Also remember the acceleration and deceleration has to be within the human body's limits....so no super blasts of the engine....slow and easy.

This also brings up another issue. Say you accelerate or decelerate at 3G's for 24 hours. How will the human body handle that kind of prolonged force? Or will it?

In a liquid or gel acceleration couch, it might be survivable, probably better if they are unconscious during that period.

how long until Elon Musk gets tired and sells SpaceX to the Chinese? The chinese are our only real hope. The fucked up thing is they cannot come up with new technology, and we're too afraid to kill people to advance the cause.

I like this guys channel.  It's good stuff, once you can get past his speech impediment.

If everyone has a sense of entitlement, nothing gets done. Except a shit ton of bitching and blameshifting.

We are doomed.

I'm tapped out, so I'll pass.
You and your bros go ahead, though.
P.S. I didn't throw anything at bitcoin.

Don't be a Debbie Downer- We should AT LEAST do feasibility studies, right? Should be good for a few hundred billion, right?

Moon landing: Mercury, Gemini, Apollo. Government wrote a blank check to make it happen. No cost control.
Space Shuttle: Cost overruns amounting to, basically, an order of magnitude over original projections.

Interstellar travel: See above, x 10. Plus, expect leftists to use this as a pretext for world government.

The propulsion system to travel to other stars is a moot point, until we learn to live in a closed environment.

It is likely that the life support system would be a high percentage of the mass.

Since no one wants to address this I'll fill in the ugly details.

If you want to travel @ 0.1C (a rather slow speed if you're planning to get to the nearest star Proxima Centauri @ 4.2 light years) how much energy is needed to bring your craft to 0.1C?

At 0.1C standard Newtonian physics will give you a a very close kinetic energy number.  -

One kilogram of ship traveling @ 0.1C has 450,000,000   Mega Joules (MJ) of kenetic energy  (from here)

This amount of energy will be needed to accelerate each kilogram of the space ship to 0.1C

So how much energy is that?
For reference:
1 kg of U²³⁵ will yield 79,390,000 MJ with 100% fission efficiency.

1 kg of hydrogen will yield 335200000 MJ with 100% fusion efficiency.

1kg of ship will need 5.6x the total fission energy of 1kg Uranium and 1.3x the total fusion energy of 1kg hydrogen.

To accelerate each kilogram of ship to 0.1C will need 450,000,000 MJ, the equivalent energy of 5.6 kg of uranium fission.

If you want to slow down at your destination then you will need to expend the same amount as used to get to 0.1C.

How big of a ship will we need? To visit our nearest neighbor Proxima Centauri will be >40 years @0.1C
To establish a self sustaining colony this will require at lease one generation born in travel. We now need to build a generational ship.

As a WAG lets say 20 people at the start and assume they will need to grow/provide their own food for most of the trip. Plus once they get there they will need suitable supplies to establish a colony.

Another WAG, looking at some vessels. A Los Angeles class sub weighs ~6000 tons. A Cyclone-class patrol ship weighs 350 tons.  The International Space Station weighs 460 tons.

If we pick 500 tons for the ship (on the small side) then we can calculate the energy needed accelerate to 0.1C.
500 tons = 453590 kg
453590 kg x  450,000,000 MJ/kg  = the fission energy of 2540104 kilograms/2794 tons of uranium.

To get your 500 ton ship up to 0.1C will need the equivalent 2794 tons of uranium fuel.

That is just the deceleration half of the equation since on arrival your ship weighs 500 tons plus the weight of fuel to slow to a stop. In this case 2794 tons of uranium.
That dictates a payload weight of 500 tons plus 2794 tons of uranium assuming 100% fission and propulsion efficiency. Our payload to be accelerated to 0.1C is 3300 tons

We now need to calculate how much energy/fuel will be needed to accelerate 3300 tons to 0.1C.
3300 tons = 2993694 kg
2993694 kg x  450,000,000 MJ/kg  = the fission energy of 36882 tons of uranium fuel to get or ship to 0.1C.

Our 500 ton ship will need the equivalent of 39676 tons of uranium fuel at liftoff to land 500 tons on an exoplanet.
All this assuming uranium as the fuel and 100% energy efficiency. If you substitute hydrogen fusion the ship is lighter by ~ one third.

For the TLDR folks
The energy requirements to get even a small ship to an exoplanet at 0.1C are beyond anything we can do at this time.

No

Beware the beast Man, for he is the Devil's pawn. Alone among God's primates, he kills for sport or lust or greed. Yea, he will murder his brother to possess his brother's land. Let him not breed in great numbers, for he will make a desert of his home and yours. Shun him; drive him back into his jungle lair, for he is the harbinger of death. -

Hell, the op is, because that’s the only way to make it happen.

Personally I think we're at the dawn of a new space race.  Countries like China and India have set some fairly ambitious nationalistic goals for space and we have various commercial ventures coming online which I think is an important component.  Ultimately good old fashion selfishness, greed, and ambition will move us out into the solar system.

So I'd really like to see interplanetary nuclear impulse drives (Orion Project) moving around the solar system, and some self-sustaining colonies and commercial operations on some of the systems moons and planets.   As a species we'll need to master that before we head to other stars.

For organizations like NASA, I'd prefer that they keep directing their efforts on pure research.   Their unmanned science missions, and directing or conducting research into the various needed technologies.  I'd actually rather SpaceX or some other private venture colonize Mars, as apposed to relying on NASA to do that.   ...for all the reasons stated in a few of the comments above.

This is the much-needed dose of simple Physics for this thread.

Here's what I expect in response:
-"But, muh Star Trek! Muh Captain Picard! Muh 'Go where no man has gone before!' Muh Warp Drive!"

-As an aside, doesn't anyone else think we should maybe put a fusion reactor together and demonstrate that it can be: efficient, stable, reliable, while it is firmly attached to the ground, before we try to build one in space and shoot it off to Alpha Centauri?

Anyway, carry on.

I voted no because who cares. We likely won't survive all that long here much less anywhere else.  Where is the closest habitable planet?

Even if we find a way to travel very fast we would need a way to support life in far away planets without other planet support and over generations leap frog to further and further planets.

It might happen but we just as likely will cease to exist first.  I don't care which.  I want too live a full life.  That which happens after concerns me not.

I don't see anyone in the thread suggesting that we're going to build a USS Enterprise any time soon.

If you like a more technical abstract on the subject, here yah go:  http://www.space-nation.org/images/a/a1/Mini-Mag_Orion_and_superconducting_coils_for_near-term_interstellar_transportation_LenardAndrews.pdf

Here's George Dyson's book on the Orion Project:  Project Orion

Nuclear pulse drive is very much possible, with design variants achieving from .09C-.10C.   Currently this probably would be best utilized for interplanetary transport, with potential interstellar transportation down the road, if physics doesn't find a better way.

In any case this isn't a next few decades kind of aspiration,  it's more like a next century or two aspiration.  But a lot of the technology could be used to move robust heavy ships around the solar system.  Perhaps even  to move large asteroids should one be found coming our way.   It's definitely not something we should forget, or shelve.

Why not start small? Figure out basic long-term life support and fire someone off towards something. Perhaps send them to orbit Jupiter or just fly out of the solar system. Whatever. We'd get a couple decades of data to improve an Enterprise style build.

 This is what it will take, to make it work long-term.

Dude, you've been shitting all over this thread for a while now.  While I realize it's fun to troll, the fact that one day, another dinosaur-killer asteroid will show up, guaranteed, or even a planetoid too big for us to move, does not seem like much of a joke to me.  If you have nothing more to contribute beyond moronic "Muh Picard!!!" mockery to what, to me, seems like rather a serious discussion, I'd appreciate it if you could at least keep your mouth shut.  Thank you.

@Qweevox

Did you just ignore what I posted on the extreme energy/fuel requirements to get a ship to 0.1C?
Care to give a WAG on where we'll get 40,000 tons of U²³⁵ or plutonium to get a modest 500 ton ship to an exoplanet?
These are the very simple constraints put on us by the physics at hand.
It takes an enormous amount of energy to get to 0.1C, no way around that without involving science fiction.

And this is where I stand on it.  This is something we need to keep working on, b/c when we need the technology, it would reeeeeeeeeeeally be nice if we have decades worth of research done, instead of months.

I think the Moon and Mars are reasonable not-too-distant-future targets.  Then on to the Jovian system of moons and beyond.   I'd like to see a fleet of fast and robust interplanetary transports developed and deployed.

Going interstellar will require a lot of new technologies to be figured out.   Probably not the least of which is "us" and our own biology.   Dramatically increasing lifespans, effective hibernation technology, the singularity, and transhumanism, all of it could send us in new directions.   What might be possible boggles the mind, but who knows what will pan out, or which path we take.

One thing is certain.   Earth will not be habitable forever, and while we probably still have a lot of time, nothing in this universe is guaranteed.

Save it. Last large asteroid hit 66 million years ago. Research indicates that these events happen on a time scale of roughly 50-100 million years.
Yeah, one could hit next week, and another the week after.
But these events are WAY down the list of my concerns.
My concern is the cavalier way that people in this thread are using their completely subjective, emotional and non-scientific feels to justify spending trillions on something that hasn't the slightest basis in present reality. Dude.

Our physical limitations cause big problems but we should strive to solve those problems. Expanding our species into the universe should be a priority. The more deep space achievements we reach the faster we will evolve.

As fast as robotics and ai are improving that is probably our easiest route for space exploration. As our technology improves I think it is more likely if we encounter an alien civilization it will most likely be their ai.

We could also try to work around our limitations by finding an alternative to 3rd dimension exploration.

Fair enough.  That is a valid concern: how likely is this vs. the $$$ it will cost to have a meaningful space program.  That I have zero problem with, as it's a very real part of the discussion.  What I'd appreciate is if you could put a hold on the sneering ridicule of those of us who see this as a very real concern, and something we need to start looking at now.  I love Star Trek; I have no illusions that technology is possible at this time.  At one time, going to the moon was the wildest Jules Verne science fiction; today, it's science fact.

Why would anyone let a simple thing like the laws of physics get in the way of a good science fiction discussion?

If you limit yourself to using fission as a power source, sure, it stays in science fiction.

Any long term development of a civilization that is aiming for even just rapid transit within its own solar system is going to have figure out how, if it's possible, to use a large fraction of the stars energy.

True, but putting all your eggs in one basket is still foolish.  You wouldnt take all your money and invest it in a single companies stock, and keep it there for the rest of time.  You diversify for a reason.

We've fucked this place up.
Locust on, humans....locust on.

Yes, that's true. But if we're going to get anywhere, we need fusion engines to get around the solar system, both for reasons of technology, and to escape the stifling oppression that is coming on Earth so the spirit of freedom can survive. We need to focus on that first, worry about everything else later.

And yet the Earth has 7 billion people, areas of desert that are now lush, and there are sprawling cities all over the globe. Whoever wrote that movie was a dumbass.

Exploring and colonizing our solar system is both doable and prudent. Without a physics breakthrough getting people to another solar system is not doable.

I for one would love to see a probe go to Europa and look for signs of life.

Good article :https://newatlas.com/orion-project-atom-bomb-spaceship/49454/

The gods would surely smite us!  Didn't you see the movie?

The Sea Dragon rocket is another 1960's proposal that would have been able to lift massive amounts of cargo into orbit.   One of the primary reasons the project never advanced was because we didn't have any use for that much cargo to be lifted into orbit at the time.   You could basically launch an entire space station worth of mass on one sea dragon.

That, was utterly fascinating.  I've always wondered about atomic rockets, and why they couldn't be used; we really need more bounce-to-the-ounce than standard chemical rockets.  That article pretty well covers it:

 Well, fuck.  That pretty well takes care of that.

Too bad we can't get the ORION-style ship into space b4 we pop the nukes; in outer space, all that radiation would be no more than a pimple on a frogs' butt.  It's the chicken-or-the-egg thing; too heavy to lift w/ conventional rockets, but the nuke blast in the atmosphere would be poisonous.  And the whole project would get the greenie idiots squealing like stuck pigs.

But, they sure are right about this:

That is the key point: we've got to boost multiple tons of material off this rock, or find what we need already in space.  The "cosmic elevator" ideas are interdasting, tho I don't think anyone actually has a practical one on the drawing board anywhere.  We really need monomolecular filaments.

I believe how our choices are judged by our children is more important than by our parents.

Any meaningful sense of morality has to extend beyond ourselves.

We could use a system like the Sea Dragon rocket to move the components of a construction/space port station into orbit, and then use the same system to construct an Orion type spacecraft to construct in orbit.   That would eliminate the needs for a 800-1000 nuclear explosions in the atmosphere.

The thing I like about an Orion spacecraft is that it's heavy and robust.   No need to save on weight, or use exotic materials.  In fact heavier is better.   A light Orion spacecraft isn't very efficient.  With a heavier design we don't have to worry as much about solar storms either.   We don't have to scrimp on living quarters, or support systems.   A fleet of Orion spacecraft would be very useful for exploring and colonizing this solar system.

And if nothing better comes along, it's at least possible to use it for interstellar transport.

It’s really good that you’re here to stop us from steering world leaders into disasterous spending sprees on the long term survival of the species. We are also reassured by the things you have no concern about personally. Keep sharing them.

In the meantime, I’m having fun here.

But while we are just discussing the supposed non-urgency of world ending events, we only recently figured out that a small pair of suns passed through the Solar System 70,000 years ago. Last year we had objects passing by the earth that we only detected days before. The events you refer to don’t happen in 60 million year cycles, they are rare but but happen at random times. Our clock running out is likely to be a surprise. The Solar System is littered with the debris of disaster. What are the most prominent features of the moons surface?  What kind of clue do you need that that we shouldn’t give some mind to this?

I think private industry will lead the way off the planet.  Political leaders, and governments, don't seem to deal with any problem, unless it affects their next election cycle or fund raising effort.  They kick the can until a crisis occurs and then they scramble.

An extinction level event is a low probability but high consequences for any given generation.  But one will eventually occur, and it probably won't telegraph an RSVP.  At best we'll probably only have weeks or months to prepare, and there's always the chance we have undiscovered party crasher show up.   Then of course there are the other things which might go wrong with our planet.

So, I'd like to get the conversation going.

I don't think most including myself understand the vastness and inhospitable environment of space.

Also, think of finding a hospitable planet and ask yourself  what microscopic organisms are there that we have no immunity to.  Think small pox in North America circa 1700.

Or, will it be so alien that it wouldn't even know what to do with a human?  Just as we quite likely may not be able to eat anything living on an alien planet; our digestive systems wouldn't know what to do with it, if it wasn't out-and-out poisonous to humans.  Think of all the things we love to eat that are poison to dogs.  And that was a creature that evolved literally right next to us.

Amen.  You can carry more radiation shielding, too.

If you did a little looking into NewSpace, you would see that most of the space development in the next 50 years will be private sector. And unless they start cutting entitlements, gov space will never use more than a fraction of them.

Getting humanity out into the Solar system can provide mitigation for most Earth-extinction events.
And being able to live in free space with no gravity well and in a closed ecology is prerequisite for any attempt at interstellar.

I know speculating on interstellar is fun and all, but we have serious baby steps to make before that.

Nevermind the radioactivation of metals in space...

The key to snowballing the space economy is cheap access to space. The SpaceX BFR is that, it's what the space shuttle should have been.