Engineering
Lunar Space Elevator
Quick fact
Unlike an Earth space elevator, a lunar space elevator could be built with existing materials like Kevlar or carbon fiber, because the Moon's weaker gravity and slower rotation reduce the required tether strength by about 30 times.
Why this is interesting
Imagine a tower stretching from the Moon toward Earth, but built of cable. It could send cargo to lunar orbit without a single rocket launch. But why is this possible on the Moon and not on Earth?