Propulsion

Jun 23, 2020
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Hello. I have 3 questions that I would like to throw out there for discussion:

1,). I have for a long time wondered why we keep doing the same thing over and over again with regard to our rockets and rocket launches, which I myself consider to be outdated and pretty much passé. I feel like we just continue to keep doing the same old thing with regard to propulsion.... with ever bigger and shinier rockets that still look like what was being thought of in the cartoons of the 1950’s.

Why have we not designed a more flat and rounded space craft that could take off, in maybe a 45 degree trajectory, rather than the typical straight upward 90 degree trajectory from Earth’s surface? It seems to me that if we had a rounded spacecraft (like a saucer-type design), and that if we projected it off Earth’s surface at more of a 45 degree angle, rather than a straight up 90 degree angle, that it would encounter less atmospheric resistance, less friction, less drag, and maybe would require less combustible fuel. I'm not an engineer, just a logical gal. Yes, it would require a longer time to get up and out of the 32 miles of Earth's atmosphere, but so what? It might be less risky for the passengers.

2). The second question I have is: Why are we still using kerosene as rocket fuel, when we have nuclear power available to us?

3.) And on a more theoretical topic with regard to propulsion...if matter and antimatter particles annihilate each other when they encounter each other, yet produce energy in that process.....is anybody in the scientific community looking at that as a means of propulsion to get us farther out into space?
 
Apr 23, 2021
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there have been several designs for a space vehicle which would be able to take off like an airplane and fly directly into space without the assistance of a rocket booster this concept is know by some as a "single stage to orbit" However apparently no one has so far produced an engine capable of lifting such a spacecraft from the ground to orbit but eventually it should come into existence. As for your second question: kerosene is still being used in rocket fuel because it is most likely cost effective and is a proven commodity. Sorry I have no answer for your third question but I'm sure someone here will.
 

Catastrophe

The devil is in the detail
3. The problem here is how do you contain the antimatter before use. It would just annihilate with the container. Currently, afaik, it can only be contained in minute amounts in static complicated equipment. Please correct me if you know better.

Cat :)
 
Jul 27, 2021
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I may put some information to the question.
2. The Apollo Constellation Engine (ACE) is a Hall effect thruster propulsion system: Multi-propellant capability with Krypton, Xenon, and proprietary propellants. Nearest announced launch is August - September this year.

Regarding antimatter, there is a reckon to be shortly contained in a small volume with a strong magnetic field, with no applicable inclinations.
 
Jul 27, 2021
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When mentioning 'rocket science' one should differentiate 2 parts of it: science itself (which would also keep effectiveness of rocket fuel) and rocket engineering.

Rocket engine carries both fuel and oxidizer (which is burned inside the combustion chamber) and then expanded through a Convergent Divergent nozzle. It doesn’t depend on ambient air for producing thrust.

Common are solid fuel, liquid propellant, hybrid rocket, depending on the fuel and oxidizer, being carried.

It is necessary to achieve 40,300 km/h - escape velocity (escape Earth gravity) as soon as possible. No vertical launch will need more fuel to be burned.

For some cases solid produces the most thrust at the thickest atmosphere layers, at higher positions - liquid propellant is used.

Further zero-lift turn, in which a spacecraft is optimizing trajectory to reduce the amount of fuel and start orbiting around the Earth.

The factors of choosing a propellant are: rocket purpose (including travel distance, reusability, multi-start), carried net load, fuel, thrust mechanics and dynamics, engineering design.

Good live comprehensive example of different purpose rockets, developed in a 'fresh' reliable evolving company Skyrora.

Throttling down of a rocket is determined with exit pressure of about one-third of ambient pressure and up to a maximum limit determined only by the mechanical strength of the engine.

Nowadays these factors and so throttle have a great variety. The typical limitation is combustion stability.

Determining a space mission requirement is performed to define what applications require engine throttling.

Throttleable liquid-propellant rocket engines can be used for planetary entry and descent, space travel, orbital maneuvering including orientation and stabilization in space.

The linear control gives the steady state nominal point, between 70% and 120%.

SpaceX engines are said to throttle down to 39%. Engines of reusable sounding rockets are said to be throttleable from 40% to 100% of thrust to sustain a vertical landing of the launch vehicle.

Boost and sustainer engines have demonstrated throttling from 17% to 100% thrust, while upper stage and lunar lander engines have demonstrated throttling in excess of 10% to 100% thrust.

Since the 1930's continuous improvements and tests are being done in the technology development to demonstrate a combination of reliability, safety, durability, throttlability, and restart capabilities of rocket engines.

Historically, cryogenic rocket engines have not been used for in-space applications due to their complexity.

While thrust profiles of rocket engines solid propellants have become better developed in recent years, it is still much simpler to develop controllable thrust profiles for liquid-propelled engines, since the combustion process is easier to control, stop, and restart.
 
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Catastrophe

The devil is in the detail
" I have nothing to add to what is already mentioned above."

Anyone else have any practical ideas for anti-matter, or can we deem it an impractical curiousoty?

Cat :)
 

Catastrophe

The devil is in the detail
"I think we just need to give it time to mature."

OK. I was actually quoting:

"3.) And on a more theoretical topic with regard to propulsion...if matter and antimatter particles annihilate each other when they encounter each other, yet produce energy in that process.....is anybody in the scientific community looking at that as a means of propulsion to get us farther out into space?"
My emphasis.

. . . . . . . . . which I took to mean 'looking at now'. Of course, "looking at" has a wide variety of meanings. I took it as looking at now with a view to use in the not-too-distant future. It could equally mean looking at with a view to far distant exploitation.

Cat :)
 
Jul 27, 2021
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Please correct me, if my formulation wrong:
'Scientific community is looking at dark matter as a means of propulsion for future, right now".

As long as the dark matter has hypothetical features right now, it's future application possibilities as propellant are being elaborated on what is currently hypothesized. Together with chameleon model and the fifth force, which was announced to be possibly detected earlier this year.

As an example:
 
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Catastrophe

The devil is in the detail
Interesting.

Is anything known about relation between DM density and availability for propulsion, and between DM density and drag characteristics? For example, one might be proportional to density ^2 and the other ^4, in which case the potential might be very great, or very limited.

Cat :)
 
Jul 27, 2021
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A not deep dive into the subject, gives only similarities of the vortex as we know it in the water and the air, for instance, related to density. The spaceship is accelerating with the background (Universe) expansion


The Chameleon theory is a dark matter/energy theory that assumes forces from the change in densities in or about an object.The modified Chameleon model produces a vortex structure aft of a moving object in the Chameleon (dark matter/energy) density field that has similarities to spacetime models as Warp-Drive and Wormholes…

The Chameleon vortex propulsion model is a natural extension of the interaction between Hawking and Unruh radiation, which provides a new roadmap toward new innovative space propulsion systems - that are founded in both nature and theory
.’
 
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Catastrophe

The devil is in the detail
Lariliss,

My impression is that this is all speculation founded on wishful imagination.
My mind is open to facts and reasonable suggestions for objective assessment and progression.
This is an important area since it is proposed that dark matter/energy make up >95% of all.

Please tell me if I am wrong.

Cat :)
 
Jul 27, 2021
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Lariliss,

My impression is that this is all speculation founded on wishful imagination.
My mind is open to facts and reasonable suggestions for objective assessment and progression.
This is an important area since it is proposed that dark matter/energy make up >95% of all.

Please tell me if I am wrong.

Cat :)
Either formulations are confusing or we are not on the same page.

My imagination wouldn't go to that (possible realization if dark matter/energy is applicable):

Vortex Formation in the Wake of Dark Matter Propulsion
DARK MATTER IN TERMS OF SPACE PHYSICS PROPULSION
Dark Matter as a Possible New Energy Source for Future Rocket Technology
 
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Catastrophe

The devil is in the detail
Perhaps I have a negative response to the word 'tweak'. Perhaps it has trans Atlantic differences.

Quote
Definition of tweak
transitive verb
1: to make usually small adjustments in or the controls especially : FINE-TUNE
2: to injure slightly
3: to pinch (a person or a body part) lightly or playfully
4: to pinch and pull with a sudden jerk and twist : TWITCHtweaked a bud from the stem
5a: ANNOY, BOTHER tweaking the establishment
b: to criticize especially in a sly or sharp manner
c: to poke fun at
Quote extracted from Merriam-Webster my emphasis

Quote
2. VERB
If you tweak something such as a system or a design, you improve it by making a slight change.
[informal]
He expects the system to get even better as the engineers tweak its performance. [VERB noun]
Synonyms: adjust, improve, alter, adapt More Synonyms of tweak
Quote Collins Dictionary my emphasis

Perhaps it is just my interpretation of the word 'tweak'. To me, it comes across as taking something imperfect, or not quite working properly, and giving it a random change, or 'whatever makes it work' style adjustment - any arbitrary change to get it to appear to be working. But, that is my personal interpretation, and, doubtless, others would disagree.

Cat :)
 
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Catastrophe

The devil is in the detail
"We try to use dark matter (DM) as fuel to solve this problem. In this work, we give an example of DM engine using dark matter annihilation products as propulsion. . . . . . . . . . . . . Moreover, in case there is a central black hole in the halo, like the galactic center, the radius of the dense spike can be large enough to accelerate the spaceship close to the speed of light."

close to the speed of light???

I have to check on dark matter annihilation. I had not heard of this.

I also have at the back of my mind, that dark mater and dark energy were ad hoc assumptions (what I, personally, call tweaks,) to solve particular problems. Still, I am here to learn, so please help me, if you can. Any assistance (added to what I am doing myself) gratefully accepted.

Cat :)
 

Catastrophe

The devil is in the detail
Quote
Dark matter annihilation

Dark matter 'annihilation' may be causing the Milky Way's center to glow. ... According to new research, heavy dark matter particles may be destructively colliding at the center of the galaxy, creating elementary particles, as well as gamma rays — the unexplained light seen emanating from the galactic center.1 Apr 2021
Quote Google My emphasis

I see the date is April the First. I trust this is accidental ;)

I cannot find a "Dark matter annihilation" Wikipedia entry??

Cat :)
 

Catastrophe

The devil is in the detail
There is an interesting article in the current edition of Astronomy Septemer 2021:
"Dark matter - the unusual aspects" by Robert Lea.
I don't know whether it points either way.

Quote
In early 2021, a team from the University of Sussex in the UK, revealed that they had managed to narrow the potential mass range of dark matter particles to between 10^-3 and 10^7 eV. Not only is this a significantly trimmed range, it also rules out both ultralight particles and their supermassive counterparts. . . . . . . . . . There also remains the possibility that the true explanation for dark matter is something scientists haven't yet dreamed up. And in that case, 85% of the mass in the universe might remain incomprehensible for years to come."
Quote

Cat :)
 
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May 11, 2021
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There is an interesting article in the current edition of Astronomy Septemer 2021:
"Dark matter - the unusual aspects" by Robert Lea.
I don't know whether it points either way.

Quote
In early 2021, a team from the University of Sussex in the UK, revealed that they had managed to narrow the potential mass range of dark matter particles to between 10^-3 and 10^7 eV. Not only is this a significantly trimmed range, it also rules out both ultralight particles and their supermassive counterparts. . . . . . . . . . There also remains the possibility that the true explanation for dark matter is something scientists haven't yet dreamed up. And in that case, 85% of the mass in the universe might remain incomprehensible for years to come."
Quote

Cat :)
I thought dark matter was invented to account for that behavior of ordinary visible matter over very large distances like those seen in a galaxy as a whole. IIRC galaxies spin faster than our current theories say they should so dark matter has been suggested as a way of balancing up the books. But I think their are a number of other possibilities. It could be that gravity works a bit differently than we thought over very long distances or something else.
 
Jul 27, 2021
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This is one of facilities to make one more step forward getting more data about dark matter.


"Cavemen could smash rocks together, to see what they're made of," [..]"SuperBIT is looking for the crunch of dark matter. It's the same experiment, you just need a space telescope to see it."
 

IG2007

"Don't criticize what you can't understand..."
Apr 5, 2020
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I thought dark matter was invented to account for that behavior of ordinary visible matter over very large distances like those seen in a galaxy as a whole. IIRC galaxies spin faster than our current theories say they should so dark matter has been suggested as a way of balancing up the books. But I think their are a number of other possibilities. It could be that gravity works a bit differently than we thought over very long distances or something else.
Um, not really. Dark Matter was actually invented as a mathematical tool to cover up the mass that is not being detected across galaxies. For example, if the 95% of the Milky Way was not made up of Dark Matter, the spiral arms of the galaxy would have ripped apart and the galaxy wouldn't even exist. That is why there came a need to account for the extra undetected amount of matter. And please, not MOND again. :)
 
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Jun 1, 2020
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I thought dark matter was invented to account for that behavior of ordinary visible matter over very large distances like those seen in a galaxy as a whole.
. Yes, but the original use came from Fritz Zwicky, who coined the term, long ago when he determined that the motions within galactic clusters are too fast with only the matter that’s visible. Decades later, Vera Rubin discovered that Andromeda’s rotation required more matter. It grew from there.
 

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