Within 50 years, governments will either put people on other planets, or get out of the space business for good

"I think it's essentially a binary choice. In 50 years time, we will either have Antarctica-style research stations elsewhere in the solar system or the era of government-funded manned space exploration will be over for good."
— John Logsdon, space historian and professor at the Space Policy Institute at George Washington University, quoted in a Reuters article, "Is Humanity Quietly Abandoning a Future in Space?"

Image by Les Bossinas/NASA.