Antimatter Propulsion.. From Earth To Mars Only Requires Milligrams?!

[Spacescifi]

Or so I heard off YouTube. Only milligrams of antimatter fuel required to reach Mars.

I reckon the video poster is vastly oversimplified matters.

Since correct me if wrong, but the only way you are going to only expand milligrams of antimatter to reach Mars is if:

1. You are mixing it with several tons of propellant.

2. You are actually using a photon rocket.

 

Thoughts?

[Nuke]

i think the important question is what would a few milligrams of antimatter do to the earth if it got away from you.

you could probably do a fast transfer on chem engines, but you would need a lot of fuel. i dont think the real hold up for mars is a faster engine. hydrolox from moon to insertion (one burn so you dont need to worry about long term storage), hypergolics for insertion burn. methalox from mars back to earth, culminating in aerocapture and reentry at earth. perquisites include a moon base with fuel production capability and a return rocket landed on mars tanked up and ready to go. 

[Fizzlebop Smith]

28 minutes ago, Nuke said:

i think the important question is what would a few milligrams of antimatter do to the earth if it got away from you.

you could probably do a fast transfer on chem engines, but you would need a lot of fuel. i dont think the real hold up for mars is a faster engine. hydrolox from moon to insertion (one burn so you dont need to worry about long term storage), hypergolics for insertion burn. methalox from mars back to earth, culminating in aerocapture and reentry at earth. perquisites include a moon base with fuel production capability and a return rocket landed on mars tanked up and ready to go. 

I am not casting aspersions merely asking..

Would this not be predicated on some kind of local fuel production on Mars?

I suppose you could launch a series or smaller payload vessels that were fuel only.

Then you could rely on manual refill and not autonomous and may decrease the time line (in terms of feasibility) a bit.

 

Edited March 9 by Fizzlebop Smith

[Nuke]

49 minutes ago, Fizzlebop Smith said:

I am not casting aspersions merely asking..

Would this not be predicated on some kind of local fuel production on Mars?

I suppose you could launch a series or smaller payload vessels that were fuel only.

Then you could rely on manual refill and not autonomous and may decrease the time line (in terms of feasibility) a bit.

 

you mean technology which has already been demonstrated on mars. you just need to upscale it.

there are of course more than one way to do this. you could launch from earth and refuel in orbit, then you dont need a moon base at all. the ship on mars would require landing a return vehicle, empty of course, and refuel it over the course of years in time for human landing. only thing im not sure about is the return aerocapture. we have done that manuver before but never on a man rated craft. and the risk of either burnup or getting flung out into the greater solar system with no hope for either rescue or survival is kind of a big risk.

im only making the point that we dont need anything fancy in the way of propulsion technology to go to mars. so many videos with something like "this new technology will get us to mars in x days" are just clickbait and the tech is either so far down the technological readiness ladder that it would take 10 years to develop, are so theoretical where we cant even be sure it would work at all. its a terrible metric. cost and risk mittigation are the real killers to a manned mars mission.

Edited March 9 by Nuke

[Piscator]

3. You are a tardigrade. Ideally made from antimatter.

4. You're buying the trip from someone who accepts antimatter as a currency.

[darthgently]

9 hours ago, Spacescifi said:

I reckon the video poster is vastly oversimplified matters.

Vastly Huge hurdles:

1. Producing antimatter efficiently.

2. Containing and storing antimatter in quantity safely and reliably.

3. Directing the energy from the reaction in one general direction.

For 3, as you imply, you need some way to direct energy composed to a large degree of extremely hard to direct energy

[farmerben]

7 hours ago, Nuke said:

you mean technology which has already been demonstrated on mars. you just need to upscale it.

there are of course more than one way to do this. you could launch from earth and refuel in orbit, then you dont need a moon base at all. the ship on mars would require landing a return vehicle, empty of course, and refuel it over the course of years in time for human landing. only thing im not sure about is the return aerocapture. we have done that manuver before but never on a man rated craft. and the risk of either burnup or getting flung out into the greater solar system with no hope for either rescue or survival is kind of a big risk.

im only making the point that we dont need anything fancy in the way of propulsion technology to go to mars. so many videos with something like "this new technology will get us to mars in x days" are just clickbait and the tech is either so far down the technological readiness ladder that it would take 10 years to develop, are so theoretical where we cant even be sure it would work at all. its a terrible metric. cost and risk mittigation are the real killers to a manned mars mission.

I agree completely.  I would create a designated orbit to orbit vehicle for the Earth-Mars transfer, and a separate vehicle for orbit-surface transfer at each end, so 3 vehicles total.

It's a two year mission because of the orbital resonance.  So roughly 3 months on Mars and roughly 20 months in transit.  

A dedicated orbit-orbit vehicle can save weight on unnecessary systems, while being more spacious than the surface transfer vehicles.

 

 

[Superfluous J]

2 hours ago, darthgently said:

1. Producing antimatter efficiently.

2. Containing and storing antimatter in quantity safely and reliably.

3. Directing the energy from the reaction in one general direction.

1. Magnets
2. Magnets
3. Magnets

Spoiler

 

[darthgently]

1 hour ago, Superfluous J said:

1. Magnets
2. Magnets
3. Magnets

  Hide contents

 

4. Profit!

[kerbiloid]

5 hours ago, Superfluous J said:

• Magnets
• Magnets
• Magnets

https://en.wikipedia.org/wiki/Magnetar

Preferrably, portable.

[magnemoe]

8 hours ago, darthgently said:

Vastly Huge hurdles:

1. Producing antimatter efficiently.

2. Containing and storing antimatter in quantity safely and reliably.

3. Directing the energy from the reaction in one general direction.

For 3, as you imply, you need some way to direct energy composed to a large degree of extremely hard to direct energy

3 Is solvable I think, you don't mix hydrogen and anti hydrogen. Use some heavier element to get charged particles. 

1 and 2 we don't know how to do. Yes we can do 2 but not for volume in anything getting close to 100 year old safety standard for explosives, it the magnetic field fails somehow or you are in an atmosphere and get an leak its boom.  Might even be hard to have redundancy for the magnetic field. 
One milligram of antimatter equal 42 ton of TNT. 

The idea makes orion pulse nuclear sound very sane and safety oriented. 

[Nuke]

8 hours ago, Superfluous J said:

1. Magnets
2. Magnets
3. Magnets

  Reveal hidden contents

 

points at the state of fusion. if we cant contain deuterium for long enough to fuse what makes you think were ready to be storing antimatter?

[tomf]

On 3/9/2024 at 10:58 PM, Nuke said:

points at the state of fusion. if we cant contain deuterium for long enough to fuse what makes you think were ready to be storing antimatter?

Not saying it would be easy but antimatter at 4k would be more likely to stay put than plasma at 150,000,000 k. Or at least be a very different problem.

[Nuke]

39 minutes ago, tomf said:

Not saying it would be easy but antimatter at 4k would be more likely to stay put than plasma at 150,000,000 k. Or at least be a very different problem.

il agree that its in a different ballpark. but a quench of your superconductors would be the primary failure mode im concerned with.

[farmerben]

Assume storage is a solved problem.  How do you generate thrust?

The matter anti-matter collision gives you mostly high energy gamma rays in random directions.  You can't mirror those.  You could absorb some of it with thick layers of heavy metal or other material, but that means lots of mass.  Suppose you absorb 33%, waste 33% and exhaust 33% as a photon drive in the proper direction.  We are talking about a very low thrust to weight ratio engine, even if the fuel is light.

[magnemoe]

3 hours ago, farmerben said:

Assume storage is a solved problem.  How do you generate thrust?

The matter anti-matter collision gives you mostly high energy gamma rays in random directions.  You can't mirror those.  You could absorb some of it with thick layers of heavy metal or other material, but that means lots of mass.  Suppose you absorb 33%, waste 33% and exhaust 33% as a photon drive in the proper direction.  We are talking about a very low thrust to weight ratio engine, even if the fuel is light.

What happen if the anti proton hit an heavier atom, It was some talk of using antimatter to generate fission who generated more energy. Then mostly in charged particles, 

Storage is solved for tiny amounts, not amounts who take out more than the launchpad. Even at an worst case scenario rockets explodes over many seconds. Antimatter does not it detonates. 

[kerbiloid]

Instead of reflecting the gamma-photons, absorb them with a tiny black hole used as a pusher plate.

The black hole should be:

• charged - to hang it in a strong magnetic field in the nozzle;
• rotating - to make it flat, and thus increase its cross-section;
• ephemeric - because it has low mass, so it's evaporating, and should be produced permanently to have it stable.

This will be an antimatter Orion with charged rotating blackhole pusher plate.

https://en.wikipedia.org/wiki/Charged_black_hole

https://en.wikipedia.org/wiki/Rotating_black_hole

https://en.wikipedia.org/wiki/Kerr–Newman_black_hole

May Kerr&Newman bless it!

 

Upd.

You can be producing the antimatter in this blackhole gravity field.

Upd 2.

BH also can be used as a waste can.

Edited March 11 by kerbiloid

[kerbiloid]

_(multipost)

Edited March 11 by kerbiloid

[Terwin]

On 3/8/2024 at 8:22 PM, Spacescifi said:

1. You are mixing it with several tons of propellant.

I remember reading that if you used antimatter as the energy source for your rocket, you could use the same reaction mass tank(possibly water?) regardless of your destination, you just use a higher energy mix by adding a higher proportion of antimatter to energies your reaction mass before you shoot it through the nozzle.

And no, antimatter is not your reaction mass, it serves the same function as the nuclear reactor in a Nerva engine, just (presumably) lighter

[Spacescifi]

5 hours ago, Terwin said:

I remember reading that if you used antimatter as the energy source for your rocket, you could use the same reaction mass tank(possibly water?) regardless of your destination, you just use a higher energy mix by adding a higher proportion of antimatter to energies your reaction mass before you shoot it through the nozzle.

And no, antimatter is not your reaction mass, it serves the same function as the nuclear reactor in a Nerva engine, just (presumably) lighter

 

While a thermal antimatter rocket is possible, engine heat limits how efficient you can get using reaction mass.

In other words, there is no getting around using tons of propellant because you would still need it. Since cranking the rocket up to max efficiency by reacting more antimatter with mass is not possible because you would destroy the engine.

Arguably one of the most efficient engines using antimatter would be a variation on mini magnetic Orion external pulse propulsion, just subbing the nuke for a photon torpedo lol.

[farmerben]

Still a very heavy engine, to say nothing of expensive and dangerous.  You don't need it to go to Mars.  Most of the delta-V required is for landing and launch.  The interplanetary transfer is relatively easy.  

[Piscator]

To expand on point 2 in the start post, using milligrams of antimatter in a photon drive probably won't get you to Mars. Assuming a 10 ton spacecraft, every milligram of emitted photons will only accelerate you by about 3 cm/s. To reach Mars, you would be well into gram territory.

[Terwin]

On 3/12/2024 at 5:13 PM, Spacescifi said:

Arguably one of the most efficient engines using antimatter would be a variation on mini magnetic Orion external pulse propulsion, just subbing the nuke for a photon torpedo lol.

External combustion is the *least* efficient option.

Not even modern trains use external combustion any more.

External combustion is only viable if there is no other option.

Thermal antimatter is entirely doable as a rocket, so external antimatter reactions can never be within an order of magnitude of the most efficient option.  Not unless we learn something that would re-write every physics textbook from jr high on up 

[Spacescifi]

10 hours ago, Terwin said:

External combustion is the *least* efficient option.

Not even modern trains use external combustion any more.

External combustion is only viable if there is no other option.

Thermal antimatter is entirely doable as a rocket, so external antimatter reactions can never be within an order of magnitude of the most efficient option.  Not unless we learn something that would re-write every physics textbook from jr high on up 

I meant efficiency with the thrust to weight ratio. Detonating a nuclear or antimatter bomb requires less mass/weight than exhausting enough propellant to gain the equivalent amount of thrust if you just detonated the bomb.

By the time you reach the TWR of the bomb with a rocket your engine will either melt or you have some type of nuclear saltwater rocket shenanigans going on that are teetering at the edge of blowing up your vessel in a catastrophic explosion the whole time.

Edited March 15 by Spacescifi

[kerbiloid]

13 hours ago, Terwin said:

External combustion is the *least* efficient option.

Not even modern trains use external combustion any more.

Because the modern trains operate with by orders  of magnitude lower energies and temperatures, easily containable in a small metal jar.

The external combustion is maybe the least efficient, but the only available way to keep your train solid when the equilibrium temperature of the energy source means it being plasma.

Orion doesn't need a solid structure around the reaction zone. And that's the only reason why it's the only viable within the known physics.

Edited March 15 by kerbiloid