New and Improved Antimatter Spaceship for Mars Missions

Tom Kalbfus · 2015-01-25 08:39:46

New and Improved Antimatter Spaceship for Mars Missions 04.14.06
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).

Nuclear-thermal rocket design Image right: A spacecraft powered by a positron reactor would resemble this artist's concept of the Mars Reference Mission spacecraft. Credit: NASA

However, in reality this power comes with a price. Some antimatter reactions produce blasts of high energy gamma rays. Gamma rays are like X-rays on steroids. They penetrate matter and break apart molecules in cells, so they are not healthy to be around. High-energy gamma rays can also make the engines radioactive by fragmenting atoms of the engine material.

The NASA Institute for Advanced Concepts (NIAC) is funding a team of researchers working on a new design for an antimatter-powered spaceship that avoids this nasty side effect by producing gamma rays with much lower energy.

Antimatter is sometimes called the mirror image of normal matter because while it looks just like ordinary matter, some properties are reversed. For example, normal electrons, the familiar particles that carry electric current in everything from cell phones to plasma TVs, have a negative electric charge. Anti-electrons have a positive charge, so scientists dubbed them "positrons".

When antimatter meets matter, both annihilate in a flash of energy. This complete conversion to energy is what makes antimatter so powerful. Even the nuclear reactions that power atomic bombs come in a distant second, with only about three percent of their mass converted to energy.

Previous antimatter-powered spaceship designs employed antiprotons, which produce high-energy gamma rays when they annihilate. The new design will use positrons, which make gamma rays with about 400 times less energy.

The NIAC research is a preliminary study to see if the idea is feasible. If it looks promising, and funds are available to successfully develop the technology, a positron-powered spaceship would have a couple advantages over the existing plans for a human mission to Mars, called the Mars Reference Mission.

diagram of positron rocket Image left: A diagram of a rocket powered by a positron reactor. Positrons are directed from the storage unit to the attenuating matrix, where they interact with the material and release heat. Liquid hydrogen (H2) circulates through the attenuating matrix and picks up the heat. The hydrogen then flows to the nozzle exit (bell-shaped area in yellow and blue), where it expands into space, producing thrust. Print-resolution copy Credit: Positronics Research, LLC

"The most significant advantage is more safety," said Dr. Gerald Smith of Positronics Research, LLC, in Santa Fe, New Mexico. The current Reference Mission calls for a nuclear reactor to propel the spaceship to Mars. This is desirable because nuclear propulsion reduces travel time to Mars, increasing safety for the crew by reducing their exposure to cosmic rays. Also, a chemically-powered spacecraft weighs much more and costs a lot more to launch. The reactor also provides ample power for the three-year mission. But nuclear reactors are complex, so more things could potentially go wrong during the mission. "However, the positron reactor offers the same advantages but is relatively simple," said Smith, lead researcher for the NIAC study.

Also, nuclear reactors are radioactive even after their fuel is used up. After the ship arrives at Mars, Reference Mission plans are to direct the reactor into an orbit that will not encounter Earth for at least a million years, when the residual radiation will be reduced to safe levels. However, there is no leftover radiation in a positron reactor after the fuel is used up, so there is no safety concern if the spent positron reactor should accidentally re-enter Earth's atmosphere, according to the team.

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. There would be no radioactive particles to drift on the wind. The flash would also be confined to a relatively small area. The danger zone would be about a kilometer (about a half-mile) around the spacecraft. An ordinary large chemically-powered rocket has a danger zone of about the same size, due to the big fireball that would result from its explosion," said Smith.

Another significant advantage is speed. The Reference Mission spacecraft would take astronauts to Mars in about 180 days. "Our advanced designs, like the gas core and the ablative engine concepts, could take astronauts to Mars in half that time, and perhaps even in as little as 45 days," said Kirby Meyer, an engineer with Positronics Research on the study.

Advanced engines do this by running hot, which increases their efficiency or "specific impulse" (Isp). Isp is the "miles per gallon" of rocketry: the higher the Isp, the faster you can go before you use up your fuel supply. The best chemical rockets, like NASA's Space Shuttle main engine, max out at around 450 seconds, which means a pound of fuel will produce a pound of thrust for 450 seconds. A nuclear or positron reactor can make over 900 seconds. The ablative engine, which slowly vaporizes itself to produce thrust, could go as high as 5,000 seconds.

positron ablation rocket Image right: This is an artist's concept of an advanced positron rocket engine, called an ablative engine. This engine produces thrust when material in the nozzle is vaporized (ablated). In the image, the engine emits blue-white exhaust as thin layers of material are vaporized by positrons in tiny capsules surrounded by lead. The capsules are shot into the nozzle compartment many times per second. Once in the nozzle compartment, the positrons are allowed to interact with the capsule, releasing gamma rays. The lead absorbs the gamma rays and radiates lower-energy X-rays, which vaporize the nozzle material. This complication is necessary because X-rays are more efficiently absorbed by the nozzle material than gamma rays would be. Credit: Positronics Research, LLC

One technical challenge to making a positron spacecraft a reality is the cost to produce the positrons. Because of its spectacular effect on normal matter, there is not a lot of antimatter sitting around. In space, it is created in collisions of high-speed particles called cosmic rays. On Earth, it has to be created in particle accelerators, immense machines that smash atoms together. The machines are normally used to discover how the universe works on a deep, fundamental level, but they can be harnessed as antimatter factories.

"A rough estimate to produce the 10 milligrams of positrons needed for a human Mars mission is about 250 million dollars using technology that is currently under development," said Smith. This cost might seem high, but it has to be considered against the extra cost to launch a heavier chemical rocket (current launch costs are about $10,000 per pound) or the cost to fuel and make safe a nuclear reactor. "Based on the experience with nuclear technology, it seems reasonable to expect positron production cost to go down with more research," added Smith.

Another challenge is storing enough positrons in a small space. 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.

If this is so, perhaps the first humans to reach Mars will arrive in spaceships powered by the same source that fired starships across the universes of our science fiction dreams.

Bill Steigerwald
NASA Goddard Space Flight Center

Can you believe it?

Excelsior · 2015-01-25 12:30:06

The production and storage issues become much easier to overcome when you have more energy available to throw at it. That means making peace with fission, using more advanced forms of fission, and then moving on to fusion, before anti-matter becomes a truly viable option.

Tom Kalbfus · 2015-01-25 23:02:32

Excelsior wrote:

The production and storage issues become much easier to overcome when you have more energy available to throw at it. That means making peace with fission, using more advanced forms of fission, and then moving on to fusion, before anti-matter becomes a truly viable option.

Why do I believe that there will already be a large community already living and working on Mars by the time the first Antimatter rocket is perfected? I think this whole NASA production is sort of like the cart before the horse, since we don't know how to store a large amount of positrons for long periods of time, the question of using them to propel rockets is sort of moot. Positrons also have very little mass, does alienating them with electrons release more energy than nuclear fusion, say by merging a tritium nuclei with a deuterium nuclei? I think we'll probably have a working nuclear fusion reactor in ten years. Its just amazing to me that NASA is trowing money at paper studies of antimatter rockets, I guess they got too much money to spend, its not like they could have built an additional space probe or something!

Quaoar · 2015-01-26 12:26:27

Excelsior wrote:

The production and storage issues become much easier to overcome when you have more energy available to throw at it. That means making peace with fission, using more advanced forms of fission, and then moving on to fusion, before anti-matter becomes a truly viable option.

The attenuating matrix of this antimatter is solid, so this antimatter rocket, at the best, will have the same specific impulse of a good nuclear thermal rocket, with more and more troubles and costs in harvesting and confining positrons.

Instead of waste public money in this science fiction like spaceship, that will need almost a century of R&D to be developed (if it works), why not seriously invest in a almost ready and mature technology like nuclear thermal rocket spaceship, that can bring us to Mars in 10 years?

Last edited by Quaoar (2015-01-26 12:37:21)

Tom Kalbfus · 2015-01-26 16:02:41

Quaoar wrote:

Excelsior wrote:
The production and storage issues become much easier to overcome when you have more energy available to throw at it. That means making peace with fission, using more advanced forms of fission, and then moving on to fusion, before anti-matter becomes a truly viable option.

The attenuating matrix of this antimatter is solid, so this antimatter rocket, at the best, will have the same specific impulse of a good nuclear thermal rocket, with more and more troubles and costs in harvesting and confining positrons.
Instead of waste public money in this science fiction like spaceship, that will need almost a century of R&D to be developed (if it works), why not seriously invest in a almost ready and mature technology like nuclear thermal rocket spaceship, that can bring us to Mars in 10 years?

Antimatter is a good choice for fuel to the stars, but it won't be ready in time for the first trips to Mars.

Quaoar · 2015-01-29 14:36:22

Tom Kalbfus wrote:

Antimatter is a good choice for fuel to the stars, but it won't be ready in time for the first trips to Mars.

At the moment we just have a very good propulsion system that is easier to harness than antimatter: Orion drive. According to the guys who work at it, if optimized an Orion Drive can reach a specific impulse up to 20000 s. An Orion propelled spaceship can reach Saturn in one year and the Oort Cloud in less than five years. And we can have it now without inventing new technologies.

I was skeptical about Orion, but I was captured by this very cool short movie:

https://www.youtube.com/watch?v=uQCrPNEsQaY

after I read this old document,

http://www.projectrho.com/public_html/r … 09vIII.pdf

where every potential problem of Orion Drive is very well addressed, from thrust vectoring control to pusher plate protection and shock-adsorbers cooling...

It seems it can really works.

Last edited by Quaoar (2015-01-29 14:53:14)

Tom Kalbfus · 2015-01-29 16:36:41

There might be a reason to use an Orion Drive. With the Cold War heating up between the US and Russia and the US and ISIS! Suppose this Cold War simply gets worse and worse, Russia closes up, and the ISIS radicals think God is on their side and they build more and more nuclear weapons, thinking to conquer the World with Allah's help.

The main difference between the 1960s and some Islamic radical nuclear power is that the Soviets didn't believe in any heavenly paradise, they didn't believe there was any God to save them, and they wanted to survive and go on living, and weren't willing to commit national suicide to achieve their objectives. What if we faced a nuclear superpower that was motivated by religious zeal, and wasn't dissuaded by the end of their mortal lives, and they figured that God wanted them to attack the West, and that they would be rewarded for doing so in the afterlife.

Now in combatting such a belief, their might be no other alternative to building a space ark to save a potion of humanity from a nuclear Jihad waged by an enemy superpower.

So by the 2060s, would this be possible?

Last edited by Tom Kalbfus (2015-01-29 16:45:41)

Quaoar · 2015-01-29 16:41:06

Tom Kalbfus wrote:

There might be a reason to use an Orion Drive. With the Cold War heating up between the US and Russia and the US and ISIS! Suppose this Cold War simply gets worse and worse, Russia closes up, and the ISIS radicals think God is on their side and they build more and more nuclear weapons, thinking to conquer the World with Allah's help. It could be that all they'll end up doing is destroying most of mankind, it being just a matter of time before they build enough weapons to accomplish this task. They launch a massive strike against Western countries and rely on Allah to shield them from the Wests nuclear retaliation. Of course Allah doesn't shield them, all the religion managed to do is shield them from fears of nuclear retaliation by the West, and so therefore they feel free to strike with impunity, or so they think. My greatest fear is of having an Islamic superpower with tens of thousands of nukes, run by a Muslim fanatic, that thinks he is on God's mission to wipe Western Civilization from the face of the Earth.
So in such an event, we need to build an Ark. There was a television series based on this premise, although that one supposed the mission was launched somehow in the early 1960s. I think such a mission would be more plausible in the 2060s. Ascension was the name of the miniseries. So by the 2060s, do you think we'll be in any position to launch any sort of space ark, and if so, to what destination? Suppose there is no hope for mankind, a nuclear superpower is determined to wage nuclear jihad against us, is not deterred by our nukes, and will not come to the peace table for anything short of our total surrender and submission to Islam. That is the scenario! We might need to build a space ark in order for humanity to survive this.

Ark may be a solution, but in this scenario it would be better to nuke them before they grow-up.

Tom Kalbfus · 2015-01-29 16:47:44

That is true, one hopes it will not come to this. We'd need a "Neville Chamberlain" for the next 40 years to get in a situation like that.

Terraformer · 2015-01-30 08:37:26

Careful with the politics, guys...

An Orion ship *would* be the only thing we could use today, if we faced an extinction-level event. Fortunately, we don't need to go into space for most such events; underground is fine. Still, I think fear of the apocalypse should motivate us to work on much better launch systems, offworld colonies and a good space infrastructure, so we can evacuate a lot more people if we need to.

Tom Kalbfus · 2015-01-30 14:15:47

Nevertheless, an extinction level "political event" is more likely than an asteroid strike. An extinction level asteroid strike is just as likely in the next one hundred years as it was during the last one hundred years, but an extinction level political event is way more likely in the next one hundred years than the last one hundred years, mostly because of the available technology, and the political willingness of those in charge to use it to achieve their ends, however insane they may be. We have things like nanotechnology coming, and more and more countries are getting nuclear weapons, and the people running some of those countries don't look entirely same. For some reason deranged lunatics tend to rise to positions of power, rather than the most competent people who should occupy those offices.

Terraformer · 2015-01-31 12:24:08

You don't need to be the leader of a state in order to have access to WMDs. Bioweapons, for example, don't need significant resources to work on (hmmm, modified H5N1, maybe even hybridised with human flu and bred [?] to be both lethal and easily transmitted?). The designs for a crude nuclear weapon (which could be used as an EMP, perhaps, or maybe even a trigger for a fusion bomb? Speculating here) aren't a secret, though you do need a lot more resources than the bioweapon requires. Chemical weapons, however, have already been used by terrorists.

All in all, we live in interesting times, and I think it is only prudent to evacuate the planet. As in, have plenty of self contained biospheres, so an attack on one does not lead to much death.

Mars_B4_Moon · 2021-06-07 07:34:32

Unlikely event but....
Stars made of antimatter?
https://www.sciencenews.org/article/ant … -astronomy

'Antistars' Made of Antimatter Get a Particle's Worth of Evidence. Circumstantial evidence could point to a mind-blowing solution to an antimatter mystery—or to the need for better space-based particle physics experiments.
https://www.scientificamerican.com/arti … -evidence/

This area of science is sometimes seen as a spooky fringe cosmology particle physics topic
previous discussion
anti-matter storage? http://newmars.com/forums/viewtopic.php?id=4631

tahanson43206 · 2021-06-07 10:12:58

For Mars_B4_Moon re #13

Following the top link you provided:

https://www.sciencenews.org/article/ant … -astronomy

By Maria Temming
APRIL 26, 2021 AT 3:41 PM
Fourteen pinpricks of light on a gamma-ray map of the sky could fit the bill for antistars, stars made of antimatter, a new study suggests.
These antistar candidates seem to give off the kind of gamma rays that are produced when antimatter — matter’s oppositely charged counterpart — meets normal matter and annihilates. This could happen on the surfaces of antistars as their gravity draws in normal matter from interstellar space, researchers report online April 20 in Physical Review D.

A version of this article appears in the June 5, 2021 issue of Science News.
CITATIONS
S. Dupourqué, L. Tibaldo and P. von Ballmoos. Constraints on the antistar fraction in the solar system neighborhood from the 10-year Fermi Large Area Telescope gamma-ray source catalog. Physical Review D. Published online April 20, 2021. doi: 10.1103/PhysRevD.103.083016.
Maria Temming
About Maria Temming
E-mail
Twitter
Maria Temming is the staff reporter for physical sciences, covering everything from chemistry to computer science and cosmology. She has bachelor's degrees in physics and English, and a master's in science writing.

(th)

Calliban · 2021-06-07 11:01:16

It turns out that a little anti-matter goes a long way.
https://en.m.wikipedia.org/wiki/Antimat … propulsion

It can be used to trigger both fission and fusion reactions. In such a scenario, the total energy delivered by antimatter reactions may be a minute proportion of total energy release. But the energy is released in such a way that a detonation wave is created. Imagine a pellet of frozen deuterium, wrapped in a thin foil of uranium. In fission driven systems, a single antin-proton annihilation in a uranium nucleus, adds so much energy to the nucleus that it undergoes fission, releasing up to 100 fast neutrons. The resulting neutron shower, results in more fission. As fission products are released, they pass into the solid hydrogen in the core of the fuel pellet. The range of fission products in matter is only about 0.01mm. As they slow down, they heat individual hydrogen ions far above fusion energy thresholds. The ions undergo fusion, releasing even more neutrons, which create even more fission, in a feedback effect.

So the idea is to use anti-protons to create an initial pulse of fission reactions in a thin uranium foil surrounding a pellet of fusion fuel. After the initial pulse, feedback between the fusion in the pellet and fission in the foil, should result in a detonation wave which ignites the pellet in a fusion micro-explosion. Fission contributes negligible energy to the process, but acts as a trigger, with the anti-protons forcing an initial rate of fission that is high energy to result in positive feedback between the inner fusion and outer fissile regions. If the anti-matter pulse is rapid enough, then the fissile foil may need be only a few atoms thick in order to produce the detonation wave. An anti-proton catalysed, fission triggered, fusion micro-explosion.

Antiprotons are created by accelerating protons to energy of tens-hundreds of GeV and then impacting high-Z materials. The resulting negative pions then decay into anti-protons. It is is interesting that both pions and anti-protons can both catalyse fusion. If the uranium foil surrounding the pellet is the target, then the pions will catalyse fusion before decaying into antiprotons, which also catalyse fusion before their annihilation. In addition, the proton beam will generate muons, which also catalyse fusion. All of these reactions would result in an intense shower of neutrons, which would produce fission in the outer shell. Hence, an anti-matter catalysed fusion rocket would not need to store any antimatter. It would be generated by proton beams colliding with the fuel pellet, less than a millisecond before pellet detonation.

Last edited by Calliban (2021-06-07 11:17:15)

tahanson43206 · 2021-06-07 12:44:37

For Calliban re #15

Bravo!

SearchTerm:Fusion via fission from anti-matter catalyst
SearchTerm:Fission from anti-matter catalyst may yield fusion
SearchTerm:antimatter not carried in spacecraft but generated as needed

Quaoar should (?) have a field day with this set of ideas!

The fuel stock would appear to include aluminum and hydrogen.

Hydrogen can be collected en route (since there is such a sea of nuclei moving through open space)

A mechanism for pulling energy out of the reaction is needed, to sustain it ....

(th)

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#1 2015-01-25 08:39:46

New and Improved Antimatter Spaceship for Mars Missions

#2 2015-01-25 12:30:06

Re: New and Improved Antimatter Spaceship for Mars Missions

#3 2015-01-25 23:02:32

Re: New and Improved Antimatter Spaceship for Mars Missions

#4 2015-01-26 12:26:27

Re: New and Improved Antimatter Spaceship for Mars Missions

#5 2015-01-26 16:02:41

Re: New and Improved Antimatter Spaceship for Mars Missions

#6 2015-01-29 14:36:22

Re: New and Improved Antimatter Spaceship for Mars Missions

#7 2015-01-29 16:36:41

Re: New and Improved Antimatter Spaceship for Mars Missions

#8 2015-01-29 16:41:06

Re: New and Improved Antimatter Spaceship for Mars Missions

#9 2015-01-29 16:47:44

Re: New and Improved Antimatter Spaceship for Mars Missions

#10 2015-01-30 08:37:26

Re: New and Improved Antimatter Spaceship for Mars Missions

#11 2015-01-30 14:15:47

Re: New and Improved Antimatter Spaceship for Mars Missions

#12 2015-01-31 12:24:08

Re: New and Improved Antimatter Spaceship for Mars Missions

#13 2021-06-07 07:34:32

Re: New and Improved Antimatter Spaceship for Mars Missions

#14 2021-06-07 10:12:58

Re: New and Improved Antimatter Spaceship for Mars Missions

#15 2021-06-07 11:01:16

Re: New and Improved Antimatter Spaceship for Mars Missions

#16 2021-06-07 12:44:37

Re: New and Improved Antimatter Spaceship for Mars Missions

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