Space Probes

The beginning of the Space Race between the United States and Soviet Union started with Sputnik 1 was the first probe to go into space. It was launched on Oct. 4, 1957, by the former Soviet Union. On Jan. 31, 1958, the United States sent a probe called Explorer 1 into space. Once probes could reach space, the two countries started sending probes to fly past the moon and other planets. Mariner 2 was the first probe to study another planet. On Dec. 14, 1962, Mariner 2 flew past the planet Venus. It confirmed that Venus is very hot. A different probe, called Mariner 4, was the first probe to snap a picture of a planet. On July 14, 1965, Mariner 4 flew past Mars. Its images of Mars showed a cold, cratered, moon-like surface. In 1971, Mariner 9 arrived at Mars and became the first probe to orbit, or circle, another planet. Mariner 9 took a picture of Mars that showed the largest volcano in the solar system.

Luna 20 (or Lunik 20) is a Soviet space probe launched on February 14,1972; The main objective of the Luna 20 mission was to return a sample of the lunar soil to Earth. This is the eighth probe in the Luna program to attempt to bring back a lunar sample. On 18 February, three days after placing itself on a circular lunar orbit of 100 km it landed unhindered on 21 February 1972 . A 55 gram sample of lunar soil was taken from a stretch arm equipped with a drill and placed in a sealed capsule. The lift stage was then ignited on February 22nd, The capsule was recovered by the Soviets on 25 February 1972.

The Luna 21 mission embarking the rover Lunokhod 2 was launched on 8 January 1973. Here again, the mission is carried out in a nominal way: the rover travels 37 km and survives for 5 months.

The Luna 21 spacecraft landed on the Moon and deployed the second Soviet lunar rover (Lunokhod 2). The primary objectives of the mission were to collect images of the lunar surface and examine ambient light levels to determine the feasibility of astronomical observations from the Moon.

Lunokhod 2 was equipped with three TV cameras, one mounted high on the rover for navigation, which could return high resolution images at different rates (3.2, 5.7, 10.9 or 21.1 seconds per frame). These images were used by a five-man team of controllers on Earth who sent driving commands to the rover in real time. After landing, the Lunokhod 2 took TV images of the surrounding area, then rolled down a ramp to the surface at 01:14 UT on 16 January and took pictures of the Luna 21 lander and landing site. It stopped and charged batteries until 18 January, took more images of the lander and landing site, and then set out over the Moon. The rover would run during the lunar day, stopping occasionally to recharge its batteries via the solar panels. At night the rover would hibernate until the next sunrise, heated by the radioactive source. Lunokhod 2 operated for about 4 months, covered 37 km of terrain including hilly upland areas and rilles, and sent back 86 panoramic images and over 80,000 TV pictures.

The Viking program is a NASA space program that placed the first American spacecraft on Martian soil. Within the framework of this program, two identical space probes, Viking 1 and Viking 2, were launched in 1974 one month apart. Each of these missions included a spacecraft intended to orbit the planet and a module that would land on the ground and conduct investigations while remaining stationary. The scientific objectives were to produce high-resolution images of the planet's surface, determine the structure and composition of the atmosphere and eventually identify the presence of life on Mars.

The Viking program remains to date the most ambitious and expensive of the missions sent to Mars with a budget of US$3.8 billion (updated to 2014). The various modules that make up the Viking program have been running for 1 to 6 years. Viking space probes discovered that many geological formations on the surface of Mars had been formed by the action of water. On the other hand, despite the use of sophisticated analytical instruments, it was not possible to determine whether life forms were present in the Martian soil.

Voyager 1 is one of two twin space probes in NASA's Voyager space program launched on September 5,1977 to study the outer planets of the Solar System that had previously been observed only through telescopes on Earth. This mission is made possible by an exceptional alignment of the outer planets that occurs only every 176 years. The main objective of Voyager 1 is to collect data on the Jupiter and Saturn systems with particular emphasis on the main moon of the latter, Titan. Voyager 1, with its twin probe, is the source of a large number of discoveries on the Solar System that sometimes call into question or refine existing theoretical models. As such, it is one of the American Space Agency's most successful space missions. Among the most remarkable results are the complex functioning of the Jupiter Great Red Spot, the first observation of Jupiter rings, the discovery of Io volcanism, the strange structure of the European surface, the composition of Titan's atmosphere, the unexpected structure of Saturn rings, and the discovery of several small moons of Jupiter and Saturn.

The space probe has a long lifespan and still has operational instruments in place by 2015 to collect scientific data on the environment it passes through. In August 2012, it left the heliosphere - the region of space under the magnetic influence of the Sun - and is now progressing in the interstellar medium. Starting in 2020, however, the instruments will have to be phased out gradually to cope with the weakening of its electric power source, supplied by three thermoelectric radioisotope generators due to the distance from the Sun. Voyager 1 will no longer be able to transmit data beyond 2025.

Voyager 2 is one of two space probes in the Voyager program. It was launched on 20 August 1977. Like Voyager 1, it was designed and built at the Jet Propulsion Laboratory near Pasadena, California. Technically identical to Voyager 1, Voyager 2 was launched on a slower and more curved trajectory, keeping it in the ecliptic plane (where the planets of the Solar System are located). Thus, it was able to be directed towards Uranus and Neptune using gravitational assistance during overflights of Saturn in 1981 and Uranus in 1986. Because of the chosen trajectory, Voyager 2 could not get as close as Voyager 1 from Titan, Saturn's largest satellite. However, it is today the only spacecraft to have approached Uranus and Neptune and flew over them. The particular configuration of the four giant planets that made their flight possible only happens every 176 years.