TIROS 1 was America's first-ever weather satellite. It was a breakthrough in modern meteorology, changing the way we view the Earth and how we collect data about the atmosphere. With Tiros 1, it was possible to observe for the first time that the Earth and the Earth's atmosphere are a single entity. It began the long series of TIROS satellites. Its successors were the ITOS and NOAA series. ¹⁾

Alexei Archipovich Leonov was a Soviet spaceman, major general pilot, twice Hero of the Soviet Union, Aviator Cosmonaut of the USSR. He flew into space twice. The first time from March 18 to March 19, 1965, in the spacecraft Voskhod 2, as co-pilot. During the flight, he was the first man to go into open space in a Bierkut type spacesuit. ²⁾

Salyut 1 was the first space station to orbit the Earth on April 14, 1971, and was part of a series of launches under the Soviet Salyut program. The original name of the station was Zarya (Russian: aurora). On June 6, 1971, the maneuver of merging Salyut 1 with Soyuz 11 was realized. The cosmonauts spent 23 days on the station. The entire crew disappeared during the entry into the atmosphere. ³⁾

The Armstrong Limit is the altitude at which atmospheric pressure is so low, 0.0618 atmospheres, that water begins to boil at human body temperature, 98.6° F. ⁴⁾

A few grams of plutonium is the simplest, lightest, and most reliable heat source. Such equipment is especially useful during missions beyond Mars orbit, where the amount of sunlight reaching the solar panels is negligible. ⁵⁾