For those brave men and women who venture into space, virtually anything you do can potentially be a first for humankind.
Mike Massimino, who served as a NASA astronaut from 1996 to 2014, has two particularly cool firsts to his name. He is the first person to tweet while in orbit. More infamously, he was also the first person to gain weight in space. "The doctors were shocked," he told a crowd at the Web Summit technology conference in Lisbon last week. "But I really liked the food."
Most astronauts lose weight in space, in part due a slight degradation in bone density and also due to the two-and-a-half hours of exercise they must do every day to minimise that loss. But Massimino gained weight and another former NASA astronaut, Terry Virts, lost only 0.02 percent of his bone density.
It showed doctors that people could spend extended periods in space without any serious impact to their health -- if they exercise enough and swallow enough Vitamin D.
That's a great sign for normal earthlings who aspire to see the things astronauts have seen and feel the things they felt. With the rise of private companies trying to democratize space travel and entrepreneurs like Elon Musk trying to get us to Mars, it's a goal that isn't entirely farfetched. But when will this happen? Experts at Web Summit shared differing views on the subject.
Naveen Jain, an early web entrepreneur who now runs space startup and Google Lunar XPRIZE project Moon Express, believes space tourism will go suborbital within two years. Not only will space travel be possible, he said, it will be affordable too.
"The cost of going to space is going to be fundamentally no different from going from LA to Sydney," he said. "Imagine the day that you'll be able to go to the moon for a weekend for fun."
Space tourism is not the main aim of Moon Express, although they could well be by-products of the venture. Jain is heading to the moon because "it's good business" and to "show the governments we can do anything they are capable of doing."
"There's an unbelievable amount of natural resources on the moon," he said. "What if we bring the moon rocks back and disrupt the diamond industry? Everyone gives somebody a diamond, but if you love them enough you'll give them the moon."
Jain is a charismatic optimist who has a talent for such crowd-pleasing lines: "The honeymoon [of the future] is going to be about taking your honey to the moon," he said.
Not everyone is so sure.
Virts is more circumspect. The process of going into space is still dangerous, he said, pointing to the crash of Virgin Galactic's VSS Enterprise in October 2014, in which the craft's pilot was killed. Virgin Galactic, Richard Branson's space travel company that aims to take regular folks into space, was founded back in 2004."It's 2016 and they're not that close," he said.
Musk's Space X has had multiple issues trying to actually get its crafts into orbit.
In spite of this, the NASA alumni seem supportive of private space ventures. "I'm a big fan of Space X," said Virts. "They brought my underwear to me."
Virts and Massimino conceded space tourism will happen in our lifetime.
"Once these companies are launching people, I think it's really going to change everything," Massimino said. Despite already getting his shot at collecting space firsts, he may be right at the front of the queue.
"I'm no longer with NASA, but I want to go back," he said.
To hear the astronauts talk about the view of Earth from space, it's easy to see why they can't stay away. "I can't imagine anything more beautiful than our planet," Massimino said.