Information: - The Viking 2 mission was part of the American Viking program to Mars , and consisted of an orbiter and a lander essentially identical to that of the Viking 1 mission . The Viking 2 lander operated on the surface for 1316 days , or 1281 sols , and was turned off on April 11 , 1980 when its batteries failed . The orbiter worked until July 25 , 1978 , returning almost 16,000 images in 706 orbits around Mars . - The Moon is an astronomical body that orbits planet Earth, being Earth's only permanent natural satellite. It is the fifth-largest natural satellite in the Solar System, and the largest among planetary satellites relative to the size of the planet that it orbits (its primary). Following Jupiter's satellite Io, the Moon is second-densest satellite among those whose densities are known. - An atmosphere is a layer of gases surrounding a planet or other material body, that is held in place by the gravity of that body. An atmosphere is more likely to be retained if the gravity it is subject to is high and the temperature of the atmosphere is low. - The Solar System is the gravitationally bound system comprising the Sun and the objects that orbit it, either directly or indirectly. Of those objects that orbit the Sun directly, the largest eight are the planets, with the remainder being significantly smaller objects, such as dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly, the moons, two are larger than the smallest planet, Mercury. - Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, after Mercury. Named after the Roman god of war, it is often referred to as the "Red Planet" because the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the valleys, deserts, and polar ice caps of Earth. - Earth, otherwise known as the world, is the third planet from the Sun and the only object in the Universe known to harbor life. It is the densest planet in the Solar System and the largest of the four terrestrial planets. - A spacecraft is a vehicle, or machine designed to fly in outer space. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, space colonization, planetary exploration, and transportation of humans and cargo. - The Viking program consisted of a pair of American space probes sent to Mars, Viking 1 and Viking 2. Each spacecraft was composed of two main parts: an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface. The orbiters also served as communication relays for the landers once they touched down. - A polar ice cap or polar cap is a high-latitude region of a planet, dwarf planet, or natural satellite that is covered in ice. - Iron oxides are chemical compounds composed of iron and oxygen. All together, there are sixteen known iron oxides and oxyhydroxides. - An impact crater is an approximately circular depression in the surface of a planet, moon, or other solid body in the Solar System or elsewhere, formed by the hypervelocity impact of a smaller body. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain. Although Meteor Crater is perhaps the best-known example of a small impact crater on Earth, impact craters range from small, simple, bowl-shaped depressions to large, complex, multi-ringed impact basins. - A terrestrial planet, telluric planet, or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun, i.e. Mercury, Venus, Earth, and Mars. The terms "terrestrial planet" and "telluric planet" are derived from Latin words for Earth ("Terra" and "Tellus"), as these planets are, in terms of composition, "Earth-like". - In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet about a star or a natural satellite around a planet. Normally, orbit refers to a regularly repeating path around a body, although it may occasionally be used for a non recurring trajectory or a path around a point in space. To a close approximation, planets and satellites follow elliptical orbits, with the central mass being orbited at a focal point of the ellipse, as described by Kepler's laws of planetary motion. - The National Aeronautics and Space Administration (NASA ) is an independent agency of the executive branch of the United States federal government responsible for the civilian space program as well as aeronautics and aerospace research. - The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process.<ref name="doi10.1146/annurev-astro-081913-040012"></ref> It is by far the most important source of energy for life on Earth. Its diameter is about 109 times that of Earth, and its mass is about 330,000 times that of Earth, accounting for about 99.86% of the total mass of the Solar System. About three quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron. - A planet is an astronomical body orbiting a star or stellar remnant that The term "planet" is ancient, with ties to history, astrology, science, mythology, and religion. Several planets in the Solar System can be seen with the naked eye. These were regarded by many early cultures as divine, or as emissaries of deities. As scientific knowledge advanced, human perception of the planets changed, incorporating a number of disparate objects. In 2006, the International Astronomical Union (IAU) officially adopted a resolution defining planets within the Solar System. This definition is controversial because it excludes many objects of planetary mass based on where or what they orbit. Although eight of the planetary bodies discovered before 1950 remain "planets" under the modern definition, some celestial bodies, such as Ceres, Pallas, Juno and Vesta (each an object in the solar asteroid belt), and Pluto (the first trans-Neptunian object discovered), that were once considered planets by the scientific community, are no longer viewed as such. - An orbiter is a space probe that orbits a planet or other astronomical object. An orbiter can be either man-made, or created naturally. - Viking 1 was the first of two spacecraft (along with Viking 2) sent to Mars as part of NASA's Viking program. On July 20, 1976, it became the first spacecraft to land successfully on Mars and perform its mission. Viking 1 held the record for the longest Mars surface mission of days or sols until that record was broken by "Opportunity" on May 19, 2010. - A space probe is a robotic spacecraft that leaves Earth orbit and explores space. It may approach the Moon; enter interplanetary space; flyby, orbit, or land on other planetary bodies; or approach interstellar space. After reading the paragraphs above, we are interested in knowing the entity with which 'viking 2' exhibits the relationship of 'instance of'. Find the answer from the choices below. Choices: - 1 - 25 - administration - agency - april - asteroid - atmosphere - bowl - branch - chemical - communication - composition - definition - depression - dwarf - eight - energy - federal government - god - government - history - ice cap - impact crater - july - machine - mass - may - mission - motion - mythology - number - orbit - orbiter - oxide - part - path - photograph - physics - planet - point - polar ice cap - range - religion - result - science - size - space - space probe - spacecraft - sphere - star - study - system - temperature - terra - terrain - terrestrial planet - three - two - vehicle - war
The answer to this question is:
space probe