After 141 days in the isolation and order of the International Space Station, Dr. Kjell Lindgren spent Wednesday afternoon with squirming children and their families at Hennepin County Medical Center, where the doctor-turned-astronaut completed his medical residency a decade ago.

Reading a book about a mouse who goes into space to an audience of pediatric patients and other children, Lindgren encouraged them to pursue their dreams.

"I was about your age when I decided I wanted to become an astronaut," he told them.

The visit was part of a U.S. homecoming tour for Lindgren since his December 2015 return from the space station. During the mission, Lindgren operated a robotic arm that launched a satellite and repaired equipment, completed two spacewalks to maintain a meter that measures cosmic rays and the station's temperature control system, and studied the effect of time in space on plants and humans. He was part of the first U.S. crew to eat a vegetable (lettuce) grown in orbit.

Lindgren used his Twitter account to engage with people on Earth during his mission — showing images of how he exercised, making references to Star Wars and playing bagpipes in space for what is believed to be the first time in history.

His account @astro_kjell also shared breathtaking images of Earth, briefly creating a Twitter fight when he posted an overhead view of Minneapolis only. He addressed that four days later after the station passed back over the Midwest.

Dr. Kjell Lindgren told children at Hennepin County Medical Center that lessons he learned at the hospital helped his space mission.

"I sensed some sibling rivalry from Tuesday's post," he said in a tweet from the station that accompanied a new picture. "Here's the twin! Good morning St. Paul!"

Lindgren served on the station with Scott Kelly, who is part of a study examining the varying effects of space on identical twins. Kelly's brother, who previously served on the station, wrote the book "Mousetronaut," which Lindgren brought to HCMC to read, along with replica stickers of his mission badge to hand out.

Lindgren also participated on Wednesday in an eye movement study at HCMC, then addressed the hospital's annual meeting. The doctor spent three years in an emergency medicine residency at HCMC, including one year as chief resident, until his training ended in 2005. He said it prepared him for work in space and for the spacewalks that were the greatest challenges he had ever faced.

"In the emergency department … we have to make decisions with incomplete information that have critical outcomes, life and death outcomes," he said. "We have to work very effectively with teams of highly skilled people … and those are things that I did in the emergency department that I continued to do while on the space station."

After the book reading, the children launched questions at the astronaut.

What did he eat for breakfast? (Breakfast burritos, because crumby bread is a mess in space.)

What was the coolest thing he saw? (The aurora lights that looked like a "confluent ocean of neon green that's not stationary but with concentrated bands of light wiggling like snakes.")

Why was the mouse in the book different? (Because he had special gifts that ended up saving the mission.)

Lindgren grimaced at the last question: Are spacesuits comfortable?

"You're going to get me in trouble," he laughed. "Let's say that they were really, really comfortable and then we'll talk afterward."

Jeremy Olson • 612-673-7744