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Is there any way for a large civilization to get objects into space without using rockets or explosions?

I'm considering a planet roughly equivalent to Earth, where (for whatever reason) rockets and explosions don't provide enough thrust to reach escape velocity, so traditional spaceships and a space cannon wouldn't work.

Could a very fast airplane build up enough speed to escape the gravity well? Is it even possible to reach such speeds without using rockets / jet engines or explosions?

I'd like to consider the earliest possible level of technological development for this to be plausible, starting around our current capacities.

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    $\begingroup$ What do you think powers fast airplanes? Hint: Jet engines are basically rockets without the need to bring their own oxygen. Space planes are much harder to make than traditional rockets and thus would be even more harder to make in your world. Chemical rockets are much more powerful than any other engine we can make. If rockets can't escape at the surface then they would need to be fired from tall mountains, if that isn't enough then the tech would be much beyond anything we have, probably involving a railgun of sorts that can fire a chemical rocket to a high enough altitude to make it. $\endgroup$
    – A. C. A. C.
    Nov 17, 2017 at 20:16
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    $\begingroup$ Railguns have been proposed for that. $\endgroup$
    – Slereah
    Nov 17, 2017 at 20:48
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    $\begingroup$ Getting to space or getting to orbit? That distinction makes a HUGE difference $\endgroup$
    – bendl
    Nov 17, 2017 at 21:00
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    $\begingroup$ keep in mind without rockets once you get to space you are stuck there. $\endgroup$
    – John
    Nov 17, 2017 at 21:11

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Plane

Could a very fast airplane build up enough speed to escape the gravity well? Is it even possible to reach such speeds without using rockets / jet engines or explosions?

The fastest airplanes use jet (or for some experimental planes, rocket) engines. So you are specifically excepting the fastest airplanes.

A propeller-based plane is not going to be able to reach space because it works by pulling the plane forward against the air. No air and the propeller doesn't do anything. That's also a problem with a jet engine, but you excepted them anyway.

A plane also relies on Bernoulli forces to hold it up. Again, these work by manipulating the atmosphere. No atmosphere and the plane would have nothing to push against gravity.

I think that we can safely say that a plane wouldn't work.

Railgun

There is a technology called Hyperloop that people are proposing to use to travel between Earth-bound locations. It's basically a tunnel through which a vehicle is accelerated by magnetism. The escape velocity at Earth's surface is basically 11 km/s. So with an acceleration of 10 m/s, it would take about 1100 seconds to accelerate to that speed. That's a distance of 600 km.

$$d = \frac{1}{2}at^2$$ $$d = \frac{1}{2}(10 \frac{\text{m}}{\text{s}^2})(1100 \text{s})^2 \approx 600 \text{km}$$

A little application of the Pythagorean theory and other geometry and we find that this would be about 8 km deep.

$$6371 - \sqrt{6371^2 - (\frac{600}{2})^2} \approx 8$$

Making a tunnel running as deep as 8 km below the surface that is stable (does not collapse) is beyond anything that we've ever done. By contrast, the Channel Tunnel is only a quarter of a kilometer under sea level and less than 40 km long. The world's longest tunnel is the Delaware Aqueduct at 137 km. The world's deepest tunnel is the Gotthard Base Tunnel at 2.3 km (but it's in mountains).

We're not that far from it though. Perhaps in another century or two we could do it. Perhaps even earlier if it were important enough.

The maglev portion is also untested at those speeds. It seems feasible to be ready when the tunneling is.

This is basically a railgun. Putting it underground allows it to be straight so that you don't need the extra acceleration of a curve.

Alternatives in space

Once in space, they could create a space elevator. That requires creating a tether strong enough. That's another thing that we can't do now but might be able to do in a century or two. But you really need to be in space to build the space elevator. You drop the tether down to the surface. It's not something that you build from the ground up. So they need launch capability first.

Moving around in space can be done with solar sails, but this wouldn't get you into space.

Electrically powered spaceship propulsion

If none of that appeals to you, there are electrically powered forms of spacecraft propulsion that might fit your requirements.

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  • $\begingroup$ We don't need to reach full escape velocity on the launch ramp, and we can do more than 10 m/s. $\endgroup$
    – Alexander
    Nov 17, 2017 at 21:32
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    $\begingroup$ Your railgun answer ignores major problems. 0) You did not factor in a heavy earth as outlined in the question. 1) You need to reach escape velocity in the question, perhaps this can be justified by building space stations with another big rail gain 2) You will have major air drag, requiring a much higher velocity at the end of the ramp. The G-force from deceleration may be fatal too. 3) The stagnation temperatures will destroy any materials quickly, i.e., hotter than the sun. $\endgroup$
    – Gary Walker
    Nov 18, 2017 at 0:22
  • $\begingroup$ I've been thinking about this a lot lately so I'll leave this here for your consideration: medium.com/@brysgo/high-altitude-mass-volley-9ee9e94f6007 $\endgroup$
    – brysgo
    Jul 25, 2019 at 6:28
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It is hard enough to get off this ball of dirt even with rockets.

Space is not too hard, if you simply mean reaching a given altitude. But staying in space requires orbital velocity.

Attaining orbital velocity is much harder, because it takes most of the energy to accelerate your vehicle and only a small fraction to lift it against gravity.

Once you reach space altitudes, you cannot accelerate without rockets or the equivalent in the form of explosion because Newtons law requires you to expel large amounts of mass at high velocity to keep from falling back to earth -- we have no practical alternatives to rockets or explosions to achieve that.

So, you have to accelerate while within the atmosphere. This is a big problem because at the necessary speeds, you vehicle will burn up (just like it does on re-entry).

Since you need even greater speed, the heating problem is even worse.

Visit Non-Rocket Spacelaunch for a catalog of proposed technologies. They are all high tech compared to rocket-base launch. Are some of them feasible, yes -- hard to know for sure until they are working. But many of them assume rockets are responsible for adding additional speed.

If you could ride the space elevator up to geosynchronous orbit, you now have the option of adding the addition needed velocity via a low-thrust message, which might be solar sails, ion-drives, etc. that might be considered acceptable. And you certainly want some way to maneuver in space.

Building the space elevator will require large-scale space access, as well on considerable advances in carbon-nanotube manufactor.

I wanted to say beamed power would work, but to actually reach orbital or escaped velocities you would need major improvement in laser targeting, etc. to deal with the problem of thermal bloom or here. Otherwise, you lose most of the laser energy en-route, and part of that which misses the target cooks your vehicle.

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Beamed power is an option. Use a very powerful ground-based laser (at least tens of gigawatts for a mid-size launch, likely) to track the reaction chamber of your craft. Early in the ascent you can use air intakes so that your propellant (which the beam heats) can be air, and later on you switch to internal propellant. This requires no power source on the craft itself, and can conceivably have much better performance than chemical rockets.

A nice video illustrating the concept with small models: https://www.youtube.com/watch?v=XhUasBcoj-Q

What's more difficult to justify is why it would be so much harder to reach orbit if your planet is Earthlike. The most obvious thing would be that the planet was larger, but that isn't part of the question anyway, and beamed power is a good choice regardless.

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  • $\begingroup$ A larger lower density earth can still have a surface gravity of about 10m/s2 but the escape velocity goes up. Given the exponential nature of the rocket equation, even a couple km/s more makes it a lot harder. $\endgroup$
    – Sherwood Botsford
    Nov 19, 2017 at 18:29
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Normally I would suggest a space elevator, as seen in "The Fountains of Paradise", by Arthur C. Clarke, but that usually needs to partially be built from space.

I don't remember the exact book (maybe a Jules Verne book?), but I've read another book that proposed the use of a multi-stage cannon. I believe it was in the early 1900's. What they did was to make a (potentially) miles long cannon barrel that had offshooting branches that were filled with propellant, which were all timed to go off as the load passed each branch.

Each branch was at an angle designed to directly help push the load, instead of just creating more expanding gasses.

This load had people (and I think dogs) in it. I don't remember there being anything but handwaving about "padding" used to protect the living beings in the load.

This could at least get material into space, and maybe robots to use the materials.

You might be able to use the space elevator to fling a load into space. I think I've read a book using that method, too.

As comments mention, railguns would be a good option, too.

Both the partial space elevator and the railgun could (potentially) be made to accelerate slow enough for people to be in the payload.

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  • $\begingroup$ There is no such thing as a partial space elevator. It works by putting half the mass outside the geosynchronous orbit height. Less than that and it falls down. Also, it can't fling things from the ground. It's a giant cable with an elevator that crawls up and down it. $\endgroup$
    – Brythan
    Nov 17, 2017 at 21:32
  • $\begingroup$ I know I've read a book about something that worked off the idea of a space elevator, but it was more of a sling, where it accelerated objects along it's length up to escape velocity and let go at the end of the machine. The device didn't actually reach orbital heights, but it flung things into at least orbit, if not farther. It might not be called a "partial space elevator", but that's what stuck in my mind. $\endgroup$
    – computercarguy
    Nov 17, 2017 at 21:49
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Nuclear power.

Even if chemicals rockets aren't powerful enough, nuclear rockets still might be. Unlike the nuclear bomb powered Orion nuclear thermal doesn't require chemical explosions to start.

It is expensive and when things go wrong it gets even more expensive to clean up, but if things go right it might be a better lifter than chemical rockets with our current technology, and seems to have more room to get better.

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A sufficiently developed large society will use its more primitive methods first to establish the capability of building anything it requires outside of a planet's gravitational field. One would have to envision mining small mass objects and such. It just doesn't make sense to continuously have to counter large gravitational forces since there is no free energy lunch to feast on, and the biosphere is quite fragile.

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