Mariner 1

Mariner 1
	Mariner 1 is identical in design with Mariner 2
Mission type	Venus flyby
Operator	NASA / JPL
Mission duration	4 minutes and 54 seconds; Failed to orbit
Spacecraft properties
Spacecraft type	Ranger Block I
Manufacturer	Jet Propulsion Laboratory
Launch mass	202.8 kilograms (447 lb)
Start of mission
Launch date	July 22, 1962, 09:21:23 GMT
Rocket	Atlas LV-3 Agena-B
Launch site	Cape Canaveral, LC-12
End of mission
Disposal	Launch failure
Destroyed	July 22, 1962, 09:26:17.5 GMT
	Mariner program Mariner 2 →

Mariner 1, built to conduct the first American planetary flyby of Venus, was the first spacecraft of NASA's interplanetary Mariner program. Developed by Jet Propulsion Laboratory, and originally planned to be a purpose-built probe launched summer 1962, Mariner 1's design was changed when the Centaur proved unavailable at that early date. Mariner 1 (and its sibling spacecraft, Mariner 2), were then adapted from the lighter Ranger lunar spacecraft. Mariner 1 carried a suite of experiments to determine the temperature of Venus as well to measure magnetic fields and charged particles near the planet and in interplanetary space.

Mariner 1 was launched by an Atlas-Agena rocket from Cape Canaveral's Pad 12 on July 22, 1962. Shortly after liftoff, errors in communication between the rocket and its ground-based guidance systems caused the rocket to veer off course, and it had to be destroyed by range safety. The errors were traced to a mistake in a specification of the hand-written guidance equations which were then subsequently codified in the computer program.