"Today is a day for mourning and remembering," he said. "Nancy and I are pained to the core over the tragedy of the shuttle Challenger. We know we share this pain with all of the people of our country. This is truly a national loss. Nineteen years ago, almost to the day, we lost three astronauts in a terrible accident on the ground. But we've never lost an astronaut in flight. We've never had a tragedy like this. And, perhaps, we've forgotten the courage it took for the crew of the shuttle. But the Challenger Seven were aware of the dangers and overcame them and did their job brilliantly. We mourn seven heroes."
Afterwards, a special commission to investigate the cause of the Space Shuttle Challenger accident was appointed by President Reagan. Headed by former secretary of state William Rogers the commission included former astronaut Neil Armstrong and former test pilot Chuck Yeager.
The commission's report cited the cause of the disaster as a the failure of an “O-ring” seal in the solid-fuel rocket on the Space Shuttle Challenger's right side. The faulty design of the seal coupled with the unusually cold weather, let hot gases to leak through the joint. Booster rocket flames were able to pass through the failed seal enlarging the small hole. These flames then burned through the Space Shuttle Challenger's external fuel tank and through one of the supports that attached the booster to the side of the tank. That booster broke loose and collided with the tank, piercing the tank's side. Liquid hydrogen and liquid oxygen fuels from the tank and booster mixed and ignited, causing the Space Shuttle Challenger to tear apart.
The commission not only found fault with a failed sealant ring but also with the officials at the National Aeronautics and Space Administration (NASA) who allowed the shuttle launch to take place despite concerns voiced by NASA engineers.
The entire space shuttle program was grounded during the Space Shuttle Challenger Commission's investigation and did not resume flying until shuttle designers made several technical modifications and NASA management implemented stricter regulations regarding quality control and safety. Shuttle missions resumed on September 28, 1988, with the flight of the shuttle Discovery.