NASA validates revolutionary propulsion design for deep space missions | Hacker News Reader

NASA validates revolutionary propulsion design for deep space missions

nasa.gov

172 pointsmpweiher55 comments

Real Engineering's video today likely causing resurfacing from Jan https://www.youtube.com/watch?v=RVxgyz_avQM

I was greatly annoyed to see the jet color scheme used in nearly all of those visualizations. We have better options!

> to deep space destinations, such as the Moon

I feel woefully underqualified to call out NASA's PR team, but I don't _think_ the Moon qualifies for most definitions of "deep space".

Exciting news all the same, and I can only assume they meant to suggest that RDRE propulsion is useful for destinations that are nearer too!

From the NASA Deep Space Communications Educator guide [1]:

> Deep space begins at approximately 42,000 km (26,098 mi) from Earth

[1] https://www.nasa.gov/sites/default/files/atoms/files/ps-0343...

The U.S. government defines deep space as anything beyond low-earth orbit. [1] Others vary. [2] The U.S. "Deep Space Network" was created because communications with low-earth orbit and beyond-LEO had very different requirements [3].

[1] https://uscode.house.gov/view.xhtml?req=granuleid:USC-prelim...

[2] https://en.wikipedia.org/wiki/Outer_space#Regions_near_the_E...

[3] https://en.wikipedia.org/wiki/NASA_Deep_Space_Network#Deep_s...

Deep space should be the furthest point reached by probes in likeness to deep ocean depth exploration. Voyager I, II and New Horizon probes should redefine the ”distance.“

I believe they call that interstellar space to distinguish from "deep" space.

Scott Manley did a video on Rotating Detonation Engines a few years ago https://m.youtube.com/watch?v=rG_Eh0J_4_s

The fuel and oxygen injectors use a variant of the Tesla Valve

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

Fascinating. I was just a kid in 1964 when I learned about fluidics. My December issue of Scientific American had an article on fluidics featured on the cover and I always wondered why there never seemed to be any applications of the devices described in that article. In particular, the use of fluidic logic gates and latches, etc.

Anybody know what Specific impulse we are talking about? According to wikipedia, current values for rockets are around 300s

This was a smaller prototype. Unless they release a theoretical Isp model for scaling up the engine (which, would we believe them if they did?) we can't know for certain yet.

Not sure the relationship, but they say 600PSI chamber pressure, or about 20 bar. Spacex is push 200 to 300 bar pressures. I would think this means they're currently at a low ISP. The challenge with RDEs has been keeping them lit, I e. Keeping the detonation wave going indefinitely. Once that's done they can work of efficiency. Seems like they're at that point now.

Pressure can tell you about thrust, but I don't think its as strongly linked to specific impulse. However looking at the wiki article on the RS25 which is pretty high up there being a hydrolox engine, I see it's also got a chamber pressure in the 200+ bar range.

NASA should release a Kerbel Space Program mod with this engine.

In the theoretical limit how much improvement in efficiency could such engines provide?

Up to 25% improvement compared to conventional rocket engines according to the Wikipedia page. I haven’t found an actual ISP measurement for this NASA engine, though.

Is that a 25% improvement in ISP/exhaust velocity or another metric?

It seems that 25% paragraph on wikipedia cites a non-technical article[1] from 2018:

    "Theoretical calculations have shown that detonation combustion is 25% more efficient than the isobaric combustion cycle, which corresponds to constant-pressure combustion, which is implemented in the chambers of of modern liquid propulsion engines."

From another article[2] of the same year:

    "Conservatively speaking, a rotating detonation combustor, or RDC, should reduce specific fuel consumption by about 5% compared to a conventional engine. This measure of fuel efficiency is calculated by dividing fuel consumption by power output. A rotating detonation engine generates more power, which drives down specific fuel consumption. A reduction on the order of 5 percent would be a breakthrough, given that designers of conventional engines “try to eke out fractions of a percent,” says Scott Claflin, director of advanced concepts at the Rocket Shop, Aerojet Rocketdyne’s innovation organization."

[1] https://rg.ru/2018/01/18/levochkin-vozmozhnost-sozdaniia-det...

[2] https://aerospaceamerica.aiaa.org/departments/increasing-eng...

> that 25% paragraph on wikipedia cites a non-technical article[1] from 2018

The article you footnoted is also in Cyrillic.

After all this time, it's amazing to see people trust Wikipedia. It's like they don't care if it's true or not; it's entertainment, pretending to know, not knowledge.

A perfect way to spin your wheels forever and go nowhere.

> The article you footnoted is also in Cyrillic.

And your comment is in Latin, going by your terminology. In the age of decent online translators, do you care to elaborate on why that’s a problem?

I mean, Russia has a fairly large space program, is that surprising?

25% sounds super disappointing from a laymans perspective and not very "revolutionary" in the grand scheme of time and space.

Can't wait until AI will be able to iterate advanced engineering designs in simulation space at incredible speed.

From 10% to 35% is a 25% improvement, you're still at 35%... From 70 to 95% is a 25% improvement, but it's a lot more. Going from 98 to 99% is only 1% but also like really a 10x improvment.

Rockets are operating at pretty decent efficiency, 25% improvment on an internal combusion engine would be mind blowing and make EVs way less interetsting.

There are theoretical maximum efficencies for various types of engines due to thermodynamics. You always lose energy to heat. Entropy is a b**.

Technically, from 10% of something to 35% of something is a 350% improvement or a 25 percent point improvement.

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

Actually, from 10% of something to 35% of something is a 250% improvement. You already had the first 10%.

yes but people often conflate/confuse that... saying the delta in %'s... not % improvement. I agree with you, I'm attempting to point out how a small % increase is a huge actual improvement. This GP was saying that a 25% improvment in the efficiency of a rocket engine was not much to a layman.

Simulations aren't really the limiter on engine efficiency, SpaceX etc already lean heavily on simulations.

The limiters on engine efficiency at this point are mostly materials and costs, and even the latter are coming down with better fuels (eg Methane, which is extremely popular with rockets debuting this decade) and different design philosophies (eg SpaceX's Raptor engine, which is supposedly under $1M per engine while being the most advanced flight tested rocket engine out there).

Agree that 25% doesn't sound very exciting or revolutionary, but computers have been used to design space-related stuff for a while, for example, https://www.jpl.nasa.gov/nmp/st5/TECHNOLOGY/antenna.html . I would be surprised if no one had tried it with propulsion systems yet.

It’s a big deal because “the tyranny of the rocket equation” works in reverse too. Just as adding fuel is a compounding problem, reducing fuel is a compounding benefit.

Looking at the size of the rocket that went to the moon vs the size of the rocket that came back from the moon says it all. It seems completely unrealistic to colonize the solar system from earth.

The only way is to set up industries on the moon to build the ships and equipment necessary to expand through the solar system.

There is never going to be a 100% improvement in 'normal' rockets - you cant gey any more energu out of a chemical reacrion. We are using all the energy that we can get out of the most powerfull fuels that exist.

The only two ways to get 'sci-fi style rocket is either nuclear, or to beam energy to the rocket from outside with giant lasers.

Other ways are:

1. air launch, which boils down to using the O2 in the air rather than carrying it with you

2. mass driver, which needs to be in a vacuum

3. gravity slingshots

But, yeah, we need a fusion drive.

>2. mass driver, which needs to be in a vacuum

Project HARP[0] disagrees. Launched a payload 110 miles (177km) into space using a 120 foot (36m) long cannon. This was in the 1960s.

[0] https://en.wikipedia.org/wiki/Project_HARP

It didn't achieve orbit.

At first, I thought it was an insanely scaled ion drive and then maybe a toroidal aerospike.

Nope, no grids and there's water. Holy damn.

So there's a rotating flame front going in one particular direction .... anyone know does it impart angular momentum to the thing it's propelling?

It reads, sounds, and looks really cool.

We live in interesting times.

I lived next to the testing range for this engine for the past few years.

It sounds amazing from a far too. The shock diamonds it creates have an audible rumble/rhythm to it.

This is not revolutionary. Quantum propulsion is.

Something that doubles rocket payload size is a huge deal.

What's up with all of these crazy technical developments after a period of relative stagnation?

Aside from it being merely random or selection bias, it's plausible that there's some kind of AI assist beyond what we know happening behind the scenes.

i dont think thats plausible? we do not have AI

People have been working on rotating detonation engines, and making steady progress, for years. The idea dates to the '60s, but i think work really picked up about a decade ago.

I said a few days ago that it is very likely 3 letter agencies and other organisations have had GPT4 equivalent models for some time now. It doesn’t seem that unlikely that some branches of the US gov would have much more advanced models.

You're right, it kind of makes me think AGI won't come about from LLMs.

Why do people always say this? It's almost like a thought-terminating cliche. Thousands of companies competing with each other were not able to do it earlier, but the NSA always has better everything, by definition.

It’s because they have always been ahead in stuff like crypto and have an endless pocket.

Maybe ChatGPT is helping cut through bureaucratic tape. I know it’s helped me become much more persuasive in my communication. If your goal is to convince the US government to spend money testing your rotational detonation engine, your odds of success go up if an LLM helps you write the email.

This has to be an April Fool's day joke right?

I hope haha.

Date on the article is 25 Jan 2023, so seemingly not.

These baseless speculations about ChatGPT are somewhat ironic given that the article itself alludes to what has unlocked this specific advance:

"The RDRE achieved its primary test objective by demonstrating that its hardware – made from novel additive manufacturing, or 3D printing, designs and processes – could operate for long durations while withstanding the extreme heat and pressure environments generated by detonations."

It's much easier to imagine that steady advances in manufacturing, computational modeling, and "mundane" technologies like that are contributing to progress like what's described in this article... Rather than some super secret AI assistant.

Please, folks, don't give up on reading just because computers can do it too now. :)

OH MY.... Came here to say "Wow, this is so much more exciting than the 123th LLM/GPT and the 2746th "this is my experience / use case with AI" (sorry) "but sure, some one will come and claim that: GPT-8 would have designed that alone given the right prompt!!" ... and then need to read this. :(

Keep it in your pants, Sulu.

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