My Astro Photo Of The Day

[Anomalocaris]

A space elevator is indeed viable considering requirements for materials are met.

The space elevator concept has major dynamics problems. When you move a mass up a space elevator, the angular momentum of the elevator/mass combination is conserved, but the mass moment of inertia of the combination increases. Hence the entire combination must reduce its angular velocity to compensate. As a result, not only must the space elevator warp and deform as the mass moves up, creating complex dynamic problems, but the center of mass of whole structure will start to lag the earth's rotation. So the space elevator must not only continuously consume fuel to compensate for the angular momentum lost to the mass which it lifts into space, it must also consume fuel just to continuously maintain the correct tension and damp out the ocillations and pertubations in its own motion.

The solution to the material problem also by no means solves the dynamic stability problem during construction. 1, dropping a cable from a station in geosynchronous orbit into the surface of the earth simply does not work. The angular momentum of every part of the cable will be conserved during the descent, and the descending cable will lead the station in rotation, until the cable eventually wraps completely around the earth going in the direction of orbital rotation long before it reaches ground. 2. The same applies to any ascending cable intended to compensate for the weight of the descending cable. The ascending cable going up from the synchronous station will wrap itself around the earth going in the opposite direction of the orbital rotation.

I think the engineering challenges of lifting the necessary mass into geosynchronous orbit to start the construction, and to move the connections to and from the ground is so immense that the problem of material of adaquate strength pales in comparison. To say space elevator is viable because material strong enough is available is a little like saying flying buttress is viable as soon as reasonably sound stone is found.

Check out the Mars Society conventions and websites for innovative ways to get to Mars, colonize or study it. It's famous and credible enough to have NASA and SpaceX present there.

One such idea involves harnessing an asteroid in a periodically adjusted elliptical orbit that intersets with Earth/Mars orbits to allow for gravitational assists. A benefit of that is that the asteroid, before it sling shots around the Earth, is in prime position of a highly elliptical orbit easily attainable from an Earth launched vehicle using funded and existing technology to rendezvous.

The challenge lies in orbital dynamics, patience (20 years to get the rock into full operational capacity).

The benefit of such is a body that can be mined for pre-existing volume, a free radiation shield negating the need for extremely dense materials required for throwing tiny ships of people at Mars, and can be used as an actual commitment to colonizing Earth's nearest neighbor for a rather cheap investment.

Remember that sending a few people to Mars ensures that colonization of it will be very delayed. With fewer people, less science can be done. And, if those people get cancer, they will lack the facilities that could be easily dumped en mass from a ship departing the asteroid before it slingshots around and the medical expertise and/or supplies.

All in all, looking at the past, sending a few explorers to the New World was suicide. Sending a fair bunch, though, is much more successful. And hopefully, unlike retarded puritans without planning, we can plan infinitely better.

Oh - yeah - this idea is mine. It's also been presented at the Mars Society, invited to 2010 COSPAR and is currently a continuing astrophysics project of mine at university.

I am confused.

To launch a spacecraft from earth and to have it dock with an asteriod in a mars transfer orbit is the same as to launch that spacecraft independently into mars transfer orbit. So using an asteroid is no gain in attaining mars transfer orbit from earth.

To make course adjustments while in a mars transfer orbit while docked with an aseroid means moving the whole asteroid, while to make course adjustment with independent spacecraft in mars transfer orbit means moving just the space craft, so using an asteroid here is a real loser.

To undock a spacecraft from an asteroid in a mars transfer orbit and put it into an orbit around mars is the same as sending spacecraft in independent mars trasnfer orbit into orbit around mars. So using an aseroid here is also no gain.

The the net effect seems to be use an asteroid to travel to mars is a net loser.