Worlds more habitable than Earth?(nytimes.com) |
Worlds more habitable than Earth?(nytimes.com) |
Interstellar travel is not impossible, no matter what anyone tells you. We know how, it's just wildly impractical. We've barely even left our own planet, and we've managed to throw a few chunks of metal out of our solar system so far. We lack the industrial capacity to build an interstellar ship, we do not lack the physics.
IIRC, it is possible to get anywhere in the observable universe in one human lifetime assuming 1g of constant acceleration.
This does not permit you to slow down and halt at your target, which greatly increases travel times.
It is also effectively a one-way ticket for anything other than objects in our immediate stellar neighborhood. If you turned around and returned to Earth after getting to an object 1,000ly away—still well within our own arm of the galaxy—at least 2,000 years will have passed on Earth. It’s probable that no civilization you know of would still exist, nor would anyone be able to understand your language.
This isn’t even beginning to address the problem of running into stray atoms at 99.99…% of the speed of light. Or god forbid a handful of stray molecules. We also haven’t discussed the real elephant in the room which is the sheer amount of energy required to accelerate a human and human life support systems at 1g for several decades.
This was provocative and intriguing so I looked into it and this is my understanding of some of the options (theoretically).
First, "interstellar" means between stars and the closes star is 4.2465 light years away (Proxima Centauri in Alpha Centauri star system) so I used that. c=speed of light
- Chemical (Voyager), ~0.006% c: ~75,000 years
- Nuclear pulse (Orion), ~3-10% c: ~40-130 years
- Fusion (Daedalus), ~12% c, flyby: ~35 years
- Laser sail (Starshot), ~20% c, flyby: ~21 years (gram-scale probes only)
- Antimatter, ~20-30% c stopping: ~14-21 years; ~50% c flyby: ~8-9 years
Apart from that - solved problem.
And IMHO that's the main explanation for the Fermi paradox: we don't see aliens everywhere because they don't have a good reason to colonize other planets than their own either.
It could help us learn how our habitable environment works and operates, it might be applicable for terraforming or habitat construction.
There is also a non-zero chance of some sort of life, possibly intelligent developing in such an environment (as proven by our sample size of 1). That life can be active at the moment (from our PoV - light speed and all) or was active in the past, so we should look for bio signatures or even signs of mega scale engineering.
There are plenty of designs that get you to 0.1c or above if you are Kardashev 2, things like light sails powered from the Dyson sphere.
Nothing plausible for anyone living today AFAIK.
https://en.wikipedia.org/wiki/Launch_loop
https://en.wikipedia.org/wiki/Space_fountain
Dense atmosphere might enable getting your air breathing first stage higher & could still enable chemical or nuclear assisted reactive launch.
And Orion would likely still launch just fine, just with less payload.
Interstellar travel is not a propulsion problem. It's a space travel problem. The medium itself, is the vast majority of the problem.
The Cologne Cathedral in Germany was started in 1248 and finished in 1880. That's 632 years.
No.
My hypothesis has always been, hey, have enough kids out there, and sooner or later, they'll learn enough about the physical sciences to at least explore far away worlds. (If not go there in person.)
But yeah, expecting we can get there with what we currently know is a bit naive. We need to, <gasp>, horror of horrors, fund more research.
There are laws of radio propagation that mean I doubt we ever will.
In turn this means a probe needs to get there, and then come back. That is a lot of energy...
I can't say it is impossible, but it is highly unlikely the laws of physics will ever give us a loop hole big enough to pull this off.
it was slated for 2040 as the successor to Roman Space Telescope
now that will never happen, at least not my lifetime
HWO would be able to directly image worlds the size of earth
(Roman cannot, only massive uninhabitable planets)
ps. just ONE day of the Iran War would have completely funded HWO
> Create your free account or log in to continue reading.
my brother in Christ I just barely read the title
- what I assume every org with a site like this's management thinks"The title was intriguing but so uninformative that you never found out what it was really about and can't even begin to look for alternate reporting? Jackpot!"
But also irrelevant.
Also past LEO you don't really have issues with fallout.
So the only real hurdle is securing the supply of couple thousand nuclear bombs for the trip.
But if you told people in 1903 that you can build a plane that will get 850 people 14000 km but you need 250 tons of kerosene to fuel it, they would also think you are insane (e.g. an Airbus A380).
But over time, even with Orion, people will just get used to it. :)
It's highly unlikely that a ship gets hit by a GRB.
On the other hand, general radiation gets worse the faster you go, so you need shielding either way. All you have to do is line the walls of your ship with a shit ton of water, which can be mined in space.
We don't have fuel sources that can run long enough for the trip, and deep space won't have enough solar radiation. We would need reliable mining spots along the way to replace metals made brittle by exposure or punctured by micro asteroids.
Even travelling at 1% the speed of light, stray hydrogen atoms become a problem. Not counting acceleration or deceleration time, that would be over 400 years just to get to the nearest star, let alone one with a habitable planet.
Collecting it while usefully en route to another star system seems like it would be tricky from a delta-v perspective, but maybe the solution is to:
1) build a small worldship from an appropriate asteroid 2) fill your internal ocean in the outer solar system over the course of a generation or three 3) dive back down the gravity well for a gravitational assist from the Sun as you head to your interstellar destination 4) en route, slowly use part of your ocean as propellant, while living inside the rest of it as shielding
https://en.wikipedia.org/wiki/Gamma-ray_burst :
> (GRBs) are extremely energetic events occurring in distant galaxies that represent the brightest and most powerful class of explosion in the Universe.
> The sources of most GRB are billions of light years away from Earth, implying that the explosions are both extremely energetic (a typical burst releases as much energy in a few seconds as the Sun will in its entire 10-billion-year lifetime)[11] and extremely rare (a few per galaxy per million years).
> All in all, a GRB within a few kiloparsecs, with its energy directed towards Earth, will mostly damage life by raising the UV levels during the burst itself and for a few years thereafter.
I'm guessing without an atmosphere protecting a ship it'd be a bit worse? But it's like winning a very bad lottery to get hit by one. I guess if you're traveling thousands of years in deep sleep odds get higher?
Nobody would chose to sacrifice themselves and their descendants (because that's what such an expedition is about), for mere curiosity. And nobody would fund an expedition that will not reach destination before multiple hundreds of years, even if the said expedition doesn't consume the entire industrial output of a major nation.
Space is BIG.
Travelling to another star would require a fully self-contained spaceship with energy, life support, food, medical facilities, even production facilities able to function for centuries or millenia. We simply don't know how to do that.
With a sustained nationwide effort comparable to WW2 we could most likely send a spaceship out if the solar system in ten years or so. But why would anyone do that?
Typical these things fall into one, two, many. Can you build one, two, many? These are very different propositions.
One means you know understand how to do it, mostly.
Two means you can repeat it, so you do understand it, it wasn't a fluke.
Many is scaling the process.
That assumes reaching 5 light years in say 50 years
However once it's done a few times, then it can't be stopped. If you're going at say 1/1000th of the speed of light (50 years to travel, 450 years to settle and build the next wave is 1% the speed of light) then your successor species will have colonised the galaxy in 100 million years, and we know that hasn't happened.
It would not really be about primarily traveling anywhere, just people settling this are with its immense resources over many generations, until possibly the ones on the furthest reaches would be able to make the jump to the next systems Oort cloud & slowly settling it down the gravity well, maybe even reaching the inner system eventually, provided something so tiny and sweltering would be of interest for them by that point. ;-)
IMHO this is actually much closer to how humans spread along the Earths surface. It was no like someone just get up and walked from Afrika to Australia. The various human group just expanded their habitat over time until they spread all over the place over many thousands of years and this would be similar.
Sealed terrariums? Unless you mean something more complex than plants, soil, sunlight, and water?
https://laidbackgardener.blog/2019/10/14/the-worlds-second-o...
"That means it has been growing inside its bottle with no additional air, water or fertilizer for 47 years."
It's bad enough to do on Mars (or an asteroid or other solar system environment) where you can get spare parts sent over in a few years and ask ground control for answers to problems, have them simulate things on Earth or in cislunar space and put a lot of engineers on it. The more I think about it the worse it seems in our solar system -- but interstellar travelers are truly on their own.
Huh? You can’t go faster than light speed, and the observable universe is way larger than ~100 light years.
This gives you energy, but I'm not sure how to turn that into velocity. Presumably you'd want some kind of ion beam emitter on board to propel your craft forward. Halfway through the journey, you'd turn the ion beam around to decelerate as you approach your destination.
In the Arthur C Clarke novel Songs of Distant Earth, spacecraft pushed huge blocks of ice ahead of them to absorb stray interstellar dust.
Some recent findings do give it lower feasibility though.
"The design and calculations discussed above are using 20%-enriched uranium salts. However, it would be plausible to use another design which could achieve much higher exhaust velocities (4,725 km/s) and use a 30,000-tonne ice comet along with 7,500 tonnes of highly enriched uranium salts to propel a 300-tonne spacecraft up to 7.62% of the speed of light and potentially arrive at Alpha Centauri after a 60-year journey."
Sure, not 99% the speed of light or continuous 1 g acceleration but IMHO good enough for an oversized nuclear squirt gun.
Or better yet, send some cancer cells so they can replicate during the journey, then switch from cancer mode to gamete mode for the final generation. That way they're fresh when you need them. You're gonna want DNA repair happening continuously, rather than all at once upon a thaw.
Second, the faster you’re going, the less useful a gravitational slingshot is because you spend less time in the object’s gravity well.
It’s a fun and useful trick within our solar system, but I don’t think the physics plays out well for interstellar travel.
But assume for example that you don't care about how long it is going to take (you are an immortal cyborg, an upload living in the computer or a popsicle in hibernation & the AI is driving. Then you can just "island hop" between Kuiper Belt/Oort Cloud objects, never gaining any high % of the speed of light but always having the next body in your sights, not farther than a few decades or a couple hundred years of flight at most.
You reach the body, refuel, repair, maybe upgrade and then off you go, to the next one. And eventually, you might be at you destination, with a fully fueled and repaired ship. It might just take like 20000 years for start to finish, but hey, you can use it for something productive like learning to play Go or something. :)
Sure, a thousand generations will live and die along the way, but once we get over there, you've got stars every 0.1 ly or so, and with very plausible future tech, you could navigate between them in a few years. You could set up a proper starfaring, interplanetary civilization, with tradeships either going back and forth between two neighboring systems, or winding on long, never-repeating routes, visiting a dozen or so star systems in a human life.
(Most globular clusters appear to be old and metal-poor, and we haven't found a lot of planets there, and this only works if you find a globular cluster where ~every star can support a colony.)