Mars (2177 words) Essay Example For Students

Mars (2177 words) Essay MarsMarsMars is the fourth planet from the sun and orbits the sun at a distance of about 141 million mi. Mars is named for the Roman god of war because it appears fiery red in the earths night sky. Mars is a small planet that has about half the diameter of Earth and about one-tenth Earths mass. The force of gravity on the surface of Mars is about one-third of that on Earth. Mars has twice the diameter and twice the surface gravity of Earths moon. The surface area of Mars is almost exactly the same as the surface area of the dry land on Earth. The Martian day, or the time it takes Mars to rotate once on its axis, is about a half an hour longer than an Earth day. Its year, or the time it takes to revolve once around the sun, is about two Earth years long. Mars has two moons, Phobos and Deimos. THE INTERIOR OF MARS Scientists believe that Marss interior consists of a crust, mantle, and core like Earths interior, but they do not know the relative sizes of these components. Because no spacecraft has ever brought instruments that can study Marss interior to the planet, the only real data that scientists have about the planets structure are its mass, size, and the structure of the gravity field. Compared to Earth, Mars probably has a relatively thick crust. Beneath the surface is an area of volcanic activity in the northern hemisphere, it may be as thick as 80 mi. Beneath the landing site of the United States spacecraft Viking 2, it may be as thin as 9 mi. The core is probably consists of mostly iron, with a small amount of nickel. Other light elements, mainly sulfur, could exist in the core also. If so, the core may be quite large. Mars does not have a significant magnetic field, so scientists believe that Marss core is probably solid. Mars does not, and probably did not ever, have active plate tectonics. Because Mars is so much smaller than Earth, it must cooled quickly after formation and the crust thickened, forming one solid piece and eliminating any possibility of plate tectonics as it was on and still is on Earth. Though the Martian crust is not broken into separate plates, Marss liquid mantle has sculpted the planets surface. The molten rock has broken through the crust to form volcanoes and its motion has cracked the crust to form large rifts. THE SURFACE OF MARS The surface of Mars would be a harsh place for humans, but it is more like the surface of Earth than any other planet. The temperature on Mars does not get much cooler than the temperature at Antarctica. At the surface it ranges from about -140? C to 15? C (about -225? F to 60? F). During most of the year wind speeds are normally low around 4.5 mph, but during dust storms they can approach 40 to 50 mph. These winds often originate in large basins i n the southern hemisphere and carry large volumes of dust from the basins to other regions, sometimes covering the entire planet in the storm. The dust is not sandy, as in a sandstorm on the earth, but has the consistency of flour. The northern and southern hemispheres of Mars have different characteristics. The southern hemisphere has many impact craters and has a generally much higher elevation than the northern hemisphere. The southern highlands are probably the oldest ground on Mars. The northern hemisphere of Mars contains a much wider variety of geologic features, including large volcanoes, a great rift valley, and a variety of channels. The northern hemisphere also contains large expanses of relatively featureless plains. Mars has the largest volcano in the solar system, Olympus Mons. It is 16 mi high (almost twice as high as the earths Mount Everest) and covers an area comparable to the state of Arizona. Near it, three other volcanoes almost as large-Arsia Mons, Pavonis Mons, and Ascraeus Mons-form a line running from southwest to northeast. These four volcanoes are the most noticeable features of a large bulge in the surface of Mars, called Tharsis. Another volcano, Alba Patera, is also part of the Tharsis bulge, but is quite different in appearance. It is probably less than 4 mi high, but has a diameter of 1000 mi. None of Marss volcanoes appear to be active. Los Angeles Politics EssayPast Space StationsOne past space station is Mir. Mir was a Russian space station designed to provide long-term accomodations for crewmembers while they orbit the earth. Mir was launched on Febraury 19, 1986. Crewmwmbers reached Mir aboard Soyuz spacecraft and, more more recently thtrough an American space program aboard a spaceshuttle. Mir was the first space station designed for expansion and was originally only a single module. Now Mir consists of seven modules. Mir replaced the Salyut series of space stations as the most important part of the Russian manned space program. The Salyut series of space stations were smaller and simpler stations that helped develop most of the technology needed to build Mir. The Mir space station is composed of seven modules that together weigh about 109,000 kg and are about 19 m long without any visiting spacecraft. The Mir core module is the control center and living quarters for the Mir station. The 20-ton module measures about 4.18 m in width and about 13 m in length. At each end of the main part is a hatch fitted to connect with other spacecraft called a docking port. The rear port leads through a tunnel into the living compartment, which contains a kitchen, exercise equipment, two sleeping compartments that are smaller than phone booths, and a toilet stall. Mirs first crew was Salyut 7 veterans Leonid Kizim and Vladimir Solovyov. They flew to the Mir core module in the Soyuz-T 15 spacecraft in March 1986 to activate and check Mirs systems. They undocked and flew to the abandoned Salyut 7 station to salvage scientific equipment and dropped off the recovered equipment at Mir. They returned to earth in July 1986. Mir flew unmanned until February 1987. Except for two short periods from July 1986 to February 1987 and from March 1989 to September 1989, Mir has been staffed without interruption. Normally, teams of two or three cosmonauts work on board in six-month shifts. There are, however, occasional exceptions. For example, medical doctor Valeri Polyakov set a new world space-endurance record by living on Mir for 438 days-long enough for a spacecraft to travel to Mars. During that time, Polyakov studied his bodys reactions to prolonged weightlessness. He returned to earth aboard Soyuz-TM 20 in March 1995. With him was Yelena Kondakova, the first woman to complete a long-duration stay in space. She lived aboard Mir for 168 days. Also in March 1995, U.S. astronaut Norman Thagard began a 114-day Mir flight, breaking the U.S. 84-day space-endurance record set on Skylab in 1974. Thagard reached Mir on Soyuz-TM 21 with cosmonauts Vladimir Dezhurov and Gennadi Strekalov. He returned to earth with his Russian crewmates on the space shuttle Atlantis, which docked with Mir for the first time on June 29, 1995. Since Thagards visit, six other U.S. astronauts have lived on Mir. German astronaut Thomas Reiter arrived at Mir aboard Soyuz-TM 22 in September 1995. He returned to earth in February 1996, after 179 days in space, having completed two space walks to install European instruments outside of the station. Mir was over a decade old when its career was nearing an end. In 1997 the station experienced a small fire, failure of the oxygen generation system, a temperature-control failure that made the living quarters uncomfortably warm, failures of Mirs main computer and navigation system, and a collision with a supply ship. None of the onboard cosmonauts and astronauts were hurt, but the incidents caused crew members and engineers to monitor the stations condition more closely. Just as scientific equipment from Salyut 7 was transferred to Mir, equipment from Mir will be transferred to Mirs planned follower ship, the International Space Station (ISS), at the end of Mirs career. Space shuttle missions to Mir ended in mid-1998 and the first component of ISS was scheduled for launch in late 1998. ISS was assembled in orbit from U.S., Russian, European, Japanese, and Canadian parts. BibliographyScience