Mercury is the first planet from the Sun and the smallest planet in the Solar System. It is a terrestrial planet with a heavily cratered surface due to the planet having no geological activity and an extremely tenuous atmosphere. Despite being the smallest planet in the Solar System with a mean diameter of 4,880 km (3,030 mi), 38% of that of Earth's, Mercury is dense enough to have roughly the same surface gravity as Mars. Mercury has a dynamic magnetic field with a strength about 1% of that of Earth's and has no natural satellites.
The Mariner program was conducted by the American space agency NASA to explore other planets. Between 1962 and late 1973, NASA's Jet Propulsion Laboratory (JPL) designed and built 10 robotic interplanetary probes named Mariner to explore the inner Solar System - visiting the planets Venus, Mars and Mercury for the first time, and returning to Venus and Mars for additional close observations.
Space exploration is the use of astronomy and space technology to explore outer space. While the exploration of space is carried out mainly by astronomers with telescopes, its physical exploration is conducted both by uncrewed robotic space probes and human spaceflight. Space exploration, like its classical form astronomy, is one of the main sources for space science.
Mariner 9 was a robotic spacecraft that contributed greatly to the exploration of Mars and was part of the NASA Mariner program. Mariner 9 was launched toward Mars on May 30, 1971, from LC-36B at Cape Canaveral Air Force Station, Florida, and reached the planet on November 14 of the same year, becoming the first spacecraft to orbit another planet – only narrowly beating the Soviet probes Mars 2 and Mars 3, which both arrived at Mars only weeks later.
The Mars 2 was an uncrewed space probe of the Mars program, a series of uncrewed Mars landers and orbiters launched by the Soviet Union beginning 19 May 1971. The Mars 2 and Mars 3 missions consisted of identical spacecraft, each with an orbiter and an attached lander. The orbiter is identical to the Venera 9 bus. The type of bus/orbiter is the 4MV. They were launched by a Proton-K heavy launch vehicle with a Blok D upper stage. The lander of Mars 2 became the first human-made object to reach the surface of Mars, although the landing system failed and the lander was lost.
Mars 3 was a robotic space probe of the Soviet Mars program, launched May 28, 1971, nine days after its twin spacecraft Mars 2. The probes were identical robotic spacecraft launched by Proton-K rockets with a Blok D upper stage, each consisting of an orbiter and an attached lander. After the Mars 2 lander crashed on the Martian surface, the Mars 3 lander became the first spacecraft to attain a soft landing on Mars, on December 2, 1971. It failed 110 seconds after landing, having transmitted only a gray image with no details. The Mars 2 orbiter and Mars 3 orbiter continued to circle Mars and transmit images back to Earth for another eight months.
The Voyager Mars Program was a planned series of uncrewed NASA probes to the planet Mars. The missions were planned, as part of the Apollo Applications Program, between 1966 and 1968 and were scheduled for launch in 1974–75. The probes were conceived as precursors for a crewed Mars landing in the 1980s.
The planet Mars has been explored remotely by spacecraft. Probes sent from Earth, beginning in the late 20th century, have yielded a large increase in knowledge about the Martian system, focused primarily on understanding its geology and habitability potential. Engineering interplanetary journeys is complicated and the exploration of Mars has experienced a high failure rate, especially the early attempts. Roughly sixty percent of all spacecraft destined for Mars failed before completing their missions and some failed before their observations could begin. Some missions have met with unexpected success, such as the twin Mars Exploration Rovers, Spirit and Opportunity which operated for years beyond their specification.
Kosmos 419, also known as 3MS No.170 was a failed Soviet spacecraft intended to visit Mars. The spacecraft was launched on 10 May 1971, however due to an upper stage malfunction it failed to depart low Earth orbit.
Mars is the fourth planet and the furthest terrestrial planet from the Sun. The reddish color of its surface is due to finely grained iron(III) oxide dust in the soil, giving it the nickname "the Red Planet". There is a sharp contrast between the two Martian hemispheres: the northern hemisphere is on average flatter and smoother than the southern hemisphere. The planet's two poles are covered by water and carbon dioxide ice caps. Surrounding the Martian surface is a dynamic thin atmosphere, made primarily of carbon dioxide. Mars has two irregularly shaped natural satellites, Phobos and Deimos.
A Mars flyby is a movement of spacecraft passing in the vicinity of the planet Mars, but not entering orbit or landing on it. Uncrewed space probes have used this method to collect data on Mars, as opposed to orbiting or landing. A spacecraft designed for a flyby is also known as a "flyby bus" or "flyby spacecraft".
A flyby is a spaceflight operation in which a spacecraft passes in proximity to another body, usually a target of its space exploration mission and/or a source of a gravity assist to impel it towards another target. Spacecraft which are specifically designed for this purpose are known as flyby spacecraft, although the term has also been used in regard to asteroid flybys of Earth for example. Important parameters are the time and distance of closest approach.
The following outline is provided as an overview of and topical guide to Mars:
Mars and the Mind of Man is a non-fiction book chronicling a public symposium at the California Institute of Technology on November 12, 1971. The panel consisted of five luminaries of science, literature, and journalism: Ray Bradbury; Arthur C. Clarke; Bruce C. Murray; Carl Sagan and Walter Sullivan. These five are the authors of this book. The symposium occurred shortly before the Mariner 9 space probe entered orbit around Mars. The book was published in 1973 by Harper and Row of New York.
In modern times, numerous impact events on Mars have been detected. Although most have been inferred from the appearance of new impact craters on the planet, some have corresponded to marsquakes felt by the InSight lander. To date, no impacting meteors have been directly observed as a fireball or discovered in space before impact.
