The Rocket-Less Future of Space Travel | What the Physics?! | NOVA | PBS

Space elevators? Nuclear rockets? The future of space travel could look radically different.

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[AdvantestInc]

Reusable rockets may only be the beginning, this video makes you wonder how far these innovations can take us.

[JustinMShaw]

I've always found a good analogy of rockets to be sitting on a raft with a pile of rocks and being able to move only by throwing the rocks in the opposite direction you're wanting to go.

Higher efficiency rockets like ion drives essentially involve much smaller rocks that get thrown faster. And nuclear rockets that get better thrust by heating the reaction mass are akin to throwing the rocks faster to get more thrust.

[Tracyusa]

I watched Nova 20 years without missing a single episode cuz there's nothing else to do on a Tuesday night.

[paulc]

Thanks for an interesting video. I think that a Space Elevator could be built on the Moon, or even Mars, (with little or no atmosphere), but would be too difficult to build and far too expensive for the Earth. To use a Nuclear Rocket, chemical rockets would still be needed to launch the Nuclear rocket engine into orbit. Nuclear Rockets would be for "in-space" use only - they would be impractical and unsafe for ground launches to orbit. The components, such as engine, fuel, shielding and habitat, would have to be launched separately and assembled on orbit.

[texasrobotics]

This was super well done. I never really knew about the rocket fuel issue!

[tedcamus]

Didn't Arthur C. Clarke predict "the space elevator would be built 50 years after everyone stops laughing" ?

[qwertyuiopst]

If we really do build a space elevator, or elevators, we should wrap a stairway with gardens around it so that someone can hike through a pleasant garden all the way to space. "a stairway to heaven".

[jakariasifat]

Instead of dismantling the international space station in the future, why not repurpose it for a space elevator? Its size and structure make it an ideal candidate for such a task?

[shawns]

The future of space travel is fission rockets. If a spaceship travels at a constant 1g acceleration rate it would get to Alpha Centauri in about 3.6 years (7.3 years would pass on Earth) and this includes turning the ship around halfway to decelerate. It would achieve about 95% light speed in 1 year. This is by far the fastest way we can get to other worlds and the ship would have gravity the whole way. A 10 ton ship would require 10 tons of continuous thrust.
All that is needed for this is a true fission rocket that can put out thrust for long periods and does not consume hydrogen. What's needed is a controlled, time released nuclear explosion. There should be a way to get uranium or plutonium to fission in a linear fashion.
In an atom bomb fission occurs when neutrons hit uranium or plutonium nuclei. This is because they won't tolerate an increase in mass. Due to the equivalence of mass and energy the same should be true if they are infused with energy.
This might be as simple as having negatively charged uranium or plutonium atoms coming into contact with positively charged uranium or plutonium atoms. Or perhaps with electromagnetic or laser energy.
With the constant acceleration method a ship can span the diameter of our galaxy in 24 ship/113, 000 Earth years. Systems with stars similar to our sun can be reached in under 10 ship years.

[Kevin_Williamson]

Two big hurdles stand in the way of most advances. 1) The fact that we have created a society based on the concepts of money and profit, and that any program requires a profit to be considered. And, 2) The fact that the people most in control of advances are the greedy and wealthy. Balance sheets have more sway than what could be done to benefit mankind.

Exploration is most often funded for exploitation.

[CHMichael]

No . The expanse is most likely the most realistic depiction of our future.... (without the fictional drive they use)

[wesdblack]

The space elevator idea forgets that there is a MASSIVE amount of sideways momentum needed for each unit of mass put into orbit. Note: SIDEWAYS! Everyone worries about going upwards, but that's just peanuts to achieving orbital velocity that whatever payload going up the space elevator must achieve to match the velocity of the geostationary tether and counterweight. Failing to impart that extra energy means the whole thing gets dragged backwards, westward, and also downwards towards Earth. The only way this energy could be injected into the system is to throw mass at some speed in the opposite direction... so a rocket of some sort. Perhaps ideally a very efficient ion propulsion system that is powered from the ground and/or solar panels on the counterweight, but mass still needs to be flung away, and then you end up with a similar rocket fuel mass problem only lessened by a more efficient way of flinging that reactive mass away faster, unless you are always sending as much mass down the tether as you are carrying up, which has its own problems and energy requirements

[mb_ytc]

How about other propelanteless propulsion ideas? I've been exploring a method that allows to transfer momentum (push against) into the quantum foam. Not only theory but quite rigorous tests with positive results

[JusticeAlways]

Magnetic powered launching like the Navy now does on aircraft carriers.
Who knows...😮

[markhodge]

The Mars trilogy series of books, by Kim Stanley Robinson, starting with Red Mars, takes an in-depth look at space elevators. All the pros and challenges ( and possible consequences ) An excellent primer for anyone curious about colonizing Mars. A must-read whether you are into sci-fi or not.

[RealSteel]

I think the elevator would throw us out of orbit

[Tracyusa]

So stupid to use liquid fuel. Never mind a speed limit. I've invented an engine that will do the speed of light. And cheap as a car . Liquid fuel, lol

[johnstrick]

Do a story n SpinLaunch, I would like to know if that is a real possibility or a dream.

[Tracyusa]

Anything tethered to the Earth could not keep up with the Earth's rotation speed so many miles out from Earth . End of that stupid ideal. Lol👉🤪👈

[Paul]

To seek new materials that defy gravity.