- noun (written as MARS)a computer network used by member countries of the EU and OECD for reporting and exchanging information on serious industrial accidents in a standard format.
- The fourth planet of the Solar System, orbiting the Sun at an average distance of 228 million km in an orbit taking 687 days. Mars is accompanied by two small satellites, Phobos and Diemos. It rotates on its axis in about half an hour longer than the Earth, and has white polar caps reminiscent of the Earth’s. But Mars is unlike the Earth in several key ways. It is far colder, with about 15° the warmest summer surface temperature at the equator. It also has far less atmosphere, with a surface pressure of 0.7 per cent that of the Earth, and its atmosphere consists mostly of carbon dioxide, with only small amounts of oxygen, nitrogen, water vapour, argon and other constituents. It is possible that the martian atmosphere has been steadily declining in pressure, with carbon dioxide and water being removed from it without the recycling machinery available on the Earth to place it back in the atmosphere later. They would then be trapped within the planet as ices, and their removal would cool the planet as their greenhouse effect was diminished. The martian atmosphere is dense enough, however, to sustain large dust storms which periodically make the surface all but invisible from space. The planet itself seems to be geologically inactive but the surface exhibits large extinct volcanoes and erosional features showing that there has been liquid water on Mars massively beyond the amounts of water now visible there. The surface of Mars exhibits two main types of terrain. The northern hemisphere is dominated by cratered plains’ below the average martian ‘sea level’, while the southern has more craters, is older, and stands 1–3km above the general level of the Martian surface. Mars has about 10 per cent the mass of the Earth, making it about twice the size of Mercury but distinctly smaller than Venus or the Earth, and has an equatorial radius of 3398km, half that of the Earth. Its average density is 3.94 gm/cc, compared to 5.52 for the Earth. Over the years, much effort has been expended on searching for life on Mars. It seems almost certain that the first humans to land on Mars will also be the first living things on the surface of the red planet.
- Series of Soviet spacecraft sent to one of the planets of the solar system between 1962 and 1973
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