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Old 09-11-2019, 07:54 PM   #1
AlexanderHowl
 
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Default Realistic STL Interstellar Missions

STL interstellar missions really only become feasible at TL10, though they requiring staging at that point. The first stage would have to use an advanced nuclear pulse drive to reach 0.01c while the second stage would have to use a ramscoop and fusion rocket to reach 0.05c (a reasonably realistic maximum for a ramscoop plus fusion rocket combination). An additional advantage to a ramscoop is that it can be used to decelerate without engaging the attached fusion drive through pushing against the interstellar medium (though the latter use would require continuous power). The end result is a reasonably efficient and realistic technology for STL interstellar missions.

Using the above combination, a STL interstellar mission would take 10 years to accelerate to cruising speed and 10 years to decelerate from cruising speed. At 0.05c, it takes 20 years to travel 1 ly, so suspended animation is advisable. A short journey of 12.5 ly would take 270 years while a long journey of 50 ly would take 1010 years. While it would be expensive, it would be feasible to spend people to the stars.

So, at what point of the journey would you have a campaign? Would it be at the beginning, before the trip? Would it be during the middle, during a rotation into wakefulness for a year? Would it be at the end, after the trip? What complications would interest you?
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Old 09-11-2019, 09:13 PM   #2
Joseph Paul
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Default Re: Realistic STL Interstellar Missions

It is not feasible to plan for missions that will take more than a few decades to complete because there is an opportunity to gain faster interstellar technology by waiting for the break through in physics and engineering. Going early means that you may very well be leap-frogged by later tech developments and pretty much lose out on having a colony world for what you wanted.

It is not infeasible that governments have changed in the 270-1010 years since the STL launch. They may not recognize the claim put forward (and primary claims are only really recognized if you can show you have physically secured it) or they may have superseded your claim with their own. If tech has advanced while the crew slept they will also be out gunned by whatever the TL difference is. And the colony ship is not built to battle but the advanced tech interloper could very well bring along a couple of ships that are.

And if the front shield of the ship can't take the hit leave it off and up the speed.
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Old 09-11-2019, 10:45 PM   #3
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Default Re: Realistic STL Interstellar Missions

Our velocity has not increased dramatically over the previous 25 years, much less than the proceeding 25 years, due to diminishing returns on investment (11 km/s for Apollo 10 versus 16.2 km/s for New Horizons). Of course, the Parker Solar probe will go much faster than anything else we have created, but it will be cheating, it is just using a particular aspect of its extreme orbit to travel its velocity.

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Old 09-12-2019, 05:56 AM   #4
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Default Re: Realistic STL Interstellar Missions

You need more stages unless you're just going to zoom through the target zone...
I'd want to game arrival but pre-departure, journey, etc are all game-able.
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Old 09-12-2019, 06:26 AM   #5
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Default Re: Realistic STL Interstellar Missions

Quote:
Originally Posted by AlexanderHowl View Post
Our velocity has not increased dramatically over the previous 25 years, much less than the proceeding 25 years, due to diminishing returns on investment (11 km/s for Apollo 10 versus 16.2 km/s for New Horizons). Of course, the Parker Solar probe will go much faster than anything else we have created, but it will be cheating, it is just using a particular aspect of its extreme orbit to travel its velocity.
Using the immediate now to counter concerns based on TL progression above TL 9 or 10 over a period of 270 to 1010 years (your numbers) is really kind of lacking in any sort of relevance.
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Old 09-13-2019, 10:36 PM   #6
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Default Re: Realistic STL Interstellar Missions

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Originally Posted by AlexanderHowl View Post
Our velocity has not increased dramatically over the previous 25 years, much less than the proceeding 25 years, due to diminishing returns on investment (11 km/s for Apollo 10 versus 16.2 km/s for New Horizons).
Which proves precisely nothing.

It's true that technology does not advance along the naïve exponentiating curve that some futurists like to imagine. It rises in S curves, slow-fast-slow, then later another S curve, as a rule, when some new development happens.

But whenever one is planning for multi-decade time spans, the risk of an S curve surge (i.e. a breakthrough) is always present, and by its very nature unpredictable.

That's also why trying to plan things centuries in advance is a crapshoot at best.
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Old 09-17-2019, 05:56 PM   #7
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Default Re: Realistic STL Interstellar Missions

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Originally Posted by AlexanderHowl View Post
Our velocity has not increased dramatically over the previous 25 years, much less than the proceeding 25 years, due to diminishing returns on investment (11 km/s for Apollo 10 versus 16.2 km/s for New Horizons).
This is an increase of almost 50%. It seems pretty dramatic to me.
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Old 09-17-2019, 10:17 PM   #8
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Default Re: Realistic STL Interstellar Missions

50% is not that much in 50 years. Even if we continued with that date of increase, it would take six or seven centuries to get to 5% c. For reasons specified above, we are unlikely to get above 5% c unless one of the FTL schemes end up working.
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Old 09-18-2019, 10:54 PM   #9
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Default Re: Realistic STL Interstellar Missions

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This is an increase of almost 50%. It seems pretty dramatic to me.
Compared to the previous time period, it's peanuts. The time period from 1850 to 1950 (roughly) saw orders of magnitude increases in speed and performance. People who travelled west in covered wagons lived to see astronauts travelling at multiple miles per second.
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Old 09-18-2019, 11:16 PM   #10
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Default Re: Realistic STL Interstellar Missions

Interstellar travel at .05c requires a minimum energy budget of 1.125e+14J/kg, and no rocket will achieve even half that, call the actual energy budget 3e+14J/kg. Low end of current electricity prices is about $4e-8/J, but less useful energy might go less, call it $1e-8/J, putting a low end price of $3M/kg or $3B/ton. It seems unlikely that we can manage less than a ton per person, so based on TL 10 wealth of $75k/person, we only need 40,000x starting wealth per person you send.
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