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Project Hyperion: Interstellar ship design competition

projecthyperion.org

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Re: Project Hyperion: Interstellar ship design competition

#231

Post by dotancohen »

JumpCrisscross wrote: post #214
mjevans wrote: post #151

Earlier quoted context omitted.

In that timeframe it would by nature need to be capable of full self repair, with the shipped materials and energy, and with no wasted byproducts. We'd have to completely re-think industrial processes. I'm in favor of realized nanotechnology and 3d printers at an atomic level. Evolution stumbled across carbon based lifeforms as it's answer on Earth.

> it would by nature need to be capable of full self repair Why? If we can accelerate a small city to 0.01g in a year, we can accelerate smaller packages to catch up with it once a year.

How is that package going to navigate, and then match velocity to dock?

Re: Project Hyperion: Interstellar ship design competition

#232

Post by m4rtink »

KineticLensman wrote: post #222

Looking at view #28 in the winning presentation, the system carries 200 shuttles that can each do a one-way trip to the target planet carrying 10 people and delivering 5 tons of cargo. So the overall system can deliver up to 2000 people and 1000 tons -in comparatively small pieces - to the planetary surface. It would be good to see some discussion of how you can bootstrap a colony (let alone a civilisation) under the…

I think this again shows an unhealthy fixation on planets. Sure, they are nice and big and if you are very lucky might be even habitable.

But given that you already have a massive mobile self sufficient workstation in space it would IMHO make much more sense to start with setting up some simple in space infrastructure first upon arrival & then using that to run a space to ground transport link. That should give you all the benefits of starting with a space based civilization in the new star system rather than stranding 2000 at potentially hostile planet with no means of support and space based assistance, battling for survival.

Well, unless you really like all those lost colony novels with low tech human societies existing on exotic planets that were not able to keep their tech level. ;-)

Re: Project Hyperion: Interstellar ship design competition

#234

Post by m4rtink »

WithinReason wrote: post #180
Ekaros wrote: post #170

Earlier quoted context omitted.

Energy is the limit. If used Wolfram Alpha right for reasonable comparison that is largest cruise ship with mass of 248663000 kg to speed up to 0.01c mentioned the kinetic energy would be 2.9 times the worlds fossil fuel reserves... Then double that to slow down. And remember efficiency and that well you need to spend some to keep people alive... Seems like energy in general is one of the true problems.

You wouldn't be burning coal for propulsion, you would fuse atoms: https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls...

Or even better - ride a continuous fission detonation powered by the worlds biggest super-soaker! :)

https://en.wikipedia.org/wiki/Nuclear_salt-water_rocket

Re: Project Hyperion: Interstellar ship design competition

#235

Post by jvanderbot »

JumpCrisscross wrote: post #114
jvanderbot wrote: post #92

Earlier quoted context omitted.

> up to 18km/s Vs > 0.1c Off by quite a bit

Where are you getting either of these figures?

The up to 18km/s is from the linked shield.

Up to 0.1c is from the interstellar spaceship competition "cruise" speeds (also used 0.01c) as presented in their deck.

They're a few orders of magnitude difference.

Also, there's plenty of resources around on interstellar travel that shows interstellar dust/debris is going to be a huge problem.

For example Atomic Rockets, which has a bunch of good reference materials (albeit poorly organized), or the Astronomy Cafe

https://sten.astronomycafe.net/at-what-speed-does-the-inters...

Re: Project Hyperion: Interstellar ship design competition

#236

Post by jvanderbot »

JumpCrisscross wrote: post #113
privatelypublic wrote: post #88

Earlier quoted context omitted.

Whipple shields are consumed by impacts.

> Whipple shields are consumed by impacts Everything is consumed on such a voyage. If we can send a generation ship at 0.01c, we can send replacement parts quicker and probes ahead to verify our estimates even faster.

Are you just casually handwaving away sending a dockable resupply ship at 0.01c to somewhere in interstellar space, then doing some kind of rendesvous with it at 0.01c with a spaceship measured kilometers in length?

There's no free lunch. Every gram of mass that you want to get to interstellar space requires exactly as much fuel to get there as you'd have to add to the original spacecraft to just carry it.

(thought experiment - have them fly side by side, then connect them by string, then shorten the string until they touch, then weld them together - the fuel required doesn't change at any point).

And a shield + a resupply ship has a lot more grams than just adding the shield to the original thing.

Re: Project Hyperion: Interstellar ship design competition

#237

Post by m4rtink »

dotancohen wrote: post #231
JumpCrisscross wrote: post #214

Earlier quoted context omitted.

> it would by nature need to be capable of full self repair Why? If we can accelerate a small city to 0.01g in a year, we can accelerate smaller packages to catch up with it once a year.

How is that package going to navigate, and then match velocity to dock?

Should be doable with beamed propulsion. Basically give each package a lightsail & you can have it maneuver when illuminated by laser arrays either in the home system or on the interstellar craft itself.

The beauty of this setup is that if you are really good at keeping the schedule, this can be all pre-computed. With time slots being allocated beforehand when the laser arrays send beams in a given direction & the packages (or the craft itself) just making really sure they stay in the beam & properly oriented when it arrives at the planed place and time.

Re: Project Hyperion: Interstellar ship design competition

#238

Post by m4rtink »

slightwinder wrote: post #228
WithinReason wrote: post #179

Earlier quoted context omitted.

We had the technology to do it in 44 years 60 years ago: An atomic (fission) Orion can achieve perhaps 9–11% of the speed of light. [...] At 0.1 c, Orion thermonuclear starships would require a flight time of at least 44 years to reach Alpha Centauri, not counting time needed to reach that speed (about 36 days at constant acceleration of 1 g or 9.8 m/s2). https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propuls..…

> We had the technology to do it in 44 years 60 years ago: No, we had not. That was only theoretical work, no real technology, not even a prototype.

IIRC there were sub-scale test done with chemical explosives. Also Feynman said it should work. :)

Re: Project Hyperion: Interstellar ship design competition

#239

Post by jvanderbot »

teiferer wrote: post #178
jvanderbot wrote: post #50

Earlier quoted context omitted.

We're one good new religion away from colonizing the solar system. Cathedrals were built over 100s of years. Imaging just living in a massive one and your whole holy purpose is to survive and thrive and spread. It's entirely reasonable we'd have the will to make it happen, and pretty reasonable we'd be able to build it with planet scale effort, but sadly quite difficult to imagine it surviving even dust impacts for 4…

> It's entirely reasonable we'd have the will to make it happen "We" are not even able to sustainably inhabit our current planet. We have hundreds of millions starving every day, we have wars in many places, the threat of thermonuclear war looming as strong as ever, and are still using natural resources at an unsustainable rate even though we know that that's the case . Settling on other planets has all these problem…

We do not have hundreds of millions starving every day. And if we did, we don't have a large portion of industrialized/militarized missions starving every day anway. We'd send the best of the best, hand picked, with the best tech we can build.

It's fine if you believe we should not go (but I disagree), but the state of the world is not evidence of failure of the mission.

Re: Project Hyperion: Interstellar ship design competition

#240

Post by jvanderbot »

ben_w wrote: post #220
JumpCrisscross wrote: post #209

Earlier quoted context omitted.

> If used Wolfram Alpha right for reasonable comparison that is largest cruise ship with mass of 248663000 kg to speed up to 0.01c mentioned the kinetic energy would be 2.9 times the worlds fossil fuel reserves This math is wrong. Back of the envelope: accelerating 250 x 10^6 kg to 1% of c over one year is about 310,000 TWh. That’s like half of current annual energy production. Even at like 10g, which would accelerat…

Your maths is correct. Shame we don't have a way to efficiently convert fuel energy directly into a ship's kinetic energy, and have to go via conservation of momentum… though I suppose magnetic launch of interstellar vehicles would be a neat use for a Dyson shell or Niven ring?: https://www.wolframalpha.com/input?i=0.5+*+1+gee+*+%280.01c%...

Is this the right time to mention the Atomic Rockets website?

https://projectrho.com/public_html/rocket/

It's _full_ of good stuff.

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