The seven-member crew will be delivering the first installment of a Japanese scientific lab called "Kibo" - or hope. The lab is so large it is being delivered to the space station on three separate flights.
"This is the first piece of the Japanese space station module and actually, the logistics module is the first manned space facility Japan has ever launched," said Japanese Astronaut Takao Doi.
Endeavour's crew will also spend two days performing spacewalks to assemble "Dextre", a two-armed, 3,400 pound Canadian robot designed to assist astronauts on future spacewalks. The robot is too heavy to be put together on earth. "It's strange to think that something that can move items that weight a thousand pounds around in space can't support its own load on the ground," said Pierre Jean with the Canadian Space Program.
The astronauts will also try out a caulking gun and some high-tech goo on deliberately damaged thermal tile samples.
Time is of the essence. NASA only has twelve more missions to complete the International Space Station before the shuttle fleet is retired in two years.