In this handout image provided by the European Space Agency (ESA) and NASA, the International Space Station and the docked space shuttle Endeavour orbit Earth during Endeavour's final sortie on May 23, 2011 in Space. Italian astronaut Paolo Nespoli captured the first-ever images of an orbiter docked to the International Space Station from the viewpoint of a departing vessel as he returned to Earth in a Soyuz capsule. (Photo by Paolo Nespoli - ESA/NASA via Getty Images)

Egmont National Park in New Zealand with Mt. Taranaki at its center is seen in a Landsat 8 satellite image taken July 3, 2014 and released by NASA November 14, 2014. The image is from the book “Sanctuary: Exploring the World's Protected Areas from Space”, published by the Institute for Global Environmental Strategies with support from NASA, which was released this week. (Photo by Reuters/NASA/USGS)

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)

European Space Agency astronaut Tim Peake will return home after a six-month long mission on the International Space Station,on June 18, 2016. Peake was the first British ESA astronaut to visit the ISS and captured hundreds of photographs of the Earth during his mission. Here: “Lots of sun-glint right now during our whole orbit – we haven't seen a sunset for over 3 days”, he wrote. (Photo by Tim Peake/ESA/NASA)

A Russian Soyuz 2.1a rocket carrying Lomonosov, Aist-2D and SamSat-218 satellites lifts off from the launch pad at the new Vostochny Cosmodrome outside the city of Uglegorsk, about 200 kilometers (125 miles) from the city of Blagoveshchensk in the far eastern Amur region Thursday, April 28, 2016. The launch of the first rocket from Russia's new space facility has been delayed after a last-minute problem. (Photo by Kirill Kudryavtsev/Pool Photo via AP Photo)

Space shuttle Atlantis launches from pad 39A on July 8, 2011 at the NASA Kennedy Space Center in Cape Canaveral, Florida. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. (Photo by Bill Ingalls/NASA via Getty Images)

In this artist's impression supplied by the ESO (European Southern Observatory) on April 25, 2007, the planetary system around the red dwarf, Gliese 581, is pictured showing what astronomers believe is the most earth like planet found outside our solar system to date. Using the ESO 3.6-m telescope in Chile, astronomers have uncovered the planet which could have water running on its surface. The planet orbits the faint star Gliese 581, which is 20.5 light-years away in the constellation Libra. (Photo by ESO via Getty Images)

Google's vice president Alan Eustace looks out of his spacesuit into the stratosphere prior to a record-breaking skydive over New Mexico, in this still image taken from video October 24, 2014, a handout courtesy of the Paragon Space Development Corporation. Eustace was lifted up 135,890 ft (41,420 metres) by an enormous balloon while wearing a specially designed pressurized space suit, the Paragon Space Development Corporation said. Eustace remained in a free fall for approximately 4.5 minutes before landing safely nearly 70 miles (43.4 kms) from his launch point, setting a world record for the highest skydive and breaking the sound barrier in the process. Eustace landed safely on the ground just 15 minutes after he was lifted into the air. (Photo by Reuters/Paragon Space Development Corporation)