What Are Realistic Mid-Journey Disasters in Interstellar Travel?

[Vanadium 50]

Also, I personally don’t think that interstellar travel is unrealistic, not even by todays technology.

How many probes have we launched to distant stars?
How many have we launched to, say, Sedna?
How many manned missions have we launched to other planets in our own solar system?

 

[Jarvis323]

How many probes have we launched to distant stars?
How many have we launched to, say, Sedna?
How many manned missions have we launched to other planets in our own solar system?

I don’t see the relevance.

 

[Strato Incendus]

How many probes have we launched to distant stars?
How many have we launched to, say, Sedna?
How many manned missions have we launched to other planets in our own solar system?

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).

Once nuclear-fusion drives are well established enough to allow us some regular trips to Mars and back, then we can talk about sending people to the outer solar system. And at some point in the far distant future, maybe even beyond that.

 

[PeroK]

Manned missions to the outer solar system at this point in time would be putting the cart before the horse.

A horse and cart won't get you to outer space, however you arrange things!

 

[Jarvis323]

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).

Once nuclear-fusion drives are well established enough to allow us some regular trips to Mars and back, then we can talk about sending people to the outer solar system. And at some point in the far distant future, maybe even beyond that.

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.

I get that it would take a lot of effort and modern technology constrains some mission parameters in ways we wish it wouldn’t. But I have never heard of a single barrier to interstellar travel that is technically insurmountable. If someone can point one out then maybe I would change my mind.

That said, I stand by my assertion that realistic is relative. To be honest, it’s also ambiguous. One’s reasons for thinking it is unrealistic may be valid, which I suppose depends on context.

 

[Jarvis323]

A horse and cart won't get you to outer space, however you arrange things!

Enough horses and carts might if you arranged them the right way on a molecular level.

 

[Vanadium 50]

don’t see the relevance.

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?

 

[Algr]

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?

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.

Our first step, in my view, is to get to a breakthrough on nuclear fusion

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.

 

[DaveC426913]

A horse and cart won't get you to outer space, however you arrange things!

"Hold my beer!" : the guys over at Spinlaunch.

 

[Vanadium 50]

I think it is variable definitions of "realistic".

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]

How about Project Dragonfly?
Honestly I don't see a reason to be stewing over Jarvis' offhand comment. It is kind of irrelevant to the point of this thread.

As for what could go wrong: It's hard to justify an interstellar ship failing to accommodate anything that could be foreseen by people on a science forum way back in year 2022. So I'd recommend imaginative technobabble. Maybe some mundane resource is being consumed faster than expected and the crew spend the whole book unable to figure out why.

 

[jrmichler]

Keep in mind that all machines fail. Some sooner, some later, but few machines last for over 100 years without maintenance. Spare parts in storage cannot be trusted to still work after 100 years. Therefore, a generation ship needs some sort of all purpose manufacturing machine. Since there will not be an outside source of raw materials, the inputs to the machine will be every bit of trash generated. That includes everything from used diapers to old underwear to floor sweepings to used oil to worn fusion plant radioactive parts. The outputs from the machine will be everything from computers to refrigerators to clean diapers to new oil to antibiotics to a new fusion plant to a replacement machine that is larger than the original machine.

One positive outcome is that, since all manufacturing will be to order, everybody will be able to get clothes and shoes that fit in whatever style they want. On the downside, what happens if the software that runs the machine gets corrupted?

 

[Drakkith]

As for what could go wrong: It's hard to justify an interstellar ship failing to accommodate anything that could be foreseen by people on a science forum way back in year 2022.

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.

Example: the ship in Passengers has a shield that protects it from impacting objects. It fails to protect the ship one time and the entire ship is almost destroyed. Perfectly fine use of something going wrong that was planned for, in addition to things going wrong that weren't planned for (reactor going critical, cryo pods malfunctioning, etc).

One has to acknowledge that people are imperfect and so is everything they make. Good lord, Apollo 11 was almost stuck on the surface of the Moon because they broke the switch that turned the ascent engine on!! Apollo 13 partially blew up! We've lost two space shuttles and their entire crews! The Soviets lost a crew because a valve malfunctioned and all the air was sucked out of the capsule! Planes fall from the sky! Bridges collapse! Nuclear reactors meltdown! The pipes in my bathroom clogged up and leaked under the slab!!!

Things break. People screw up.

 

[PeroK]

Keep in mind that all machines fail. Some sooner, some later, but few machines last for over 100 years without maintenance. Spare parts in storage cannot be trusted to still work after 100 years. Therefore, a generation ship needs some sort of all purpose manufacturing machine. Since there will not be an outside source of raw materials, the inputs to the machine will be every bit of trash generated. That includes everything from used diapers to old underwear to floor sweepings to used oil to worn fusion plant radioactive parts. The outputs from the machine will be everything from computers to refrigerators to clean diapers to new oil to antibiotics to a new fusion plant to a replacement machine that is larger than the original machine.

One positive outcome is that, since all manufacturing will be to order, everybody will be able to get clothes and shoes that fit in whatever style they want. On the downside, what happens if the software that runs the machine gets corrupted?

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.

I don't believe a generation ship could viable. The travellers would have to sleep through the journey and consume the minimum.

 

[Algr]

Part way through the journey, the crew realize that they can't afford the royalties that Strato Incendus owes Physics Forums.

 

[pinball1970]

I don't believe a generation ship could viable. The travellers would have to sleep through the journey and consume the minimum.

At rest, bed ridden, asleep, coma your cells still require energy for repair /replace, cell division, peristalsis involuntary muscle movements, brain activity etc etc
8 hours sleep is ok, years travelling near light speed would require a huge amount of O2 water and nutrients for a crew.
Freezing them removes all of that. Not impossible as some species of fish manage can manage a near frozen state.
The on board computer thaws them out them in time for reaching the next star.

The timing would have pretty good.

 

[Dr Wu]

Quite possibly Dias, Vasco da Gama, Magellan and other mariners from the late mediaeval period would have found themselves reflecting on the many things likely to go wrong while planning their oceanic voyages into the unknown: for them the deep space continuum of their times. Plenty of naysayers back then, of course, cultural distinctions notwithstanding.

 

[Vanadium 50]

One can argue it's realistic today, but one should not use as evidence a web site that hopes to have the technology by 2050. Further, it's hard to argue that it is realistic today, but we can't come up with a list of risks and hazards today.

 

[Algr]

Quite possibly Dias, Vasco da Gama, Magellan and other mariners from the late mediaeval period would have found themselves reflecting on the many things likely to go wrong while planning their oceanic voyages into the unknown: for them the deep space continuum of their times. Plenty of naysayers back then, of course, cultural distinctions notwithstanding.

 

[Algr]

one should not use as evidence a web site that hopes to have the technology by 2050

No matter how far into the future you start, the first interstellar voyage is not going to be a spur of the moment thing.

 

[PeroK]

Quite possibly Dias, Vasco da Gama, Magellan and other mariners from the late mediaeval period would have found themselves reflecting on the many things likely to go wrong while planning their oceanic voyages into the unknown: for them the deep space continuum of their times. Plenty of naysayers back then, of course, cultural distinctions notwithstanding.

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.

The logic of "nothing is impossible" demands that those you mention could not only have sailed the oceans but sailed their ships to the Moon and back.

 

[pinball1970]

Why do you think that is a deal breaker?

Ionising radiation is a deal breaker for your DNA.

 

[phinds]

The same things that can go wrong anywhere else. Everything.

this

 

[Jarvis323]

Ionising radiation is a deal breaker for your DNA.

Obviously you would want to shield it.

 

[pinball1970]

Obviously you would want to shield it.

With? Lead? Boron and sand? (I watched Chernobyl)
Mass is an issue in terms of acceleration and a shield would add mass.
If this is going to be realistic.

 

[Jarvis323]

With? Lead? Boron and sand? (I watched Chernobyl)
Mass is an issue in terms of acceleration and a shield would add mass.
If this is going to be realistic.

How about with beer?

 

[pinball1970]

How about with beer?

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.
If the crew are frozen (my idea with synthetic fish anti freeze, you're welcome OP) they can take more than 9g?

 

[PeroK]

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.
If the crew are frozen (my idea with synthetic fish anti freeze, you're welcome OP) they can take more than 9g?

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.

It's impossible to know what engineering solutions will eventually be devised.

 

[pinball1970]

The bigger problem eventually if you keep accelerating is radiation blueshift. Any ship would have a limit to what it can sustain.

Radiation blue shift? What is the issue?

 

[DaveC426913]

Radiation blue shift? What is the issue?

Higher frequency radiation is more destructive.

UV B is more damaging than UV A. X-rays are more damaging than both.

 

[Strato Incendus]

How about with beer?

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.

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.

It's impossible to know what engineering solutions will eventually be devised.

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.

But yes, if you have a ship that can maintain constant 1-g acceleration for one year, it would theoretically get close to light speed. Such a ship would have to be constructed differently, like a “skyscraper”, since over the course of that year, gravity would point towards the back of the ship. Yet, it would also need rings, or a cylinder, to create artificial gravity once the acceleration phase ends.

And of course, all of the radiation problems would become even worse at such speeds. It would make trips to quite a few nearby potentially habitable worlds feasible, though — there are quite a few candidate planets at a distance from Earth in the 10-12 light-year range.

 

[PeroK]

Radiation blue shift? What is the issue?

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.

That said, the onboard journey time may not be critical. It you send a probe to a star system 1000 light years away, the mission will take 2000 years in any case. Whether the onboard equipment experiences 500 years, 50 years or 5 years may not be critical.

Likewise for a human transport ship. It does matter in a generation ship, of course. The difference between a 500 year and 50 year journey is enormous. If everyone is in long-term suspended animation, it may not matter too much.

This is the potential engineering trade off: 1) get to a low gamma factor and have a long onboard journey time; or 2) get to high gamma factor with a much shorter onboard journey time but have to develop the acceleration capability and radiation shields

 

[pinball1970]

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.

That said, the onboard journey time may not be critical. It you send a probe to a star system 1000 light years away, the mission will take 2000 years in any case. Whether the onboard equipment experiences 500 years, 50 years or 5 years may not be critical.

Likewise for a human transport ship. It does matter in a generation ship, of course. The difference between a 500 year and 50 year journey is enormous. If everyone is in long-term suspended animation, it may not matter too much.

This is the potential engineering trade off: 1) get to a low gamma factor and have a long onboard journey time; or 2) get to high gamma factor with a much shorter onboard journey time but have to develop the acceleration capability and radiation shields

Read it twice.

 

[DaveC426913]

Such a ship would have to be constructed differently, like a “skyscraper”, since over the course of that year, gravity would point towards the back of the ship. Yet, it would also need rings, or a cylinder, to create artificial gravity once the acceleration phase ends.

That's not the only way to skin the artificial gravity cat.

Switching between two configurations - skyscraper and centrifugal rings comes at some cost. You can avoid that cost. Keep the skyscraper configuration - design your skyscraper to break into equal mass halves halves that string between a tether or arbitrary length.

(Caveat: This does not solve the radiation sleet problem - in fact, it makes it worse.)

 

[Lren Zvsm]

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”.

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.

two: The other posters are correct in stating that there is no currently realistic plan to send people to other star systems. For example, if the people are frozen on the way, the air that they would breathe would have to be frozen as well. Gas under pressure would leak over interstellar transit times.

three: You would have to assume, and might want to briefly mention, that a lot of problems with interstellar travel will have been solved. For example, sealed and self-contained artificial ecologies are not a thing yet. Though Biosphere 2 has become a fruitful ecological research facility, its original goal has yet to be achieved.

https://www.scientificamerican.com/...n-terrarium-is-transforming-climate-research/

four: Depression might be a significant problem. It is apparently common for astronauts who see Earth from space to become very depressed at the dark lifelessness of space and have a correspondingly strong sense of how precious Earth and our species is.

.

This wouldn't have to be the escalating problem that drives the story but the latter doesn't have to be the only problem in the story. Ancillary problems that make things even more difficult for the characters could add suspense to the plot.

five: One aspect of interstellar travel that could create a problem that starts out small then escalates is the necessity of long term maintenance, which could be performed by small self-replicating robots. What if a transcription defect of some kind caused the little mechanical varmints to run amok?