2003 SPACE SCIENCE VIDEOTAPES |
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Tape Title | Record ID | Date Produced | TRT: |
Synopsis |
| VOYAGER NEARS THE EDGE OF THE SOLAR SYSTEM | G03-060 | 11/05/03 | 00:22:20 | The 26-year-old Voyager 1 spacecraft is moving toward the boundary of our solar system. At eight billion miles from the Sun, Voyager is brushing up against the edge of the heliosheath, a region where the supersonic winds blowing from the Sun slow and eventually stop when they meet up with interstellar space. A dynamic boundary referred to as the termination shock represents the entry into this region, which may or may not have 'washed over' Voyager earlier this year. This is the first boundary; the heliopause, which should be achieved sometime around 2020, is the ultimate entry into interstellar space.
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TAPE CONTENTS: |
| ITEM (1): Where is Voyager? The first animation shows the location of the two pertinent boundaries separating Voyager from leaving our solar system (the influence of the solar wind) and entering into interstellar space. The dramatic orange border at the end of the animation represents the bow shock, a theoretical area created as interstellar gas runs into the solar atmosphere. In the second sequence, the orange gas throughout is the interstellar medium. The sequence ends with a view of the Sun surrounded by the heliosphere. Voyager 1 is over four billion miles from Pluto and the farthest path of Halley's Comet.
Courtesy: NASA
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| ITEM (2): What's In Question? - Two science teams from the Voyager mission are debating whether some readings between August 2002 and January 2003 can be interpreted as Voyager entering the heliosheath temporarily, or whether it was just brushing up against the boundary of the termination shock. At the termination shock, the solar wind slows abruptly; the exact location is unknown and was originally thought to be closer to the Sun than Voyager 1 currently resides. For those six months, unusual instrument readings indicated Voyager had entered a region of the solar system unlike any encountered before.
The controversy could be resolved easily if Voyager could measure the speed of the solar wind (which slows abruptly within the heliosheath), but that instrument no longer functions. Instead, other instruments have had to make educated interpolations of the situation, hence the two differing interpretations and theories.
Courtesy: NASA
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| ITEM (3): Demonstrating The Heliosphere - The heliosphere is like water splashing onto a plate and creating a rough ring radiating from the water pouring from the faucet. Like the gushing water spreads until it hits a limit, the solar wind races away from the Sun and flows out into space until encountering stronger forces beyond our solar system that slow it down and turn it around. The first boundary is the termination shock, like the first ripple after the smooth center of the water. It takes you into the heliosheath, the region where the solar wind gets deflected to the sides by the interstellar wind blowing on the solar system. Like the water on the plate depends on the faucet strength, the boundary moves depending the fluctuating solar cycle. The heliopause is the next boundary - like the rim of the plate, after that you drop off into interstellar space and out of the solar system.
Courtesy: NASA
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| ITEM (4): Exploring The Heliosheath - This is a computer model demonstrating scientist's notions of the heliosphere and behavior of the bow shock. It is derived from actual observations of density, temperature, velocity and ionization states of the solar and interstellar wind. The model was done by Hans Mueller (Dartmouth) and Gary Zank (UC Riverside). The next image from the Hubble Space Telescope provides further evidence of its validity.
Courtesy: NASA
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| ITEM (5): HST Spots Similar Bow Shock - How are scientists so certain a bubble blown by the solar wind surrounds us? Beyond models, they've actually seen bow shocks created from gas blowing from powerful stars, like this one imaged by the Hubble Space Telescope in 1995. Like the crescent-shaped wave made by a ship moving through water, bow shocks can be created in space when two streams of gas collide. LL Orionis emits a strong solar wind that collided with slow-moving gas evaporating away from the center of the Orion Nebula, located to the lower right. The surface where the two winds collide is the bow shock.
Courtesy: NASA / STSCI
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| ITEM (6): Riding The Solar Wind - Supersonic winds from the Sun encircle the solar system in heliosphere, but that wind is not constant. As seen in these SOHO movies, it fluctuates in both space and time, and on a large scale with the Sun's 11-year cycle of activity; when the Sun is most active, the size of the heliosphere is smallest. At solar max, defined by many sunspots, magnetic activity reduces the winds that escape from the Sun. We're now entering a quiet phase of the solar cycle, which helps explain the confusion and the potential observation that the boundary washed over Voyager for a period of six months. The peak of the current cycle was 2000-2001.
Courtesy: ESA
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| ITEM (7): Sun's Impact In Our Neighborhood - Solar wind is an invisible stream of electrons and protons that pours outward into space from the Sun at a rate of hundreds of kilometers per second (about 1 million mph). Not at all constant, it shifts in output depending on the activity of the Sun. This EIT view of the Sun shows a minimum period in 1996 and an active period in 2000 defined by many sunspots and subsequent flares, or explosions. The other view from the LASCO instrument shows a CME (about a billion tons of plasma) escaping out into space.
Courtesy: NASA / ESA
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| ITEM (8): Historical: Jupiter Exploration - First up for Voyager 1 was Jupiter in January 1979; in four months of observations, it took nearly 19,000 pictures and other scientific measurements. Although astronomers had studied Jupiter from Earth, Voyager helped to understand the physical, geological and atmospheric processes going on in the planet, its moons and its powerful magnetosphere. Between Pioneer's 10 and 11 flybys six years earlier and the flybys from the two Voyagers, scientists noticed changes on the planet.
Courtesy: NASA
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| ITEM (9): Historical: Volcanoes of Io - Voyager's March 1979 spotting of volcanoes outside of Earth is considered to be the most exciting and unexpected discovery by most project scientists. One of Jupiter's moons, Io is the most volcanic body known, with lava flows, lava lakes, and giant calderas covering its sulfurous landscape. In fact, Voyager 1 identified nine currently active (erupting) volcanoes on Io, probably driven by tidal heating. Io's mountains are daunting compared to Earth's, reaching heights of 16 km (52,000 feet); Earth's Mount Everest is less than 9 km (29,000 feet).
Courtesy: NASA
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| ITEM (10): Historical: Rings of Saturn - Voyagers 1 and 2 explored Saturn about nine months apart in 1980 and 1981 respectively. They found Saturn's atmosphere composed almost entirely of hydrogen and helium with high speeds measuring about 500 meters a second (1,100 mph) at the equator. In addition, Voyager found aurora-like ultraviolet emissions of hydrogen at mid-latitudes in the atmosphere, and auroras at polar latitudes. Both spacecraft took pictures of the rings - ending notions of tiny satellites orbiting between the rings, and providing data needed to understand their structure, composition and dimensions.
Courtesy: NASA
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| ITEM (11): Historical: Voyager 2 & Uranus - Nearly three billion km (1.8 billion miles) from Earth, Uranus is the most distant object yet visited by a spacecraft. In fact, it's so far away that scientists knew comparatively little about it before Voyager 2's 1986 encounter. Voyager confirmed the rotation rate and discovered the planet is tipped on its side, with its orbiting moons and rings forming a giant celestial bull's-eye. As a result, the northern and southern polar regions are alternatively exposed to sunlight or to the dark of space during the planet's 84-year orbit around the Sun.
Courtesy: NASA
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| ITEM (12): Historical: Voyager 2 & Neptune - In 1989 Voyager 2 became the first spacecraft to observe Neptune. Passing about 4,950 km (3,000 miles) above its north pole, Voyager 2 made its closest approach to any planet since leaving Earth. The most obvious feature in Voyager images is its blue color, the result of methane in the atmosphere. It's a dynamic planet with dark spots reminiscent of Jupiter's hurricane-like storms - the largest spot is the size of Earth. Called the 'Great Dark Spot,' it's more variable in size and shape than Jupiter's with bright, wispy cirrus-type clouds forming above, similar to clouds forming over mountains on Earth.
Courtesy: NASA
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| ITEM (13): Clean Room / Launch - The Voyager 1 and 2 spacecraft are identical in build but have different flight paths. Voyager 2 was actually launched first, on August 20, 1977; Voyager 1 was launched September 5. Voyager 1 is about 8 billion miles from the Sun and traveling at a speed of 3.6 AU per year while Voyager 2 is about 6.5 billion miles from the Sun and moving slightly slower at about 3.3 AU per year. One 'AU' equals the distance between the Sun and Earth, or 93 million miles.
Courtesy: NASA
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| ITEM (14): Message In A Bottle: The Record - Recognizing that Voyager 1 and 2 could be the first object encountered by another space-faring civilization, a greeting was organized by Dr. Carl Sagan and others in the form of a 12-inch gold-plated copper disc. The intention was to tell the story of Earth's diversity, culture and knowledge through 115 images, natural sounds like animals and nature, spoken greetings in 55 languages, messages from President Carter and U.N. Secretary General Wadheim and 90 minutes of Eastern and Western classical and ethnic music. The cover of the record uses symbolic language to explain the origin of the spacecraft and indicate how to play the record.
Courtesy: NASA
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| ITEM (15): Spacecraft Animation - The two Voyager spacecraft send back about 12 hours worth of data per day at about the speed of a slow modem and with the power of a 28-watt nightlight. At launch, the Voyager mission was designed for a five-year mission to Jupiter and Saturn. With the success of Voyager 1, Voyager 2 was allowed to continue on to Uranus and Neptune; the entire mission covered four planets and 48 moons. They have enough power and attitude control propellant to operate until around 2020. Electrical power is supplied by nuclear Radioisotope Thermoelectric Generators (RTGs) that decay, but still represent better performance than pre-launch predictions.
Courtesy: NASA
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| ITEM (16): Soundbites With
Dr. Eric Christian, NASA Program Scientist, Voyager Mission
Courtesy: NASA
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| ITEM (17): Soundbites With
Dr. Tom Krimigis, Principal Investigator, Low Energy Charged Particle (LECP) Experiment on Voyager 1 & 2, Johns Hopkins University Applied Physics Laboratory
Courtesy: NASA
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| ITEM (18): Soundbites With Dr. Edward Stone, Voyager Project Scientist
NASA Jet Propulsion Laboratory
Courtesy: NASA
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Space Science Gallery