This picture showcases a gravitational lensing system called SDSS J0928+2031. http://www.nasa.gov/sites/default/files/thumbnails/image/potw1903a.jpg

NASA astronaut Alvin Drew participated in the STS-133 mission's first spacewalk. http://www.nasa.gov/sites/default/files/thumbnails/image/iss026e030929.jpg

Earnest C. Smith in the Astrionics Laboratory in 1964. http://www.nasa.gov/sites/default/files/thumbnails/image/ec_smith_1.jpg

The Curiosity Mars Rover took this image with its Mast Camera (Mastcam) on Feb. 10, 2019 (Sol 2316). http://www.nasa.gov/sites/default/files/thumbnails/image/pia23047_0.jpg

Two days remain until the planned liftoff of a SpaceX Crew Dragon spacecraft on the company’s Falcon 9 rocket—the first launch of a commercially built and operated American spacecraft and space system designed for humans. http://www.nasa.gov/sites/default/files/thumbnails/image/demo-1.jpeg

Mae Jemison was the first African Ameican woman in space. http://www.nasa.gov/sites/default/files/thumbnails/image/mae_jemison_29487037511.jpg

A SpaceX Falcon 9 rocket with the company's Crew Dragon spacecraft onboard launches from Launch Complex 39A, Saturday, March 2, 2019. http://www.nasa.gov/sites/default/files/thumbnails/image/33384173438_dfb4fa5e4a_o.jpg

On March 2, 2:49 a.m. EST, a two-stage SpaceX Falcon 9 rocket lifts off from Launch Complex 39A at NASA’s Kennedy Space Center in Florida for Demo-1, the first uncrewed mission of the agency’s Commercial Crew Program. http://www.nasa.gov/sites/default/files/thumbnails/image/46531972754_27aefcb3cb_k.jpg

One of the greatest challenges of the fourth phase of Air-to-Air Background Oriented Schlieren flights, or AirBOS flight series was timing. http://www.nasa.gov/sites/default/files/thumbnails/image/f4_p3_cam_plane_drop_new_2-22-19.jpg

Nancy Grace Roman, NASA's first chief astronomer, is known as the 'Mother of Hubble.' http://www.nasa.gov/sites/default/files/thumbnails/image/27154773587_c99105746d_k.jpg

NASA Administrator Jim Bridenstine was photographed inside the Super Guppy aircraft that will carry the flight frame with the Orion crew module to a testing facility in Ohio. http://www.nasa.gov/sites/default/files/thumbnails/image/47300989392_663a074b76_k.jpg

The Soyuz rocket is transported by train to the launch pad, Tuesday, March 12, 2019 at the Baikonur Cosmodrome in Kazakhstan. http://www.nasa.gov/sites/default/files/thumbnails/image/46634947384_8ecb255750_o.jpg

Stephanie Wilson is a veteran of three spaceflights--STS-120, STS-121 and STS-131--and has logged more than 42 days in space. http://www.nasa.gov/sites/default/files/thumbnails/image/jsc2007e08828.jpg

The Soyuz rocket is seen at dawn on launch site 1 of the Baikonur Cosmodrome, Thursday, March 14, 2019 in Baikonur, Kazakhstan. http://www.nasa.gov/sites/default/files/thumbnails/image/33498981418_5880fa2253_k.jpg

The Soyuz MS-12 spacecraft lifted off with Expedition 59 crewmembers on a journey to the International Space Station. http://www.nasa.gov/sites/default/files/thumbnails/image/47328135122_85619ed320_o.jpg

​Electronics technician Anna Noe makes final checks to the Doppler Aerosol Wind Lidar (DAWN) before it begins a cross-country road trip for use in an upcoming airborne science campaign. http://www.nasa.gov/sites/default/files/thumbnails/image/lrc-2019-h1_p_dawn-031115.jpg

Apollo 11 backup crew members Fred Haise (left) and Jim Lovell prepare to enter the Lunar Module for an altitude test. http://www.nasa.gov/sites/default/files/thumbnails/image/apollo_11_bu_crew_lovell_haise_lm_alt_test_mar_20_1969_ap11-69-h-548hr.jpg

The waxing gibbous moon is pictured above Earth's limb as the International Space Station was orbiting 266 miles above the South Atlantic Ocean. http://www.nasa.gov/sites/default/files/thumbnails/image/stationmoon.jpg

Margaret W. ‘Hap’ Brennecke was the first female welding engineer to work in the Materials and Processes Laboratory at NASA’s Marshall Space Flight Center. http://www.nasa.gov/sites/default/files/thumbnails/image/hap_brennecke_1.jpg

This fuzzy orb of light is a giant elliptical galaxy filled with an incredible 200 billion stars. http://www.nasa.gov/sites/default/files/thumbnails/image/potw1911a.jpg