A memorial that honors the Challenger and Columbia space shuttle crews opened Saturday at the Kennedy Space Center visitor complex.

The tragedy of the nation’s first two shuttles and the loss of 14 astronauts galvanized the agency to learn from previous events to ensure the safely return of future space shuttle missions, according to the Kennedy Space Center.

“The crews of Challenger and Columbia are forever a part of a story that is ongoing,” said NASA Administrator Charles Bolden. “It is the story of humankind’s evolving journey into space, the unknown, and the outer-reaches of knowledge, discovery and possibility. It is a story of hope.”

The “Forever Remembered” memorial, which began four years ago, contains the largest collection of memorabilia and personal items of both flight crews including a recovered hardware from both shuttles.

Individual collections line the walls of the exhibit. The items are a reflection of the astronauts’ personalities. Some of the items include a husband’s cowboy boots, a Bible and a small handcrafted aircraft.There are also flight jackets, family photographs and numerous other artifacts that document the challenges involved in the recovery of the shuttles.

Investigators said they spent months looking at recovered hardware, pouring over data and conducting analysis to determine what went wrong.

The exhibit concludes with “a focus on the recovery and return-to-flight efforts, including the emotional toll these events had on the nation, the challenges involved in recovery, and the triumph of return to flight,” according to the Kennedy Space Center.

Family members gathered at a small ceremony as the memorial was formally opened by Bolden and Kennedy Space Center Director Bob Cabana.

NASA’s Mike Ciannilli referred to the memorial as an emotional experience.

“Emotion is timeless,” Ciannilli said. “It’s important that we don’t lock this experience into a certain time, a certain place.”