Space Elevator Challenge

MattSparkes writes "For the second year in a row, no team has won the $200,000 prize in the Space Elevator Challenge at the Wirefly X Prize Cup. Three teams were disqualified before the contest even started. Another competition at the event has been held up by confusion. Incredibly, it seems the organisers of the competition are not sure whether the ribbon used was 50 or 60 metres long, and whether any team completed the climb fast enough to win."

Comments

X-Prize Foundation

[Raynor]

is already responsible for a major advancement: the first private space ship able to relaunch in two weeks (SpaceShipOne).

The prize is definately motivation, and the X-Prize foundation has a few contests going:
-The Ansari X-Prize (Get 3 people to 100km twice in two weeks) - WON
-The Archon X-Prize (Sequence 100 people in 10 days with $10,000 cost per person) - OPEN
-The Automotive X-Prize (Currently being developed. Create super-efficent cars or alternative energy) - FUTURE

Those are the three the X-Prize Foundation has created. An interesting fact from the X-Prize website: "Ten times the amount of the prize purse was spent by the competitors trying to win the prize."

Re:X-Prize Foundation

[Shadowmist]

Important thing to remember, SpaceShipOne did not acheive anything near orbital velocity. In fact I'm not even sure it was close to the velocity of Alan Shepard's suborbital Mercury flight. Hence it did not have to deal with severe re-entry heating, so was spared one of the critical neccessities of the Space Shuttle. I'm not knocking the acheivement of this group, just putting it in perspective.

Re:X-Prize

[lgw]

This prize addressed the climber, not the cable, so it's not entirely silly.

What I'd like to see addressed is the fundamental structural problem of stabilizing a space elevator. In getting a payload to geostationary orbit, only about half the energy required is needed for lifting. A similar amount of energy is required to accelerate the payload laterally by roughly 9000 km/h, giving it enough angular momentum to achieve a stable orbit.

A space elevator can lift a payload easily (given some advancement in materials technology), but has no real prospect of pushing sideways on a payload. As a result, conservation of angular momentum will cause the far end of the pendulum to swing. The counterweight tethered past geostationary will swing backwards in orbit, then swing forwards again as a pendulum.

The this very long pendulum will oscillate, not simply be pulled from orbit, and the amplitude won't be that high on the first payload, but every payload lifted will add energy to this pendulum - effectively all of the energy needed to accelerate the payload by 9000 kh/m. That will add up fast, and the space elevator doesn't have much prospect for damping the pendulum. The friction in the cable as it bends will shed some energy, but that's about it. It's like a car with good springs, but no shocks - it's going to bottom out eventually.

The period of a 40000 km pendulum is less than 4 hours, far shorter than the likely time for lifting the payload, so the energy of oscillation will be added somewhat chaotically as the payload ascends. It's not like to can just send of a second payload to "cancel out" the consequences of the first. You really need a strong mechanism that stops the pendulum from swinging.