Венераға ұшқан алғашқы американдық ғарыш кемесі: Mariner-1 миссиясы

1962 NASA unmanned mission to fly by Venus

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.

Three Mariner R spacecraft were built: two for launching and one to run tests, which was also to be used as a spare. silver zinc storage battery. Two more included the radio receiver, the three watt transmitter, and control systems for Mariner's experiments. The fifth case held electronics for digitizing the analog data received by the experiments for transmission. The sixth case carried the three gyroscopes that determined Mariner's orientation in space. It also held the central computer and sequencer, the "brain" of the spacecraft that coordinated all of its activities pursuant to code in its memory banks and on a schedule maintained by an electronic clock tuned into equipment on Earth. (but eventually disproven) hypothesis that the planet was tidally locked with respect to the Sun (as the Moon is with respect to the Earth). No oxygen had been detected in Venus' atmosphere, suggesting that life as existed on Earth was not present. It had been determined that Venus' atmosphere contained at least 500 times as much carbon dioxide as the Earth's. These comparatively high levels suggested that the planet might be subject to a runaway greenhouse effect with surface temperatures as high as , but this had not yet been conclusively determined. at the same time, the spacecraft could determine if there was a significant disparity between night and daytime temperatures.

The launch window for Mariner, constrained both by the orbital relationship of Earth and Venus and the limitations of the Atlas Agena, was determined to fall in the 51 day period between from July 22 through September 10. Only Cape Canaveral Launch Complex 12 was available for the launching of Atlas Agena rockets, and it took 24 days to ready an Atlas Agena for launch. This meant that there was only a 27 day margin for error for a two launch schedule. The hand written guidance equations contained the symbol "R" (for "radius"). This "R" should have had a line over it ("R bar" or R̄), denoting smoothing or averaging of the track data coming from an earlier calculation. But the bar was missing, and so the computer program based on those equations was incorrect. The error was in the original specification, and not in the process of writing the program. When lock was reestablished, however, the faulty guidance logic caused the program to erroneously report that the "velocity was fluctuating in an erratic and unpredictable manner", which the program tried to correct for, causing actual erratic behavior, which prompted the range safety officer to destroy the rocket. The incident underscored the importance of a thorough pre launch debugging of software as well as a need to engineer programs such that minor errors could not cause catastrophic failures. The procedures implemented as a result served NASA well, ultimately salvaging the Project Apollo Moon landings; though there were program errors in the Lunar Excursion Module software during descent, they did not cause mission failure. With the logic error quickly discovered, no undue delay was necessary. The identical Mariner 2 was already on hand, and a second launch from the same pad was manageable before the end of August. On August 27, 1962, Mariner 1's sister spacecraft was successfully launched, becoming on December 14, 1962, the first spacecraft to return data from the vicinity of Venus.