February 4


4 February 1906


Clyde W. Tombaugh in Flagstaff, Arizona, 1931

American astronomer Clyde William Tombaugh was born in Streator, Illinois, on February 4, 1906. He was raised on farms in Kansas and became interested in astronomy as a boy. In 1926, at the age of 20, Tombaugh built his first telescope. Using his homemade telescopes, he made drawings of the planets Mars and Jupiter and sent them to Lowell Observatory in Flagstaff, Arizona. The astronomers at Lowell were so impressed with the young amateur’s powers of observation, they invited him to work at the observatory. Tombaugh worked there from 1929 to 1945.

   Vesto Melvin Slipher (1875–1969), director of the observatory, commissioned Tombaugh to resume the search for Planet X, which had previously been led by Percival Lowell (1855–1916), founder of the Lowell Observatory. Tombaugh's task was to systematically image the night sky in pairs of photographs, then examine each pair and determine whether any objects had shifted position using a blink comparator. Tombaugh’s search had been underway for 10 months before he found Pluto on plates exposed on January 23 and 29 and blinked on February 18, 1930. The discovery was announced on March 13, 1930. At the time of discovery, Pluto was considered the planet, but was reclassified as a dwarf planet in 2006.

   In 1932, Tombaugh entered the University of Kansas, where he earned his bachelor of science degree in 1936. He continued to work at Lowell Observatory and in 1938 received a master’s degree from the University of Kansas. Tombaugh also discovered 15 asteroids, a comet, and hundreds of variable stars, star clusters and galaxy clusters. He worked on the captured V-2 rockets at White Sands, and became professor at New Mexico State University, where he confirmed the rotation period of Mercury on its axis, determined the vortex nature of Jupiter’s Great Red Spot, and looked for small, natural Earth satellites. He died on January 17, 1997.

Discovery images of Pluto. Credit: Lowell Observatory

Clyde Tombaugh circa 1930 at his family's farm with his homemade telescope


© 2026, Andrew Mirecki



4 February 1961


1VA No. 1 spacecraft. Credit: Roscosmos

Soviet 1VA No. 1 probe, the first attempt to send a spacecraft to Venus, was launched on February 4, 1961. Due to a problem with the fourth stage of the launch vehicle, it failed to leave low Earth orbit and on February 26, the spacecraft reentered the Earth's atmosphere. In order to avoid acknowledging the failure, the Soviet press instead announced that the entire spacecraft, including the upper stage, was a test of a "Heavy Satellite" which would serve as a launch platform for future missions. It was officially named Tyazhely Sputnik (Russian: Тяжёлый спутник, meaning Heavy Satellite).

1VA No. 1 probe. Credit: Roscosmos

Full Description

   This was the first attempt to send a spacecraft to Venus. Original intentions had been to send the 1V spacecraft to descend and take pictures of the Venusian surface, but this proved to be far too ambitious a goal. Engineers instead downgraded the mission and used the 1VA spacecraft for a simple Venus atmospheric entry and impact. The probe carried a 3-axis magnetometer, a variometer (vertical speed indicator), and charged particle monitors. It also carried a small globe which held medallions and other commemorations of the mission.

   The 1VA was essentially a modified 1M spacecraft used for Martian exploration (albeit with a different main engine). It had a mass of about 645 kg. It was also the first Soviet mission to use an intermediate Earth orbit to launch a spacecraft into interplanetary space. 

   Although the Molniya 8K78 launch vehicle successfully placed the probe into Earth orbit, the fourth stage (the Blok L) never fired to send the spacecraft to Venus. A subsequent investigation showed that there had been a failure in the PT-200 DC transformer that ensured power supply to the Blok L guidance system. The part had evidently not been designed for work in vacuum. The spacecraft and the upper stage stack remained attached in a 212 x 318 km, 64.95 degree inclination, 89.8 minute Earth orbit and reentered on February 26, 1961. The Soviets announced the total weight of the combination as 6,483 kilograms without specifying any difference between the payload and the upper stage. 

See also: Venera 1


© 2026, Andrew Mirecki


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