This weekend has sad memories for NASA and all of us associated with the exploration of space.

Forty years ago Saturday, NASA experienced its first loss of life in a spacecraft. Three brave pioneers of the space age, Lt. Col. Virgil Grissom, a veteran of Mercury and Gemini missions; Lt. Col. Edward White, the astronaut who had performed the first United States extravehicular activity during the Gemini program; and Roger Chaffee, an astronaut preparing for his first space flight were training for their mission, died when their Apollo 1 command module caught fire during a "plugs-out" test on the launch pad.

Sunday will be the 21st anniversary of the next major disaster to befall NASA. On January 28, 1986, the Space Shuttle Challenger exploded just 73 seconds after liftoff, killing the entire crew; Francis Scobee - Mission Commander, Michael Smith - Pilot, Ronald McNair - Mission Specialist, Ellison Onizuka - Mission Specialist, Judith Resnik - Mission Specialist, Gregory Jarvis - Payload Specialist and Sharon Christa McAuliffe - Payload Specialist, the first teacher to fly in space.

Both of these events led to major investigations and sweeping changes of the space exploration processes of NASA, as did the disintegration of the Space Shuttle Columbia, whose anniversary we recall just a few days later on February 1. As Columbia was making final preparations for landing, flying over Texas, it disintegrated, killing the entire crew; Rick Husband - Commander, Willie McCool - Pilot, Kalpana Chawla - Mission Specialist, Laurel Clark - Mission Specialist, Mike Anderson - Mission Specialist, David Brown - Mission Specialist and Ilan Ramon - Payload Specialist.

In all of human endeavor, there is danger. It is not possible to completely avoid risk. Even if you choose to hide in your home, some danger still exists. To live is to risk, but there are those, particularly those who work for the betterment of mankind, who risk more than others. Without risk, we remain in our caves, never daring to see what lies beyond our immediate sight. An old Chinese proverb says, "When you see what is right, have the courage to do it." These brave heroes who lost their lives in the pursuit of knowledge had that courage and they shall be missed.

• Apollo 1
• Space Shuttle Challenger
• Space Shuttle Columbia

Image Credit (Apollo 1 Mission Patch):NASA Johnson Space Center (NASA-JSC)
Image Credit (STS-51L Mission Patch):NASA
Image Credit (STS-107 Mission Patch):NASA

• Related Resource: Apollo 13
• Related Resource: Astronaut/Cosmonaut Memorial
• Related Resource: Space Disasters and Tragedies

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