depot would also provide the mass for the lunar "soft landing".

qraal said...

Hi Brian

The Liberty Ship's gas-core has some serious problems with heat management before I can take it seriously - the quartz nuclear light-bulb is clever, but the active cooling it will need hasn't been adequately studied.

As for water - as Anthony Zuppero has demonstrated very simple steam rockets can supply water in multi-thousand ton payloads from the Near Earth Objects that are obvious inactive comets. A 1900 K NTR can both propel the water-tankers and liberate the water from the dead comets. There's billions of tons of water available in the NEOs alone.

bw said...

the water truck concept of Anthony Zuppero mentioned by qraal

A related 13 page paper by Anthony from 2005

More of anthony zuppero work

Btw: thanks qraal

Mark said...

You can find most of the Bussard article regarding IEC fusion applications for space flight at

Also, various articles by Tom Ligon, including the slides from his presentation quoted in the post can be found there.

Chris In A Strange Land said...

Tom Craver said...:
Luna-made aluminum rods for reaction mass, mechanically pulled into an electric smelter (or directly heated by the arc ) would seem less wasteful, and more sustainable for the long term.

Oxygen has a much lower molecular weight than aluminium and is equally plentiful on the moon. It would be a much better choice. Carbon dioxide could be used on Mars as reaction mass, albeit with crap isp.