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Rendezvous with a Comet Challenger Mission: Slide 2 Rendezvous To meet up in a location Slide 3 Courtesy: Pat Rawlings - Deep Impact -NASA & JPL A probe entering a comet Slide 4 Simulation Acting out an activity (space mission) Slide 5 Our Solar System Slide 6 Earth is a part of The Solar System Slide 7 Our Solar System is part of the Milky Way Galaxy Which is part of the Universe. Slide 8 Galaxies Slide 9 Our Sun Hot ball Of gases Slide 10 Inner Planets Slide 11 Outer Planets Slide 12 Asteroids, Meteoroids and Comets Slide 13 asteroids Rocky metallic objects that orbit the sun Slide 14 1801 Year Giuseppe Piazzi discovered the first asteroid, Ceres Slide 15 4.6 Earth years it takes the asteroid Ceres to travel around the sun (Ceres Biggest Asteroid with a 960 km circumference) Slide 16 2880 Year asteroid 1950 DA will pass close to Earth The greatest known impact hazard Slide 17 Asteroids Asteroids are small, rocky worlds. Most asteroids revolve around the sun between the orbits of Mars and Jupiter. (asteroid belt) Slide 18 Earth has been struck many times in its history by asteroids. Slide 19 Slide 20 Slide 21 100 km 212 Million years old Canada Slide 22 Slide 23 Slide 24 Slide 25 ASTEROIDBELTASTEROIDBELT Slide 26 meteorite A chunk of metal or rock that reaches Earth from space Meteor shower Slide 27 Meteoroid A meteoroid is a chunk of rock, metal, or dust in space. Slide 28 A Meteor: A shooting star Shooting stars are not actually stars. These flashes of light across the sky are small bits of rock burning up in the Earths Atmosphere. Slide 29 Meteorite Meteoroids that survive as they pass through the atmosphere and hit Earths surface are called meteorites. Slide 30 http://www.meteorlab.com/METEORLAB2001dev/Open1.htm There are three major types of meteorites: stone, iron and stony-iron. Slide 31 Barringer Meteor Crater, Arizona A meteorite can make a hole, or crater, in the ground when it hits it. The larger the meteorite, the bigger the hole. Slide 32 METEOROID: A piece of stone or metal that travels in outer space. METEOR: An object from space that becomes glowing hot when it passes into Earth's atmosphere. METEORITE: A piece of stone or metal from space that falls to Earth's surface. Slide 33 comets Lumps of ice and dust that periodically come to the center of the solar system from the outer reaches. Slide 34 Dirty Snowballs Comets are dusty chunks of ice During each orbit around the sun they partially vaporize Have elliptical orbits They are about the size of an earth mountain. (dirt and ice) Comets orbits are usually very long, narrow ellipses. They produce tails of gas and dust when they approach the sun. Courtesy: Calvin J. Hamilton Slide 35 History Unlike the other small bodies in the solar system, comets have been known since antiquity. There are Chinese records of Comet Halley going back to at least 240 BC. The famous Bayeux Tapestry, which commemorates the Norman Conquest of England in 1066, depicts an apparition of Comet Halley. Comet Halley Bayeux Tapestry As of 1995, 878 comets have been cataloged and their orbits at least roughly calculated. Of these 184 are periodic comets (orbital periods less than 200 years); some of the remainder are no doubt periodic as well, but their orbits have not been determined with sufficient accuracy to tell for sure. Slide 36 The history of comet watching dates back to 1000 BC from the Chinese records and Chaldea, a place in present Iraq. Comets have been regarded as omens, even as recently as 1986. Battle of Hastings - 1066 Today astronomers study comets from scientific perspectives, and our understanding of these fascinating objects have grown tremendously. Slide 37 Structure of a Comet Solar heat vaporizes the nucleus to produce Coma - Hydrogen gas Envelope Dust tail Ion tail Courtesy: Deep Impact - NASA & JPL Slide 38 Parts of a Comet When they are near the Sun and active, comets have several distinct parts:Sun nucleus: relatively solid and stable, mostly ice and gas with a small amount of dust and other solids; coma: dense cloud of water, carbon dioxide and other neutral gases sublimed from the nucleus; sublimed hydrogen cloud: huge (millions of km in diameter) but very sparse envelope of neutral hydrogen; dust tail: up to 10 million km long composed of smoke-sized dust particles driven off the nucleus by escaping gases; this is the most prominent part of a comet to the unaided eye; Ion tail: as much as several hundred million km long composed of plasma and laced with rays and streamers caused by interactions with the solar wind.solar wind Slide 39 Comet Nucleus (plural: Nuclei) A drawing of what the surface of a comet might look like. The nucleus of a comet is the central portion of the head of a comet. It is a solid part of the comet, made of a special sort of dust which is called "fluffy" because it could be as light weight and full of holes as a sponge. The holes of this "sponge" are filled with ices like water, carbon dioxide (dry ice), and carbon monoxide (what comes out of your car).made of Slide 40 Coma This cloud, called the coma, is the atmosphere of the comet and can extend for millions of miles. The cloud is very thin, however, 10,000 times thinner than a cloud in the Earth's atmosphere!cloud Earth's atmosphere The neutral particles that are in the coma can actually become excited by the solar wind causing the particles to become ions. A continual stream of neutral particles is produced as long as the nucleus is evaporating, and these neutral particles are continually converted to ions. These ions are what help form the comet tail.solar windions tail Slide 41 A comet generally has two tails, not one. One tail is due to the comet's dust particles, the other is due to ionized gas from the comet coma. Dust particles form the first tail. This comet tail generally points back along the comet path (so if the comet is traveling right, the dust tail extends to the left).coma Ions (electrically charged particles), which first come from the nucleus as (neutral) gaseous particles, are swept into the second comet tail. Because of the special interaction with the Sun's magnetic field, this tail always points directly away from the Sun.swept Tails Slide 42 Schematic of a Comet This image is a schematic of a comet. The center part of the comet, or nucleus, is represented by the flame. The solar wind particles are shown as green dots with arrows. And the ionized particles are shown as green/red dots with arrows. Neutral particles are shown by the other dots (without arrows). Slide 43 Orbits of Comets Elliptical in Shape Randomly oriented Sun Comet Earth Perihelion distance Aphelion distance Slide 44 Comet Hunters Comet are named by International Astronomical Union (IAU) after the person who first discovers them. Many comets are discovered by amateur astronomers. Charles Messier, E. E. Bernard, Shoemaker and Levy, Hale and Bopp, Ikeya, Seki and Hayakutake are popular comet hunters. Slide 45 Origins of Comets Comets are thought to be the left over debris from during the time of formation of the solar system. The elliptical orbits of comets suggest that they underwent gravitational pull from the giant planets. This all lead us to infer two possible locations where comets could start their journey towards the sun. Slide 46 Possible Homes for Comets Kuiper Belt Oort Cloud Courtesy - Deep Impact - NASA - JPL Slide 47 Slide 48 Kuiper Belt Discovered by Gerard Kuiper in 1951 The belt is 30 to 500 AU from the Sun The plane of the belt is close to the ecliptic Probably contains more than 100,000 objects Some of these objects are 100 km or larger in diameter Slide 49 Oort Cloud Hypothesized by a Dutch Astronomer Jan Oort in 1950. Shape is spherical distribution around the Sun. 50,000 AU from the Sun. May contain 5 trillion objects. Probably created 4.6 billion years ago. Slide 50 Comets and their Spectra Spectroscopy is a technique in which light is broken into its component colors. Each chemical element show their fingerprint in the spectrum of the object. We can thus find the composition of comets by identifying the fingerprints. Most of the information on comets comes from infrared radiation, because comets are cold objects they radiate strongly at infrared radiation. Slide 51 Comet Collisions Comet collisions with Earth can bring devastation to life on Earth. Jupiter in our solar system is the largest planet and thus exerts greater gravitational pull on incoming Comets. Study of Shoemaker-Levey collision with Jupiter gave us important facts about Comet collisions. Slide 52 Comet Collisions Courtesy: NASA/JPL Slide 53 Halleys Comet. Orbits every 76 years Slide 54 Halleys Comet Orbit next seen in 2062 Slide 55 Comet: Hale-Bopp Winter and early spring of 1997 Next sighting: 4380 Slide 56 Facts Comets are invisible except when they are near the Sun. Most comets have highly eccentric orbits which take them far beyond the orbit of Pluto; these are seen once and then disappear for millennia. Only the short- and intermediate-period comets (like Comet Halley), stay within the orbit of Pluto for a significant fraction of their orbits.Pluto Slide 57 Approaching the Sun As a comet approaches the Sun, it begins to evaporate, forming the coma and a spectacular comet tail.approachesevaporatecomatail. Evaporation is not quite the correct term to describe what happens to a comet as it approaches the sun. The correct term is sublimation. The term describes what happens when a frozen material changes to gaseous form. (Evaporation describes what happens when a liquid changes to a vapor). Slide 58 Sublimation The most common example of sublimation is that of dry ice, which is the common name of frozen CO 2. When dry ice is exposed to the air it begins to sublimate, or change to vapor, before your very eyes. This happens to dry ice because at room temperature the frozen gas would rather be a gas than frozen solid. Slide 59 Long Period Comets A comet with an orbital period of more than 200 years. Slide 60 Short Period Comets A comet with an orbital period of less than 200 years. Short period fade over time as more and more of their ices melt with each passage of the Sun. Examples: Comet Halley, 76-year orbit; Comet Encke, 3.3-year orbit; Comet Wild 2, 6.2 year orbit. Slide 61 orbit The path a planetary body makes as it revolves around the sun The orbit of a comet tends to be far more elliptical than planets orbits. Slide 62 Circle A geometric shape where all points on a plane are the same distance from the center Slide 63 ellipse A geometrical shape where all the points on a curve is the constant sum of the distances from two fixed points, called focal points. Slide 64 Perihelion The point where an object orbiting the Sun is closest to the Sun Slide 65 Astronomical unit (AU) One AU is equal to the average distance between the Sun and Earth, approximately 150 million kilometers (93 million miles) Slide 66 Ejecta The debris that is ejected from the site of impact when a crater forms Slide 67 Gravity Force of attraction between two objects Just as Earth pulls on you, you pull on Earth with the exact same amount of force. Slide 68 mass The amount of matter in an object The measure of an objects inertia. Mass is not the same as weight, which measures the gravitational force on an object. Your mass is the same everywhere, whether you are at home, on the Moon, or floating in interplanetary space. Slide 69 particle A tiny quantity of a substance Slide 70 Flight Director The commander working with the crew in mission control Slide 71 Image A picture that can be sent from Mission Control to the spacecraft to assist you with your work Slide 72 Data Log Used in Mission Control to record experimental data Slide 73 Mission Commander The Commander working with the crew in the spacecraft Slide 74 Mission Status A television monitor that shows the task each team is working on and the time left in the mission Slide 75 Monitor A screen that shows mission activities Slide 76 Priority Something that is very important Slide 77 Start Code A number entered into the computer system when a spacecraft crew member is starting a new task Slide 78 Flight Manual Step-by-step instructions for each task found in Mission Control Slide 79 Task Card Step-by-step instructions for each task found in the spacecraft Slide 80 Data Team: Data Information collected during the crews experiments Slide 81 Data Team: Image A digital picture of equipment or materials used by a team on the Spacecraft Slide 82 Isolation Team: Balance A scale for weighing materials Slide 83 Isolation Team: CPM (counts per minute); the number of radioactive particles striking the sensor of a Geiger counter during each minute. Slide 84 Isolation Team: Filter A device used to separate impurities from the air Slide 85 Isolation Team: Geiger Counter A device for measuring radioactivity Slide 86 Isolation Team: Isolation Chamber An airtight, enclosed work area Slide 87 Isolation Team: Micrometeoroid Tiny bits of asteroids that travel at 18,000 miles per hour in earths orbit: can damage spacecraft upon impact Slide 88 Isolation Team: Radioactivity A physical property of some hazardous materials that causes the material to emit particles that can be measured with a Geiger counter Slide 89 Isolation Team: Transmittance The penetration of radioactive particles through materials such as water and aluminum Slide 90 Remote: Balance An electronic scale used for measuring mass Slide 91 Remote: Glovebox A special experiment area that is enclosed to protect your experiments Slide 92 Remote: Mass A measurement of the amount of matter within any object Slide 93 Remote: Volume A measurement of the amount of space an object takes up Slide 94 Medical: Auditory Reaction Time How long it takes to react to a sound you hear Slide 95 Medical: Blood Pressure The pressure of the blood on the walls of the blood vessels Slide 96 Medical: Peripheral Vision The field seen in a surrounding space while looking straight ahead Slide 97 Medical: Gravity The force that pulls bodies toward the center of the planet Slide 98 Medical: Pulse Rate The pressure in the arteries due to the beating of the heart Slide 99 Medical: Respiration Rate The number of breaths per minute Slide 100 Medical: Skin Temperature External temperature of the body; lower than internal temperature Slide 101 Medical: Visual Reaction Time How long it takes to react to a light you see Slide 102 Probe: Airlock The special drawer in which the probe is securely kept Slide 103 Probe: Cable A wire that carries electricity from one component to another in the probe Slide 104 Probe: Component An electronic part that is plugged into the probe Slide 105 Probe: Deploy Launch Slide 106 Probe: Probe A data-collecting device which will explore a comet Slide 107 Life Support: Ammeter A device for measuring light Slide 108 Life Support: Barometer An instrument for measuring air pressure Slide 109 Life Support: Beaker A laboratory device for measuring liquid Slide 110 Life Support: Dissolve To change from a solid to a liquid state Slide 111 Life Support: Environmental Conditions The temperature, air pressure and humidity in the spacecraft Slide 112 Life Support: Graduated Cylinder A laboratory device for measuring liquids Slide 113 Life Support: Hygrometer An instrument used to measure relative humidity Slide 114 Life Support: Indicator A chemical used for testing if a liquid is acid base or neutral Slide 115 Life Support: Liter The basic unit of volume in the metric system; one liter equals 34 fluid ounces, or 1.06 quarts Slide 116 Life Support: MA (milliamperes or Milliamps); the units attached to the number determined by the ammeter, one thousandth of an Ampere Slide 117 Life Support: milli- One thousandth of something Slide 118 Life Support: mL One thousandth of a liter Slide 119 Life Support: pH A number which tells how acidic or basic a liquid is Slide 120 Life Support: ppm (parts per million); the units attached to the number determined by the TDS meter Slide 121 Life Support: Solar Energy Energy provided by the sun Slide 122 Life Support: TDS (total dissolved solids); a number telling how much solid material is dissolved in water, measured by the TDS meter Slide 123 Life Support: Valve A device used to control the flow of air or water Slide 124 Navigation Team: Angle The point formed by the joining of two lines Slide 125 Navigation Team: Detector A device used to gather information Slide 126 Navigation Team: Grid A system of X and Y coordinates used in launching detectors Slide 127 Navigation Team: Initialize To begin or name something Slide 128 Navigation Team: Particle density A number telling how tightly packed the material in a comet is Slide 129 Navigation Team: Star Chart A paper map of the stars Slide 130 spectrometer An instrument used to obtain and record a spectrum of an astronomical object A spectrum is a series of colors that is produced when light is spread out in order of wavelength. Slide 131 Navigation Team: Starfield A group of stars in view of the spacecrafts camera Slide 132 Navigation: Density Mass of a substance contained per unit of volume Slide 133 Navigation: Coma The atmosphere of a comet, which surrounds the nucleus Slide 134 Navigation: Nucleus The solid part of a comet made up of rocks, dust, gas and ice (dirty snowball) Slide 135 Navigation: Tail The longest part of the comet caused by solar wind Slide 136 Navigation: Constellation A group of stars that form a pattern in the sky Slide 137 Navigation: Declination The label for the Y-axis on a star chart. The declination of an object is its distance in degrees above or below the celestial equator. Decline numbers range from 0 degrees to +90 degrees and 0 degrees to -90 degrees. It is similar to latitude on Earth Slide 138 Navigation: Right Ascension The label for the X-axis on a star chart. The right ascension of an object in the sky is its position, simply put relative to the vernal equinox. It is measured in hours minutes and seconds from 0 hours, 0 minutes and 0 seconds of right ascension at the starting point (vernal equinox), to 23 hours, 59 minutes of right ascension. Right ascension is equivalent to longitude. Slide 139 Navigation: Eccentricity A numerical value for the shape of an orbit ranging from 0, which equals a circular orbit, to 1 which equals a flattened, elliptical orbit. Planets, moons, asteroids and short period comets have eccentricity values close to 0. long period comets have eccentricity values of 0.5 or more Slide 140 Navigation: Short Period Comet A comet with an orbital period of less than 200 years. (Comet Halley is 76 years and comet Encke is 3.3 years. Slide 141 Navigation: Long Period Comet A comet with an orbital period of more than 200 years. (Hale-Bopp is 2425 years and Hyakutake is 15,000 Years) Slide 142 Navigation: Magnitude A numerical value for the brightness of a celestial object. The brighter an object appears in the sky, the smaller its magnitude the dimmer an object appears in the sky, the larger its magnitude. Slide 143 Navigation: Stellar Object A celestial object that produces its own light (the sun)