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

[LMT]

6 Fusion Tugs in LEO for Settlement Transit

Setting some notional, and merely ballpark, values for pulse-averaged acceleration:

-  For the settlement Starship, 0.2 g
-  For the unloaded tug, 2.0 g

With these averaged accelerations, the tug delivers 29 km/s and returns to LEO quickly.  It docks at a depot, perhaps a Terrestation, and stages the next Starship with 12-hour turnaround. 

Quick turnaround cuts the number of fusion tugs needed.  The number of LEO tugs delivering a notional 667-ship settlement fleet over 60 days is now just 6.

[john smith 19]

Quick turnaround cuts the number of fusion tugs needed.  The number of LEO tugs delivering a notional 667-ship settlement fleet over 60 days is now just 6.

While I like the idea of pulsed fusion I'm not aware of anyone having built a sustained operating fusion reactor yet.

Pulsed fission reactors however have been a thing since at least the late 50's. IOW 60+YO technology.

If you want to apply this anytime soon you're going to need to start with something with a pretty high TRL.

Pulsed fusion isn't there. 

[LMT]

Quick turnaround cuts the number of fusion tugs needed.  The number of LEO tugs delivering a notional 667-ship settlement fleet over 60 days is now just 6.

..you're going to need to start with something with a pretty high TRL.

Don't clutter; read the thread before weighing in.

[LMT]

Limited Test Ban Treaty

Narrative

The Test Ban Treaty of 1963 prohibits nuclear weapons tests "or any other nuclear explosion" in the atmosphere, in outer space, and under water. While not banning tests underground, the Treaty does prohibit nuclear explosions in this environment if they cause "radioactive debris to be present outside the territorial limits of the State under whose jurisdiction or control" the explosions were conducted. In accepting limitations on testing, the nuclear powers accepted as a common goal "an end to the contamination of man's environment by radioactive substances."

Radioactive debris in a tug's notional 3F plume could not be allowed to enter Earth's atmosphere at any significant concentration, and the plume should not endanger satellites.  Each detonation in space would be tiny relative to past nuclear atmospheric tests, but protective methods must be thought out, even in casual chat.

Some possibilities:

-

To protect satellites, a tug in LEO could first raise apogee on methalox, so that the fusion drive is ignited well above LEO constellations. 

To protect Earth, the tug could adjust thrust orientation to ensure plumes pass far above the atmosphere (and LEO constellations).  In practice, that means burning for Mars some minutes ahead of the optimal window, with fusion plumes angled slightly "up-and-out" initially, relative to Earth. 

Note:  3F exhaust is extremely fast.  The lightest exhaust particles plunge into the Sun in about 4 hours.  Most particles exit the solar system.  The heaviest particles, such as radioactive 137Cs, are deflected by solar radiation pressure and the solar wind near perihelion, to enter random outer-solar-system trajectories.

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What are some other potential methods?

[Vultur]

Quick turnaround cuts the number of fusion tugs needed.  The number of LEO tugs delivering a notional 667-ship settlement fleet over 60 days is now just 6.

..you're going to need to start with something with a pretty high TRL.

Don't clutter; read the thread before weighing in.

This is pretty insulting. Fusion pulse in the near term just isn't the slam dunk you're presenting it as. Few things are until they're already operating. A lot of space technology projects that looked a lot more straightforward have failed (ASRG... the first attempted magnetometer for Europa Clipper...)

[LMT]

Quick turnaround cuts the number of fusion tugs needed.  The number of LEO tugs delivering a notional 667-ship settlement fleet over 60 days is now just 6.

..you're going to need to start with something with a pretty high TRL.

Don't clutter; read the thread before weighing in.

This is pretty insulting. Fusion pulse in the near term just isn't the slam dunk you're presenting it as. Few things are until they're already operating. A lot of space technology projects that looked a lot more straightforward have failed (ASRG... the first attempted magnetometer for Europa Clipper...)

You keep fabricating stories for yourself, Vultur; but then again, many other thread posters struggle.  Who here even knows how a 3F DT fusion device works, and why it's useful?  Who can demonstrate knowledge, instead of "emoting"?  DT fusion is old news, but here...

-

Protective methods -- onboard and downwind -- are needed for most any useful engine.  Posters could contribute something there.

[Vultur]

Whatever. I'm done with this thread. I might start another in Advanced Concepts for possibilities of very thin film solar cells for SEP, though.

[LMT]

Whatever. I'm done with this thread. I might start another in Advanced Concepts for possibilities of very thin film solar cells for SEP, though.

Oho.

"I was assuming 6 kW/kg."  No advanced info there, either.  You might start with an exploration of, say, 30 - 70 kW/kg tech. 

[LMT]

Mike Shot

How many similarities can posters see between the "mini fission-fusion-fission" design (Winterberg 2004) and the primary stage of the Teller-Ulam design of Mike Shot, 1952 (Rafique 2023)? 

How many differences?

Who can find the most?  (You might team up and share notes.)

Refs.

Rafique, M.M.A., 2023. Design of Non-Tactical Deployable 20 Gwh (17.20841 Kilo Ton TNT) Fusion Device-Energy Basis.

Winterberg, F., 2004. Mini fission-fusion-fission explosions (mini-nukes). A third way towards the controlled release of nuclear energy by fission and fusion. Zeitschrift für Naturforschung A, 59(6), pp.325-336.


https://www.youtube.com/watch?v=tdv9XDUJHEs

[Solarsail]

At that point you're just describing project Orion, or analogues to it.  Nukes in space is similarly politically palatable to Zubrin's nuclear salt water concept.  Exotic-yet-plausible within 15 years is something like... a Kilopower reactor.  Which is only allowed to star once your perigee is no lower than 10000 km, or what ever.

Superconducting parts in a SEP system would probably also be on the exotic end of things that could plausibly be done within 15 years.  JWST is passively sitting colder than the max temperatures of some ceramic superconductors.

[LMT]

..a Kilopower reactor.  Which is only allowed to [start] once your perigee is no lower than 10000 km, or what ever.

Check DRACO orbit.  Compare.

[LMT]

Scrapyard Scaling

Boca Chica scrap could take a 3F reflector / mirror concept far.

- We saw that a 1.5 m prototype steel reflector may manage the 100 MPa blast from a minimized, ~ 0.3 gram fissile core releasing perhaps 3 tons of TNT-equivalent energy.

- Scaling reflector to full Starship 9-m diameter, and holding pressure at 100 MPa, a reflector must manage roughly a 100-ton equivalent.

Challenge:  Can we estimate the diameter required to push a Starship to Mars in a month, with quick turnaround?  Taking a notional averaged acceleration of 0.2 g for 12-hour turnaround, and...

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"Hot Rod"

More tests followed at Point Loma, San Diego, California in 1959. Initially, they were tethered, starting with a one-foot model and then a series of one-meter models, all with a single explosive suspended below them.

An amendment to their ARPA contract gave them permission to try for a free-flying model, which they achieved in just five months. Called the “Hot Rod”, it was one meter in diameter, weighed 270 pounds, and used five 2.3 pound charges. Each charge consisted of a grapefruit-sized ball of C-4 shaped by hand and contained in a coffee-can-sized canister and cushioned with polystyrene. They were ejected from the middle of the pusher plate using nitrogen gas. Shock absorbing foam held a miniature pusher plate to the bottom of each canister to protect it from the previous blast.

A combination of electronics, mechanics, and pneumatics controlled the timing and ejection and made sure that the charges didn’t explode if there was a jam or the if the craft crashed. Each canister was connected to an umbilical cord which uncoiled as the canister dropped. When the canister reached the end of the cord, a switch discharged a capacitor which powered a detonator, igniting the PETN high-explosive in the cord which then ignited the C-4. The detonation of the final charge triggered a shotgun shell which ejected a parachute from the nose for a soft landing. As an added safety feature, bleeder resistors across the capacitors made sure the capacitors discharged within fifteen minutes...

Flight successful in all respects. Height of rise about 185 feet. Parachute deployed at peak of trajectory. Model landed undamaged.

-

Image:  Dall-E 3's fanciful interpretation of Boca Chica fusionworks prototyping, just for min notional prototype scale.

Image:  replica of Orion "Hot Rod" test article from General Atomics Division, General Dynamics; donated to Smithsonian / Steven F. Udvar-Hazy Center.

[Coastal Ron]

Scrapyard Scaling

Boca Chica scrap could take a 3F reflector / mirror concept far.

Elon Musk and SpaceX don't care about your "3F DT fusion device", they are relying on KNOWN technologies that they feel can scale.

Google doesn't even show any results for the phrase "3F DT fusion device", which should be telling. And no, I'm not going to download something from a website I don't know and trust, so it appears you are predicating this entire idea on an idea that has no widespread scientific validation. In other words, on a scale of 0-10 on the Technology Readiness Level (TRL), this appears to be a "0".

If you disagree, please show proof of why it should be rated higher.

[LMT]

Scrapyard Scaling

Boca Chica scrap could take a 3F reflector / mirror concept far.

Google doesn't even show any results for the phrase "3F DT fusion device", which should be telling. And no, I'm not going to download something from a website I don't know and trust, so it appears you are predicating this entire idea on an idea that has no widespread scientific validation. In other words, on a scale of 0-10 on the Technology Readiness Level (TRL), this appears to be a "0".

Imagine such shouting at the on-ramp. 

Who's up for the Mike Shot challenge?

[Coastal Ron]

Scrapyard Scaling

Boca Chica scrap could take a 3F reflector / mirror concept far.

Google doesn't even show any results for the phrase "3F DT fusion device", which should be telling. And no, I'm not going to download something from a website I don't know and trust, so it appears you are predicating this entire idea on an idea that has no widespread scientific validation. In other words, on a scale of 0-10 on the Technology Readiness Level (TRL), this appears to be a "0".

Imagine such shouting at the on-ramp.

Stating facts is not shouting. You just don't want to respond, likely for obvious reasons... 

Who's up for the Mike Shot challenge?

No matter how many times you do it, quoting your own posts doesn't provide any backup for your arguments - it is just circular reasoning. 

[Todd Martin]

Mike Shot

How many similarities can posters see between the "mini fission-fusion-fission" design (Winterberg 2004) and the primary stage of the Teller-Ulam design of Mike Shot, 1952 (Rafique 2023)? 

How many differences?

Who can find the most?  (You might team up and share notes.)

Looking over the "mini fission-fusion-fission" paper by Winterberg, I'll say this:
1) Apparently, the scientists at Sandia National Laboratories think it won't work.  I would tend to believe the experts over a physics professor.
2) The guy has 12 citations in this unpublished piece, but fully half of them are him quoting himself.
3) Where is ITAR in all this?  He's proposing a novel means of making low yield atomic bombs.  You'd think there would be some sanity check on publishing how to do that if it was accurate.

All in all, the premise here of 30 days to Mars by 2039 does not make sense.  There simply isn't a sufficient justification compared to the cost, risk, and difficulty.  As an abstract thought exercise, some humility and socially friendly behavior would go a long way toward those willing to engage.
Lastly, I find this thread generally rude

[Emmettvonbrown]

Lastly, I find this thread generally rude

Spot on. Lots of arrogance, and also circular reasoning. I wonder why people keep posting since the OP is essentially talking to himself.

[kenny008]

I only have 3 people on my Ignore list (LMT is one).  It really cleans up threads he participates in.

I can see the moderate benefits of trying to get to Mars in 30 days vice 6 months.  I just haven't seen anything that makes sense from an engineering or fiscal sense to balance the enormous effort.

[LMT]

Looking over the "mini fission-fusion-fission" paper by Winterberg, I'll say this:
1) Apparently, the scientists at Sandia National Laboratories think it won't work.  I would tend to believe the experts over a physics professor.
2) The guy has 12 citations in this unpublished piece, but fully half of them are him quoting himself.
3) Where is ITAR in all this?  He's proposing a novel means of making low yield atomic bombs.  You'd think there would be some sanity check on publishing how to do that if it was accurate.

re Sandia, as you saw, he simply explained the autocatalytic process to them, back in 1984.  DT reflector, etc.  You should have noticed.  He's spearheaded declassification of military nuclear research for civilian use, over many years; if something surprises you, oftentimes that's the source.  Plus a glance at his publications gives you an idea of his career.  Expert, yes.  Teller certainly respected his fusion work; maybe posters should, too.

re citations, well, above.

re ITAR, that's State Dept.  DoD declassifies military research; their coordination with State isn't a forum issue.

Do you understand how Mike Shot worked, btw?  It seems many posters would view the Mike Shot diagram as sci-fi, had I shown it without context and video.

[LMT]

I only have 3 people on my Ignore list (LMT is one).

I found one trivial mistake in Winterberg's work.  Kenny says he's a nuclear engineer.  Let's see how many mistakes he can find.