One Month to Mars -- Methods for Very Fast Settler Transit

[LMT]

3F was a surprise.  When the Soviets saw it, they certainly did consider weaponization, as Winterberg himself noted.  But prospective commercial value is for fast fleets; a novel need, thanks to SpaceX. 

When you mention 3F, is it a generally recognised name, or something your coined? Can you unpack the acronym?  Winterberg used Mini-nuke, is it the same thing?

"3F" previously, since "['mini-nuke'] should not be confused with the recent use of this same word for small nuclear explosive devices intended for military applications."

BIS might do something with this.  E.g., David Homfray is chasing "TOKNEP" fusion electric propulsion at 1 kW/kg, very far below PV's near-term 200 kW/kg.  BIS might look instead at 3F tug fusion.  Have you raised 3F with them?  You imagine it doesn't work, but BIS engineers could explore useful optimizations.

[lamontagne]

3F was a surprise.  When the Soviets saw it, they certainly did consider weaponization, as Winterberg himself noted.  But prospective commercial value is for fast fleets; a novel need, thanks to SpaceX. 

When you mention 3F, is it a generally recognised name, or something your coined? Can you unpack the acronym?  Winterberg used Mini-nuke, is it the same thing?

"3F" previously, since "['mini-nuke'] should not be confused with the recent use of this same word for small nuclear explosive devices intended for military applications."

BIS might do something with this.  E.g., David Homfray is chasing "TOKNEP" fusion electric propulsion at 1 kW/kg, very far below PV's near-term 200 kW/kg.  BIS might look instead at 3F tug fusion.  Have you raised 3F with them?  You imagine it doesn't work, but BIS engineers could explore useful optimizations.

3F is Fission-Fusion-Fission, I presume?  Winterberg uses Mini-nuke and doesn't approve of the term being used by others for similar but less refined devices?
So in correspondence with others outside this forum I should use mini-nuke, or Winterberg Mini-Nuke?

I don't oppose 3F per se, I'm just very skeptical and yes, I start with the expectation that it does not work, because I've read hundreds of papers that have failed to materialize anything substantial as far as advanced propulsion goes.

At the BIS, the current focus is on Scorpion, https://www.bis-space.com/event/missions-with-the-scorpion/, a much less powerful nuclear thermal rocket by Mark Hempsell.  However, the BIS journal is starved for articles, and if you wanted to put your proposals in article form, I expect they would be interested.
In general there is interest for a mission out to the solar focus point, so again, you might write an article in the form of a proposal to reach the solar focal point at 600 AU and you might find some interest.

For the work I am currently doing for the BIS the focus is more on the space settlement construction side.  If there was an article we could refer to it as an equivalent, or possibly superior, version of an interplanetary transport.  For the moment we use a modified D-D or D-He3 Z-pinch with injected propellant.  We would need to know how much fission material is required for the engine.

Alternatively, I am a member of the AIAA committee: Nuclear and Future Flight Propulsion Technical Committee
Scope: Conduct activities toward the understanding of physical mechanisms and associated technologies that lead to the implementation and design of nonchemical, high energy propulsion systems other than electric thruster systems. Propulsion systems included are: nuclear thermal, gas core, fusion, antimatter, beamed energy, solar sails, tethers, and electromagnetic launchers.

You might find some interest there, if you produced an abstract that could be read quickly and easily.  You might also produce a paper for one of the various AIAA regional or national meetings.  There are a lot of those, and it's not very difficult to publish and present there.

[lamontagne]

If you want to get involved with the AIAA people, you might want to follow the guidelines they publish on fusion propulsion in the presentation of your design.  See the joined guidelines.

[LMT]

Scorpion, a much less powerful nuclear thermal rocket...

Much, much less.  Any NTR would be.

I start with the expectation that [3F] does not work, because I've read hundreds of papers that have failed to materialize anything substantial...

None invalidate the old implosion methods, which aren't controversial.  Your experienced BIS or AIAA members can likely confirm.

the BIS journal is starved for articles, and if you wanted to put your proposals in article form...

You could pass tug links to your BIS cohort first; that might stir thought.

[lamontagne]

I was just suggesting ways you might promote your work. I'm not interested in arguing the case.

I have no stake in the 3F idea, it is of no use to me and I have no interest in promoting it.  I am happy to mention it if the subject comes along, but an actual peer reviewed paper would make it much easier to refer to.  In a way, referring to a link involves putting my credibility at stake, what little there is.  A paper shifts the responsibility to the publishing organism.

[LMT]

I'm not interested in arguing the case.

Obviously.  No, if you fwd, your cohort could consider things independently.  Who knows, BIS might have structural insights, useful in a paper, etc.

[LMT]

Pulsed Plasma Rocket (PPR)

More Martian nuclear pulse rocketry:  NIAC has selected PPR for Phase II study.  h/t StraumliBlight.

In Phase II, we plan to:

- Optimize the engine design for reduced mass and higher Isp

- Perform proof-of-concept experiments of major components

- Complete a ship design for shielded human missions to Mars

PPR (Howe et al. 2022) builds on PuFF, but with many changes and stated issues.  PuFF seemed unsuited for notional tug use, not least due to mass.  1 2  Notably, PPR aims to cut mass.

PPR has an interesting bullet structure:

The bullet is comprised mostly of water ice to act as a neutron moderator, homogeneously distributed uranium particles, and an iron skin to couple to the field generated by the injector coils. The estimated energy release from the PPR explosion is around 3.2e9 J per pulse.

Energy release from a feasible 2.2 kg PPR bullet is 3.2e9 J.  Cf. 3F / MOX energy release from a 20 kg example, ~ 1e11 J.  If PPR issues are resolved, this difference in energies might yet disqualify PPR for tug use.

Refs.

Howe, S.D., Howe, T., Bennett, F.G., Blaylock, N., Jackson, G. and Cassibry, J., 2022. Pulsed plasma rocket-developing a dynamic fission process for high specific impulse and high thrust propulsion. Acta Astronautica, 197, pp.399-407.

[LMT]

One Month with Minimized Nuclear Fuel + Propellant Cost

Nuclear fuel and propellant costs can range over many orders of magnitude, depending on a drive's specific energy, fuel breeding, ISRU, etc.  The 3F / MOX concept aims for extremely fast transit with extremely low net fuel + propellant cost.

Some recent notes on cost:  1 2 3

[Twark_Main]

...with extremely low net fuel + propellant cost.

I'm glad to see, after our discussion in your hyperlink #1 above, that the idiosyncratic "the tritium revenue applies against the nuclear fuel cost but not the LOX cost, because I said so" accounting has been dropped. Sounds like you're (quite sensibly) now just lumping all the costs and revenues into one "net" bucket.

[LMT]

...with extremely low net fuel + propellant cost.

I'm glad to see, after our discussion in your hyperlink #1 above, that the idiosyncratic "the tritium revenue applies against the nuclear fuel cost but not the LOX cost, because I said so" accounting has been dropped. Sounds like you're (quite sensibly) now just lumping all the costs and revenues into one "net" bucket.

As though there were some great expense in scooped oxygen and waste methane.    Rhetorical straws there.

[Twark_Main]

...with extremely low net fuel + propellant cost.

I'm glad to see, after our discussion in your hyperlink #1 above, that the idiosyncratic "the tritium revenue applies against the nuclear fuel cost but not the LOX cost, because I said so" accounting has been dropped. Sounds like you're (quite sensibly) now just lumping all the costs and revenues into one "net" bucket.

As though there were some great expense in scooped oxygen and waste methane.    Rhetorical straws there.

"There Ain't No Such Thing As A Free Extremely Below-Market Lunch" still applies.

Surely the investors for your Scooper project will want to get their money back, no?      And if the investors aren't getting their money back, then surely you disclose that fact in your slide deck when you're pitching investors, no?   

Ditto for "waste" methane. As an operator I have much lower risk, time-in-space, and (as a minor cost) ground control staff if I simply vent that methane, versus adding an extra rendezvous and docking operation to visit with your depot. Who will compensate me for that?


But anyway, I'm just glad you account for these costs, and no longer push them into the "ignore" pile using weird accounting tricks.

[LMT]

...with extremely low net fuel + propellant cost.

I'm glad to see, after our discussion in your hyperlink #1 above, that the idiosyncratic "the tritium revenue applies against the nuclear fuel cost but not the LOX cost, because I said so" accounting has been dropped. Sounds like you're (quite sensibly) now just lumping all the costs and revenues into one "net" bucket.

As though there were some great expense in scooped oxygen and waste methane.    Rhetorical straws there.

"There Ain't No Such Thing As A Free Lunch" still applies.

Surely whoever your investors are for your Scooper project will want to get their money back, no?     And if the investors aren't getting their money back, then surely you disclose that in your slide deck when you're pitching investors, no?   

Ditto for "waste" methane. As an operator I have much lower risk, time-in-space, and ground control staff if I simply vent that methane, versus adding an extra rendezvous and docking operation to visit with your depot. Who will compensate me for that?

But anyway, I'm just glad you're actually accounting for these costs, and no longer pushing them aside with weird accounting tricks.

No, the posts are reasonable.  Posters should explore cost reductions for other drive concepts.  Some would cost $ hundreds of millions, or even $ billions, per flight, as currently sketched.  You don't want to overlook that.

[Twark_Main]

...with extremely low net fuel + propellant cost.

I'm glad to see, after our discussion in your hyperlink #1 above, that the idiosyncratic "the tritium revenue applies against the nuclear fuel cost but not the LOX cost, because I said so" accounting has been dropped. Sounds like you're (quite sensibly) now just lumping all the costs and revenues into one "net" bucket.

As though there were some great expense in scooped oxygen and waste methane.    Rhetorical straws there.

"There Ain't No Such Thing As A Free Extremely Below-Market Lunch" still applies.

Surely the investors for your Scooper project will want to get their money back, no?      And if the investors aren't getting their money back, then surely you disclose that fact in your slide deck when you're pitching investors, no?   

Ditto for "waste" methane. As an operator I have much lower risk, time-in-space, and (as a minor cost) ground control staff if I simply vent that methane, versus adding an extra rendezvous and docking operation to visit with your depot. Who will compensate me for that?


But anyway, I'm just glad you account for these costs, and no longer push them into the "ignore" pile using weird accounting tricks.

No, the posts are reasonable.  Posters should explore cost reductions for other drive concepts.  Some would cost $ hundreds of millions, or even $ billions, per flight, as currently sketched.  You don't want to overlook that.

Thanks! I do pride myself in being reasonable.    And yes it is important to note that conventional chemical drive concepts will also benefit from such extremely low costs.

What were your actual cost estimates (dollars per ton) for methane and oxygen again?  I forgot.

[LMT]

Cross-post:  Marathon Fusion's commercial "superpermeation" approach to tritium recovery is potentially very useful in a D-T tug's vital tritium breeding cycle.

[LMT]

The Altered Carbon posts 1 2 applied Type-II glassy carbon throughout a fusion tug, notionally.  Recent advances point toward cheap bulk production.  Yang et al. 2023.

See esp. Fig. 6 (b) "curved surface" and (d) "honeycomb".  Do posters see where these two forms would slot into the cartoon?

-

It seems tech is maturing on several fronts, to make possible tiny and efficient fusion-drive tug prototypes along the lines of Winterberg's concepts. 

Now that SpaceX has recommitted to a Mars shot in 2026, fast settler transit is shaping up as a business case, to justify more creative thought on fusion tugs.

Refs.

Yang, Y., Dang, Y. and Ruan, H., 2023. Structural Evolution in Glassy Carbon Investigated Based on the Temperature Dependence of Young’s Modulus. Materials, 16(13), p.4794.