How many probes have we launched to distant stars?Jarvis323 said:
Vanadium 50 said:
Manned missions to the outer solar system at this point in time would be putting the cart before the horse. Our first step, in my view, is to get to a breakthrough on nuclear fusion — since that hasn’t just implications for space travel, but also for Earth-based problems (most notably, renewable energy sources).Vanadium 50 said:
A horse and cart won't get you to outer space, however you arrange things!Strato Incendus said:
Fusion would be nice, but it is not required, and for all we know won’t be solved, to this degree, soon enough to wait for it.Strato Incendus said:
Enough horses and carts might if you arranged them the right way on a molecular level.PeroK said:
If interstellar travel is, as you claim, realistic by today's technology, why haven't we gone already? Why haven't we done even simpler things?Jarvis323 said:
I think it is variable definitions of "realistic". The voyager probes could technically be counted as "interstellar travel". They even have a gold record that functions to this intent.Vanadium 50 said:
Humans spent decades trying to do nuclear fusion, and just when they almost had it, someone invented Charm Swapping, and everything everyone else did became irrelevant.Strato Incendus said:
"Hold my beer!" : the guys over at Spinlaunch.PeroK said:
It will make it to alpha centauri in a mere 100,000 years, or would if it were pointed in the right direction, is not my definition of realistic.Algr said:
Sure, in a perfect world full of perfect people who aren't under time and resource constraints, never make mistakes, have perfect understanding of their specialties, etc etc. But people aren't like this. Look at any large-scale project. It WILL be flawed. No exceptions.Algr said:
The scope and scale of the manufacturing required for a generation ship must be a major issue. It's a bit like the ark. We just need two of every animal, and then you realise just how many different animals there actually are.jrmichler said:
At rest, bed ridden, asleep, coma your cells still require energy for repair /replace, cell division, peristalsis involuntary muscle movements, brain activity etc etcPeroK said:
Dr Wu said:
No matter how far into the future you start, the first interstellar voyage is not going to be a spur of the moment thing.Vanadium 50 said:
They already had ships and were experienced sailors. What they didn't do was go to the Moon. If someone in the days of Magellan had suggested going to the Moon, that would have been impossible.Dr Wu said:
Ionising radiation is a deal breaker for your DNA.Jarvis323 said:
thisDrakkith said:
pinball1970 said:
With? Lead? Boron and sand? (I watched Chernobyl)Jarvis323 said:
How about with beer?pinball1970 said:
I googled getting 1g at 1g acceleration to near light speed is a year. Plenty of guys on here can refine dispute that. No idea.Jarvis323 said:
Constant acceleration at ##1g## may be important for health reasons, although if everyone is in some form of suspended animation it may not matter. It doesn't make too much difference in the long run as long as you get to near light speed (##1g## or ##9g##). The bigger problem eventually if you keep accelerating is radiation blueshift. Any ship would have a limit to what it can sustain.pinball1970 said:
Radiation blue shift? What is the issue?PeroK said:
Higher frequency radiation is more destructive.pinball1970 said:
So far, the primary shielding against radiation indeed consists of lots of water. In particular, the tanks that are supposed to provide the hydrogen for the nuclear-fusion reactor and engine (those shield to the front and back, which is necessary once the ship turns around for braking). From the sides, it’s the water supply for regular consumption that runs through the walls. On the ring habitats, this means the water has to run through the ground (since the “ground” of the rings is what points outward, the direction in which the centrifugal force works). The rings are at a 90-degree angle to the axis of the ship, so that they can be shielded entirely by the water tanks at the front and bottom.Jarvis323 said:
Both the maximum travel speed and the acceleration are lower in my case (0.125 c, with an acceleration phase of 25 years, and the same for braking, at 0.048 m/square-second). The calculation was kindly provided by @mfb.PeroK said:
The CMBR blushifts eventually to x-rays and then gamma rays. This probably puts a physical constraint on the idea of accelerating at ##g## for long periods.pinball1970 said:
Read it twice.PeroK said:
That's not the only way to skin the artificial gravity cat.Strato Incendus said:
Strato Incendus said:Alright, since I’m still stuck on my sci-fi story because I can’t exactly outline the mid-point plot twist with a realistic catastrophe on board an interstellar spaceship, I thought I’d widen the scope a little — towards full-on open brainstorming:
What, if anything, can realistically go wrong on an interstellar journey?
(By “realistically”, I mean “without making any extra assumptions about aliens, unknown forces of physics etc.” — just based on what we currently know.)
I may have underestimated this challenge a little because, in real life, at least based on our current knowledge, there are of course several huge obstacles to interstellar travel: fuel and food supply, achieving a travel speed that makes the trip feasible (i.e., a significant portion of the speed of light), radiation, dust particles and micro-meteors, etc.
The problem is that all of these challenges are so big that, if a ship cannot handle them, there’s no point in it even leaving the solar system. For example, a micro-meteor hitting the ship out of nowhere mid-journey should not happen, because the ship will need some kind of deflector system anyway to deal with stuff like this countless times per day. And if it has a deflector system, but it randomly fails when the story needs it to, the resulting collision, given the intensity of the impact, for all I know wouldn’t just severely damage the ship, but would probably destroy it completely.
So these disasters are all kind of “too big”. When you have a story set on Earth, and you want to create a challenge for your characters, or come up with some catastrophe that leads to some severe casualties, you wouldn’t immediately jump to “meteor hits Earth and wipes out all mammalian life”, would you?
Once all of these major challenges are out of the way, though — those that wouldn’t even make the journey worth starting if they hadn’t been dealt with in advance — the emptiness of the interstellar medium, as well as the inability to stop without wasting fuel or exposing the crew to unsurvivable g forces, create a pretty non-interactive environment for any story set between two stars.
Even internal failures of the ship aren’t that easy to create. A hull breach, as it seems to happen quite frequently in Star Trek (or even more vividly in one episode of The Expanse), shouldn’t happen too easily, either: Not just because even minor collisions with dust speckles have to be avoided anyway; but also because the ship hull will have to be thick enough to shield everyone inside against radiation. And one effective way to do that is to place a layer of water between the hull and the interior.
Now it’s hard for any given crew member to just be “randomly blown out into space”, if there’s a thick wall of water in between. You could of course have that water seep into the ship, but most likely it would not happen in such quantities that anyone would drown in a corridor or something.
Radiation, even if the ship’s protective measures against it may fail to some reasonable degree, would be comparatively slow to kill humans — probably slow enough for the crew to notice the holes in the protective layers in time to patch them up.
Finally, deliberate human sabotage is also hard to justify — since anyone with such intentions is stuck on board the ship together with everyone else for the time of the journey. Even people with malicious intent still have survival instincts.
So, what likely “medium-size disasters” do we have available at all? It seems to me like I only have the choice between “something that would destroy the entire ship” and “nothing at all happens, because the ship can’t interact with anything around it”.
one: If you're writing a story, it's best to have a problem that starts out small, escalates to medium-sized, threatens catastrophe when attempts to solve it fail, and is finally solved in the nick of time with a wing and a prayer.Strato Incendus said:Alright, since I’m still stuck on my sci-fi story because I can’t exactly outline the mid-point plot twist with a realistic catastrophe on board an interstellar spaceship, I thought I’d widen the scope a little — towards full-on open brainstorming:
What, if anything, can realistically go wrong on an interstellar journey?
(By “realistically”, I mean “without making any extra assumptions about aliens, unknown forces of physics etc.” — just based on what we currently know.)
I may have underestimated this challenge a little because, in real life, at least based on our current knowledge, there are of course several huge obstacles to interstellar travel: fuel and food supply, achieving a travel speed that makes the trip feasible (i.e., a significant portion of the speed of light), radiation, dust particles and micro-meteors, etc.
The problem is that all of these challenges are so big that, if a ship cannot handle them, there’s no point in it even leaving the solar system. For example, a micro-meteor hitting the ship out of nowhere mid-journey should not happen, because the ship will need some kind of deflector system anyway to deal with stuff like this countless times per day. And if it has a deflector system, but it randomly fails when the story needs it to, the resulting collision, given the intensity of the impact, for all I know wouldn’t just severely damage the ship, but would probably destroy it completely.
So these disasters are all kind of “too big”. When you have a story set on Earth, and you want to create a challenge for your characters, or come up with some catastrophe that leads to some severe casualties, you wouldn’t immediately jump to “meteor hits Earth and wipes out all mammalian life”, would you?
Once all of these major challenges are out of the way, though — those that wouldn’t even make the journey worth starting if they hadn’t been dealt with in advance — the emptiness of the interstellar medium, as well as the inability to stop without wasting fuel or exposing the crew to unsurvivable g forces, create a pretty non-interactive environment for any story set between two stars.
Even internal failures of the ship aren’t that easy to create. A hull breach, as it seems to happen quite frequently in Star Trek (or even more vividly in one episode of The Expanse), shouldn’t happen too easily, either: Not just because even minor collisions with dust speckles have to be avoided anyway; but also because the ship hull will have to be thick enough to shield everyone inside against radiation. And one effective way to do that is to place a layer of water between the hull and the interior.
Now it’s hard for any given crew member to just be “randomly blown out into space”, if there’s a thick wall of water in between. You could of course have that water seep into the ship, but most likely it would not happen in such quantities that anyone would drown in a corridor or something.
Radiation, even if the ship’s protective measures against it may fail to some reasonable degree, would be comparatively slow to kill humans — probably slow enough for the crew to notice the holes in the protective layers in time to patch them up.
Finally, deliberate human sabotage is also hard to justify — since anyone with such intentions is stuck on board the ship together with everyone else for the time of the journey. Even people with malicious intent still have survival instincts.
So, what likely “medium-size disasters” do we have available at all? It seems to me like I only have the choice between “something that would destroy the entire ship” and “nothing at all happens, because the ship can’t interact with anything around it”.
