50 year ago today, #Apollo13 launched on the third planned mission to land humans on the Moon. An explosion in an oxygen tank crippled the spacecraft and forced them to orbit the Moon and return to Earth without a lunar landing: s.si.edu/2nv1gjc #Apollo50

All dressed up and somewhere to go. About three hours before launch, the #Apollo13 astronauts, in their Apollo spacesuits, made their way to the transfer van to head to the launch pad. #Apollo50

The #Apollo13 crew (L-R Fred Haise, Jim Lovell, and Jack Swigert) were all smiles at breakfast before launch on this day in 1970. #Apollo50

We lay out our clothes before a big day, and astronauts aren't any different. #Apollo50 📷: Jim Lovell's #Apollo13 spacesuit, launch day.

On this day 50 years ago, just one day before the launch of #Apollo13, NASA announced that Jack Swigert would replace Ken Mattingly as command module pilot on the mission due to Mattingly's lack of immunity to German measles. Read the full story: s.si.edu/3c2b4WC #Apollo50

In the days leading up to the launch of #Apollo13, the crew was hard at work training for the mission. These photos show lunar module pilot Fred Haise working in the LM simulator and mission commander Jim Lovell exiting the command module simulator. #Apollo50

This photo, taken the week before the launch of #Apollo13, shows the mission's original prime crew: LMP Fred Haise, CDR Jim Lovell, and CMP Ken Mattingly. Jack Swigert replaced Mattingly as CMP just days before launch. More from NASA: s.si.edu/3c2b4WC #Apollo50

Why don’t as many people know much about the #Apollo12 Moon landing? Apollo curator Teasel Muir-Harmony talks about that question with @NPR’s @gbrumfiel. npr.org/2019/11/19/780602012…

The crew of #Apollo12 had fun on their mission to the Moon, and that included singing along to music on special-made mixtapes, including Dusty Springfield and Elvis Presley, and comically, the Archies' "Sugar Sugar." Music of Apollo: s.si.edu/2Sv2A1O #SmithsonianMusic

On this day 50 years ago, the #Apollo12 astronauts were in the middle of their journey back to Earth. So now is a great time to introduce you to the hilarious and entertaining crew of #Apollo12: Pete Conrad, Dick Gordon, and Alan Bean. An #Apollo50 thread ⬇️

This 16mm data acquisition camera documented the undocking of the #Apollo12 LM from the CM and its landing on the Moon on this day 50 years ago. It also captured some of the only moving images of the astronauts on the lunar surface. s.si.edu/2q8x9Rp #Apollo50

Do it for the gram. After #Apollo12 astronaut Alan Bean climbed down the lunar module ladder, Pete Conrad asked him to pose for a photo as he stepped off the LM footpad for the first time, becoming the fourth person to walk on the Moon. #Apollo50

Today's relateable moment in space history is brought to you by #Apollo12. Today in 1969, Pete Conrad became the third person to set foot on the Moon and his first word was an expression of glee: "Whoopie!" Same, Pete, same. #Apollo50

50 years ago today, the Apollo 12 lunar module "Intrepid" landed on the Moon in the Ocean of Storms. It made a precision landing, 600 feet from the Surveyor 3 spacecraft. #Apollo50

50 years ago today, Apollo 12, the second crewed lunar landing mission, launched with astronauts Pete Conrad, Dick Gordon, and Alan Bean. Learn more about the mission: s.si.edu/2zPNwF9

You think you're just looking at a picture of astronauts having a pre-launch breakfast, and then you notice the monkey in the corner. 🐵 50 years ago this morning, the Apollo 12 crew was getting ready for launch. #Apollo50

"This is Apollo Saturn Launch Control. T minus 4 hours, 19 minutes and counting. We’re still proceeding satisfactorily with the Apollo 12 countdown at this time." On this day 50 years ago, NASA was gearing up for the launch of #Apollo12. #Apollo50

The Apollo 10 command module was named Charlie Brown. A fitting name, because, as @NASAHistory explains, "as in the [Peanuts] comic, the CM Charlie Brown would be the guardian of the LM Snoopy."

The Apollo 10 lunar module was named Snoopy, a reference to the fact that the LM would be “snooping” around the Moon in low orbit, with the astronauts photographing the area where #Apollo11 would land. #Apollo50

"Good grief!" Charlie Brown and Snoopy were the mascots of Apollo 10, which is celebrating its 50th anniversary this week. The mission's spacecraft were named for them, and in this photo, replicas of the characters decorate the top of a console in Mission Control. #Apollo50