REFERAT-MenüDeutschGeographieGeschichteChemieBiographienElektronik
  EnglischEpochenFranzösischBiologieInformatikItalienisch
  KunstLateinLiteraturMathematikMusikPhilosophie
 PhysikPolitikPsychologieRechtSonstigeSpanisch
 SportTechnikWirtschaftWirtschaftskunde  

Space




Space

1        Space - History

1.1        A dream

On October 4, 1957, the USSR blindsided the United States in what was called a 'technological Pearl Harbor' with the launch of Sputnik I, the first man-made earth orbiting satellite. The satellite was of little scientific value but was of a big one political. Circling the earth roughly every 90 minutes, its beeping radio signal shocked the U.S. and the world. This was followed closely by Sputnik II on November 3, 1957, which carried a dog named Laika, the first live organism launched into space. Although she died when her oxygen ran out, the flight did bring back scientific data on the effects of weightlessness and space travel on a living animal.

It wasn't until January 31, 1958 that Explorer I, America's first satellite, was launched on top of a version of the Redstone rocket, known as the Jupiter C. On board was an important scientific experiment of James A. Van Allen and it discovered the radiation belts around the earth. These belts were later named after him. The U.S. had finally entered the space race but had a lot of catching up to do.



1.2        Project Mercury

Project Mercury began on October 7, 1958, one year and three days after the Soviet Union launched Sputnik 1 and was the United States' first manned space program. The objectives of the program, which was made up of six manned flights from 1961 to 1963 were specifically: 1) to orbit a manned spacecraft around Earth, 2) to investigate man's ability to function in space and 3) to recover both man and spacecraft safely. However, three weeks after Alan Shepard's first U.S. human suborbital flight, on May 5, 1961, and with only 15 minutes of U.S. space flight experience, President John F. Kennedy announced the goal of landing a man on the moon before the end of the decade. Project Mercury was America's first 'small steps' toward that 'Giant Leap for mankind.'

1.3        Gemini

Project Gemini was a transitional step between the pioneering Mercury Program and the actual landing a man on the moon. Its success was critical to achieve the goal of reaching the Moon and was not without its problems and difficulties. The main objectives of the ten Gemini missions spanning a period of 20 months from 1965 to 1966, were to learn how to 'fly' a spacecraft by 1) maneuvering it in orbit and by 2) rendezvousing and docking with other vehicles, which were essential skills for the later Apollo missions. One of these missions, Gemini VIII, nearly killed the man who would go on to be the first person to walk on the moon, Neil Armstrong.


1.4        Houston, we have a problem.

The Apollo Program began with a tragedy, when fire swept through a Block One Apollo spacecraft on January 27, 1967 killing Virgil I. 'Gus' Grissom, Edward White, and Roger Chaffee during a 'plugs out' test on the pad. The subsequent redesign produced a safer and superior spacecraft for the 45 astronauts that flew in them from Apollo 7 in October of 1968 to Apollo-Soyuz in July of 1975. All in all, twelve men, starting with Neil Armstrong and ending with Eugene Cernan, walked on the moon before Apollo was completed. The first man on the moon was Neil Armstrong on the 20th of July in 1969 being carried to glory by Apollo 11.

2        Mars - The Red Planet

2.1        Introduction

Mars is the fourth planet from the sun and sixth largest planet, named after the Roman god of war. Mars weighs 0.64185*1024 kg (earth: 5.9736*1024 kg), its volume is 16.318*1010 km3 (earth: 108.321*1010 km3), the radius (measured at the equator) is 3397km (earth: 6378.1km) and the Surface gravity is 3.69 m/s2 (earth: 9.78m/s2). One Day on Mars is 24.6229 hours long.

Mars has two small moons, Phobos and Deimos. Phobos is about 22.4 km diameter, Deimos about 12.2 km.

2.2        Appearance from Earth

Viewed without a telescope, Mars is reddish and varies in brightness. When closest to Earth, Mars is the second-brightest planet in the night sky, after Venus. A telescope shows Mars to have bright orange regions and darker, less red areas. The reddish color results from its rusted surface. The brighter areas seem to contain more dust-sized particles than do the dark regions. Yellow dust clouds are often extensive.

Bright caps mark the planet's polar regions. Each autumn, clouds form over the cooling pole. Carbon dioxide frost is deposited during autumn and winter. By late winter, the cap may extend down to latitudes of 45°. In spring the clouds scatter, and the cap recedes poleward as sunlight evaporates the frost. Some frost and ice, believed to be mostly frozen water, lasts through out the summer.

2.3        Atmosphere

The Mars' atmosphere mainly consists of Carbon Dioxide (CO2) (95.32%) and Nitrogen (N2) (2.7%). There are only 0.13% Oxygen (O2) and trace amounts of other gases



Daily temperature variations of 100° C are common, because the atmosphere is very thin. The average temperature is about ~210 K.

The amount of water vapor present in the atmosphere is slight. Mars is like a very cold, high-altitude desert. Temperatures are mostly too cold and pressures too low for liquid water, but liquid water may exist just below the surface in a few places.


2.4        Surface and Interior

The southern half of the Martian surface is cratered terrain dating from earliest times, when Mars and the other planets were subjected to intense meteoroidal bombardment. The northern half is younger terrain, believed to be ancient volcanic flows.

The most spectacular geologic features on Mars are channels resembling the valleys of dried-up rivers. Less compelling but possible evidence for erosion by liquid water.

The low average density of Mars indicates that it cannot have an extensive metallic core. Any core that may be present is probably not fluid, because Mars does not have a measurable magnetic field. The crust of Mars may be as thick as 200 km (five or six times as thick as earth's crust).

2.5        The Search for Life

In 1877 Italian astronomer Giovanni Schiaparelli claimed to have seen a planet wide system of channels on Mars. Spacecraft observations have shown that there are no canals on Mars. The strongest evidence against the presence of life is the thin atmosphere and the fact that the surface of the planet is exposed not only to lethal doses of ultraviolet radiation but also to highly reactive substances. In 1996, however, scientists announced the discovery of possible evidence of primitive life on Mars inside a meteorite that collided with Earth about 13,000 years ago. In 1997 the Mars Pathfinder spacecraft landed on the planet.

2.6        Mars Probes

1964 "Mariner 4" was the first probe that reached Mars. It was the second try of the NASA. Mariner 4 sent 650 kilobytes of data back to earth, including the first black/white pictures of Mars' surface.

In 1965 the Soviet Union's first successful mission was the "Zond 3" probe which was launched from an earth orbiting platform and was the first probe ever with electro jet plasma ion engines. The probe still sent data from a distance of 31,500.000 km! Before that great success 6 missions had failed since 1960.

In 1975 the US launched the Viking 1 and 2 probe, each consisting of an orbiter and a lander. The two orbiters imaged the whole planet. Viking 1 powered down mid 1980 after 1400 orbits. The landers ended communications in 1980 (Viking 2) and 1982 (Viking 1).

In 1988 NASA launched Phobos 1 and 2. Phobos 1 had a software error which caused the probe to orient the solar arrays away from the sun; communication was lost on September 2nd in 1988. Phobos 2 worked till it had to release two landers and a stationary platform 50m above Phobos' surface.

NASA's Pathfinder mission was a great success in 1996. The rover called "Sojourner" analyzed a lot of rock samples and the orbiter "Global Surveyor" is still orbiting Mars.

In 1998 Japan launched the Nozomi probe, which is now parked in an earth orbit, because a maneuver in space had used too much fuel. The probe will start off to Mars in 2003 when Mars is near to Earth.

The NASA is planning a mission for 2005 called "Mars Surveyor 2005". A probe will take a lander with a rover to Mars, the rover will collect rock samples, which will be returned back to Earth! The samples are expected to arrive back "home" in 2008.


3        Science Fiction and Reality

3.1        The need to exceed light speed

Simply put, the universe is big. The fastest thing known is light, yet it takes over four years for light to reach our nearest neighboring star. When NASA's Voyager spacecraft left our solar system is was traveling around 37- thousand mph. At that rate it couldn't reach the nearest star until after 80-thousand years. If we want to cruise to other stars within comfortable time spans (say, less than a term in Congress), we have to figure out a way to go faster than light.




3.2        The need to manipulate mass and spacetime coupling

This need is less obvious than the light speed issue. The problem is fuel, or more specifically, rocket propellant. Unlike a car that has the road to push against, or an airplane that has the air to push against, rockets don't have roads or air in space. Rockets have to carry along all the mass that they will need to push against. To circumvent this problem, we need to find a way to interact with spacetime itself to induce propulsive forces without using propellant. This implies that we will need to find a way to alter a vehicle's inertia, its gravitational field, or its connectivity to the structure of spacetime itself.

Just how limited are rockets for interstellar travel? Although rockets are reasonable for journeys into orbit or to the moon, they become unreasonable for interstellar travel. If you want to deliver a modest size payload, say a full Shuttle cargo (20,000 kg), and you are patient enough to wait 900 years for it to just fly by the nearest star, here's how much propellant you will need: If you use a rocket like on the Shuttle (Isp~ 500s), there isn't enough mass in the universe to get you there. If you use a nuclear fission rocket (Isp~ 5,000s) you need about a billion super-tankers of propellant. If you use a nuclear fusion rocket (Isp~ 10,000s) you only need about a thousand super-tankers. And if you assume that you'll have a super-duper Ion or Antimatter rocket (Isp~ 50,000s), well now you only need about ten railway tankers. It gets even worse if you want to get there sooner. (Based on mass fractions from ref 1, p. 52)

3.3        Energy: - yet another challenge

Our big challenge is energy. Even if we had a nonrocket space drive that could convert energy directly into motion without propellant, it would still require a lot of energy. Sending a Shuttle-sized vehicle on a 50 year one-way trip to visit our nearest neighboring star (subrelativistic speed) would take over 7 x 10^19 Joules of energy. This is roughly the same amount of energy that the Space Shuttle's engines would use if they ran continuously for the same duration of 50 years. To overcome this difficulty, we need either a breakthrough where we can take advantage of the energy in the space vacuum, a breakthrough in energy production physics, or a breakthrough where the laws of kinetic energy don't apply.

3.4        What are black holes?

When a star collapses and becomes super dense, its gravity becomes so strong that light can't even escape. That is why it is black - no light. Although they are considered to be real, there is still room for debate on whether they really exist.

 Black holes are deep wells in the fabric of space and time. They have such immense gravity that nothing, not even light, can escape them. This makes studying black holes difficult - how can you see something when it does not emit or reflect any form of energy? A black hole seems to be the study of the invisible.

3.5        Are Wormholes real?

That is still completely unknown. Wormholes are just theoretical constructs, and we are still not sure if the theories are correct. Astronomical searchers are under way to look for evidence of wormholes, but nothing has been found.

3.6        Status of 'Warp Drive'

'Warp Drives', 'Hyperspace Drives', or any other term for Faster-than-light travel is at the level of speculation, with some facets edging into the realm of science. We are at the point where we know what we do know and know what we don't, but do not know for sure if faster than light travel is possible.










Haupt | Fügen Sie Referat | Kontakt | Impressum | Datenschutz







Neu artikel