To cope with this situation an active adjustment of the cable's position might be required to avoid a collision. The moons Phobos and Deimos are in low orbit and intersect the cable in intervals.

An interesting complement to the elevator concept is that the end can serve as an economical launch platform, as it is moving faster than Mars escape velocity.

So the advantage on Mars is less important than for the Earth. However, the mass ratio to reach orbit on Mars is 3, while the mass ratio for Earth is 19. Due to the rocket equation, a rocket necessary requires more energy than a space elevator. On Mars, propellant is produced from electricity so the costs are directly comparable.

The space elevator uses less energy than a chemical rocket for the same service.

There are already competitions to build climbing technologies, aiming to construct a machine that is able to climb a cable with a velocity of at least 1 meter per second.

The cable extends beyond the geostationary orbit to act as a counterweight to the cable. The standard concept is for a system with a cabin, otherwise known as a climber, moving up or down a cable, often called a tether. Space elevator and radius of Martian moons.

Once attached, the cable would be under tension, allowing payloads to be transported into the satellite's orbit. As the cable is lowered, a counterweight is attached to the satellite and pushed into higher and higher orbit, thus keeping the cable's center-of-mass in a constant position. Artsutanov, a Russian engineer, conceived the possibility of using a 'skyhook' where a satellite is inserted into geosynchronous orbit and a cable lowered to the Earth's surface. Naturally, the Space Tower would be crushed under it's own weight, so the idea of a Space Elevator was born. On the earth the gravity is finally eliminated at the top of the tower, at an elevation of 5.5 radii of the earth (22,300 miles).'

but the centrifugal force operating in the reverse direction increases. on the tower, as one climbed higher and higher up it, gravity would decrease gradually and if it were constructed on the Earth's equator and, therefore, rapidly rotated together with the earth, the gravitation would disappear not only because of the distance from the centre of the planet, but also from the centrifugal force that is increasing proportionately to that distance.

The original concept for a 'Space Tower' can be traced back to Konstantin Tsiolkovsky, a Russian rocket and space pioneer.

Green Mars by Kim Stanley Robinson