Presentation on theme: "Frazer proponed that scientific inquiry [e.g. Astronomy] sprung from elements of rituals, religious doctrine/or philosophy, i.e. human sacrifice (Messianic."— Presentation transcript:
Frazer proponed that scientific inquiry [e.g. Astronomy] sprung from elements of rituals, religious doctrine/or philosophy, i.e. human sacrifice (Messianic Monotheism) and dying gods (Pagan Polytheism) as well as many other symbolisms and ritualistic practices resulting in the formation constituting the cognitive rationalization of the human psyche thus later culminating to scientific thought. Rituals (Sympathetic magic/ imitation) + Religion (Philosophy) = Science Simply: Experiment + Results = Scientific Thought
Ammisaduqa tablet Pythagoras (Greek) Antichthon (Venus): Counter-Earth The Babylonians were the first civilization known to possess a functional theory of the planets called, Venus tablet of Ammisaduqa [7th-century BC]. It is the earliest evidence that planetary phenomena were recognized as periodic. Pythagoras, [6th and 5 th centuries BC] appeared to have developed his own independent planetary theory, which consisted of the Sun, Earth, and Venus (all planets) revolving around a "Central Fire" at the center of the Universe. In Philolaus's system (Counter-Earth) [6th and 5th centuries BC], Moving the earth from the center of the cosmos and making it a planet". First coherent system in which celestial bodies move in circles non- geocentric and non-heliocentric system.
An important calendar for the Maya was the Venus cycle: A 584-day Venus, which tracked the heliacal risings of Venus as the Morning Star and Evening Star. Dresden Codex: It is a detailed account of the astronomical observations of the Mayas Dresden Codex Venus Deity
Who contributed/or stimulated the astronomical pursuits in science? A) Ancient Maya Civilization B) Greco-Roman Society C) Babylonian Civilization D) All of the Above [Correct Answer]: D
Name: Venus Aka Morning/Evening Star Minimum Distance to the Sun: 108 million km Maximum Distance to the Sun: 109 million km Discovery – Unknown Observed before recorded history Hottest planet in the solar system Galileos discovery of Venus phases helped disprove the geocentric model Satellites: Zero Period of Rotation About Axis: 243 days Retrograde (clockwise) Period of Revolution About Sun: 0.62 years
Venus atmosphere consists mostly of Carbon Dioxide with thick clouds of Sulfuric Acid The atmosphere is so thick that it traps the small amounts of the suns energy that reaches the surface Greenhouse Effect The atmospheric pressure on Venus is about 90 times greater than that of Earths Equivalent to 3,000ft below Earths sea level
SIMILAR to Earth, Venus has two poles: North Pole, South Pole Vortex – a visible, whirling mass of air Think tornado! Plural: Vortices Vortices have been discovered in both polar regions North Pole – NASA in 1978 South Pole – ESA in 2006 For some odd and undiscovered reason, these vortices circle about two points Like an eye of a storm, but two…
UNLIKE Earth, whose axis of rotation is tilted at about 23 o, Venus axis of rotation is tilted only at about 3 o Lack of seasons Average surface and lower atmosphere temperature stays nearly the same throughout the year Stays consistent even throughout day and night Average Surface Temp: 730 K Thats 457 o C or 855 o F all the time
Space probes have found over 1600 major volcanoes Very limited data to prove whether the volcanoes are active/extinct Very young surface age, due to lack of wear and tear from water or wind No long, linear volcanic chains No evidence for plate tectonics or subduction zones like Earth No evidence for violent eruptions Fluid-like lava flow Ishtar Terra – continent near North Pole containing four main mountain ranges About the size of mainland USA Volcanoes: Sacajawea, Collete, Cleopatra Tessera – a shortening of crust created folding, breaking, clumping of crust Shows signs that the surface of Venus may be in motion
MAY OCTOBER 1994
Built partially with spare parts from other missions, the Magellan spacecraft was 15.4 feet long, topped with a 12-foot high-gain antenna. The spacecraft weighed a total of 7,612 pounds at launch.The high-gain antenna, used for both communication and radar imaging, was a spare from the NASA/JPL Voyager mission to the outer planets, as were Magellan's 10-sided main structure and a set of thrusters. The command data computer system, attitude control computer and power distribution units are spares from the Galileo mission to Jupiter. Magellan's medium-gain antenna is from the NASA/JPL Mariner 9 project. Magellan was powered by two square solar panels, each measuring 8.2 feet on a side; together they supplied 1,200 watts of power. Over the course of the mission the solar panels gradually degraded, as expected.
Magellan was the first planetary spacecraft to be launched by a space shuttle when it was carried by the shuttle Atlantis from Kennedy Space Center in Florida on May 4, Atlantis took Magellan into low Earth orbit, where it was released from the shuttle's cargo bay. A solid-fuel motor called the Inertial Upper Stage (IUS) then fired, sending Magellan on a 15-month cruise looping around the sun 1- 1/2 times before it arrived at Venus on August 10, A solid-fuel motor on Magellan then fired, placing the spacecraft in orbit around Venus.
Magellan's initial orbit was highly elliptical, taking it as close as 182 miles from Venus and as far away as 5,296 miles. Magellan was in a polar orbit, meaning that the spacecraft moved from south to north or vice versa during each looping pass, flying over Venus's north and south poles. Magellan completed one orbit every 3 hours, 15 minutes.
During the part of its orbit closest to Venus, Magellan's radar mapper imaged a small section of the planet's surface approximately 10 to 17 miles wide. At the end of each orbit, the spacecraft radioed back to Earth a map of a long ribbon-like strip of the planet's surface captured on that orbit. Because of the images taken from Magellan, scientists were able to determine that Venus itself rotates once every 243 Earth days. As the planet rotated under the spacecraft, Magellan collected strip after strip of radar image data, eventually covering the entire globe at the end of the 243-day orbital cycle.
By the end of its first such eight-month orbital cycle between September 1990 and May 1991, Magellan had sent to Earth detailed images of 84 percent of Venus's surface. The spacecraft then conducted radar mapping on two more eight- months cycles from May 1991 to September This allowed it to capture detailed maps of 98 percent of the planet's surface. The follow-on cycles also allowed scientists to look for any changes in the surface from one year to the next. In addition, because the "look angle" of the radar was slightly different from one cycle to the next, scientists could construct three-dimensional views of Venus's surface. As pictured in the next slide.
Maxwell Montes, the planet's highest mountain at 6.6 miles above the average elevation, is the bright feature in the lower center of the image.
During Magellan's fourth eight-month orbital cycle at Venus from September 1992 to May 1993, the spacecraft collected data on the planet's gravity field. During this cycle, Magellan did not use its radar mapper but instead transmitted a constant radio signal to Earth. If it passed over an area of Venus with higher than normal gravity, the spacecraft would slightly speed up in its orbit. This would cause the frequency of Magellan's radio signal to change very slightly due to the Doppler effect, and example would be that the pitch of a siren changes as an ambulance passes. Thanks to the ability of radio receivers in the NASA/JPL Deep Space Network to measure frequencies extremely accurately, scientists could build up a detailed gravity map of Venus.
At the end of Magellan's fourth orbital cycle in May 1993, flight controllers lowered the spacecraft's orbit using a technique called aerobraking. This maneuver sent Magellan dipping into Venus's atmosphere once every orbit; the atmospheric drag on the spacecraft slowed down Magellan and lowered its orbit. After the aerobraking was completed between May 25 and August 3, 1993, Magellan's orbit then took it as close as 112 miles from Venus and as far away as 336 miles. Magellan also circled Venus more quickly, completing an orbit once every 94 minutes. This new, more circularized orbit allowed Magellan to collect better gravity data in the higher northern and southern latitudes near Venus's poles.
After the end of that fifth orbital cycle in April 1994, Magellan began a sixth and final orbital cycle, collecting more gravity data and conducting radar and radio science experiments. By the end of the mission, Magellan will have captured high-resolution gravity data for an estimated 95 percent of the planet's surface. In September 1994, Magellan's orbit was lowered once more in another test called a "windmill experiment." In this test, the spacecraft's solar panels were turned to a configuration resembling the blades of a windmill, and Magellan's orbit was lowered into the thin outer reaches of Venus's dense atmosphere. Flight controllers then measured the amount of torque control required to maintain Magellan's orientation and keep it from spinning. This experiment gave scientists data on the behavior of molecules in Venus's upper atmosphere, and lent engineers new information useful in designing spacecraft.
On October 11, 1994, Magellan's orbit is scheduled to be lowered a final time. This experiment was to test the spacecraft to see how much torque will be needed to keep the spacecraft from spinning on its axis. Within two days after that maneuver, the spacecraft is expected to become caught in the atmosphere and plunge to the surface. Although much of Magellan would be vaporized, some sections are expected to hit the planet's surface intact. Magellan was the first planetary spacecraft to be terminated intentionally.
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