CAPE CANAVERAL, FLORIDA: The Space Shuttle Columbia thundered off the launch pad at 3:18 pm EST Thursday, carrying with it a satellite which may change the future of space exploration. The mission, which involves suspending the half ton satellite at the end of a 12.8-mile tether will culminate on Saturday when the satellite is deployed. The tethered satellite will use the earth's magnetic field to generate 5,000 volts of electricity for the shuttle. NASA originally tried this mission in 1992, but the satellite tether jammed. This new mission is especially significant since the use of this new source of electricity may allow space travelers to accomplish a great deal more in orbit. The ultimate limitation on any activity on a space craft is the amount of electrical power it uses; more available power dramatically expands the capabilities of the astronauts aboard the shuttle. "The satellite generates power as it moves through the earth's magnetic fields," says TIME's Michael Lemonick "which is technically an inexhaustible power source."