Interstellar travel
Discussion
Mr Whippy said:
Can a balloon get to 200,000ft?
You’re still missing the point about going very fast at high altitude too.
Once you’re out of the bulk of the atmosphere surely a fast moving carriage type release is pretty simple too, unlike running rocket launches off aircraft in the thick of it.
It sounds like you’re saying the atmosphere and starting speed are currently not impediments to getting into space, which begs the question what is?
A balloon can get you well above 100,000 feet. With certain tweaks, I bet you could get one near to 200,000 feet. You’re still missing the point about going very fast at high altitude too.
Once you’re out of the bulk of the atmosphere surely a fast moving carriage type release is pretty simple too, unlike running rocket launches off aircraft in the thick of it.
It sounds like you’re saying the atmosphere and starting speed are currently not impediments to getting into space, which begs the question what is?
Getting out of the atmosphere is not that big a deal, to be honest. A normal rocket will have cleared the worst effects of the atmosphere just over a minute after it leaves the pad.
Also, what do you mean by "a fast moving carriage type release"?
What type of carriage do you have in mind?
How does the carriage get to 200,000 feet?
How fast do you want the carriage to be travelling at the moment of release?
In reality, we already use a "fast carriage" system - it's called "staging".
The main "impediment" to getting into space from the surface of a planetary body is GRAVITY. To get into orbit or to escape entirely from a planet (or sun or moon or asteroid) you need to achieve certain velocities, as set out by Newtownian physics.
These velocities are dependent on the mass of those bodies. For example, the escape velocity for the sun is higher than for the earth or moon.
On the subject of balloon assisted rocket launches, the technique has been used for over 70 years, but mainly for small "sounding rockets" which are used for upper atmospheric research and above atmosphere astronomy (x-ray and infra-red mainly). The rockets are too small and not powerful enough to achieve earth orbit but can zoom to altitudes exceeding 300,000 feet.
Such devices are referred to as "rockoons" - a portmanteau of "rocket" and "balloon".
Such devices are referred to as "rockoons" - a portmanteau of "rocket" and "balloon".
Eric Mc said:
Mr Whippy said:
Can a balloon get to 200,000ft?
You’re still missing the point about going very fast at high altitude too.
Once you’re out of the bulk of the atmosphere surely a fast moving carriage type release is pretty simple too, unlike running rocket launches off aircraft in the thick of it.
It sounds like you’re saying the atmosphere and starting speed are currently not impediments to getting into space, which begs the question what is?
A balloon can get you well above 100,000 feet. With certain tweaks, I bet you could get one near to 200,000 feet. You’re still missing the point about going very fast at high altitude too.
Once you’re out of the bulk of the atmosphere surely a fast moving carriage type release is pretty simple too, unlike running rocket launches off aircraft in the thick of it.
It sounds like you’re saying the atmosphere and starting speed are currently not impediments to getting into space, which begs the question what is?
Getting out of the atmosphere is not that big a deal, to be honest. A normal rocket will have cleared the worst effects of the atmosphere just over a minute after it leaves the pad.
Also, what do you mean by "a fast moving carriage type release"?
What type of carriage do you have in mind?
How does the carriage get to 200,000 feet?
How fast do you want the carriage to be travelling at the moment of release?
In reality, we already use a "fast carriage" system - it's called "staging".
The main "impediment" to getting into space from the surface of a planetary body is GRAVITY. To get into orbit or to escape entirely from a planet (or sun or moon or asteroid) you need to achieve certain velocities, as set out by Newtownian physics.
These velocities are dependent on the mass of those bodies. For example, the escape velocity for the sun is higher than for the earth or moon.
Carriage reaches apex of 150,000ft hill at say 10,000km/h.
Carriage track curves away at a sufficient rate to offset gravity. Ie over about 9m/s/s
Item being carried “floats up”
Item being carried then uses relatively teeny rockets to get it where it wants to be.
Main advantage is rockets don’t need to be rocket shaped now.
You don’t need billions of litres of liquid oxygen and hydrogen.
You can haul a finished structure up the hill and fling it into space. Or another big tank full of fuel. Or whatever.
Of course you can launch 1,000,000 Falcon rockets to get all your required kit into space.
I’m sure eventually the cost/benefit intersect, I’m just curious where it is.
Easier to use rockets and industrialise space, obviating the need for other solutions?
Or is there a point where it works out cheaper to do a mega project to allow easier space access (both ways) for initial space industrialisation, and then continually into the future also?
Gary C said:
Mr Whippy said:
If we want a space faring future we need to invest in getting off this rock easily and massively.
And do what ? We can't meaningfully go anywhere without a fundamental shift in our understanding of Physics and discovery of something we currently believe is impossible.
Industrialise space and remove the need to do lots of things like mining etc on Earth.
The boost in space use alone would perpetuate rapid technological advances, which would accelerate understanding.
Ie, we didn’t go straight from early aircraft to the SR71.
We started with wood and fabric, and ended up with advanced alloys.
Started with piston engines and ended with ramjets.
With your logic we wouldn’t ever do anything unless we could see the end goal.
Did the inventor of the jet engine have today’s commercial airline industry in mind?
Eric Mc said:
On the subject of balloon assisted rocket launches, the technique has been used for over 70 years, but mainly for small "sounding rockets" which are used for upper atmospheric research and above atmosphere astronomy (x-ray and infra-red mainly). The rockets are too small and not powerful enough to achieve earth orbit but can zoom to altitudes exceeding 300,000 feet.
Such devices are referred to as "rockoons" - a portmanteau of "rocket" and "balloon".
Interestingly I just watched a video last night with a chap getting his DIY rocket to 290,000ft (iirc)Such devices are referred to as "rockoons" - a portmanteau of "rocket" and "balloon".
My only concern with solid boosters is pollution.
Lots of launches surely isn’t sustainable in that regard, just as we’re all worrying about ICE car pollution today.
I assume oxygen hydrogen is ‘clean’ if the energy used to create and store it is too.
Mr Whippy said:
Did the inventor of the jet engine have today’s commercial airline industry in mind?
No but they did have the concept of using one to power an aircraft in mind. A better one for you to have used here would have been something like penicillin which had no practical objective. In other words you are talking about discovery rather than invention. geeks said:
Mr Whippy said:
Did the inventor of the jet engine have today’s commercial airline industry in mind?
No but they did have the concept of using one to power an aircraft in mind. A better one for you to have used here would have been something like penicillin which had no practical objective. In other words you are talking about discovery rather than invention. With our current understanding of physics, interstellar travel in any practical sense is simply not possible. Unless we discover some hitherto unknown physical phenomena, we are stuck looking at the universe through telescopes.
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.
As I have mentioned in another thread on this sub, would it even be worth it when after n years we have a craft that does (hypothetically) more than twice the speed of the one already on its way? The first craft will be overtaken by the second. And the second potentially by the third after another n+x years.
Not to mention the effect that extended space travel in zero, or perhaps low, gravity would have on the human body, even if in sci-fi-esque stasis. Perhaps we send a generation ship (which would take twice as long as a fly-by as the ship would be accelerating half the time, and then decelerating the other half). The ship arrives, and then what? There's nothing in the Alpha Centauri system except maybe a planet that may have some habitable qualities, but probably not. They send their data back, and the response from Earth is, "great, thanks but we know this already from Earth based observations because our technology is now 900 years more advanced than when you left, and by the way a probe reached the Alpha Centauri system 600 years ago." That's even if the passengers are A. still alive, and B. the slightest bit interested in completing a mission their forebears started nearly a millennia ago.
And that's just for our closest neighbour!
As I say, unless there is some gap in our scientific knowledge that allows covering vast distances in human time-frames then we're stuck in the solar system (or we transfer our consciousnesses to non-biological hosts and become essentially immortal).
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.
As I have mentioned in another thread on this sub, would it even be worth it when after n years we have a craft that does (hypothetically) more than twice the speed of the one already on its way? The first craft will be overtaken by the second. And the second potentially by the third after another n+x years.
Not to mention the effect that extended space travel in zero, or perhaps low, gravity would have on the human body, even if in sci-fi-esque stasis. Perhaps we send a generation ship (which would take twice as long as a fly-by as the ship would be accelerating half the time, and then decelerating the other half). The ship arrives, and then what? There's nothing in the Alpha Centauri system except maybe a planet that may have some habitable qualities, but probably not. They send their data back, and the response from Earth is, "great, thanks but we know this already from Earth based observations because our technology is now 900 years more advanced than when you left, and by the way a probe reached the Alpha Centauri system 600 years ago." That's even if the passengers are A. still alive, and B. the slightest bit interested in completing a mission their forebears started nearly a millennia ago.
And that's just for our closest neighbour!
As I say, unless there is some gap in our scientific knowledge that allows covering vast distances in human time-frames then we're stuck in the solar system (or we transfer our consciousnesses to non-biological hosts and become essentially immortal).
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.Whatever way you try and work this out it is still say 10 years in space for a round trip.
Assuming that we could approach 95% of the speed of light!
The limitation isn't distance it is the human life span.
No point thinking of embryos. There is so much to learn and no guarantee that those born could absorb the information.
Assuming that we could approach 95% of the speed of light!
The limitation isn't distance it is the human life span.
No point thinking of embryos. There is so much to learn and no guarantee that those born could absorb the information.
It's possible, but the fundamental issue is energy.
So if we could accelerate 1g (that's grams, not gravity) mass to 99.9% C, the thrust would be roughly 682t.
Propellant for 6 years at constant use would be ~190t, leaving roughly 492t for ship mass and giving a ~1G constant acceleration.
Relitavistic Kinetic Energy required = 1.9203 * 10^15 J, this is per second so converts directly to Watts, so 1.9203 petawatts!
At an optimistic 80% efficiency this would correlate to a power requirement of approx 2.4 petawatts.
The main issue (after generating that much energy) would be heat dissipation, with roughly 500Gw of heat to be removed from the ship.
Travel time would be IRO 5-6years to Proxima Centauri, with the occupants experiencing a time duration iro 2-3yrs (due to acceleration/deceleration and time dilation).
While this is highly impractical with current tech, it's not beyond the laws of physics.
You can trade propellant mass for energy,
So if we could accelerate 1g (that's grams, not gravity) mass to 99.9% C, the thrust would be roughly 682t.
Propellant for 6 years at constant use would be ~190t, leaving roughly 492t for ship mass and giving a ~1G constant acceleration.
Relitavistic Kinetic Energy required = 1.9203 * 10^15 J, this is per second so converts directly to Watts, so 1.9203 petawatts!
At an optimistic 80% efficiency this would correlate to a power requirement of approx 2.4 petawatts.
The main issue (after generating that much energy) would be heat dissipation, with roughly 500Gw of heat to be removed from the ship.
Travel time would be IRO 5-6years to Proxima Centauri, with the occupants experiencing a time duration iro 2-3yrs (due to acceleration/deceleration and time dilation).
While this is highly impractical with current tech, it's not beyond the laws of physics.
You can trade propellant mass for energy,
geeks said:
Mr Whippy said:
Did the inventor of the jet engine have today’s commercial airline industry in mind?
No but they did have the concept of using one to power an aircraft in mind. A better one for you to have used here would have been something like penicillin which had no practical objective. In other words you are talking about discovery rather than invention. Like flying encouraged more flying stuff ~ jet engine ~ composite airframes ~ ramjets, blah blah.
You need to be doing it to justify developing it. We need to be up there doing more in space to start to see meaningful developments.
But then yes there is also the “accidental” discovery but that could occur at any point for anything.
My point was, if you want space innovations it’s arguably a good idea to get lots of people wanting to do space stuff and it generates an innovative mindset.
All we’ve got good at is filling the local space with a nice potential debris field.
The 60s and 70s vision wasn’t just a load of satellites and a few probes, it was literally colonising space.
We’re no closer to that than we were I don’t think.
To even get near interstellar travel we’d need to be masters of travel within our solar system and that requires industrialisation and colonisation of space.
And that probably requires a way to do very big launches multiple times a day for decades on end.
Can we do that with oxygen and hydrogen powered rockets?
Edited by Mr Whippy on Thursday 5th October 14:08
Mr Whippy said:
WrekinCrew said:
It doesn't matter how high you get, you need velocity to go anywhere, hence "escape velocity", 7 miles/second.
So there is no advantage to being high to get out of the bulk of the atmosphere for both inward and outward journeys, at any scale of operations?Eric Mc said:
Precisely.You can climb half way to the moon but if you haven't given yourself enough velocity, you'll fall all the way back to earth.
That's exactly what happened to some of the earliest attempts to send probes to the moon.
Unless you climbed to the Lagrange point ?That's exactly what happened to some of the earliest attempts to send probes to the moon.
Bloody long ladder though.
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