Interstellar travel

[Eric Mc]

That was the Schrödinger thread.

[SpudLink]

But I read it, therefore it does exist.

Just as the cat observed whether or not the isotope released the poison in the box, therefore it was either alive or dead, not both.

[Gary C]

SpudLink said:

But I read it, therefore it does exist.

Just as the cat observed whether or not the isotope released the poison in the box, therefore it was either alive or dead, not both.

Now you have collapsed my wave function !

[AW111]

[Alias218]

Eric Mc said:

Alias218 said:

And even if we could reach a significant fraction of lightspeed, lets say 1%, it would still take us 450 years to each the nearest extra-solar star if we gunned it and whizzed on by. Bear in mind that the Solar Parker Probe reached 0.054% the speed of light.

What about the laser/solar sail system that was being developed? That seemed to offer the possibility of getting a probe to Proxima Centauri in around 20 years - a lot less than 450 years.

That’s the Breakthrough Starshot project, championed by the late Professor Hawking. From what little I know about it, it is / was proposed to send one or more very tiny probes. However, even these would require an enormous power source to deliver the requisite juice to push them along situated in space somewhere (orbit / Lagrange) which is just not even close to being feasible. We’re talking nuclear power station levels of power, in space. It’s a paper project until we can increase the power density of our plants to something that can reasonably be built in space without bankrupting the planet. Or we get wireless power transmission working on a large scale. Or we build one on earth and struggle with the atmosphere messing with the laser beam.

I was also generally talking about manned missions, which would require spacecraft rather larger than tiny cube sats and the correspondingly huge increase in power requirements needed to get people to the other end in a reasonable time frame.

We are a long way off putting something - anything - into another star system.

[Skeptisk]

Sending people is a non starter. How would you keep them warm, feed them and provide electricity to power all functions on a spacecraft? People survive on space stations because of solar power and occasionally supplies from earth. There is no energy source in the deep space between solar systems so you would have to send an energy source with them. Either you would need to send all the food or have enough extra space and equipment to somehow grow it all. All that extra mass would make it more difficult to accelerate and decelerate.

[LimaDelta]

Skeptisk said:

Sending people is a non starter. How would you keep them warm, feed them and provide electricity to power all functions on a spacecraft? People survive on space stations because of solar power and occasionally supplies from earth. There is no energy source in the deep space between solar systems so you would have to send an energy source with them. Either you would need to send all the food or have enough extra space and equipment to somehow grow it all. All that extra mass would make it more difficult to accelerate and decelerate.

"Take care of the forest, Dewey."

[Gadgetmac]

Skeptisk said:

Sending people is a non starter. How would you keep them warm, feed them and provide electricity to power all functions on a spacecraft? People survive on space stations because of solar power and occasionally supplies from earth. There is no energy source in the deep space between solar systems so you would have to send an energy source with them. Either you would need to send all the food or have enough extra space and equipment to somehow grow it all. All that extra mass would make it more difficult to accelerate and decelerate.

All of this is almost certainly the reason no extra terrestrials have swung by us…it’s very likely that no matter how far advanced a civilisations is these basic constraints make interstellar travel infeasible.

[glazbagun]

Gadgetmac said:

All of this is almost certainly the reason no extra terrestrials have swung by us…it’s very likely that no matter how far advanced a civilisations is these basic constraints make interstellar travel infeasible.

Even if they did, they'd be so far removed from the culture which sent them by the time thet returned it would be irrelevant.

It would be like Magellan coming back now to say he's found a really cool island that's a total mission to reach but they're happy to trade high quality pelts. In fact that's probably too recent.

[Simpo Two]

Skeptisk said:

Sending people is a non starter. How would you keep them warm, feed them and provide electricity to power all functions on a spacecraft? People survive on space stations because of solar power and occasionally supplies from earth. There is no energy source in the deep space between solar systems so you would have to send an energy source with them. Either you would need to send all the food or have enough extra space and equipment to somehow grow it all. All that extra mass would make it more difficult to accelerate and decelerate.

It's a question of scale. You'd need to build a spaceship that was a self-sustaining ecosystem, with nuclear power at the heart rather than a sun (ie just swap fusion for fission lol)

glazbagun said:

Even if they did, they'd be so far removed from the culture which sent them by the time thet returned it would be irrelevant.

It would be like Magellan coming back now to say he's found a really cool island that's a total mission to reach but they're happy to trade high quality pelts. In fact that's probably too recent.

Worthy of a Red Dwarf script. But the mission is not to return, I think.

Edited by Simpo Two on Monday 9th October 12:12

[julian64]

Eric Mc said:

Unless affected by a gravity field in which case it will follow a curve. In fact, genuine straight line trajectories are rare.

And of course, if you're David Beckham (or Rivelinho if you are old enough to remember him).

The figures at the end of my moniker would suggest I do

I don't think any short answer will be right for every position in the universe. I would say if you picture yourself as GOD and look down on the thrower the ball will be a straight line, unless you are standing very close to a very very large mountain and have access to some very precise measuring equipment.

Magnus effect excepted - just in case you were drafting a comeback

Edited by julian64 on Monday 9th October 08:46

[Ian974]

A space elevator is a great concept but even compared to some of the largest cables made it's going to be (several?) orders of magnitude larger/ longer/ heavier stronger.
Even a 135 mm steel rope at a long enough length and ignoring the strength requirements would be in the region of 4 million tonnes.
If it's going to happen, it's not going to happen for a very, very long time!

[glazbagun]

Ian974 said:

A space elevator is a great concept but even compared to some of the largest cables made it's going to be (several?) orders of magnitude larger/ longer/ heavier stronger.
Even a 135 mm steel rope at a long enough length and ignoring the strength requirements would be in the region of 4 million tonnes.
If it's going to happen, it's not going to happen for a very, very long time!

I think the longest cable is USA-New Zealand at 8000km. ish.

Space elevator needs to be just shy of 38000km long.

[Whoozit]

glazbagun said:

Ian974 said:

A space elevator is a great concept but even compared to some of the largest cables made it's going to be (several?) orders of magnitude larger/ longer/ heavier stronger.
Even a 135 mm steel rope at a long enough length and ignoring the strength requirements would be in the region of 4 million tonnes.
If it's going to happen, it's not going to happen for a very, very long time!

I think the longest cable is USA-New Zealand at 8000km. ish.

Space elevator needs to be just shy of 38000km long.

This isn't a topic I know at all. But won't the cable be self-supporting to some extent due to centripetal force?

[glazbagun]

Whoozit said:

glazbagun said:

Ian974 said:

A space elevator is a great concept but even compared to some of the largest cables made it's going to be (several?) orders of magnitude larger/ longer/ heavier stronger.
Even a 135 mm steel rope at a long enough length and ignoring the strength requirements would be in the region of 4 million tonnes.
If it's going to happen, it's not going to happen for a very, very long time!

I think the longest cable is USA-New Zealand at 8000km. ish.

Space elevator needs to be just shy of 38000km long.

This isn't a topic I know at all. But won't the cable be self-supporting to some extent due to centripetal force?

I too must admit to a minor deficiency in the Space Elevator design section of my CV, but my understanding is that you need to tether the other end to an object in geostationary orbit otherwise it would just flop back to earth.

I have no idea how the load would be spread between the two ends.

[Boom78]

I’m no expert but the distances involved are just too great. The nearest star to us would take 6000 years with current technology to get to. There’s also nothing there if/when we arrive and would take another 6000 years to get to the next star/planet. Even if some nutcase did decide to plan for it, it would be doomed to fail, mechanical/electrical things just don’t last that long, if anything like my beko fridge it will be doomed after a year!

Humans will never get further than mars. The distances between things in space pickles my brain big time!

[V41LEY]

I’d recommend the Space Elevator Wiki page to understand the many challenges involved in such a project.

[budgie smuggler]

Boom78 said:

Humans will never get further than mars.

What makes you say that? I would have thought some of Jupiter and Saturn's moons would be potentially be prime candidates for scientific visits or maybe even semi-permanent scientific outposts given that some have potentially life harbouring conditions, volcanoes, oceans, hydrocarbons etc.

[Eric Mc]

budgie smuggler said:

What makes you say that? I would have thought some of Jupiter and Saturn's moons would be potentially be prime candidates for scientific visits or maybe even semi-permanent scientific outposts given that some have potentially life harbouring conditions, volcanoes, oceans, hydrocarbons etc.

The area around Jupiter is pretty lethal from a radiation standpoint.

[deckster]

Eric Mc said:

budgie smuggler said:

What makes you say that? I would have thought some of Jupiter and Saturn's moons would be potentially be prime candidates for scientific visits or maybe even semi-permanent scientific outposts given that some have potentially life harbouring conditions, volcanoes, oceans, hydrocarbons etc.

The area around Jupiter is pretty lethal from a radiation standpoint.

Indeed. Notwithstanding the engineering challenges of creating a spacecraft that can get there and back again, there are some fairly fundamental issues with the squishy inhabitants of said spacecraft, including exposure to radiation and the impact to the human body of extended periods living in microgravity. "Never" is a bold statement but we shouldn't underestimate the difficulty of taking humans beyond even the orbit of the moon.