Space shuttle Endeavour and seven astronauts finally launched off into orbit on Wednesday on a flight to the international space station, making it its sixth attempt.

On the eve of the 40th anniversary of the liftoff of man's first moon landing, Endeavour blasted off at 6:03 pm ET from the Kennedy Space Center on the southeastern U.S. state of Florida, the same one used to launch Apollo 11 on July 16, 1969.

Endeavour suffered delays from weather and two hydrogen leaks. However, this time that skies cleared and the shuttle was cleared to lift off.

The weather is finally cooperating, so it is now time to fly, launch director Pete Nickolenko called out to the crew, according to AP.

Persistence pays off.

The shuttle and its crew are set to deliver and install the third and final piece of Japan's $1 billion space station lab, named Kibo, which is Japanese for hope.

If the flight gets away, Endeavour will carry into space a seven-strong crew, including six Americans and one Canadian.

The seven shuttle astronauts plus six station residents will make for the biggest crowd ever in orbit. Endeavour is carrying astronaut Timothy Kopra to take the place of Japan's Koichi Wakata, who has been on the space station since March.

Endeavour is making the 127th space shuttle flight, and the 29th to the station. Five spacewalks are planned during the 16-day flight.