Space Shuttle Atlantis lands at the Kennedy Space Center July 21, 2011 in Cape Canaveral, Florida. The landing brings to a close the 30-year era of the space shuttle program that began in 1981, and has included 135 missions. (Photo by Bill Ingalls/NASA via Getty Images)

The NASA Extreme Environment Mission Operations (NEEMO) 21 mission began on July 21 as an international crew of aquanauts splashed down to the undersea Aquarius Reef Base, located 62 feet below the surface of the Atlantic Ocean in the Florida Keys National Marine Sanctuary. The NEEMO 21 crew will perform research both inside and outside the habitat during a 16-day simulated space mission. During simulated spacewalks carried out underwater, they will evaluate tools and mission operation techniques that could be used in future space missions, including journeys to Mars. (Photo by Karl Shreeves/NASA)

“NASA's Pathfinder, Pathfinder Plus, Centurion and Helios Prototype were an evolutionary series of solar- and fuel-cell-system-powered unmanned aerial vehicles. AeroVironment, Inc. developed the vehicles under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program. They were built to develop the technologies that would allow long-term, high-altitude aircraft to serve as “atmospheric satellites”, to perform atmospheric research tasks as well as serve as communications platforms”. – Wikipedia

Photo: The solar-electric Helios Prototype flying wing is flies over the Hawaiian islands of Niihau and Lehua during the first solar-powered test flight July 14, 2001 from the U.S. Navy's Pacific Missile Range Facility on Kauai, HI. The 18-hour flight was a functional checkout of the aircraft's systems and performance in preparation for an attempt to reach sustained flight at 100,000 feet altitude later in the summer. (Photo Courtesy of NASA/Getty Images)

“The scientists behind NASA's $2.5 billion Curiosity rover mission on Mars on Tuesday explained the nature of a tiny, gleaming "flower" embedded in Red Planet rock, and revealed where they'll be using the SUV-sized robot's drill for the first time”. – Alan Boyle via NBCNews.com

Photo: Scientists say that a “Martian flower”, seen here in an image from the Curiosity rover's Mars Hand Lens Imager, is a 2-millimeter-wide grain or pebble that's embedded in the surrounding rock. Another, darker-colored mineral grain can be seen above and to the left. (Photo by NASA)

A gopher tortoise walks the grounds of NASA's Kennedy Space Center in Florida, near the Vehicle Assembly Building on January 18, 2024. An all-European crew including Turkey's first astronaut are poised to blast off to the International Space Station in a mission with Axiom Space, as countries hungry for a taste of space turn increasingly to the private sector. (Photo by Chandan Khanna/AFP Photo)

A model of the New Horizons spacecraft is seen at a live television program on NASA television celebrating the spacecraft's closest proximity to Pluto, at Johns Hopkins University Applied Physics Laboratory, site of the mission operations center, in Laurel, Maryland, USA, 14 July 2015. At approximately 7:49 am ET (11:49 am GMT), 14 July, New Horizons was scheduled to be as close to Pluto as the spacecraft will get; about 7,800 miles (12,500 kilometers) above the surface, following a journey of more than nine years and three billion miles. This is the first mission to the Pluto System and the Kuiper Belt. (Photo by Michael Reynolds/EPA)

A meteor streaks over the sky during the Perseid meteor shower at the Maculje archaeological site near Novi Travnik August 12, 2014. According to NASA, the annual Perseid meteor shower reaches its peak on August 12 and 13 in Europe. The fireballs from the meteorites are fast and plentiful, although a nearly full moon (Supermoon) makes it difficult to view them this year, the agency adds. (Photo by Dado Ruvic/Reuters)