10 years ago today, these swirling clouds above the Gulf of Alaska were captured by the MODIS instrument on NASA's Aqua satellite. Aqua, part of NASA's Earth Observation System, is dedicated to the study of Earth's water cycles, and celebrates 22 years since its launch on May 4!

In 1969, NASA's Johnson Space Center engineer John Hirasaki spent three weeks in quarantine along with the Apollo 11 crew. Along with deactivating and decontaminating the Command Module, he was one of the first to see the lunar samples. #AANHPI

Read his oral history: go.nasa.gov/4a1h282

Genesis, NASA's first sample-return mission to return material from beyond the Moon, made a flyby of Earth 10 years ago today in preparation for delivering its solar wind samples in September 2014.

What is solar wind? ☀️ go.nasa.gov/4dnJ3JV

#OTD in 1979, Launch Pad 39A at NASA's Kennedy Space Center received its first space shuttle. Over 8 hours, Enterprise made the 3.5-mile trek to the launch pad, atop the historic Mobile Transporter. This trip helped get processes ready for STS-1, the first shuttle launch go.nasa.gov/3Unz9Pv

That's no moon!

It's Mercury! NASA's MESSENGER spacecraft, the first to orbit the innermost planet of our solar system, took this image during it's 10+ year mission—A mission that ended #OTD in 2015. MESSENGER mapped the entire planet, including water ice deposits at its poles.

Space Shuttle Discovery approaches for landing at Edwards Air Force Base in California, completing its five-day mission to deploy the Hubble Space Telescope #OTD in 1990.

April showers bring Shuttle flight hours 🚀

Challenger launched #OTD in 1985 for STS-51B, the 17th flight of NASA's Space Shuttle program and Challenger's seventh flight. The month of April is tied with November for the most Shuttle launches: 16!

How do you train astronauts to land on the Moon, a place with no atmosphere and 1/6 the gravity of Earth?

Read about the ups and downs of NASA's simulators, including the Lunar Landing Research Vehicle (L) and the Lunar Landing Training Vehicle (R) go.nasa.gov/4aPGoXE

The Mercury 7 astronauts reported for training 65 years ago today! To prepare for flying into space, the new astronauts underwent grueling training, including time in a centrifuge, 'vomit comet' flights, and spinning in the gimbal rig at NASA's Glenn Research Center. Watch: go.nasa.gov/3JBvvNi

Briefly experiencing a force of about 7G as they decelerated through Earth's atmosphere in their command module, the Apollo 16 astronauts splashed down in the Pacific #OTD in 1972, completing their 11-day lunar mission. More about the end of the mission: go.nasa.gov/3UzzAXp

Celebrating the people who have taken us to new heights.

#WorldPilotsDay

Remember quarantine? The Apollo 11, 12 and 14 astronauts each spent 21 days in quarantine after their missions to the Moon, in case they had been infected with lunar organisms. NASA Administrator George Low announced that future Apollo crews would not be quarantined #OTD in 1971.

#TBT to April 28, 2003, when our GALEX telescope launched on what became a decade-long mission to observe the universe in ultraviolet light. It helped us trace the history of star formation and learn about how galaxies evolved over cosmic history.

The Hubble Space Telescope was just beginning more than three decades of unprecedented exploration 🔭

Once in space, procedures verified that Hubble’s systems were functioning properly and #OTD in 1990, it was successfully deployed into orbit by the STS-31 crew.

POV: Inside the firing room in 1990 during the launch of Space Shuttle Discovery.

Discovery launched #OTD as part of the STS-31 mission. With five astronauts onboard, its primary goal was to deploy Hubble. The rocket launch itself can be seen through window on the top left.

Astronaut Peggy Whitson made history (again) #OTD in 2017 when she broke the U.S. record for cumulative days in space at 534 days. She still holds this record, now with 675 days in space. She was also the first woman to command the International Space Station and the first to do it twice!

One of NASA's greatest photographers was launched on this day in 1990!

Space Shuttle Discovery launched with the Hubble Space Telescope, one of the world's largest and most versatile space telescopes, as part of STS-31. Learn about Hubble's origins: go.nasa.gov/4baiTZa

Hubble's 34th launch anniversary is this week! 🥳

We're celebrating with this new image of the Little Dumbbell Nebula. Located about 3,400 light-years away, this nebula formed when lobes of gas expanded out from a dying star at the center.

For more: go.nasa.gov/49OpEP1

Annie Easley, born #OTD in 1933, began her 34-year career at NASA in 1955, working as a human computer. When human computers were replaced by machines, she evolved too, becoming a computer programmer. go.nasa.gov/3Ulw2sF