— Ch. 1 · Cold War Space Race Origins —
Mariner 2.
~6 min read · Ch. 1 of 7
The United States and the Soviet Union raced to dominate space during the Cold War. Both superpowers launched ambitious programs to prove military, technological, and political superiority. The Soviets achieved a major milestone on the 4th of October 1957, when Sputnik 1 became the first Earth-orbiting satellite. American scientists followed with Explorer 1 on the 1st of February 1958. By that time, the Soviets had already sent Laika into orbit aboard Sputnik 2. After reaching Earth's orbit, focus shifted toward the Moon. Three Pioneer satellites failed in their lunar attempts during 1958. In early 1959, Luna 1 flew by the Moon for the first time. Luna 2 then became the first artificial object to impact the lunar surface. With the Moon conquered, attention turned to Venus as the next target. Venus offered an appealing interplanetary destination due to its proximity to Earth. Every 19 months, Earth and Venus align in orbits allowing minimum fuel consumption via Hohmann Transfer Orbits. These windows marked the best times to launch exploratory spacecraft. The first such opportunity occurred in late 1957 before either nation possessed the necessary technology. A second window around June 1959 lay just within technological feasibility. U.S. Air Force contractor Space Technology Laboratory planned to exploit this window. Their January 1959 draft involved two probes evolved from Pioneer satellites. One would launch via Thor-Able rocket while another used the untested Atlas-Able. Space Technology Laboratory could not complete the probes before June, missing the launch window. The Thor-Able probe later became Pioneer 5, launched the 11th of March 1960. No American missions were sent during the early 1961 opportunity. The Soviet Union launched Venera 1 on the 12th of February 1961. It became the first probe to fly by Venus but stopped transmitting on February 26.
Mariner R Development History
NASA contracted Jet Propulsion Laboratory in July 1960 to develop Mariner A. This spacecraft weighed approximately 340 kilograms and was designed for launch using the yet-undeveloped Atlas-Centaur vehicle. By August 1961, it became clear that the Centaur booster would not be ready in time. JPL proposed a lighter spacecraft using the less powerful but operational Atlas-Agena system. They suggested a hybrid combining Mariner A with JPL's Block 1 Ranger lunar explorer already under development. NASA accepted the proposal immediately. JPL began an eleven-month crash program to create what they called Mariner R. This designation reflected its status as a Ranger derivative. Three Mariner R spacecraft were built: two for launching and one for testing plus spare use. Serious developmental problems with the original Atlas-Centaur forced this switch to the smaller Agena B second stage. The design of these vehicles underwent great simplification compared to earlier plans. Far less instrumentation was carried than on Soviet Venera probes of this period. Engineers forgave TV cameras entirely because the Atlas-Agena B had only half the lift capacity of the Soviet 8K78 booster. Original plans called for probes launched on Atlas-Centaur before the switch occurred. The missions of Mariner 1 and Mariner 2 became known collectively as the Mariner R missions.