Strictly speaking, no human has left Earth since the 1970s. The last people to actually go to space were the crew of Apollo 17 in 1972. But all that could be set to change very soon. Tomorrow, NASA is ready to go with its first test flight of the Orion capsule. This is the agency's first long-distance crew capsule since the Apollo era. If everything goes well, Orion will put America on the path to Mars.
For the past 42 years, humanity hasn't had a space ship capable of carrying people beyond low Earth orbit. For all their engineering splendor, neither the International Space Station nor the Space Shuttle have ever actually been to space. As high as it is, the ISS is still technically within the realm of Earth's thin upper atmosphere.
Tomorrow's test flight will be uncrewed, says the Washington Post. The Orion capsule will launch atop a Delta IV Heavy rocket and blast into space for a 4.5 hour trip. But even this test flight is huge, says the Post: the ship will hit “an altitude of about 3,600 miles above the surface of the planet. That’s farther than any spacecraft designed for humans has gone in more than 40 years.”
NASA has sent big, heavy things to space in the interim period, but none of them were designed to, one day, carry humans.
The launch is Orion's only scheduled test until 2018, says Space.com; the 2018 test will take the ship back to the Moon. In 2021, the first group of actual people will get on board. If that test goes well, two decades from now the space capsule could be taking passengers to Mars.