Spacecraft failure; first US lunar impact on 26 Apr 1962 after 64,01 hours flight.
Impact: 130,7° W, 15,5°S
Mass at launch
1,52 dia - 2,51 long
Technicians prepare the Ranger 4 spacecraft for launch.
Image Credit: Jet Propulsion Laboratory
Second Block II spacecraft to land a sphere relatively softly on the moon.
This time the launch vehicle worked well and Ranger-4 was put on the right
course for moon impact, but soon after the on-board timer failed to operate and
the first thing that this prevented was the solar panels deploying shortly after
2 hours into the mission. The batteries had run down completely by 10 hours and
the craft with its 10.5 kg capsule slammed into the moon after 64 hours at 9600
km/h at 15°30' S, 130°42' W being the US first lunar impact.
An impact absorbing sphere made of balsa wood sits atop the spacecraft, painted with a saw-tooth pattern to maintain thermal
balance during its mission to the Moon. The sphere contained a lunar seismometer, which was to rough land just south of the equator
on the rim of the Ocean of Storms and measure "lunarquakes."
The master clock in Ranger 4's computer failed during flight and the spacecraft did not respond to commands. It crashed into
the far side of the Moon on April 26, 1962. Despite the failure to return information, the use of balsa wood was an important
precursor in the design of other rough landings on extraterrestrial bodies, particularly Mars. Aerobraking, gliding, impact
absorption, parachuting, and retro rockets have all been considered.