Can we build a lift that could take us into space?

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Rockets are an expensive way of taking people to the final frontier, so James May finds out whether the concept of an elevator could ever get off the ground.


Space is the final frontier. Or is it? Could we not think of it perhaps as the 4,000th floor instead? James May looks at why we need alternatives to rockets, and the physics and practicalities behind constructing a space lift.


continue to source article at bbc.com

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  1. I would only support the idea of a space elevator if we lived in the sort of alternate reality in which no large engineered projects EVER go wrong and you never see corruption and graft causing corners to be cut and decisions to be made for political or greed reasons rather than engineering reasons.

    Since we don’t live in that reality, the idea of a space elevator frightens me.

    If a space elevator breaks due to poor construction or upkeep maintenance or metal fatigue, then the portion of it that is higher than the break point will fling up away from Earth and the portion of it that is lower than the break will fall to Earth. (And remember the thing is designed to work via tidal forces pulling it straight, so it will be under IMMENSE tensile force stronger than anything we’ve ever built in human history, so this breakage scenario is a very likely possibility.) Remember, the thing will have to be 71,570 kilometers long (twice geostationary orbit, so it’s center is at geostationary orbit). And a break anywhere along its length will make the entire part fall (even if the break is higher than geostationary orbit, as the remaining object below that will have a new center of mass below stationary orbit).

    To put that in perspective, the circumference of the Earth at the equator is 40,075 kilometers. The falling space elevator would wrap quite a significant distance around the planet. Granted, it would be located somewhere at the equator, where none of the rich people live, so it would be okay, right?

    The “what if it fails” scenario for a space elevator is terrifying.

    • In reply to #1 by Steven Mading:

      … Remember, the thing will have to be 71,570 kilometers long (twice geostationary orbit, so it’s center is at geostationary orbit)…

      But shorter if one used a counterweight,

      .. Granted, it would be located somewhere at the equator, where none of the rich people live, so it would be okay, right?….

      It would only work at the equator.

      And there is the weight of the lift going up and down to consider, … and coriolis acceleration … still may work if there was a suitable material.

      The problem with rockets is that the energy of supplied by the on-board fuel, (hence the weight problem), Perhaps there are other ways to get the energy to the spacecraft from the ground (or space). A very long rail gun from sea level to the height of everest (50-100km long at an angle), would be technically easier.

      • In reply to #7 by old-toy-boy:

        The problem with rockets is that the energy of supplied by the on-board fuel, (hence the weight problem), Perhaps there are other ways to get the energy to the spacecraft from the ground (or space).

        There are a number of solutions to this problem. There is the reduction of the need to carry oxidiiser by using air-breathing engines:-

        In the past, attempts to design single stage to orbit propulsion systems have been unsuccessful largely due to the weight of an on-board oxidiser such as liquid oxygen, needed by conventional rocket engines. One possible solution to reduce the quantity of on-board oxidizer required is by using oxygen already present in the atmosphere in the combustion process just like an ordinary jet engine. This weight saving would enable the transition from single-use multi-stage launch vehicles to multi-use single stage launch vehicles.

        SABRE is the first engine to achieve this goal by operating in two rocket modes: initially in air-breathing mode and subsequently in conventional rocket mode:

        There is the avoidance of lifting materials out of Earth’s gravity well, by mining asteroids and manufacturing fuel and components in space – as I posted on this discussion;

        There are also proposals to heat rocket propellants, by accurately directing ground based laser or microwave beams at the propellant in the combustion chamber. http://www.technologyreview.com/view/420700/microwave-powered-rocket-ascends-without-fuel/

      • In reply to #7 by old-toy-boy:

        In reply to #1 by Steven Mading:

        … Remember, the thing will have to be 71,570 kilometers long (twice geostationary orbit, so it’s center is at geostationary orbit)…

        But shorter if one used a counterweight,

        Well, okay but it cannot possibly be shorter than half that. The counterweight still has to be higher that geostationary orbit in order to put the center of mass at geostationary orbit. That’s still plenty long enough to have the problem I mentioned.

        It would only work at the equator.

        I know. That’s why I said it would be at the equator.

        technically it doesn’t have to be if you don’t mind it being untethered, and it being a moving target that goes north and south oscillating with a period of 1 day, but that’s an even more horrible idea.

      • In reply to #7 by old-toy-boy:

        A very long rail gun from sea level to the height of everest (50-100km long at an angle), would be technically easier.

        Appalled at the stupidity of Fireball XL5 I designed just such a system (with a lot of help from my dad and his love of linear motors) when I was nine.

        StarTram ignored my pencil sketches from 1962 but seem to have got it mostly right, nevertheless.

        There were a few other problems to overcome.

  2. The concept of a space elevator may have a possible use on moons or dwarf planets with little gravity, but the material strength v weight ratio of a tether 22,000+ miles long and capable of bearing its own weight + the load on an elevator, seems to rule it out on Earth.

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