Explorer 4 launched 1958

Explorer 4, launched July 26, 1958 from Cape Canaveral, was the first of two planned satellites from the Department of Defense's Advanced Research Projects Agency (ARPA) to study the Van Allen radiation belts.  It reached a height of 163 miles.  Soon after orbit insertion, Explorer 4 developed a tumbling motion with a period about 6 seconds, which made interpretation of the data collected from the satellite very difficult.

Explorer 4 performed until the low-power and plastic scintillator detector failed on September 3, 1958.  The Geiger-Muller tubes and the cesium/iodide crystal detectors operated until September 19.   The high-power transmitter worked until October 5, likely due to the exhaustion of the power batteries.

Explorer re-entered Earth's atmosphere October 23, 1959.

Discovery (STS-53) launched 1992

STS-53 crew

Back row (L-R): David Walker, Robert Cabana, Michael Clifford

Front row (L-R): Guion Bluford, James Voss

STS-53 mission patch

Space Shuttle Discovery (STS-53) launched December 2, 1992, carrying a classified payload for the Department of Defense. Its crew consisted of Commander David Walker, Robert Cabana, Guion Bluford (final flight), Michael Clifford (first flight), and James Voss.

One of the unclassified payload was the Orbital Debris Radar Calibration Spheres (ODERACS), which put objects of known size and shape into orbit.  The experiment was used to calibrate radars and telescopes for measuring orbital debris.

The crew returned to Earth December 9.

Happy birthday, Atlantis astronaut Thomas J. Hennen!

Thomas John Hennen, born August 17, 1952 in Albany, Georgia, went into space aboard Space Shuttle Atlantis (STS-44), a Department of Defense mission in November 1991.  Hennen is the first Warrant Officer within the US Army and Department of Defense to have been selected as a member of a Space Shuttle crew.

He spent almost 7 days in space and completed 10 orbits.  He retired from the Army in December 1995 and lives in Houston, Texas.

David Walker, Space Shuttle astronaut, born 1944

David Walker, born May 20, 1944 in Columbus, Georgia, is a veteran of four space shuttle flights.

His first flight was aboard Discovery (STS-51-A) as pilot in November 1984.  The flight recovered two satellites.

His second flight was aboard Atlantis (STS-30) as commander in May 1989.  The primary objective of the mission was to deploy the Magellan spacecraft to Venus.

His third flight was aboard Discovery (STS-53) as commander in December 1992.  It was a mission dedicated to the US Department of Defense.

His fourth and final flight was aboard Endeavour (STS-69) as commander in September 1995.  It was the second flight of the Wake Shield Facility.

He passed away from cancer in April 2001.

Happy birthday, Space Shuttle astronaut Frank Culbertson!

Frank Culbertson, born May 15, 1949 in Charleston, South Carolina, has been in space three times, and is the only American not on Earth during the 9/11 terrorist attacks.

His first flight was aboard Atlantis (STS-38) as pilot in November 1990.  The mission carried a classified payload for the Department of Defense.

His second flight was aboard Discovery (STS-51) as commander in September 1993.  The astronauts were filmed by a camera crew from the United Kingdom and the documentary was released as Space Shuttle Discovery.

His third and final flight was aboard Discovery (STS-105), launched in August 2001 as mission specialist to the International Space Station.  He was commander of the ISS during Expedition 3.  He conducted one space walk with fellow astronaut Vladimir Dezhurov for just over 5 hours.  He returned to Earth on Endeavour (STS-108) in December 2001.

Happy birthday, Space Shuttle astronaut Blaine Hammond!

Blaine Hammond, born January 16, 1952 in Savannah, Georgia, has been in space twice.  He became a pilot and an instructor in the US Air Force.

His first mission was aboard Discovery (STS-39) as pilot in April-May 1991.  Its main purpose was dedicated to the Department of Defense.

His second and last flight was aboard Discovery (STS-64) as pilot in September 1994.  The mission was the first untethered EVA in 10 years.

He spent over 19 days in space.

Happy birthday, Space Shuttle astronaut Guy Gardner!

Guy Gardner, born January 6, 1948 in Altavista, Virginia, is a veteran of two space flights.  He has been a test pilot and pilot instructor for the US Air Force and attained the rank of colonel.

His first trip was aboard Atlantis (STS-27) as pilot in December 1988.  It was a mission for the Department of Defense.

His second and final trip was aboard Columbia (STS-35) as pilot in December 1990.  The mission was dedicated to astronomical observations with ASTRO-1.