🚀Countdown to Launch 🚀

July 16, 1969, three astronauts departed on a mission that would captivate the world. In celebration of #Apollo50, we're counting down to the launch of #Apollo11 by sharing an artifact each day that tells the story of our journey from Earth to the Moon.

The artifacts we will be highlighting — big and small, critical and amusing, familiar and never-before-seen — are expanded on in the new book "Apollo to the Moon: A History in 50 Objects" by National Air and Space Museum curator Teasel Muir-Harmony. #Apollo50

Yesterday marked 50 days to #Apollo11 launch, so let's start at the beginning of the Space Race: the failed launch of the Vanguard TV-3 satellite in December 1957, a response to the Soviet Union's Sputnik success two months earlier: s.si.edu/2iYQ0e9 #Apollo50

When the first satellites were being launched, there weren't systems in place to track them. So @saoastro director Fred Whipple came up with a solution: Operation Moonwatch, in which 8,000 volunteers watched the sky with telescopes like this one: s.si.edu/2JJ2Jgv

In April 1961, cosmonaut Yuri Gagarin became the first space traveler in history. This 10-Kopek stamp celebrated that achievement. It features a stylized, fictitious rocket, due to the strict secrecy surrounding the Soviet space program: s.si.edu/2XgiFu2

President Kennedy's decision to propose Project Apollo was rooted in his belief in the importance of image in politics -- a lesson he learned when he impressed the nation seated in this chair during a 1960 presidential debate vs Richard Nixon. #Apollo50 (From @amhistorymuseum)

@amhistorymuseum On May 5, 1961, Alan Shepard became the first American in space aboard Freedom 7: s.si.edu/2HNlnQu

His spaceflight, three weeks after Gagarin's, proved that the U.S. was still a contender in the Space Race and that NASA's system to launch spacecraft was viable. #Apollo50

John Glenn believed sharing the adventure of spaceflight with the world was essential, so for his Mercury mission he purchased an Ansco Autoset camera and had it modified for space: s.si.edu/2EOmm2H

Photography would play a major role in future Apollo missions. #Apollo50

Next up: Gemini. Frank Borman and Jim Lovell flew in this capsule for two weeks to study the effect of microgravity on the body over a longer mission. Gemini 7 proved that astronauts could fly to the Moon and back without risking their health. s.si.edu/2EOpxaJ #Apollo50

The Apollo Guidance Computer was the brains of the Apollo spacecraft. It performed flawlessly throughout each of the Apollo missions without even a single hardware failure: s.si.edu/2JTc7hV #Apollo50 #AirSpacePhoto

The Apollo Mission Simulators pushed the state of the art in simulator technology, providing necessary training for all involved in the mission. In fact, the phrase "just like the simulator" can be found in the transcripts of every Apollo mission. #Apollo50

Each command module had on board a survival kit in case it splashed down a far from the recovery vessels. This kit from #Apollo11, never used, contained an emergency beacon, water jugs, survival lights, sunscreen, a machete, and more: s.si.edu/2JTDR5I #Apollo50

Hundreds of thousands of people worked to make the Moon landings a reality. This jacket belonged to McDonnell Aircraft Corporation engineer Robert Foster. He was chief electrical engineer for Mercury and operations manager for Project: s.si.edu/2WnewTA #Apollo50

🚀39 Days to Launch 🚀

To lift the unprecedented payload of three space vehicles, NASA had to create an unprecedented rocket. This Saturn V Instrument Unit, the computerized brain of the towering rocket, is on display at the Udvar-Hazy Center: s.si.edu/2Zg4C8q #Apollo50

The lunar module, which took the astronauts to the surface of the Moon, was extremely lightweight and had to withstand the vacuum of space. LM-2, on display at the Museum in DC, is configured to look like the #Apollo11 lunar module Eagle: s.si.edu/2ETps5F #Apollo50

Next up: "Spacecraft 107, alias Apollo 11, alias "Columbia." The Best Ship to Come Down the Line." - CMP @AstroMCollins

After a successful lunar landing in the LM, it was command module Columbia that brought the astronauts home: s.si.edu/2WrN5Iv #Apollo50 #AirSpacePhoto

The race for space sparked the imaginations of many. This Airfix model kit, with 57 pieces including 15 astronauts, allowed enthusiasts to imagine the missions however they wanted, even though only two astronauts ever actually walked on the Moon at a time. #Apollo50

We're 5 weeks away from the launch of #Apollo11 (c.1969, of course!). So let's take a look at the mission emblem. Did you know it was designed by @AstroMCollins? It features a bald eagle (the national bird and the LM's name) with an olive branch (the symbol for peace). #Apollo50

On #Apollo11 launch day, thousands of people turned up to watch, many donning RCA sun visors handed out that day. This gave RCA great visibility, so they repeated the visors for future missions. Apollo 16 visor: s.si.edu/2WC5rGO #Apollo50

Before the Saturn V could launch, it had to be moved into position on massive tracked crawlers. This one-ton steel tread helped carry the Apollo spacecraft on this slowest portion of its journey to the Moon: s.si.edu/2ZlNSwj #Apollo50 #AirSpacePhoto

The day before the #Apollo11 launch, protestors organized by the Southern Christian Leadership Conference arrived at NASA Kennedy to draw attention to poverty in America. More from @NASAHistory: s.si.edu/2IiyGdP

📷: This SCLC collection can is in @NMAAHC's collection.

The first meal on the Moon consisted of bacon bars, peaches, sugar cookie cubes, coffee, and a pineapple-grapefruit drink. This packet of cookies flew on #Apollo11 but weren't eaten. More on space food: s.si.edu/2HMwMQD #Apollo50

"Things which were fun a couple days ago, like shaving in weightlessness, now seem to be a nuisance..." - @AstroMCollins

Collins used this razor & shaving cream during #Apollo11, but with no sink & limited water, it wasn't as easy as on Earth. s.si.edu/2RkLyCV #Apollo50

We're always asked: how do you go to the bathroom in space? During #Apollo11, the answer was this urine collection assembly: s.si.edu/2Rl30Hv

A small amount of urine was freeze-dried and stored for testing back on Earth. (The things we do for #science!) #Apollo50

To prevent loss in muscle tone and mass and bone density during their week-long spaceflights, #Apollo astronauts used an exerciser. This Exer-Genie, which attached to the wall of the command module, was used during #Apollo11: s.si.edu/2LqS8nC #Apollo50

You've seen #Apollo17's iconic "Blue Marble" image, but how about the camera that captured it? Astronauts used cameras like this Hasselblad from Apollo 17 to capture over 18,000 still photographs during the #Apollo missions: s.si.edu/31HUIOP #Apollo50

Millions of Americans tuned in to watch Walter Cronkite's coverage of #Apollo11 on @CBSNews. After launch, he spent 27 of the next 32 hours on the air. He used this small-scale model of the lunar module to explain stages of the mission on air. #Apollo50

@CBSNews This #Apollo11 Data Acquisition Camera captured the first steps and the astronauts' lunar activity. It was supposed to be left on the Moon, but was discovered in a Beta cloth bag in a closet at Armstrong's home a few years ago: s.si.edu/2WT2DKe #Apollo50

In mid-July 1969, Apollo 11 wasn't the only spacecraft on its way to the Moon. The Soviet Union's uncrewed lunar mission Luna 15 launched on July 13. This Estonian toy is a motorized model of the Luna program's Lunokhod robotic rovers: s.si.edu/2x8uK9e #Apollo50

Checklists, like the #Apollo11 Command Module Operations Checklist pictured here, were critical to operating the Apollo spacecraft, leading @AstroMCollins to refer to them as the "fourth crew member whose views had to be considered." s.si.edu/2xaaHHq #Apollo50

The Moon has limited atmosphere and no wind, so NASA engineers had to be creative to find a way for the American flag to “fly.” The solution: a crossbar on the flagpole to extend the flag. Replica of flag and flag pole: s.si.edu/2LfFJWo #Apollo50

🚀Three Weeks to Launch 🚀

Let's fast forward to the last spacesuit to leave the Moon, worn by Apollo 17 astronaut Gene Cernan: s.si.edu/2X79gJg The most visible part of the suit, the outer layers, are made from Beta cloth, a wearable fiberglass. #Apollo50

The robotic Surveyor landers (1966-68) provided important information about the conditions humans would encounter on the lunar surface. This camera from Surveyor 3 is the only piece of robotic spacecraft retrieved and brought back to Earth by a human crew (Apollo 12). #Apollo50

The Apollo missions weren't just about small steps and giant leaps -- they were also about science! We learned a lot about the Moon from Apollo, using instruments like the Apollo Lunar Surface Experiment Package. More on the science of Apollo: s.si.edu/2XA7C26 #Apollo50

The Far Ultraviolet Camera/Spectrograph, designed by @USNRL astronomer George Carruthers, became the first telescope to make astronomical observations from the surface of another planetary body on Apollo 16: s.si.edu/2Xpzhik #Apollo50

Later Apollo missions covered greater distances on the lunar surface thanks to the Lunar Roving Vehicle. The LRV's wheels were hand-woven mesh made of zinc-coated piano wire and were virtually unaffected by extreme temperature fluctuations: s.si.edu/2UYgkSP #Apollo50