Risky year-long mission 'grew on' astronaut Kelly

• Scott Kelly and Mikhail Kornienko will spend a year on the International Space Station beginning in spring of 2015
• Mission will perform experiments in seven areas, including the impact on astronauts' bodies
• The pair face double the 7% average risk of encountering a serious illness during their mission

CAPE CANAVERAL -- Scott Kelly's 9-year-old daughter thought the idea was "awesome!"

Mikhail Kornienko's wife cried.

The NASA astronaut and Russian cosmonaut know their year-long expedition together aboard the International Space Station will present risks and challenges, but both look forward to advancing knowledge that could enable trips to more distant destinations.

"We'll hopefully set the stage for sending humans beyond low Earth orbit some day, and one day to Mars," Kelly said during a news conference Wednesday.

Expected to launch in the spring of 2015, the mission will be twice as long as typical "long-duration" stays on the station, though not record-setting.

Four cosmonauts spent between 12 and 14 months on Russia's Mir station, and two more just under a year.

But those flights were a long time ago, the most recent in 1999.

Scientists say an equivalent mission on ISS, employing the latest technologies and protocols for counteracting microgravity's effects, will update their base of knowledge.

"We saw significant value in doing sort of a spot check," said Julie Robinson, NASA's ISS program scientist.

The year-long mission will perform experiments in seven areas, including impacts to the astronauts' vision, immune system and bone mass, plus behavioral issues and challenges readapting to Earth's gravity.

Igor Ushakov, director of the Institute for Biomedical Problems in Russia, said the cosmonauts who have flown the longest missions "all are alive and well today."

But he said Kelly, 48, and Kornienko, 52, would face double the 7% average risk of encountering an illness that required medical intervention during their mission.

"The risk is increased for this flight, that's for sure," said Ushakov.

Kelly and Kornienko, both veterans of prior station expeditions who know each other from their training, thought long about committing to a one-year mission.

"The whole notion of it kind of slowly grew on me, over probably about a three- or four-month period," said Kelly, until he became "very excited about the opportunity."

Said Kornienko, through a translator: "I had some doubts. Of course, you know, a year is a serious time. But they were not for long. And actually it was my initiative."

NASA selected Kelly from a group of four finalists, said Bob Behnken, chief of the astronaut office.

The field was narrowed by the flight's timing and by criteria including prior experience on station and the ability to be its commander, interact with multiple crews and perform spacewalks and robotic operations; and screening for medical issues such as vision impairment and radiation exposure.

"Of that group, Scott Kelly on the U.S. side was the best balance of all those needs for a one-year mission," Behnken said.

While the flight will produce valuable biomedical data, much of Wednesday's discussion about the mission centered on the mental challenge of living in an isolated, confined space for so long.

Missing loved ones and friends is the most difficult part, said Kelly, a divorced father of two daughters, ages 9 and 18, who is in a long-term relationship. Kornienko also has a daughter.

As before, Kelly plans to hold videoconferences weekly with family and occasionally with friends.

"Imagine being in your office for a whole year and you never get to leave," Kelly said.

"That is a challenge and presents its own set of issues, but I think I'm up for it and I look forward to it."

Of course, his office will offer stunning views of Earth spinning 260 miles below. Kelly looks forward to seeing a full cycle of changing seasons during a year orbit, though he'll miss the feeling of wind and rain, and eating fresh fruit and vegetables.

Late in the mission, Kelly acknowledged the test of endurance might come to feel like "Type 2 fun — you know, it's fun when you're done with it, not while you're doing it," more like climbing Mt. Everest than riding a roller coaster.