Thirty years ago on Thursday, the space shuttle Challenger broke apart shortly after lift-off, its shattered remains—and its crew—plunging 60,000 feet into the Atlantic Ocean. It is tempting, on this anniversary, to revisit the accident and the horror of watching Challenger’s rocket explode, an event that crippled the U.S. space program for several years.

But time’s arrow points only one way, and reliving catastrophes doesn’t change their outcome. No matter how badly we might wish that this time, as we watch that footage, Challenger will safely sail into space, it won’t.

Instead, now is a time to remember those who have lost their lives in humankind’s quest to unchain themselves from the bonds of Earth and touch the faces of the moon, planets, and stars. Lists of the fallen, which include astronauts, cosmonauts, and test pilots, contain fewer than 40 names—yet each is a painful reminder that space exploration is difficult, and dangerous.

In a strange coincidence, this week is when the three major U.S. space accidents happened: the Apollo 1 launchpad fire and the losses of the space shuttles Challenger and Columbia. Now, the fallen are remembered in memorials on Earth, and beyond. Some of the memorials are the kinds of things people build, and others are more personal. And perhaps, in the future, more of those memorials should be placed in space—the dominion these astronauts worked to reach.

An Astronaut Remembers

“It’s all very real to us, and we keep it in front of us,” says NASA astronaut Doug “Wheels” Wheelock. Every year, around New Year’s Day, Wheelock travels to Cape Canaveral and visits the Apollo 1 launch site, where three astronauts trapped in their space capsule died in a fire on Jan. 27, 1967.

“I stand there in silence,” he says. “You can hear the waves, because you’re pretty close to the water there, and it helps to kind of re-engage what set you on your own personal journey.”

View Images The space shuttle Challenger blew apart 73 seconds after lift-off on January 28, 1986. The main engine exhaust, solid rocket booster plume, and an expanding ball of gas are visible seconds after the explosion. Photograph by NASA

The Apollo and space shuttle programs helped inspire Wheelock to become an astronaut. Eventually, he would fly on space shuttle Discovery and spend five months on the International Space Station. The space station, he says, is filled with photos of lost astronauts, as are the hallways of NASA’s Johnson Space Center in Houston. Walking down those hallways, he says, brings inevitable thoughts of his fallen friends.

“The Columbia crew—I can still hear their voices,” Wheelock says, referring to the seven astronauts who died on February 1, 2003, when space shuttle Columbia disintegrated in the skies over Texas. “If I could repeat what I'm hearing in my mind … I can still hear their inflections and mannerisms and characteristics. We're doing this for them, and to advance their goals and the dreams they had.”

There’s also a memorial grove of oak trees at Johnson Space Center, with each tree representing a fallen astronaut. At Kennedy Space Center, in Cape Canaveral, Florida, there’s the ethereal Space Mirror, where 24 names are inscribed in granite. Arlington National Cemetery houses memorials for the Apollo, Columbia, and Challenger crews. Places on Earth, the moon, Mars, and Pluto are named in remembrance, as are countless streets, schools, civic centers, and parks.

“If we die, we want people to accept it. We’re in a risky business, and we hope that if anything happens to us, it will not delay the program,” said astronaut Virgil “Gus” Grissom, who later died in the Apollo 1 launchpad fire. “The conquest of space is worth the risk of life.”

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The Apollo program would later put the first humans on the moon. And in 1971, when the Apollo 15 crew arrived, they brought a secret memorial with them. Now called Fallen Astronaut, the sculpture is a small, aluminum figurine of a human. Nestled in moon dust, it sits next to a plaque bearing the names of 14 astronauts.

“It was left there to honor all of the deceased astronauts and cosmonauts to that point,” says Valerie Neal, curator at the National Air & Space Museum. “And I would guess any craft bearing humans to Mars, or humans back to the moon, will have a plaque or a sculpture on board to be placed there.”

Living Memorials

Other memorials don’t assume a physical presence.

In 1986, planetary scientist Alan Stern had two experiments set to fly on Challenger, including his first as the lead scientist; and so as he watched the explosion, Stern saw years of work coming down in pieces, in addition to the crushing loss of his friends.

“I had a really hard time with it,” says Stern, of the Southwest Research Institute. “And it was really difficult because it was on the national news every night.”

View Images A plaque left on the moon during the 1971 Apollo 15 mission commemorates 14 NASA astronauts and USSR cosmonauts who died. Photograph by NASA

For months, he had difficulty sleeping and fell into recurring spells of gloominess. Eventually he decided, “I’m going to go back to graduate school and become a scientist and do this for the people I knew that got killed,” he says. “Any research contribution, anything I do as a result of being a scientist, is dedicated to them.”

That includes sending the New Horizons spacecraft whizzing by Pluto, where some of the surface features are informally named after both the Challenger and Columbia missions. “I still think about them,” he says. “But it gets easier. It’s the salve of time going by.”

Others have also turned tragedy into change. June Scobee Rodgers, widow of Challenger commander Richard Scobee, channeled her grief into helping inspire the next generation of space explorers. Three months after the accident, she says, the Challenger families convened in her home to talk about how to memorialize the crew. They decided to celebrate what the astronauts cared about, which meant focusing on education.

“Challenger ended up being known most appropriately as the ‘teacher in space’ mission because we had the first civilian on board,” Scobee Rodgers says, referring to astronaut and teacher Christa McAuliffe. They came up with the Challenger Center, where students learn science and engineering lessons by simulating space missions. Today, there are more than 40 Challenger Centers around the world, and more than 4.4 million students have passed through them.

“It’s a celebration,” says Scobee Rodgers. “It reflects on their life, and what they were as a team and what they were willing to risk their lives for... in truth, the Challenger mission continues, and Christa’s lessons are being taught.”

A Space-Based Memorial?

“Sometimes when we reach for the stars, we fall short,” President Reagan said in his Challenger eulogy. “But we must pick ourselves up again and press on despite the pain.”

The space program has gone on. And so it seems fitting to consider the idea of creating a space-based memorial for our lost astronauts, and in some way marking their sacrifices in the realm they set out for.

View Images Christa McAuliffe trained to be the first teacher in space for the Teacher in Space Project on the space shuttle Challenger. Photograph by NASA, Reuters

Yes, there’s already a small memorial on the moon—and perhaps more on the way—but what about a memorial sailing forever toward the stars, like the Voyager record carrying our message to other worlds? Or maybe in orbit around the Earth, where we might occasionally see it, reflected in the light of the rising and setting sun?

Scobee Rodgers says she’d like that, as long as whatever the memorial is helps humanity in some way. “I would want it to serve a purpose, other than just being a static satellite,” she says. “Something like helping people to advance the space program, or advance civilization, or do something that was important to our nation and to our planet.”

Alan Stern has another idea. “What if every human spaceflight, every time, carried a memorial—the same memorial?” he says. “It would recognize everybody lost in spaceflight and be in solidarity with those pioneers. It could be very understated, but every astronaut on every spaceflight would know, and every space tourist would know, that they’re a part of saluting that.”