Explorer 49

Launch data: Designation  06686 / 73039A Launch date  10 June 1973 - 14:13 UT Launch site  CC, LC-17B Launch vehicle  Delta-1913 (#581/D95) Mission   Selenocentric orbit on 1973 Jun 15.31: Periselene / Aposelene  1120 x 1331 km Eccentricity  0.036 Inclination  38.26° Period  241 min Selenocentric orbit on 1974 Aug 14: Periselene / Aposelene  1051 x 1077 km Eccentricity  0.005 Inclination  55.34° Period  221.9 min Selenocentric orbit on 1975 Sep 01.0: Periselene / Aposelene  1020 x 1109 km Eccentricity  0.016 Inclination  76.2° Period  222.0 min

Spacecraft data: Prime contractor   Customer   Platform   Mass at launch  328 kg Dry Mass  200 kg Basic shape  Cylinder + booms Dimension  0.79 long - 0.92 dia Solar array   Stabilization   DC power   Design lifetime  In lunar orbit

Mission details:

• Explorer 49 was to be placed into lunar orbit in order to be able to use the Moon as a shield against radio interference from Earth as it listened for radio emissions from the rest of our solar system, the galaxy and beyond.
• The spacecraft achieved lunar orbit and was used successfully to study low-frequency radio emissions from sources including the Sun, Jupiter, the galaxy and extra-galactic sources.
• With its vast antenna array, Explorer 49 was the largest (in physical dimensions) lunar orbiter of the 20th century.
• Last contact with the spacecraft was in August 1977

External links:

• NASA: NASA report: "NASA-TM-X-70844"
• Satellite tracking (n2ya.com): Real time satellite tracking