Thirty years later, they remember the Challenger disaster as if it were yesterday.

Claude Onizuka and Rob Kelso were at the Kennedy Space Center launch site in Florida on Jan. 28, 1986. They witnessed the horror of the space shuttle’s explosion 73 seconds after liftoff that killed Hawaii’s own Ellison Onizuka and six other crew members.

They still feel the pain of that tragedy, the wave of shock and disbelief that day and the intense sorrow that followed.

Both Claude Onizuka, the younger brother of Hawaii’s first astronaut, and Kelso, a NASA colleague and friend, will help Hawaii remember Ellison Onizuka and the Challenger during events marking the 30th anniversary of the tragedy.

Among the tributes today are ceremonies honoring the Hawaii astronaut at Keaau High School on Hawaii island and at the state Capitol, featuring proclamations from both the state Legislature and Gov. David Ige, who will declare it Ellison Onizuka Day in Hawaii.

The 16th annual Astronaut Ellison Onizuka Science Day, featuring free science activities for students in grades four to 12, will be held Saturday at the University of Hawaii at Hilo.

Starting Friday and into next week, Claude Onizuka will accompany NASA astronaut Edward Michael Finke on school visits commemorating Ellison Onizuka and the Challenger tragedy. Among his stops will be Challenger Center Hawaii at Barbers Point Elementary School.

The worst accident in the history of the U.S. space program until that time shocked and horrified America and forever changed the space program at a time when shuttle flights were almost becoming routine.

This particular mission flew under an additional spotlight as thousands of schoolchildren watched on television. Christa McAuliffe was scheduled to become the first teacher in space, and she was even going to conduct a couple of classes aboard the shuttle.

Also on the historic flight was Onizuka, a 1964 graduate of Konawaena High School and an Eagle Scout. He attended the University of Colorado before earning an Air Force commission through ROTC. He would become a test pilot and rise to the rank of colonel before being accepted into NASA’s astronaut program in 1978.

The Hawaii hero became the first Asian-American, the first person of Japanese ancestry and the first Buddhist to reach space.

Facilities named for him today include Onizuka Air Force Station in California, the Onizuka Village housing complex at Joint Base Pearl Harbor-Hickam, the Onizuka Center for International Astronomy on Mauna Kea and the Ellison S. Onizuka Space Center at the Kona Airport. An asteroid and a crater on the moon are also named for him.

He is buried at the National Memorial Cemetery of the Pacific at Punchbowl.

For Claude Onizuka, it’s hard to believe three decades have passed since he lost his brother. He was part of a group of 65 Hawaii friends and family members invited to a special VIP viewing site just a few miles from the launch.

Having watched his brother’s first space shuttle launch just a year before, Claude Onizuka said he realized there was something wrong as soon as it happened.

“It happened so fast,” Claude Onizuka recalled. “I was thinking, ‘Is this really happening?’”

NASA officials quickly ushered the families onto buses to keep them away from the spotlight. Onizuka’s sister ended up in the hospital, having gone into shock.

Kelso watched the launch from the mission manager room.

“It was horrific,” he remembered. “I was stunned, in shock and disbelief.” He added that “it was just devastating to lose a close friend and colleague.”

Of all those on board, he knew Onizuka best, having worked closely with him on his first space shuttle mission.

They were teamed together on a mission to launch a classified Department of Defense spacecraft from the shuttle. For 2-1/2 years, Kelso and Onizuka prepared and trained for a mission launched in January 1985. Kelso was responsible for the flight operations in NASA’s Mission Control Center while Onizuka was responsible for spacecraft activities on board the shuttle.

Kelso, who would go on to become executive director of Hawaii’s Pacific International Space Center for Exploration Systems (PISCES) in 2011, recalled that the astronaut was a pleasure to be around.

“Ell was full of life, a dynamic individual with a great sense of humor. He loved to joke and kid around,” he said.

At the same time, Onizuka took his mission with NASA seriously, Kelso said.

During his NASA career, Onizuka regularly visited classrooms and schools. When he was the guest speaker at the 1980 commencement of his alma mater, Konawaena High School, Onizuka urged the graduates to reach for not only the stars but the moon as well.

He urged them to go beyond what your eye can see to “what your mind can imagine,” according to an account in the Honolulu Advertiser. “Many things that you take for granted were considered unrealistic dreams by previous generations. If you accept these past accomplishments as commonplace then think of the new horizons that you can explore.”

After the tragedy, Claude Onizuka was thrust into the spotlight as family spokesman.

He would spend much of the next 30 years helping to perpetuate the legacy of his brother, establishing the Ellison Onizuka Memorial Foundation and the Ellison Onizuka Space Center museum at the Kona Airport in 1991.

Last month, the foundation announced that the space center would be closing at the end of March, replaced by a new gateway to a $70 million airport renovation.

The state Department of Transportation offered to construct a new building across the street. But after considering four different sites, the space center’s governing board decided it would not be able to afford the higher operational costs of a much larger building.

The center — featuring displays of space shuttle missions, lunar landers, a moon rock, videos from inside the International Space Station as well as memorabilia from Ellison Onizuka’s life — welcomed some 22,000 visitors annually, including about 8,000 students.

Claude Onizuka said he’s hopeful another location for the museum and its treasured contents can be found someday.

Kelso said that as the Challenger anniversary approaches, memories of the tragedy seem to be coming into greater focus.

“Thursday will be hard for everybody,” he said.