Jan. 28, 1986, 7 spacefarers were killed when shuttle Challenger exploded midair after launching from Kennedy Space Center in Florida

Dave Reynolds was in second grade at Lakeview Elementary in Roy, Utah, on January 28, 1986, when his teacher wheeled in a TV to watch what was supposed to be a historic moment in space exploration.

LAS VEGAS (KLAS) — Today marks the 40th anniversary of the Space Shuttle Challenger explosion. Challenger launched from Kennedy Space Center in Florida on Jan. 28, 1986, at 8:39 a.m. Just 73 seconds after liftoff, the shuttle broke apart in midair, killing all seven crew members.

For the millions of people across the country and around the world that watched the tragic loss of Challenger live, the memory is still lives on.

40 years ago today, millions watched in horror as NASA’s Space Shuttle Challenger exploded in mid-air. All seven crew members on board were killed—including a teacher who was about to become the first educator in space.

NASA Administrator Jared Isaacman appeared to suggest that space shuttle Discovery may not be relocated to Houston's Johnson Space Center in Texas.

NASA is getting ready to launch its massive, fully expendable rocket for the first crewed flight to the Moon since Apollo. The agency’s new era of spaceflight comes with a few parts from its past, specifically three rocket engines that have previously flown on space shuttle missions.

"I would say this is the most important human spaceflight mission for NASA in more than a half century," NASA administrator Jared Isaacman said. "Artemis II, you've got 8.9 million pounds of thrust, the most powerful human space launch system ever created that will accelerate to near-earth escape velocity, so nearly 25,000 miles per hour."

NASA's Space Shuttle Program, which ran from 1981 to 2011, was a complex and ambitious project that pushed the boundaries of space exploration, but was marred by two tragic accidents during the shuttle era.