After nearly a year in space, astronaut Scott Kelly's first Earth-bound food was a banana. His bed wasn't as comfortable as he had hoped. And the initial rush that made him feel pretty good when he landed has leveled off.

But he could've stayed in the International Space Station for a little bit longer, Kelly said in his first NASA press conference and a short Facebook interview.

"I could've gone longer on this flight if there was a good reason," he said. "Whether it's science or going to a certain destination, I think people rise to the occasion."

The reason for Kelly's journey was to see what kind of impact long space flights have on the body. That research will help us prepare for manned missions to Mars, which will likely take several years.

"I personally think going to Mars, if it takes two years or two and a half years, that's doable," Kelly said. "Certainly, the first people who go there, that's going to be a big motivator, being first getting to Mars."

Looking tired and maybe a bit uncomfortable from his new Earth-bound aches, Kelly fielded questions from members of the media and fans on social media.

There were many questions about how he felt physically.

"Initially I felt better than I did last time," he said, referring to his last space trip, which lasted 159 days. "I think probably adrenaline plays a part in that. I was up there longer (this time), maybe more excited to get home or whatever ... But I don’t feel better now."

Kelly said he has muscle aches and fatigue and his skin is very sensitive, with a burning feeling where he sits or lies down. In fact, he pointed at his dress shoes and joked that he would be wearing comfortable sneakers if it weren't for the occasion.

astronaut Scott Kelly gives thumbs-up after landingFeeling pretty good: Kelly rests in a chair outside of the Soyuz spacecraft just minutes after landing in Kazakhstan. (Photo: NASA/Bill Ingalls)

When Kelly and Russian cosmonaut Mikhail Kornienko landed March 1 in Kazakhstan, the testing started immediately, he told Facebook users in a quick interview before the NASA press conference.

"Testing starts right next to the capsule in a tent," he said.

There was a type of fitness test obstacle course, tests of the vestibular system and more testing of motor skill functions.

"It's pretty tough after being in space for so long," Kelly said.

From there, he flew to Norway and then to Canada and Houston. His first food was a banana that someone had left on the plane seat as a joke, he said, likely in reference to his dressing up in a gorilla costume aboard the ISS.

Kelly said he's been undergoing MRIs, blood tests and providing many other bodily specimens since his return to Earth.

"Samples I'll be providing to the U.S. government for quite some time," he joked.

When Kelly returned home, sleep didn't come easy and his bed wasn't the welcoming place you might expect.

"Kind of painful, actually — joints, muscles. I like the bed and the sheets and stuff, but not all that comfortable. Your body does not respond that well to gravity after not having it for so long."

Kelly credited his girlfriend, NASA public affairs officer Amiko Kauderer, for encouraging his online presence and helping him with social media. He was asked about the striking photos of the Earth he shared on social media.

"The Earth is a beautiful planet. The space station is a great vantage point to observe it and share our planet in pictures," he said. "It makes you more of an environmentalist."

Mary Jo DiLonardo Mary Jo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.