New engines for space travel?

[skybadger]

4 hours ago, iapa said:

It's posing some the same issues I just did

OK, leaving interstellar traffic out for the time being, it still seems that we need something to 'protect' the forward facing surfaces, even for journeys to the Jovian satellites.

I expect that means massively dense materials, and more power required to overcome inertia, force fields or something like graphene?. c.f. Theodore Sturgeon's story ‘It Was Nothing—Really!’, inventor find perorated paper never tears on the perforations and concluded the holes are stronger.

Force fields would probably be electromagnetic in nature, weak, strong and gravitation forces won't cut it.

So, electro-osmotic drive, with electo-magnetic shielding. Job done

Except the former needs improved nanotube manufacture, could maybe do that on a space station on near zero g? But could get as much thrust as you need, the paper suggested >90% efficiency.

The latter may well depend on CERN producing more exotic particles, or is dark matter a possibility - if anyone knew what it was

 

. c.f. Theodore Sturgeon's story ‘It Was Nothing—Really!’, inventor find perorated paper never tears on the perforations and concluded the holes are stronger.

I'd forgotten about that story .thank you for the reminder. It's great.

[Alien 13]

I have to ask how we can be sure interstellar space is mostly empty with a few grains of dust, it could be jam packed with large rocks and as far as I know nobody has been there to check..

Alan

[Andy ES]

17 minutes ago, Alien 13 said:

I have to ask how we can be sure interstellar space is mostly empty with a few grains of dust, it could be jam packed with large rocks and as far as I know nobody has been there to check.

I remember seeing a programme about the Voyager probes where they were worrying how to shield the plaque as they assumed over billions of years of hitting tiny bits of dust that it would be completely worn away.

hope I don’t fall foul of the CoC with these naked people😂

[iapa]

70days @ 9.81ms-2 should get you to 0.2c, and about 1200 AU distant.

Pluto is c40AU.

So, lets assume Mars @ 1.5AU

Earth is 1 AU, so, if we assume a straight line path to Mars' solar orbit we need to cover 0.5AU, so halve that distance for acceleration/deceleration, and if my math is right

• s=0.5at^2
• 2s=at^2
• 2s/a=t^2
• t = sqrt(2s/a)

 

• t=sqrt(2AU/9.81)

our distance is 0.25 AU, so

• t=sqrt(2 * (0.25*1.5*10^11)/9.81)
• t= 1.5 days

So, mars orbit in 3 days.

Propulsion? NASA's SRB get to 3G in 8 seconds, but burn out after 2 minutes. Throttle those back, and add a few more and it could be done.

 

 

 

 

 

[iapa]

49 minutes ago, Alien 13 said:

I have to ask how we can be sure interstellar space is mostly empty with a few grains of dust, it could be jam packed with large rocks and as far as I know nobody has been there to check..

Alan

I seem to remember the some exo-planets were not orbiting stellar masses, so, that would be a significant mass to collide with a fractional 'c' speeds.

 

Edit: e.g.. PSO J318.5−22

 

Edited August 26, 2022 by iapa
grammar:changed where to were

[Alien 13]

7 minutes ago, iapa said:

I seem to remember the some exo-planets were not orbiting stellar masses, so, that would be a significant mass to collide with a fractional 'c' speeds.

I wonder if all this dark matter nonsense is due to far more large rocks/rogue planets etc everywhere 😀

Alan

[iapa]

5 hours ago, iapa said:

It's posing some the same issues I just did

OK, leaving interstellar traffic out for the time being, it still seems that we need something to 'protect' the forward facing surfaces, even for journeys to the Jovian satellites.

I expect that means massively dense materials, and more power required to overcome inertia, force fields or something like graphene?. c.f. Theodore Sturgeon's story ‘It Was Nothing—Really!’, inventor find perorated paper never tears on the perforations and concluded the holes are stronger.

Force fields would probably be electromagnetic in nature, weak, strong and gravitation forces won't cut it.

So, electro-osmotic drive, with electo-magnetic shielding. Job done

Except the former needs improved nanotube manufacture, could maybe do that on a space station on near zero g? But could get as much thrust as you need, the paper suggested >90% efficiency.

The latter may well depend on CERN producing more exotic particles, or is dark matter a possibility - if anyone knew what it was

 

Wonder if dark energy would help as it is apparently the reason galaxies are ming away from each other

[DaveS]

This is getting off the original point, but hey ho...

I do think that we don't know enough about interstellar debris etc to go blindly charging off at even 0.2C (The practical limit suggested in the PBS video). Perhaps if we manage to launch the Starshot Swarm, that might give us an idea.

For charging around the Solar System, I think we have a reasonable idea of the hazards, just keep the speeds down to a sensible value, 0.1C is likely to be plenty, once we get beyond the zodiacal debris. Until then I suspect something lower will be more sensible.

 

Dark Energy is something inherent in the structure of space I think, not something we can use for any practical purposes.

 

I wonder if a Warp Drive bubble will act as a barrier to debris? If it should ever become a reality.

[tomato]

I think Project Orion was great, imagine a huge spacecraft being pushed along by successive nuclear detonations from bombs dropped through a shock absorbed pressure plate  just bonkers…

Edited August 27, 2022 by tomato
Typo corrected

[ONIKKINEN]

Some kind of nuclear propulsion sounds like the best bang for buck in terms of thrust, ISP, and available tech now or in the near future. But... Shooting a nuclear anything in to orbit is not a very popular option in the eyes of the public. After all, anything with enough nuclear matter to act as proper propulsion will also be a very convenient way to spread radiation over the entire Earth in case of an accident during launch. In paper, best choice, but not sure i want to see one of these make a debut any time soon.

Ion thrusters, including the VASIMIR, all suffer from 2 major showstopper issues at the moment which are: power required per 1N of thrust (40 KILO watts per 1N for the VASIMIR...) and the difficulty of actually getting just that one newton of thrust. Solar power is hardly realistic for this kind of power requirement, because solar panels are also quite heavy which is terrible for an engine in the single digit newton thrust range and most places humans would want to travel to are further away from the sun, so it only gets worse as distance increases. Realistically any propulsion intended to accelerate humans to any speed in a timely manner will need to have more like a kilonewton of thrust, rather than just a single N. So nuclear reactors are still the only way for power, but again i am not sure i want a megawatt reactor doing an oopsie after a failed launch.

[Andy ES]

Again after watching Discovery Chanel or something  I remember a discussion about space “Arcs”that would take humanity to distant stars over thousands of years.

This all seemed like a good idea but it was eventually worked out that such a small population would create a race of people that in the end would probably not even remember why they were there.

Blimey,  that’s a bit depressing, sorry....😬

[DaveS]

Project Orion would work.

It's been tested, albeit with non-nuclear explosives, the maths and engineering has been well worked out, if we need it, it's there.

But even without such engines nuclear power is the only viable prospect for space travel. There are plenty of new designs of reactors that are inherently safe, plus there are regulations prohibiting weapons grade nuclear fuel in space.

We just need to tell the bunny-huggers to take a long walk on a short pier.

[Zeta Reticulan]

Oh no, not the bunnies!

[Louis D]

I remember reading a sci-fi novel about 40+ years ago where no one on a multi-generational interstellar ark had any idea they were even on a spaceship.  There was no "crew" on the bridge, and it was only a nosy teenager who went exploring and discovered that they were nearing their destination after reaching the bridge and looking out the windows to see an approaching sun.  I can't recall the details, but no one would believe his story or theory of their existence.  In the end, I think he figured out how to take a shuttle launch by himself down to the planet they were supposed to colonize while the ark sailed on past the planet into oblivion.

[cajen2]

SF stories about 'generation ships' abound, often with the original aim becoming just a legend or myth.

[iapa]

there are so many on that theme, but I think I read that one. My thought was at the time that the population when landed was insufficient to survive.

 

Anyway, I digress.

 

Seems even the existing tech has issues getting things of Earth given Artemis was snubbed today.

[Ags]

Earth is a generation ship trapped in the Sun's gravitational well...

[DaveS]

For centuries long journeys the sort of deep frozen hibernation used in several SF novels makes more sense than generation arks. You're not using / recycling resources during the trip, and the people arriving are the ones who started, with all the drive that sent them out in the first place.

The Magellan starship in Clarke's "Songs of Distant Earth" (Novel, not short story) is a good example (Leaving out the rather improbable drive).

[Guest]

It will be just like the Epstien drive.  A complete accidental discovery that will change everything.  

[DaveS]

I'm going to put this here, as it's one of the less barking ideas from AstronX.

Some of the comments are just plain woo-woo, but ignore them, this channel does seem to attract to nut-jobs.

[iapa]

On 29/08/2022 at 21:54, DaveS said:

 

The Magellan starship in Clarke's "Songs of Distant Earth" (Novel, not short story) is a good example (Leaving out the rather improbable drive).

That's what we are missing, the Infinite Improbability Drive, finite improbability generator and a really nice hot cup of tea........

[DaveL59]

On 29/08/2022 at 21:54, DaveS said:

For centuries long journeys the sort of deep frozen hibernation used in several SF novels makes more sense than generation arks. You're not using / recycling resources during the trip, and the people arriving are the ones who started, with all the drive that sent them out in the first place.

The Magellan starship in Clarke's "Songs of Distant Earth" (Novel, not short story) is a good example (Leaving out the rather improbable drive).

I'd worry tho about deep freezing, organics decay even when frozen, albeit a lot slower, but 1000 years, who knows what we'd be defrosting at the end...

[iapa]

On 29/08/2022 at 21:54, DaveS said:

For centuries long journeys the sort of deep frozen hibernation used in several SF novels makes more sense than generation arks. You're not using / recycling resources during the trip, and the people arriving are the ones who started, with all the drive that sent them out in the first place.

The Magellan starship in Clarke's "Songs of Distant Earth" (Novel, not short story) is a good example (Leaving out the rather improbable drive).

And doesn't address the drive - popsicles on a non-FTL drive will still be passed by when FTL comes along

[DaveS]

That assumes that FTL will be possible, even with warp drive technology.

[DaveS]

11 hours ago, iapa said:

That's what we are missing, the Infinite Improbability Drive, finite improbability generator and a really nice hot cup of tea........

The improbability is down to using "Vacuum Energy"

This is what Sabine Hossenfelder has to say.

 

Edited August 31, 2022 by DaveS
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