Maximum Velocity Currently Attainable? The Future?

[Nuke]

we could probibly get pretty fast with a nuclear-electric ship. we have flown nuclear reactors in space and we have flown ion engines, we just have never flown both in the same spacecraft (i may be wrong about this though). you would probably burn up your reactor fuel (not to mention propellant) before you made any significant progress on an interstellar mission, but you would be going pretty damn fast.

[WestAir]

As a complete aside, faster speeds are obtainable, but not in a meaningful time-span. A good ion engine can provide the Isp to get to distant stars at (comparatively) faster speeds than Voyager. The downside is it will inherently take decades, if not longer, to accelerate to the speeds you're looking for.

Orion concepts would surely work, but concepts like Orion and Solar-sails have a marginal future outlook at best due to their theoretical, or political, nature.

Fairy tale solutions like worm holes and FTL also coincide with your earlier statement. The reality of the situation is that the first Earthlings to set foot on an interstellar world will be rovers and by the time they arrive, humanity will either evolved into trans-humanism or faded away.

[Diche Bach]

As a complete aside, faster speeds are obtainable, but not in a meaningful time-span. A good ion engine can provide the Isp to get to distant stars at (comparatively) faster speeds than Voyager. The downside is it will inherently take decades, if not longer, to accelerate to the speeds you're looking for.

Orion concepts would surely work, but concepts like Orion and Solar-sails have a marginal future outlook at best due to their theoretical, or political, nature.

Fairy tale solutions like worm holes and FTL also coincide with your earlier statement. The reality of the situation is that the first Earthlings to set foot on an interstellar world will be rovers and by the time they arrive, humanity will either evolved into trans-humanism or faded away.

To me this is the single most important 'lesson' of space travel and physical sciences: we are "stuck" here. No matter how creatively and ingeniously we may dream about other stars and other habitable worlds, we are effectively Earthbound, or "Sol - bound" at least.

Yes, we have an amazing (inhospitable, dangerous and harsh) solar system + Kuiper belt + Oort cloud that are (more-or-less) at our disposal in the immediate future. But beyond that is pretty much fantasy, else a long, long, long time in the future.

What this means to me is: we had better appreciate the _potentially_ unique planet that we are fortunate to dwell on.

[SargeRho]

Just the mindset we need to get rid of.

We need to stop thinking "We're stuck here.", and start thinking "Let's find a way to get over there.", because we can expand into space or go extinct, we have no other options. /Rant

The technology for interstellar travel exists, at least prototypes thereof. We don't neccesarily need to get to other Stars in weeks. Years, decades even would do, really. Avatar for instance has 12 ships flying back and forth between Earth and Pandora, the trip taking 5.6 years for the crew of the ship and like 8 years for an outside observer., 1 at Earth, 1 at Pandora and 5 on the way to each destination. We don't need superluminal communications either, not yet anyway,

[Person012345]

Can't they produce a fair bit of antimatter now, but they just can't really store it?

If by "a fair bit" you mean "the entire sum of which couldn't power a light bulb for 10 minutes" then sure.

[PakledHostage]

Just the mindset we need to get rid of. We need to stop thinking "We're stuck here.", and start thinking "Let's find a way to get over there.", because we can expand into space or go extinct, we have no other options.

While I agree it is a good idea to think about ways to "get over there", Diche Bach's mindset is exactly what more people need to appreciate.

If you've ever been to sea in a small boat, you will have at some time stopped to reflect on the fact that you are totally dependent on your boat for survival. You are vulnerable and won't survive long in the alien environment of the open ocean, but if you take care of your boat, it will take care of you. The Earth is much like that boat, but having been born here, many of us are ignorant of the fact that this is all we've got and all we ever will have for many generations to come.

Scientific progress has been incredibly rapid over the past century, but we need a lot more of it before we can build colonies in space that are anything more than prisons for the few willing inhabitants that live there. Short sighted ideas like Orion make great science fiction, but do nothing to ensure the long term well being of this "unique planet that we are fortunate to dwell on" for the hundreds or possibly even thousands or tens of thousands of years that it will take before we move out into the stars.

[NGTOne]

To me this is the single most important 'lesson' of space travel and physical sciences: we are "stuck" here. No matter how creatively and ingeniously we may dream about other stars and other habitable worlds, we are effectively Earthbound, or "Sol - bound" at least.

Yes, we have an amazing (inhospitable, dangerous and harsh) solar system + Kuiper belt + Oort cloud that are (more-or-less) at our disposal in the immediate future. But beyond that is pretty much fantasy, else a long, long, long time in the future.

What this means to me is: we had better appreciate the _potentially_ unique planet that we are fortunate to dwell on.

You're right - there's enough "at home" for us to explore for generations (even if we develop more-efficient propulsion systems that would decrease intrasystem travel times to weeks rather than months or years - hell, we don't even know what's at the bottom of our own oceans). Doesn't mean we shouldn't try to see what's on the other side of the pond.

Just the mindset we need to get rid of.

We need to stop thinking "We're stuck here.", and start thinking "Let's find a way to get over there.", because we can expand into space or go extinct, we have no other options. /Rant

The technology for interstellar travel exists, at least prototypes thereof. We don't neccesarily need to get to other Stars in weeks. Years, decades even would do, really. Avatar for instance has 12 ships flying back and forth between Earth and Pandora, the trip taking 5.6 years for the crew of the ship and like 8 years for an outside observer., 1 at Earth, 1 at Pandora and 5 on the way to each destination. We don't need superluminal communications either, not yet anyway,

The technology may exist, but the scale most certainly does not. In order to achieve even reasonably efficient one-way travel to the nearest star (~5 LY away, if memory serves), you would need to scale up our current propulsion and power-generation technologies a thousandfold. You would need the equivalent of millennia of research into closed-cycle environmental systems, long-term habitation solutions, the psychological and physical effects of living in a small community over an extended time (I'm discounting the cryosleep option), and that's just the beginning of a list longer than my arm. In order to achieve the relativistic effects described in the Pandora ships, you would be looking at accelerating yourself to a very sizable fraction of c (far outside the range of chemical rockets or even ion propulsion - fission fragment rockets may be a possible way around this, at the cost of YEARS of nonstop acceleration), and then slowing back down again when you got there (and imagine if there was nothing there when you did?) On top of that, you would have to prepare for EVERY POSSIBLE situation when you got there - what if there's no atmosphere? Loads of radiation? Hell, no planets to live on at all? While all of this is certainly POSSIBLE, it would likely bankrupt the entire human race to DO IT, even once.

In short: Is it possible? Yes. Is it practical? Barring a breakthrough in FTL research, not in the slightest.

'course, the scenario I always find both funny and depressing is that the generation ship arrives at its destination after decades or centuries - only to find that they've developed FTL travel back home in the meantime and beaten the ship there.

If by "a fair bit" you mean "the entire sum of which couldn't power a light bulb for 10 minutes" then sure.

More like, "the entire sum couldn't heat up your cup of morning coffee".

Edited August 16, 2013 by NGTOne

[Mr Shifty]

'course, the scenario I always find both funny and depressing is that the generation ship arrives at its destination after decades or centuries - only to find that they've developed FTL travel back home in the meantime and beaten the ship there.

I believe this concept is sort of treated by Alastair Reynolds's Revelation Space novels (particularly Chasm City) wherein generation ships are sent to colonize a distant planet, but by the time they arrive, humanity has already spread to many other star systems using much faster "lighthugger" ships.

[Diche Bach]

Don't get me wrong. I'm not "anti-space exploration," nor anti-science, nor anti-dreaming or "trying to get over there." By all means, lets be unitary in these dreams.

But lets also be realistic about what these prospects are: dreams.

We shouldn't slip into talking about exoplanets, starships, and the like as if we were talking about the next impending Operating System or development in mobile technology. The journey from our currently primitive abilities in space travel to successful interstellar exploration and interstellar colonization is likely to be hundreds if not thousands or tens of thousands of years in the making. Doesn't mean we shouldn't keep on that journey as we (sort of) are. After all, the journey of a thousand miles begins with a single step and all that.

But for the time being, we are stuck. We do not have the capacity to even learn about everything in our own solar system, much less the real prospects of colonizable worlds in other star systems. To say nothing of our limited maximum attainable velocities and all the other impediments to our long-term achievement of our dream of interstellar colonization.

As far as the issue of human extinction. Eventually Sol will destroy Earth, tis true. Unless we have spread into other systems by then we are sure to go extinct. But a billion years (even 500 million) is an insanely long way in the future; honestly it might as well be infinity compared to how rapidly we have evolved, biologically, much less culturally. The couple thousands or tens of thousands of years it is likely to take us to become an interstellar species is nothing compared to our total projected lifespan of our sun-Earth system. To put a billion years into perspective: modern humans are only about (at most) 500,000 years old (with at least 200,000 being the widely accepted age of anatomically modern humans). Our ancestors likely didn't walk bipedally before 10 million years ago (5 to 8 being the preferred range at present I think). Mammals didn't exist at all until something like 200 million years ago, and multicellular life for about a billion years. So a lot of cultural evolution, and even biological evolution, can happen in humanity before time runs out to escape Earth's inevitable destruction.

With respect to other threats to human survival (nuclear war, plagues, famines, asteroids), it is of course possible that many sorts of cataclysmic events could kill our species.

But we have been close to the brink of extinction at least once before (probably more than once if you think about the long haul of mammalian and primate evolution). Given our ingenuity, tenacity and resourcefulness, I think cataclysms are more likely to result in scenarios like post-apocalyptic disorder and dramatic reductions in population size rather than true extinction.

Edited August 16, 2013 by Diche Bach

[SargeRho]

If you've ever been to sea in a small boat, you will have at some time stopped to reflect on the fact that you are totally dependent on your boat for survival.

And then something comes by and wrecks your boat. (Such as a civilisation-killer asteroid)

I said it before I think: We need a breakthrough in antimatter production. Lasers fired at a common point in empty space produce antimatter, and not little either. A ship would be capable of producing positronium that way. Or perhaps even antihydrogen. To get to .75% the speed of light you need to accellerate at 1G for 6 months or so.

More importantly than reaching the stars, we need to reach the planets first. Or hell, a large orbital colony to start off with. What's clear is that we need to expand to other worlds if we are to survive in the long term.

Edited August 16, 2013 by SargeRho

[PakledHostage]

And then something comes by and wrecks your boat. (Such as a civilisation-killer asteroid)

In the near future, it is a lot more technologically feasible to build a "Project SPACEGUARD" and the means to do something about it if we discover a threat, than it is to expect to disperse to colonies around the solar system or beyond.

[SargeRho]

It isn't, actually. Currently we can not do anything about a civilisation-killer asteroid or comet. We don't have the technology to deviate a 1km+ sized asteroid. We do have the technology to colonise the Moon and Mars.

[Diche Bach]

It isn't, actually. Currently we can not do anything about a civilisation-killer asteroid or comet. We don't have the technology to deviate a 1km+ sized asteroid. We do have the technology to colonise the Moon and Mars.

I can't speak to the asteroid issue.

As to the moon colony, I doubt that if every nation on Earth contributed what it honestly could contribute that we could afford such a thing. Do we have (theoretically) the science and technology to do it? I wouldn't doubt we do. Based on what we know about Antarctic life and life onboard nuclear submarines and the like, such a community, if it was the result of an intensive selection process, would probably even function effectively. We know that living in these sorts of harsh, confined, stressful environments are hard on even the mentally and physically healthiest of individuals. But with short tours of duty, yes it should be doable.

So in terms of the science, the engineering, the human management, even probably the collective will. I have little doubt that if President Obama had a "Kennedy Moment" and proclaimed "We will colonize the moon by the end of this decade!" that you'd have a literally tens-of-thousands of over-qualified candidates clamoring to jump on board. You'd probably even get enough startup donations to make it happen too if you opened it to public investment.

So I won't disagree that we "have the technology." There probably are some very serious technological issues that would need to be addressed, but that was also true when Kennedy had his moment and they got to the moon nonetheless, so . . . where there is a will there is a way.

There are two questions I'd have to wonder about though: (a) could enough money be raised to pay for the planning, design and initiation of building phase alone? ( obviously such a place would have enormous operating costs; is it gonna pay for itself somehow?

[Seret]

we can expand into space or go extinct, we have no other options.

Expanding into space is no guarantee that we won't go extinct. It's pretty much a certainty that humans will go extinct at some point between now and the heat death of the universe. The vast majority of species on Earth have, and the fact that our 14 billion year old universe isn't obviously teeming with spacefaring civilisations suggests that spacefaring isn't a guaranteed shot at exceptional longevity.

I tend to think the "tin can full of meatbags" paradigm is a dead-end when it comes to interstellar travel. It's too inefficient, too expensive, too slow. If I was to put money on any future technology for interstellar human travel I would put it on the transmission of digitised consciousness. The actual transfer between planets would be cheap, move at light speed, and the person being transfered would perceive no passage of time. All the infrastructure would stay on the ground at either end.

Establishing the original arrival node at the other end would have to be done the slow way, sending an actual ship, but once the (presumably fully automated) colony was established and able to provide some kind of body for new arrivals then there's no reason subsequent transfers to or from would have to physically fly the journey. Assuming it's actually possible to digitise the contents of a mind it'd be far easier to just send that.

[Moon Goddess]

The best plan for colonizing another world is pretty unromantic.

Send a robot when a cloning lab, and a selection of human dna.

It sets up shop, builds a camp, and builds some humans.

If we set these up as Von Neumann machines, we'll probably survive.

[Seret]

The best plan for colonizing another world is pretty unromantic.

Send a robot when a cloning lab, and a selection of human dna.

It sets up shop, builds a camp, and builds some humans.

If we set these up as Von Neumann machines, we'll probably survive.

I agree, but the main question with this is how do you raise the first generation? Could we build a robot that could raise the children to be effective adults? I'm inclined to go back to the digitised mind idea, where the first generation born on the new world would be raised by real human minds in synthetic bodies.

One thing people forget is that the bodies we humans currently inhabit won't work very well on exoplanets. The chances of finding a planet with exactly the same gravity and the same mix of atmospheric gases (which means the same geology) as Earth is a bit ludicrous IMO. Compatibility with any existing biosphere would also be required, such as the ability for the colonist's immune systems to handle alien pathogens and for them to be able to digest local food. If you want to set up human colonies on exoplanets then the humans would need to be extensively modified to do so, which means growing custom ones on site, possibly heavily hybridised with local life. We're beautifully adapted to surviving on Earth, the colonists would have to be designed to survive on their new home planet. Sending Earth humans to try and survive elsewhere seems obtuse.

[Nuke]

i was about to say cloneship myself. but ninja'd.

once you get your ship to a reasonable cruising velocity (say 75% c) you dont really need to slow down. what you do is send an autonomous lead ship far enough ahead of you to give you the space neccisary to slow down (and enough time for the signal to travel). the lead ship has the advanced sensor equipment and sends telemetry back to the clone/sleeper/generation ship. if a planet with the correct parameters is found then the data is transmitted back to the colony ship. the lead ship's job is done at this point, it wouldnt need the capacity to slow down from relativistic flight and would just keep going, transmitting data about each new system as long as it can and eventually eject itself from the galaxy. the other ship can begin deceleration and colonization efforts. otherwise you slightly tweak your course for the intercept of the next system. it would be kinda foolish to slow down without confirmation that you have a habitable location to colonize. likely a course would be decided on long before the mission was launched using extensive exoplanet surveys. so all the systems you go through would be high probables anyway. also by the time we are technologically capable of doing this our capacity to colonize more hostile worlds would be greatly improved.

take it a step further, given the time neccisary for long term space flight, you could send probes out to collect extensive data about potential habitable worlds and to drop a single cell ecosystem, life forms like bacteria and algae, on those planets. then send colonization efforts. this way all the question marks are gone, you have a pre terraformed planet which should have an o2 atmosphere when you get there.

Edited August 16, 2013 by Nuke

[Seret]

it would be kinda foolish to slow down without confirmation that you have a habitable location to colonize.

Be a bit foolish to set off in the first place without one. We're likely to be able to determine quite a lot about exoplanets remotely. Spectrographic analysis can tell you what the atmosphere is, and you'd be mad not to send an advance guard of probes and satellites to map and monitor before commiting to a colony. I suppose it's possible that you could have two good candidate planets that lay close enough along the same route so it didn't burn too much more fuel than going direct, but it seems a bit unlikely.

[PakledHostage]

It isn't, actually. Currently we can not do anything about a civilisation-killer asteroid or comet. We don't have the technology to deviate a 1km+ sized asteroid. We do have the technology to colonise the Moon and Mars.

There’s a big difference between setting up an outpost similar to the Amundsen-Scott station and setting up a proper self-sustaining colony… And the motivation to avoid an impact by a 1km+ sized asteroid would be sufficient that we very likely would be able to do something about it with today’s technology if we had enough advanced warning. Remember that it may only require a delta-V of 1-2 mm per second to avoid an impact if we’ve got enough time. Not only that, but even a dinosaur killer impact wouldn’t kill off everyone. Very likely we’d do the same thing that our mammal ancestors did: hide underground. At least here you can go outside, breath the air and be protected from the cosmic radiation, without being dependent on life support.

you could send probes out to collect extensive data about potential habitable worlds and to drop a single cell ecosystem, life forms like bacteria and algae, on those planets.

I think I recall seeing something like that in a movie once... It had some nice footage of Iceland in it.

[Pigbear]

'course, the scenario I always find both funny and depressing is that the generation ship arrives at its destination after decades or centuries - only to find that they've developed FTL travel back home in the meantime and beaten the ship there.

You could compare such a scenario to one found in SOTS (Sword of the Stars) where Hivers have these slow ships that take forever to get anywhere, and when you get stronger engines even if you sent the ship on turn 1 you could easily get to the star before the other ship, And when you get to the star you set up a gate and then there are ~50 ships around that star before the 1 gateship gets to the star.

[nhnifong]

The speed of the sun relative to the barycenter of the solar system on a good day when the barycenter is not inside the sun is about 11 m/s

Iv'e tried to calculate the amount of speed gain you can get from a solar surface flyby in the right direction with a 1 ton probe going at solar escape velocity and I only got an increase of about 100 m/s (0.014% of the probe's initial speed.) I'm probably wrong, can somebody verify?

[nhnifong]

On a side note, you may have more luck with a combined gravitational and magnetic assist, in which you opportunistically take advantage of the magnetic field lines of the sun to accelerate your craft with a superconducting electromagnet, while also getting a grav job, while thrusting with oberth effect, while surfing a CME with a sail

[SargeRho]

[...]without being dependent on life support.

Domes made of Glass and Polycarbonate. Keeps the radiation that gets through Mars' atmosphere out, lets Sunlight in, produces air and food, and possibly clean water. Perhaps add shutters that can close down in the event of a solar flare.

[Nuke]

I think I recall seeing something like that in a movie once... It had some nice footage of Iceland in it.

humans are capable of surviving in iceland. we know from our own geological record that introduction of photosynthetic lifeforms will eventually lead to a snowball earth, but we also know that it will thaw out eventually. this may not be the case for other planets, for example ones on the warmer side of the habitable zone. settlers would need to adapt environmental protocols early on to steer the evolution of the climate under its new oxygen rich atmosphere.

[Diche Bach]

The best plan for colonizing another world is pretty unromantic.

Send a robot when a cloning lab, and a selection of human dna.

It sets up shop, builds a camp, and builds some humans.

If we set these up as Von Neumann machines, we'll probably survive.

I am a huge fan of Blade Runner and similar type films.

Only two major problems with such Sci Fi. The human female reproductive tract where we all grow from zygote into fetus is by far more sophisticated and complex than any machine ever conceived. Replicating DNA is one thing; replicating a womb and mammary glands, not to mention mothering are something else entirely.

Second, assuming these physiological and behavioral systems could somehow be replicated by cyborg mothers, I'm quite confident of what you would rear from it: insecure, neurotic, short-lived, dysfunctional wrecks. If that is the only choice we got I say lets go extinct.