Nasa's new and improved ANTI-MATTER space ship

[kaos]

What about antimatter catalyzed fusion? I heard about it some time ago.
Is this a seriuos proposal?

 

[scott1]

Is this a seriuos proposal?

Well since Antimatter is hard to produce and it's extremley rare in nature, I don't think anything involing antimatter would be serious proposal until more advacements in technology.

 

[pervect]

What about antimatter catalyzed fusion? I heard about it some time ago.
Is this a seriuos proposal?

It's being actively reasearched at the university of Pennsylvania, see for instance

http://www.engr.psu.edu/antimatter/introduction2.html

(Technical details are in the documents section).

I tend to agree that a fission rocket would be more realistic, though - if we were really serious about getting to Mars.

Rather than digress on the role "pork-barrel politcs" in US space policy, though, I'll simply say that low levels of funding for far-out projects like the UPenn antimatter proposals should/could be viewed as being in the category of fundamental research rather than a short-term engineering development proposal.

 

[Andrew Mason]

http://www.nasa.gov/centers/goddard/news/topstory/2006/antimatter_spaceship.html"
Where are they going get anti-matter and is this even possible with technology we have now

I would have thought that a design team would be brought in when the concept was clear and it is just a matter of working out the technical stuff.

A positron engine has serious conceptual problems. Since a positron/electron annihilation produces 2 gamma rays each going in opposite directions, if you want to make it work as an engine, you have to either 1. capture both gamma rays and use the resultant heat to propel matter out one end to produce thrust, or 2. capture one and direct the other out the back and use the resulting photon momentum: p = h/\lambda = E/c to propel the ship or 3. a combination of 1 and 2.

In either case, you have to have a lot of lead and lead is massive. In 1, which is just a conventional rocket engine with a different heat source, you need a supply of mass to expel - eg. hydrogen.

In 2. and 3 you need to be able to direct the gamma rays. Even then, I think the thrust would be minimal. For 10 mg. of positrons, the maximum thrust would be:

p = E/c = mc = 10^{-5}\cdot 3\cdot 10^8 = 3,000 kg m/sec

or enough to increase the speed of a 3000 kg ship by 1 m/sec.

Perhaps the date on the article is wrong. It should have been 4.1.06.

AM

 

[pervect]

The technical details are at http://www.engr.psu.edu/antimatter/Papers/ICAN.pdf

Another good website is

http://ffden-2.phys.uaf.edu/213.web.stuff/Scott Kircher/fissionfusion.html

The proposal is far-out, not silly. IMHO it makes a lot more sense to fund something like this than to start (and stop! - look at the history) yet another nuclear fission rocket program that won't actually be launched, even though nuclear fission rockets are known to work and capable of doing the job of a Mars mission. (They are known to work because we've actually built and tested some, back in the days when enviornmental regulations were not so tough).

Where would the antimatter come from? Let's quote from the Upenn proposal in detail.

Antiproton sources exist worldwide at two sources, CERN in Geneva, Switzerland and Fermilab, in Batavia, Illinois.
These two laboratories utilize high energy proton synchrotron accelerators, with accumulator storage rings attached to
collect antiprotons produced by collisions of protons on targets. Presently, Fermilab collects 6 x 1010 antiprotons per hour
in its Accumulator. This means that in one year of dedicated production, it could produce a maximum of 0.85 ng of
antiprotons. A new and funded facility, called the Main Injector, will turn on in 1999, with a maximum annual production
capacity of 14 ng. A new Recycler Ring presently under construction and located inside the Main Injector ring will increase
the collection rate by another factor of 10. This would place Fermilab in the 100 ng range, making it attractive for future
space applications.

It is estimated (I haven't gone over the details) that about 140 ng would be needed for a mission to Mars, this is about 1-2 years supply from Fermilab, after it is upgraded.

[add]
It's estimated that a single shot takes only 10^11 antiprotons. That's 1.6e-13 grams. 140ng would give enough antiprotons for about 850,000 shots. This is larger than the 450,000 shots I calculate from the reference design in the ican-2 paper.

Here's the appropriate quote from the Upenn paper:

In 1992 large fission and neutron yields from antiproton annihilation at rest in a natural uranium target were observed by
our group.1 Calculations indicate that short bursts of antiprotons could induce temperatures of several keV in a small
compressed pellet.2 These conditions are appropriate for ignition of a hydrogen fusion burn within the microsphere. Targets
with yields up to 302 GJ have been considered, with compression provided by light ion beams or lasers. Baseline parameters
for ignition are: antiproton energy, 1.2 MeV; number, 10^11; pulse length, 2 ns; and deposition volume, 1 mm3. An experiment
at the Phillips Laboratory to demonstrate subcritical antiproton-catalyzed microfission is in progress.3-7

Remember that the antimatter here is not being used to directly propel the space-craft. It is being used to create a fission reaction which will create a fusion reaction, and the fission + fusion will actually be used to power the spacecraft .

The antimatter is not even the sole heating source, if one reads the technical specs - ion beams are also used in the design.

[add]
Of course, when one looks at the 700 ton design, and figures out how much it will cost to get all that mass into LEO, one sees that the biggest problem is getting the thing off the ground :-)

 

[laurelelizabeth]

I thought I read somewhere we have enough to heat a cup coffee.

In the movie Apollo 13 (which was based on reality) didn't they say that it only had enough power left to power the coffee maker for 8(?) hours? And then they managed to use gravity to their advantage and get it back :)

So it sounds feasible, not now but in the future... But it would be another thing to worry that terrorists might get a hold of. With destructive technology like nuclear weapons and stuff, every country has to be more mature about that sort of stuff

 

[russ_watters]

That comment in Apollo 13 was about electricity for powering their electronics. The energy released by their engines in course correction burns was, of course, many many many orders of magnitude larger than that.

 

[laurelelizabeth]

That comment in Apollo 13 was about electricity for powering their electronics. The energy released by their engines in course correction burns was, of course, many many many orders of magnitude larger than that.

oopsie.

 

[blunt187]

well we built cars, planes, and made electricity. All things are possible! The question you should be asking is will the human race survive long enough to figure it out, or will we just make bombs out of it, and sell it to people that hate us, so they can fulfill there ultimate goal of making jesus come back? Jesus was cool, he was the only white guy in the desert:-)