Astronauts, from the left, Gus Grissom, Ed White II and Roger Chaffee stand near Cape Kennedy's Launch Complex 34 during training for Apollo 1 in January 1967. http://www.nasa.gov/sites/default/files/thumbnails/image/s67-19766.jpg

Dione's lit hemisphere faces away from Cassini's camera, yet the moon's darkened surface features are dimly illuminated in this image, due to Saturnshine. http://www.nasa.gov/sites/default/files/thumbnails/image/pia20514-1041.jpg

This panorama, photographed by an astronaut aboard the International Space Station, shows nearly the full length of Lake Powell, the reservoir on the Colorado River in southern Utah and northern Arizona. Note that the ISS was north of the lake at the time, so in this view south is at the top left of the image. http://www.nasa.gov/sites/default/files/thumbnails/image/iss048e073279_lrg.jpg

Dr. George Carruthers, right, and William Conway, a project manager at the Naval Research Institute, examine the gold-plated ultraviolet camera/spectrograph, the first moon-based observatory that Carruthers developed for the Apollo 16 mission. Apollo 16 astronauts placed the observatory on the moon in April 1972. http://www.nasa.gov/sites/default/files/thumbnails/image/hrs_720125-n-zz999-001.jpg

The Calabash Nebula, pictured here is a spectacular example of the death of a low-mass star like the sun. http://www.nasa.gov/sites/default/files/thumbnails/image/potw1705a.jpg

Seen from outside, Enceladus appears to be like most of its sibling moons: cold, icy and inhospitable. http://www.nasa.gov/sites/default/files/thumbnails/image/pia20522-1041.jpg

The Larsen Ice Shelf is situated along the northeastern coast of the Antarctic Peninsula, one of the fastest-warming places on the planet. In the past three decades, two large sections of the ice shelf (Larsen A and B) collapsed. A third section (Larsen C) seems like it may be on a similar trajectory, with a new iceberg poised to break away soon. http://www.nasa.gov/sites/default/files/thumbnails/image/scarinlet_oli_2016006_lrg.jpg

A sunrise photo of Edwards Air Force Base’s Rogers Dry Lake was taken after heavy rainfall in southern California. NASA’s Armstrong Flight Research Center is seen in the foreground. http://www.nasa.gov/sites/default/files/thumbnails/image/afrc2017-0022-01.jpg

Jeanette Scissum joined NASA’s Marshall Space Flight Center in 1964 after earning bachelor's and master's degrees in mathematics from Alabama A&M University. Scissum published a NASA report in 1967, “Survey of Solar Cycle Prediction Models,” which put forward techniques for improved forecasting of the sunspot cycle. http://www.nasa.gov/sites/default/files/thumbnails/image/415205_2.jpg

The Andromeda constellation is one of the 88 modern constellations and should not be confused with our neighboring Andromeda Galaxy. http://www.nasa.gov/sites/default/files/thumbnails/image/potw1706a.jpg

When seen up close, the F ring of Saturn resolves into multiple dusty strands. This Cassini view shows three bright strands and a very faint fourth strand off to the right. http://www.nasa.gov/sites/default/files/thumbnails/image/pia20519.jpg

Pine Island Glacier has shed another block of ice into Antarctic waters. The loss was tiny compared to the icebergs that broke off in 2014 and 2015, but the event is further evidence of the ice shelf’s fragility. http://www.nasa.gov/sites/default/files/thumbnails/image/pineisland_oli_2017026_lrg-crop.jpg

On March 2, 1963 Engineer Thomas Byrdsong checks the Apollo/Saturn 1B Ground-wind-loads model in the Transonic Dynamics Tunnel at Langley Research Center in Hampton, Virginia. http://www.nasa.gov/sites/default/files/thumbnails/image/l-63-385.jpg

NASA provider SpaceX's Falcon 9 rocket and Dragon spacecraft are vertical at Launch Complex 39A at NASA’s Kennedy Space Center in Florida. Liftoff of SpaceX's tenth Commercial Resupply Services cargo mission to the International Space Station is scheduled for 10:01 a.m. EST on Saturday, Feb. 18, 2017. http://www.nasa.gov/sites/default/files/thumbnails/image/32945170225_58129f00dc_o.jpg

A SpaceX Falcon 9 rocket lifts off from Launch Complex 39A at NASA's Kennedy Space Center in Florida. This is the company's 10th commercial resupply services mission to the International Space Station. Liftoff was at 9:39 a.m. EST from the historic launch site now operated by SpaceX under a property agreement with NASA. http://www.nasa.gov/sites/default/files/thumbnails/image/32993070285_ab8a4b50bd_o.jpg

When viewed from a distance with the sun directly behind Cassini, the larger, brighter craters really stand out on moons like Dione. http://www.nasa.gov/sites/default/files/thumbnails/image/pia20521-1041.jpg

A NASA Black Brant IX sounding rocket soars skyward into an aurora over Alaska following a 5:13 a.m. EST, Feb. 22, 2017 launch from the Poker Flat Research Range in Alaska. The rocket carried an Ionospheric Structuring: In Situ and Groundbased Low Altitude StudieS (ISINGLASS) instrumented payload examining the structure of an aurora. http://www.nasa.gov/sites/default/files/thumbnails/image/zap10018.jpg

On Feb. 22, engineers successfully installed ESA’s European Service Module Propulsion Qualification Module (PQM) at NASA’s White Sands Test Facility in New Mexico that was delivered by Airbus – ESA’s prime contractor for the Service Module. The module will be equipped with a total of 21 engines to support NASA’s Orion spacecraft. http://www.nasa.gov/sites/default/files/thumbnails/image/p1010141.jpg

These images of the sun were captured at the same time on January 29, 2017 by the six channels on the Solar Ultraviolet Imager or SUVI instrument aboard NOAA’s GOES-16 satellite. Data from SUVI will provide an estimation of coronal plasma temperatures and emission measurements which are important to space weather forecasting. http://www.nasa.gov/sites/default/files/thumbnails/image/suvi_horz2.png

Frequent cloud cover in the southern Atlantic Ocean often obscures satellite images of South Georgia and the South Sandwich Islands. But occasionally the clouds give way. On September 14, 2016, the Operational Land Imager (OLI) on Landsat 8 captured natural-color images of South Georgia Island, where several glaciers are in retreat. http://www.nasa.gov/sites/default/files/thumbnails/image/neumayer_oli_2016258_lrg.jpg