Space (U)

Outer space represents a challenging environment for human exploration because of the dual hazards of vacuum and radiation. Microgravity also has a negative effect on human physiology that causes both muscle atrophy and bone loss. In addition to these health and environmental ...

U.S. Flag on Moon (Apollo 11)

U.S. Flag on Moon (Apollo 11)

1600x1200, 541K

USA Spacecraft Space Shuttle Rocket

USA Spacecraft Space Shuttle Rocket

1024x768, 152K

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