Astronaut Leland Melvin, who flew two missions on the space shuttle Atlantis and is now in charge of education programs for NASA, visits with children at the D.C. General homeless shelter. Melvin has been visting the shelter on his own every year for the past three years. (Courtesy of the Homeless Children's Playtime Project)

The families living in the District’s homeless shelter get beds and two meals a day. The basics, right?

But that’s not enough if you’re a kid.

“Play spaces. They need that room to play and just be kids,” said Sharisse Baltimore, who has been in the shelter at the former D.C. General Hospital with her children since November. “Not homeless kids. But kids.”

Playing is a crucial part of growing up. But until a former school social worker named Jamila Larson showed up in 2005, playtime at the shelter was little more than running around in the parking lot, riding training wheels over broken glass.

Larson is the founder of the Homeless Children’s Playtime Project, which offers the record-breaking number of children packed into the shelter — about 600 of them — a place to have fun. Two places, actually. For the older kids, there’s a large recreation room on the second floor filled with glitter pens, construction paper, toys and books. And for the younger kids, another room with play kitchens, bouncy seats and puzzles is on the first floor.

Larson is a stickler for quality. Everything is donated but in great condition. Although she and an aide are paid, most of her operation is run by 100 volunteers and paid for with nearly $300,000 in individual donations.

She’s got lawyers, PhD candidates, lobbyists, fellow social workers and a museum intern moonlighting as my kids’ babysitter, who come to the shelter for one reason only — to play.

Larson explains the need for play as a matter of simple chemistry. Our brains get pickled by cortisol, a stress-induced chemical we manufacture, when we are confronted with trauma. For kids, too much cortisol from too much stress can damage their developing brains.

The antidote is serotonin — the juice that floods our brains when we’re happy. For homeless kids, crushing glass shards on their bikes or trying to play chase on trash-strewn concrete can’t produce enough serotonin to combat the trauma of being evicted, living on the streets, never knowing where they are going to sleep at night.

So Larson, through dogged fundraising and deft political maneuvering, created this amazing program that gives little ones a colorful, warm, happy place to retreat to twice a week and takes teens on field trips to the White House or an ice-skating rink.

Because otherwise, life in the shelter is a hospital bed in a tiny room where no snacks are allowed, or maybe a cot in a cafeteria, surrounded by temporary walls. Getting into that shelter every night requires a full-body metal scan, TSA-style.

A lot of the moms drop the kids at the playtime project and run. It is a respite, to get a couple of hours alone in the evening. But others, like Baltimore, stay and watch the rare times their kids are truly being kids, playing, laughing, creating and dreaming.

On Thursday, the children arrived in the big recreation room and found a spacesuit waiting for them.

“There’s no one inside. That’s fake!” one girl insisted.

“I”m right here,” said Leland Melvin, standing behind her, delighted at her defiant challenge.

Melvin is an astronaut.

“What do you think I do in this blue suit?” he asked, pointing to his flight suit.

“Nothing,” a bunch of kids wisecracked. It’s a tough crowd.

Every year, Melvin brings a NASA spacesuit and a slide show of his adventures in space. It doesn’t hurt that he also tells the kids about his time in the NFL, getting drafted to play with the Detroit Lions. And then getting injured.

“Playing football in college led me to the NFL. But my education, that’s what led me to space,” he told them.

He had 50 kids in front of him, some squirming, some riveted.

“I remember one time years ago, there was this girl in the front row who kept falling asleep. It was really obvious. She’d wake up and look at me, then turn around and go back to sleep,” he said.

Years later, he was at a symposium and a young woman came up to him after his lecture. She told him that she was now in medical school but was inspired by a lecture he gave a long time ago about believing in yourself. “She told me that she was falling asleep in the front row but heard what I said.”

Melvin goes to the homeless shelter every year looking for stars, in an old hospital full of kids who have a hard time dreaming about their futures.

I talked to an 8-year-old after Melvin’s lecture.

“I miss home,” he said. “I think I want to be an astronaut.”

I asked him if he’d always wanted to be one.

“Nah. But he told me I can,” the boy said. “No one’s said that to me before.”

Follow me on Twitter at @petulad. To read previous columns, go to washingtonpost.com/dvorak.