Zond 1 was a member of the Soviet Zond program. It was the second Soviet research spacecraft to reach Venus, although communications had failed by that time. It carried a 90 cm spherical landing capsule, containing experiments for chemical analysis of the atmosphere, gamma-ray measurements of surface rocks, a photometer, temperature and pressure gauges, and a motion/rocking sensor in case it landed in water.
The spacecraft, a Venera 3MV-1, was launched on April 2, 1964 from Tyuratam. During the cruise phase, a slow leak from a cracked sensor window caused the spacecraft to depressurize. An ill-timed command from ground control turned on its radio system while there was still a rarefied atmosphere inside, causing the electronics to short out by corona discharge. Communication was subsequently maintained via the transmitter in the landing capsule, and space radiation and atomic-hydrogen spectrometer measurements were performed. However, all communications had failed by May 14. It passed 100,000 km from Venus on July 14, 1964.
Payloads are separated by bullets ( · ), launches by pipes ( | ). Manned flights are indicated in bold text. Uncatalogued launch failures are listed in italics. Payloads deployed from other spacecraft are denoted in brackets.