Nasa's new and improved ANTI-MATTER space ship

[scott1]

Most self-respecting starships in science fiction stories use antimatter as fuel for a good reason – it’s the most potent fuel known. While tons of chemical fuel are needed to propel a human mission to Mars, just tens of milligrams of antimatter will do (a milligram is about one-thousandth the weight of a piece of the original M&M candy).

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

 

[batboy]

Stand by for superluminal motion, Jordie.


Do you have the link?

 

[scott1]

Do you have the link?

I'am going to add into the first post.

 

[Rach3]

Harebrained. I especially enjoyed this one:

"Based on the experience with nuclear technology, it seems reasonable to expect positron production cost to go down with more research," added Smith.

Oh and this one:

Because they annihilate normal matter, you can't just stuff them in a bottle. Instead, they have to be contained with electric and magnetic fields. "We feel confident that with a dedicated research and development program, these challenges can be overcome," said Smith.

Of course, if you can store ten positrons in an ion trap, you can easily store 10 milligrams of them! (10^28, or 10^9 coulombs)

And this:

It will be safer to launch as well. If a rocket carrying a nuclear reactor explodes, it could release radioactive particles into the atmosphere. "Our positron spacecraft would release a flash of gamma-rays if it exploded, but the gamma rays would be gone in an instant.

Hehe, "safe" indeed.

 

[Kurdt]

not to mention the sterilisation of the Earth with gamma rays produced by however much fuel they were carrying! That would be one big explosion.

To answer the original question. We can create a few particles of antimatter in particle accelerators and yes we can actually trap them for periods of time before they go annihilating things with our current technology. I still wouldn't bet on an anti-matter fuelled 'reactor' powering a rocket or anything else in the near future though, but maybe someday because as they mentioned you do get an awful lot of energy for a small volume of fuel.

 

[Beam me down]

Why are they researching ship design? We can't even produce anywear near the number of required anti-matter particles. In fact we probably won't be able to before the end of the centuary alright, maybe not before 2050. Ship design is an inconsequential part of the quest for anti-matter fueled spacecraft : we need the fuel first!

 

[batboy]

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

I'd suspect that if a facility found groundbreaking ways to make a lot, it would be kept top secret.

 

[JustinLevy]

To answer the original question. We can create a few particles of antimatter in particle accelerators and yes we can actually trap them for periods of time before they go annihilating things with our current technology.

When people hear anti-matter most think of big particle accelerators smashing things together with new particles coming out.

Yes, you are correct that this is possible. And it is indeed inefficient. Creating the particles a few at a time would never allow one to build up milligrams worth.


However, do not forget that there are natural sources of anti-matter. For instance, when you see those colorful pictures of brain activity, it is usually done with a PET scanner (Positron Emission Tomography). The positrons come from isotropes in the tracers that naturally decay by emitting positrons.

I assume this is why they chose positrons instead of anti-protons or something. Just like we can create plutonium in macroscopic quantities using nuclear chain reactions, it may be possible to create short lived isotopes (that emit positrons) in macroscopic quantities, and then collect the positrons as they decay.

I am very skeptical of how one could store that massive amount of charge though. We have no easy way of creating anti-protons in macroscopic quantities, so we can not have neutral anti-matter. Until we do, I do not believe storage is feasible.

Just my two cents.

 

[scott1]

Why are they researching ship design? We can't even produce anywear near the number of required anti-matter particles. In fact we probably won't be able to before the end of the centuary alright, maybe not before 2050. Ship design is an inconsequential part of the quest for anti-matter fueled spacecraft : we need the fuel first!

It's NASA they just reseach this kind of stuff because it's cool and to make it look like that there spending government money usefully.

 

[Pengwuino]

Can't wait when some serious people start commenting on this...

 

[selfAdjoint]

Can't wait when some serious people start commenting on this...

Well your two sig lines:

"You don't really know something until you have to explain it to the uninitiated"

Current math subject I hate: Linear Algebra

don't present you yourself as terribly serious

And why does NASA need to research antimatter propulsion when they have the Heim theory to go FTL with?

 

[scott1]

And why does NASA need to research antimatter propulsion when they have the Heim theory to go FTL with?

I agree but I doupt that the President ever heard of Heim theory.But he probally does know what anti-matter is.

 

[Chronos]

Anti-matter storage is a real headache. Transporting usable quantities would make a nuclear reactor look about as dangerous as a car battery. Finding a way to produce anti-matter on demand looks like the only practical approach, IMO. Of course you still have the not so minor problem of shielding the crew from the radiation emitted.

 

[Pengwuino]

don't present you yourself as terribly serious

Duh, that's why serious people need to get in here

 

[JustinLevy]

Can\'t wait when some serious people start commenting on this...

Several posters have already explained details of how anti-matter can be generated/collected, as well as the issues of storage (safety and the huge amount of charge).

So please be more explicit. What would you want to discuss in more depth?

 

[Pengwuino]

So please be more explicit. What would you want to discuss in more depth?

im waiting for astronuc or morbius to come in here and plunk down a page full of information that blows my mind again like they normally do. Up until that point, there was only 1 reply with any decent information.

I'm wondering exactly how such matter could ever be controlled and delivered to a propulsion device.

 

[scott1]

Anti-matter storage is a real headache. Transporting usable quantities would make a nuclear reactor look about as dangerous as a car battery. Finding a way to produce anti-matter on demand looks like the only practical approach, IMO. Of course you still have the not so minor problem of shielding the crew from the radiation emitted.

I wouldn't be surprised if the spaaceship blows up on the lunchpad and destroy the kendey space center.

 

[Chronos]

Do the math. The energy required to propel a spacecraft to Mars would make Georgia the most southern state on the eastern seaboard if released on the launch pad at Cape Canaveral.

 

[Entropy]

The energy required to propel a spacecraft to Mars would make Georgia the most southern state on the eastern seaboard if released on the launch pad at Cape Canaveral.

Errmm... Techniquely all you have to do is break Earth orbit and you can go to Mars. Maybe not very quickly, but you'd get there. And that kind of energy isn't nearly as devistating as you make it sound. Really it probably only destory the launch pad.

 

[Janus]

Errmm... Techniquely all you have to do is break Earth orbit and you can go to Mars. Maybe not very quickly, but you'd get there.

Merely breaking Earth orbit will only put you into an independent Solar orbit. You will have to apply additional $\Delta v$ to alter that orbit enough such that it intersects Mars' orbit.

 

[EP]

Heres a good site.

http://www.antimatterenergy.com/stoage.htm

So, they do know how to store it.

One problem down.

 

[scott1]

Heres a good site.

http://www.antimatterenergy.com/stoage.htm

So, they do know how to store it.

One problem down.

But it's VERY diffuclt to keep it stored.They need to find a better way to store or find a way how to produce just before it gets used.

 

[Kurdt]

The problem with storage of anti-matter is two fold. You can't store it in anything made of matter otherwise it will anihilate with matter from the container. The other option is storing it in an electromagnetic field which requires energy to produce the field and requires the anti-matter to be charged. which brings up the problem of the more stuff you want to store the stronger the E.M. field and the more energy is wasted in just storing the stuff.

Its all well and good saying you only need a gram of it to get to wherever you want to go but then the problem occurs as to how one converts gamma rays as the product of anihilation into useful energy. So there are some serious technical problems to overcome if antimatter were ever to be used as an energy source. In my opinion nuclear fusion is a better use of research and development money at our current technological state.

 

[Janus]

Do the math. The energy required to propel a spacecraft to Mars would make Georgia the most southern state on the eastern seaboard if released on the launch pad at Cape Canaveral.

Just to propel a ship to Mars, requires 1.4e8 joules per kilogram. This includes leaving Earth, making the transfer orbit insertion, and matching velocities with Mars at the end of the Trip. If we assume that our ship's mass is equivalent to the mass of a fully fueled shuttle stting on the Pad (2,000,000 kg) this works out to about the equivalent of a 69 KT nuclear device (3 1/2 times the size of the one dropped on Hiroshima)

If we include the energy for a return trip it jumps up to the equivalent of a a 27 MT bomb.

These figures are of course ideal, as they assume 100% efficiency for our drive. The lower the efficiency of our drive the larger these numbers will become. They are also based on the slowest, lowest energy trajectory.

One other point should be made about the round trip figure. Depending on the ratio of the mass of the drive section to our payload section, a considerable savings can be found in doing this trip by the "two launch" method. In this method, you send the fuel (and maybe a whole drive section) needed for the return trip with a separate launch. It is there waiting for you upon arrival.

This method saves you even more energy if you need to send your payload on a fast, high energy trajectory, as you can send the return trip fuel/supplies on the slower, low energy trajectory.

 

[Astronuc]

I wish NASA wouldn't publish stuff like this.

I would echo the comments of Rach3, Chronos, and Janus. It just isn't practical.

The storage anti-matter is accomplished in special accelerators (storage rings) that are kilometers in diameter and store much less than picograms of particles, and not for weeks or months.

Storing roughly 1.766 E6 coulombs of positrons and an equivalent quantity of electrons (mutual annihilation requires equal numbers) in anything that isn't hugely massive is impossible.

Homework problem - calculate the pressure from 10²⁵ electrons uniformly distributed in a sphere 10 m in diameter. Actually, just calculate the particle density and compare that to the density of a fusion plasma (which is neutral).

And calculate the attractive force between a + and - charge of 1.766E6 C each - separated by 20 m.

Then there is the matter of the effectiveness of using 0.511 MeV gamma rays to heat hydrogen, which I believe is pretty transparent to such gammas, which means the system would have to heat a heavy metal like tungsten. Even with its high melting temperature, the heating will have to be limited and so will the mass flow rate of the hydrogen propellant, in order to heat it to a reasonable temperature.

From the Cern Antimatter site -

Antimatter is storied in a vacuum and electromagnetic fields to keep the antimatter from coming in contact with matter. Making antimatter is extremely expensive. A gram would cost over $60 trillion/gram or twice the World's Gross National Product.

It's a good thing they only need 10 mg.

 

[AlphaNumeric]

From the Cern Antimatter site -
It's a good thing they only need 10 mg.

http://www.antimatterenergy.com/stoage.htm isn't a CERN site. Browsing around there's some rather odd pages, such as claiming comets are made entirely out of antimatter.

 

[Astronuc]

http://www.antimatterenergy.com/stoage.htm isn't a CERN site. Browsing around there's some rather odd pages, such as claiming comets are made entirely out of antimatter.

Oops. I went through the CERN link on that page to the LHC pages.

Here is the page to which I was referring with regard to size of a accelerator/collider/storage ring - http://public.web.cern.ch/public/Content/Chapters/AboutCERN/CERNFuture/HowLHC/HowLHC-en.html

The cost for antimatter is actually estimated on a NASA page -
http://science.nasa.gov/newhome/headlines/prop12apr99_1.htm

antimatterenergy.com does have two nice pictures, one each of Fermilab and CERN.

 

[pervect]

I just noticed this thread. While I think antimatter rockets are interesting theoretical exercises, for an actual mission I think that nuclear-thermal or nuclear-electric propulsion makes a lot more sense.

The biggest problem is probably political - we'd have to put a nuclear reactor in space.

Of course, this is hardly new news. See for instance

http://www.fas.org/nuke/space/c07sei_1.htm

A - PROGRAM HISTORY

Responding to the President's (ed: Bush Sr.) July 1989 speech, NASA prepared a blueprint for achieveing these goals, known as "the 90 Day Study" (discussed below). On 19 December 1989 Vice President Quayle, who chairs the National Space Council, wrote to NASA Administrator Richard Truly requesting study of "different architectures, new systems concepts, promising new technologies, and innovative uses of existing technologies" to implement the SEI. This was included in a Presidential National Security Directive on 16 February 1990, which established the "Synthesis Group" to evaluate these alternatives.

The Synthesis Group was chartered by the National Space Council in the Summer of 1990 to review NASA plans for the Space Exploration Initiative, as well as to incorporate suggestions from other sources. It will recommend at least two alternative architectures for SEI implementation, one of which has been characterized as "nuclear rich." Although the deliberations of the Synthesis Group will continue through March 1991, this review process has already reached a number of preliminary conclusions:

"1 - Contrary to popular opinion, the first trip to Mars may have to be fast rather than slow, because humans are the weak link in the chain; human psychology is a big unknown.

"2 - One architecture proposed by the Synthesis Group will be "nuclear rich" because nuclear is probably safer and cheaper (and faster).

"3 - There has been a discussion about improving the overall system reliability by using multiple engines, i.e., rather than trying to put all of the reliability in one engine, have "engine-out" capability so that the overall system reliability is high.

"4 - Chemical/Aerobrake will probably cost tens of billions of dollars to develop and prove out and doesn't provide much gain. It was described as "disappointing.""(1)

General Stafford has testified that:

"Today it looks like technology has advanced so that in the year 2010 or 2020 a nuclear thermal rocket would certainly be feasible, assuming that you added all the safety criteria and had political acceptance... We are convinced that nuclear rocket propulsion can make an important contribution to the Space Exploration Initiative if it proves feasible and safe and can gain public acceptance. For example, a nuclear thermal rocket can reduce the travel time to Mars by 60-70%."(2)

http://www.space.com/businesstechnology/050406_prometheus_techwed.html

Cycle of boom and bust

"If one stood on top of a pile of all the studies of space nuclear power that have been performed over the past 20 years, one would be several feet closer to Mars…at least during some hours of the day," explained Steven Aftergood, head of the Project on Government Secrecy for the Federation of American Scientists in Washington, D.C.

Aftergood noted in a recent newsletter that, as a technology enterprise, space nuclear reactors have been "subject to a remarkable cycle of boom and bust over the past 50 years."

Start-stop work has dead-ended ambitious programs every decade or so, Aftergood said, noting the SP-100 program – a NASA, Department of Defense, Department of Energy initiative -- that was killed ten years ago after some $400 million had been doled out.

Other related Mars efforts are looking at the approach of just accepting a longer mission, for instance

http://pda.physorg.com/lofi-news-gravity-artificial-centrifuge_3921.html

(This isn't a new idea either). My prediction - more flip-flops as politicians (mainly) waffle on the issue.

 

[dimensionless]

Might it be equally practical to build a small scale fusion reactor? I mean, we'll need exotic materials either way, right?

 

[scott1]

Might it be equally practical to build a small scale fusion reactor? I mean, we'll need exotic materials either way, right?

They should just dump the anti-matter spaceship and use nuclear fuisson. It's a lot more realistic.

 

[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 :-)