-- What does an astronaut do during his or her last night in space?
Count down the hours.
"The night prior is full of anticipation and of course you're excited to come home," Doug Wheelock, a NASA astronaut who has spent 178 days in space over the course of two missions, told ABC News. "There is a bit of sadness leaving this incredible home orbiting the earth but you’re ready to come back, as most people are."
Barry Wilmore, the American Commander of Expedition 42, will be living that reality tonight as he spends his final few hours of a six month stay at the International Space Station. On Wednesday, he will hitch a ride back to Earth with two Russian cosmonauts on board the Soyuz.
There's no denying the U.S. Navy captain is eager to come home and see his wife and children. A Vine taken by Wilmore and posted to the International Space Station shows a gorgeous view last week as the station passed over his home.
Wilmore has packed his bags and cleaned his crew quarters, according to NASA, and now all that's left for the Expedition 42 commander is to tie up any loose ends before he hands over the commander's post to American Terry Virts on Wednesday.
When Wilmore straps into the Soyuz, he's in for a wild ride.
Wheelock, who has traveled on the Discovery space shuttle during his first mission and the Soyuz during his second, likened the experience of traveling in the Russian capsule to "going over Niagara falls in a barrel, but the barrel is on fire."
"It is a feast for the senses," he said. "It's incredibly bumpy and hot and cramped. You have a lot of G-forces pushing you down."
After undocking and firing the engines, an approximately 45 minute free-fall to Earth awaits Wilmore. Wheelock said he was able to see pieces of the Soyuz spacecraft's heat shield melting off as he re-entered the Earth's atmosphere and ultimately landed in Kazakhstan.
"When you hit, some people stick the landing," Wheelock said. "We bounced. We hit again and rolled over. It depends on the winds and things like that and then it’s about 10-20 min before they open the hatch and pull you out."
After months in space, it's not always easy to arrive home with two feet firmly on the ground.
"You've got this little bit of paranoia that you want to be able to stand up when you walk home," Wheelock said. "You feel the physiological changes when you get to space and you are beginning to feel that your body and brain think you don’t need your legs anymore."
Clay Anderson, who has spent 167 days in space over the course of two missions, said aside from seeing family, the next thing most astronauts want most is to take care of the cravings they weren't able to indulge in space.
"One of the things I was looking forward to was a really good meal. Being a husker from Nebraska I wanted a steak, a stuffed baked potato and a Cabernet," he told ABC News.
Anderson, who is releasing a memoir in June of his time as an astronaut, said after being in the sterile environment of space, everything has a sharper smell when returning to Earth.
"I craved smelling fresh cut grass and the sounds of birds chirping in the trees and animals barking," he said. "It was amazing to me the things I missed and how acute those senses are when you first come home."
After his dizzying return home, Wheelock said a big meal wasn't the first item he enjoyed. Instead, it was the simple smell of "Earthiness."
"Your sense of smell and taste are dulled in space. I craved the aroma of leaves and grass and flowers and trees," he said. "These things are not present on the space station. When you get back to Earth they are literally intoxicating."