The space shuttle Discovery launched into orbit on its final voyage Thursday afternoon, marking the culmination of nearly three decades of service.

The shuttle's last trip will take it to the International Space Station, allowing crews to install more storage space and perform some maintenance during scheduled spacewalks.

It's been a long time to get to this point for this mission. The first launch was scrubbed in November, when cracks were found on the external fuel tanks during the countdown.

It took until January for NASA to understand the cracking and to be assured the repairs would work. Then last month, the lead spacewalker was injured in a bicycle crash and had to be replaced on the crew.

The launch occurred just before 5 p.m. ET in Cape Canaveral, and thousands turned up to watch the event.

After Discovery returns from its 11-day mission, it will be retired, the first of three shuttles to be mothballed this year. NASA has decided to bring the shuttle program to an end, ushering an uncertain future for the U.S. space program.

The White House has said it wants to retire the 30-year-old shuttle program to free NASA up for grander outer space travel, with plans to explore asteroids and Mars.

Discovery has had an impressive career since its first launch in 1984. It carried the Hubble Space Telescope into orbit in 1990 and returned veteran astronaut John Glenn to space at age 77. It's flown to the Space Station 12 times and spent a total of 352 days in space, circling the Earth 5,628 times.

For this final mission, the crew of six will be bringing up two major payloads.

One is a load of spare parts for the International Space Station. The other is a pressurized module, called the Permanent Multipurpose Module, which that will provide more working space on the space station.

The PMM will also carry Robonaut 2 -- better known as R2 -- the first human-like robot in space, which will become a permanent resident of the station.