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Mercury Report Essay, Research Paper
The magnificent planet Mercury is the planet I have chosen to research. I this report I have explained all there is to know about Mercury and its aura.
The Romans gave Mercury its name after the fleet-footed messenger of the gods because it seemed to move quicker than any other planet. It is the closest planet to the Sun, and second smallest planet in the solar system. Its diameter is 40% smaller than Earth and 40% larger than the Moon. It is even smaller than Jupiter’s moon Ganymede and Saturn’s moon Titan.
Mercury’s history of formation is similar to that of Earth’s. About 4.5 billion years ago the planets formed. This was a time of intense bombardment for the planets as they scooped up matter and debris left around from the nebula that formed them. Early during this formation, Mercury probably differentiated into a dense metallic core, and a silicate crust. After the intense bombardment period, lava flowed across the surface and covered the older crust. By this time much of the debris had been swept up and Mercury entered a lighter bombardment period. During this period the intercrater plains formed. Then Mercury cooled. Its core contracted which in turn broke the crust and produced the prominent lobate scarps. During the third stage, lava flooded the lowlands and produced the smooth plains. During the fourth stage micrometeorite bombardment created a dusty surface also known as regolith. A few larger meteorites impacted the surface and left bright rayed craters. Other than the occasional collisions of meteorites, Mercury’s surface is no longer active and remains the same as it has for millions of years.
Plains cover the majority of Mercury s surface. Much of it is old and heavily catered, but some of the plains are less heavily cratered. Scientists have classified these plains as intercrater plains and smooth plains. Intercrater plains are less saturated with craters and the craters are less than 15 kilometers in diameter. These plains were probably formed as lava flows buried the older terrain. The smooth plains are younger still with fewer craters. Smooth plains can be found around the Caloris basin. In some areas patches of smooth lava can be seen filling craters.
Like our Moon, Mercury has almost no atmosphere, mostly burned off millions of years ago by the planet’s close proximity to the Sun. What little atmosphere exists is made up of atoms blasted off its surface by the solar wind and has less than a million- billionths the pressure of the Earth’s atmosphere at sea level. It is composed chiefly of argon, neon and helium. Because of Mercury’s extreme surface temperature, these atoms quickly escape into space and are constantly replenished. With no atmosphere to protect the surface, there has been no erosion from wind or water, and meteorites do not burn up due to friction as they do in other planetary atmospheres.
Mercury’s surface very much resembles Earth’s Moon, scarred by thousands of impact craters resulting from collisions with meteors. While there are areas of smooth terrain, there are also cliffs, some soaring up to two miles high, formed by ancient impacts.
Until Mariner 10, little was known about Mercury because of the difficulty in observing it from Earth telescopes. At maximum elongation it is only 28 degrees from the Sun as seen from Earth. Because of this, it can only be viewed during daylight hours or just prior to sunrise or after sunset. When observed at dawn or dusk, Mercury is so low on the horizon that the light must pass through 10 times the amount of Earth’s atmosphere than it would if Mercury was directly overhead.
During the 1880’s, Giovanni Schiaparelli drew a sketch showing faint features on Mercury. He determined that Mercury must be tidally locked to the Sun, just as the Moon is tidally locked to Earth. In 1962, radio astronomers looked at radio emissions from Mercury and determined that the dark side was too warm to be tidally locked. It was expected to be much colder if it always faced away from the Sun. In 1965, Pettengill and Dyce determined Mercury’s period of rotation to be 59 +- 5 days based upon radar observations. Later in 1971, Goldstein refined the rotation period to be 58.65 +- 0.25 days using radar observations. After close observation by the Mariner 10 spacecraft, the period was determined to be 58.646 +- 0.005 days. Mercury s rotational period on its axis is 2/3 of its revolution period around the sun, which is 88 earth days.
Mercury is not tidally locked to the Sun; its rotational period is tidally coupled to its orbital period. Mercury rotates one and half times during each orbit. Because of this 3:2 resonance, a day on is 176 Earth days long as shown by the following diagram, quite a long day for earthlings.
Mercury has no evident satellites or rings for its exists so very close to our scorching sun.
Mercury s mean distance from the sun is 58 million kilometers (about36 million miles). Mercury s diameter is 4875 km (3030 miles). Mercury s volume and mass are about 1/8 that of Earth. Mercury s gravitational pull is .38 times that of Earth.
Scientists believe that during Mercury’s distant past, its period of rotation may have been faster than its speed today. Scientists speculate that its rotation could have been as rapid as 8 hours, but over millions of years it was slowly despun by solar tides. A model of this process shows that such a despinning would take 109 years and would have raised the interior temperature by 100 degrees Kelvin.
Most of the scientific findings about Mercury come from the Mariner 10 spacecraft, which was launched on November 3, 1973. It flew past the planet on March 29, 1974 at a distance of 705 kilometers from the surface. On September 21, 1974 it flew past Mercury for the second time and on March 16, 1975 for the third time. During these visits, over 2,700 pictures were taken, covering 45% of Mercury’s surface. Up until this time, scientists did not suspect that Mercury would have a magnetic field. They thought that because Mercury is small, its core would have solidified long ago. The presence of a magnetic field indicates that a planet has an iron core that is at least partially molten. Magnetic fields are generated from the rotation of a conductive molten core and are known as the dynamo effect.
Mariner 10 showed that Mercury has a magnetic field that is 1% as strong as Earth’s. This magnet field is inclined 7 degrees to Mercury’s axis of rotation and produces a magnetosphere around the planet. The source of the magnetic field is unknown. It might be produced from a partially molten iron core in the planet’s interior. Another source of the field might be from remnant magnetization of iron-bearing rocks, which were magnetized when the planet had a strong magnetic field during its younger years. As the planet cooled and solidified remnant magnetization was retained.
Even before Mariner 10, Mercury was known to have a high density. Its density is 5.44 g/cm3 which is comparable to Earth’s 5.52g/cm3 density. In an uncompressed state, Mercury’s density is 5.5 g/cm3 where Earth’s is only 4.0 g/cm3. This high density indicates that the planet is 60 to 70 percent by weight metal, and 30 percent by weight silicate. This gives a core radius of 75% of the planet radius and a core volume of 42% of the planet’s volume.
The pictures returned from the Mariner 10 spacecraft and revealed a world that resembled the moon. It is pocked with craters, contains huge multi-ring basins, and many lava flows. The craters range in size from 100 meters (the smallest resolvable feature on Mariner 10 images) to 1,300 kilometers. They are in various stages of preservation. Some are young with sharp rims and bright rays extending from them. Others are highly degraded, with rims that have been smoothed from the bombardment of meteorites. The largest crater on Mercury is the Caloris basin. Hartmann and Kuiper (1962) defined a basin as a “large circular depression with distinctive concentric rings and radial lineaments.” Others consider any crater larger than 200 kilometers a basin. The Caloris basin is 1,300 kilometers in diameter, and was probably caused by a projectile larger than 100 kilometers in size. The impact produced concentric mountain rings three kilometers high and sent ejecta 600 to 800 kilometers across the planet. The seismic waves produced from the Caloris impact focused onto the other side of the planet and produced a region of chaotic terrain. After the impact the crater was partially filled with lava flows.
Mercury is marked with great curved cliffs or lobate scarps that were apparently formed as Mercury cooled and shrank a few kilometers in size. This shrinking produced a wrinkled crust with scarps kilometers high and hundreds of kilometers long.
Because Mercury is the closet planet to the sun and without a doubt the hottest, few life forms can survive there. I have tried to find out whether or not a human could survive on Mercury. I have discovered as many astronomers have discovered that naturally it would be impossible for any human to survive on Mercury.
Without a spacesuit, you’d die of suffocation in under a minute on Mercury. This is true of every other planet or moon in the solar system. Even the planets that have an atmosphere are full of deadly gases.
A spacesuit can help. A spacesuit does two things: it surrounds your body with breathable air, and it keeps you from getting too hot or cold. Even Space Shuttle astronauts need heaters and refrigerators in their suits to keep them comfortable. A spacesuit can help. A spacesuit does two things: it surrounds your body with breathable air, and it keeps you from getting too hot or cold. Even Space Shuttle astronauts need heaters and refrigerators in their suits to keep them comfortable.
My calculations show that a human in a Space Shuttle spacesuit would last for under an hour if he were on Mercury. The problem is that space shuttle suits keep the temperature constant by using electricity from batteries, and batteries don’t have a whole lot of power. The astronauts could go much longer if they could plug themselves into their spaceship’s power supply using an “extension cord”.
The way to solve the problem is the same as it is here on earth: wear thicker clothes. By wearing extra layers of insulation, an astronaut can keep the cold out when he’s at Pluto, and (surprisingly) can keep the heat out when he’s on Mercury. However, you might need so much insulation that the spacesuit would be too bulky to let you move around.
When I make these calculations assuming an outside temperature of 480 K on Mercury, and 50 K on Pluto. Heat loss assumed dominated by thermal conductivity through spacesuit material 5 cm thick with thermal conductivity of .03 W/(m K), interior temperature 290 K, surface area 4 m^2, giving 450 watts of heat into the suit on Mercury. Add 100 watts of body heat. If you were to use a refrigerator on Mercury you would need 360 watts of power to stay cool (but for realistic refrigerator efficiencies, it’s probably twice that amount) Lets assume that 10 kilograms of batteries with specific energy of 30 watt-hours per kilogram, giving 300 watt-hours of power. If you triple the insulation thickness, power requirements go down to 160 watts on Mercury; however, the suit’s arms are now at least 40 cm in diameter. A mammoth suit for a measly carbon based life form to wear.
As I have so intricately stated in the previous paragraphs, Mercury is indeed a spectacular entity, with characteristics similar to those of our moon.
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