"The Earth looks totally different now," Grunsfeld said. "We are very visibly and significantly modifying the surface of the Earth, modifying the atmosphere. You can see that easily from space."
Back in the 1960s, Apollo astronauts noted that national borders aren't visible from space. But this inspiring observation, which lent some much-appreciated perspective at the height of the Cold War, is no longer true, Grunsfeld said.
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"It looks like a Rand McNally map. You can see where there's rich countries and poor countries," he said. "You can see where people have agriculture and irrigation and where people don't. It's very clear."
The planet's shrinking pockets of wilderness are also clearly visible, Grunsfeld said.
"You can see the boundaries of national parks," he said. "They look like somebody's drawn a dark line around them, with trees inside and nothing outside. It's really very striking."
Spaceflight Opening Up Soon?
To date, about 530 people have flown in space, most of them NASA astronauts or Soviet/Russian cosmonauts. But the list could soon start getting much longer.