The countdown has begun! After a four-month delay since the last scheduled Discovery launch, the NASA countdown clocks started again today for the scheduled blast-off on Thursday afternoon at 4:50. The weather is looking great, and the launch is something truly remarkable to see.

The last scheduled launch, in November, was scrubbed due to a hydrogen gas leak, which lead to the discovery of more issues. The repairs have been fixed rather quickly, some of which were cracks in the metal struts, which increased the risk of broken insulating foam, the problem that doomed Columbia in 2003.

With all the repairs complete, the 6-member crew is looking forward to this 11-day mission. After this mission, the shuttle Discovery will be retired and sent to a museum. Its final destination is expected to be the Smithsonian Institution. Since its first flight in 1984, Discovery has logged nearly 143 million miles in space! Another 4.5 million miles are expected during this upcoming journey. Discovery carried up the Hubble Space Telescope in 1990, returned John Glenn to orbit in 1998, and got shuttles flying again after the deadly Challenger and Columbia tragedies. It is the oldest of the surviving space shuttles.

Only two other shuttle flights remain, by Endeavour in April and Atlantis at the end of June. NASA is under presidential direction to turn over orbital trips to private business and focus on expeditions to asteroids and Mars. Until private spacecraft are ready to start hauling up space station crews, U.S. astronauts will have to continue hitching rides on Russian Soyuz capsules for a steep price. NASA test director Jeff Spaulding told reporters that it’s a bittersweet time for the team that has prepared Discovery for liftoff for so many decades. While it’s sad to say goodbye to shuttle flying, “everybody’s proud in what they’ve done and they’re really happy to see her go off on this last mission.”