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Interstellar Flight: Perspectives and Patience

centauri-dreams.org

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Re: Interstellar Flight: Perspectives and Patience

#51

Post by trhway »

sorcerer-mar wrote: post #40
trhway wrote: post #30

Earlier quoted context omitted.

Our civilization has been driven by expansion. Without it we'd probably collapse into a neurally-connected well-organized ant colony without need for further technological/social/economic progress (which would naturally select/cull out corresponding features in our brain). And, i'd guess that is possible one of the forms of the Great Filter stopping many civilizations. At 53 and good health, i'm contemplating that my…

That's a truly awful way to die (all your fluids and gases suddenly surging through your tissue). Seems much easier to reframe the "chains" of earth into acceptance of a remarkable cycle that we're privileged to get a glimpse of from the inside and just die happily here with your loved ones.

The technicalities would be worked out. The awfulness isn't a goal here.

The acceptance would have me still in Russia :)

Re: Interstellar Flight: Perspectives and Patience

#52

Post by JumpCrisscross »

KineticLensman wrote: post #2

> those of us with an interstellar bent naturally start musing about ‘sundiver’ trajectories, using a solar slingshot to accelerate an outbound spacecraft, perhaps with a propulsive burn at perihelion. . The latter option makes this an ‘Oberth maneuver’ and gives you a maximum outbound kick. You can't do a solar slingshot like you can with (say) Jupiter because the sun is essentially at rest with respect to the rest…

> the sun is essentially at rest with respect to the rest of the solar system

But not with respect to other star systems.

Re: Interstellar Flight: Perspectives and Patience

#53

Post by sorcerer-mar »

trhway wrote: post #51
sorcerer-mar wrote: post #40

Earlier quoted context omitted.

That's a truly awful way to die (all your fluids and gases suddenly surging through your tissue). Seems much easier to reframe the "chains" of earth into acceptance of a remarkable cycle that we're privileged to get a glimpse of from the inside and just die happily here with your loved ones.

The technicalities would be worked out. The awfulness isn't a goal here. The acceptance would have me still in Russia :)

Presumably you left Russia to get to something better, not worse on pretty much every dimension except novelty

Re: Interstellar Flight: Perspectives and Patience

#54

Post by [deleted] »

tejtm wrote: post #49
sorcerer-mar wrote: post #20

Earlier quoted context omitted.

What resources are on asteroids that justify the energy expenditure to get from space and back? Can't be many of them...

"What resources are on asteroids that justify the energy expenditure to get from space and back? Can't be many of them..." I suggest re-framing the the question as the cost of preserving the objectively limited and to the best of our knowledge singularly unique in the Universe resource, which is the surface of Earth. Acquiring resources that do not deplete or spoil the future of life on this planet should be in every…

[deleted]

Re: Interstellar Flight: Perspectives and Patience

#55

Post by dylan604 »

rbanffy wrote: post #35
dylan604 wrote: post #10

Earlier quoted context omitted.

So it passes through the sail and then hits the spacecraft attached to the sail. Now what? kaboom? small holes in the hull would not be good for the occupants.

The sail is much, much larger than the craft. The odds of that happening are tiny. In any case, we should launch more than one.

more than one basket for those eggs will be important.

Re: Interstellar Flight: Perspectives and Patience

#56

Post by sorcerer-mar »

tejtm wrote: post #49
sorcerer-mar wrote: post #20

Earlier quoted context omitted.

What resources are on asteroids that justify the energy expenditure to get from space and back? Can't be many of them...

"What resources are on asteroids that justify the energy expenditure to get from space and back? Can't be many of them..." I suggest re-framing the the question as the cost of preserving the objectively limited and to the best of our knowledge singularly unique in the Universe resource, which is the surface of Earth. Acquiring resources that do not deplete or spoil the future of life on this planet should be in every…

Yeah no. Unless someone can answer basic questions like “what even comes close to net positive in energy expenditure to mine elsewhere,” then this is just a cover story.

The reality is that saving our environment will be a whole set of difficult and profoundly boring solutions to real, known problems.

Would be cool if we could solve it with badass rockets, explosions, big noises, and adventure, but the complete lack of even remotely convincing answers to first order questions on how this actually works belies the fact that it doesn’t. It makes no sense.

We need to develop better plastics, proteins, and pesticides. Not send protein blobs to other planets because it looks cool in sci fi movies.

Re: Interstellar Flight: Perspectives and Patience

#57

Post by trhway »

sorcerer-mar wrote: post #53
trhway wrote: post #51

Earlier quoted context omitted.

The technicalities would be worked out. The awfulness isn't a goal here. The acceptance would have me still in Russia :)

Presumably you left Russia to get to something better , not worse on pretty much every dimension except novelty

Yep, and dying on Mars feels to me better than on Earth.

Re: Interstellar Flight: Perspectives and Patience

#58

Post by trhway »

JumpCrisscross wrote: post #50
trhway wrote: post #15

Earlier quoted context omitted.

alternatively you ionize that particle, may be make in into plasma by laser for ease of "digestion" down in the engine, direct in into the engine where it is used as working mass for your ion thruster, kind of similar to scramjet. As far as i see with today's tech - like Starlink's ion thruster + classic nuclear reactor - we can get to 300km/s in about 4 stages. Straightforward improvement of ion thrusters - mainly v…

> alternatively you ionize that particle, may be make in into plasma by laser for ease of "digestion" down in the engine, direct in into the engine where it is used as working mass for your ion thruster, kind of similar to scramjet This is a Bussard ramjet [1]. The interstellar medium is too thin to make it work. (Maybe we'll find the husk of an ancient ramjet from an earlier era of the universe floating around one d…

Bussard would collect gas to be used as fuel. For ion thruster it is only a working mass.

Re: Interstellar Flight: Perspectives and Patience

#59

Post by os2warpman »

umpalumpaaa wrote: post #37
os2warpman wrote: post #6

>To get around thousand-year generation ships, we are examining some beamed energy solutions that could drive a small sail to Proxima in 20 years. The odds of a spacecraft hitting a single particle of dust while in space are 100%. A spacecraft hitting a single particle of dust at 0.2c will impart tens of millions of joules into the body of the spacecraft, the equivalent of getting hit with hundreds of pulses from the…

"A 0.1 µm interstellar dust grain (≈10⁻¹⁴ kg) striking a spacecraft at 0.2 c carries ≈20 J of kinetic energy—millions of times below “tens of millions of joules.” Reaching 10–50 MJ would require a ≈0.14 mm grain (≈10 µg), vastly rarer than ordinary dust, and even that impact equals only a few shots from the world’s highest-energy laser (~2 MJ per pulse), not “hundreds.”"

I used something something 10^-10 for my dust. To reach ~50MJ.

As far as the laser goes, ~2MJ is the total output. Energy that reaches the fuel pellet due to inefficiencies throughout the path of the laser, the actual "hitting power", is hundreds-ish kJ.

Re: Interstellar Flight: Perspectives and Patience

#60

Post by sorcerer-mar »

trhway wrote: post #57
sorcerer-mar wrote: post #53

Earlier quoted context omitted.

Presumably you left Russia to get to something better , not worse on pretty much every dimension except novelty

Yep, and dying on Mars feels to me better than on Earth.

On what dimensions would that be preferable?
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