Planetary Science Reviewer AST01-AST15-part-2

AST02 - Planetary Science FORMULAS Non-computational Topics The Solar System There are eight major planets with nearly circular orbits, in the same direction and nearly in the same plane. ○ Arranged by distance to the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn,...

AST02 - Planetary Science FORMULAS Non-computational Topics The Solar System There are eight major planets with nearly circular orbits, in the same direction and nearly in the same plane. ○ Arranged by distance to the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune ○ Planets are very tiny compared to the distances between them. The Earth-Sun distance is 200 times larger than the Sun’s radius. Dwarf planets are smaller than the major planets and some have quite elliptical orbits. ○ Arranged by radius: Pluto, Eris, Haumea, Makemake, Ceres Asteroid Belt between Mars and Jupiter; Kuiper Belt beyond Neptune; Oort Cloud located at 2000-5000 AU to 10000-100000 AU from the sun. Comparative Planetology: Comparing the planets reveals patterns among them and those patterns provide insights that help us understand our own planet. The Sun Age: 4.6 Billion years Type: G2V main sequence star Radius: 695,700 km Mass: 1.989 E30 kg Composition: 70% H; 28% He; 2% C, N, O Surface Temperature: ~5770K The Sun is 99.8% of the Solar System’s Mass. G2V means: ○ G - Spectral Type - Surface Temp and color ○ 2 - Subclass ○ V - Luminosity Interior Layers: ➔ Core - innermost part where nuclear fusion occurs. 200,000 km across and has a temp. of 15 million °C ➔ Radiative Zone - the energy from core is carried by photons for 200,000 years ➔ Convective Zone - the opaque, outermost part of the Sun’s interior with a temp. of 2 million °C Atmosphere Layers: ➔ Photosphere - the visible surface of the Sun that emits sunlight. It is relatively cool at about 6,700°C ➔ Chromosphere - 2,000 km thick and glows red as it is heated by energy from the photosphere ➔ Corona - Sun’s halo or ‘crown’, it is the outermost plasma layer with temperatures of 2 to 5 million°C Regions: ➔ Sunspots - lower temp. and associated with facula; classified using the Zürich/McIntosh Classifications ➔ Faculae - bright, granular, and hotter than the surrounding photosphere ➔ Granulation - grainy appearance of granule convective cells ➔ Prominence - bright magnetic loops of cool, dense gas ➔ Solar Flares - sudden explosion of energy by twisted magnetic lines ➔ Filament - magnetic loops that appear as dark lines Terrestrial Planets The four small, dense, rocky planets that orbit closest to the sun Faster period of revolution Slower Rotation Mercury Nomenclature: Hermes (Greek name of Mercury) is the messenger of the God of Olympus, Zeus. 0.39 AU from the Sun Mercury has a heavily cratered, moonlike surface, composed mainly of volcanic rock. It has a massive iron core. Only has a thin exosphere Very hot, very cold: 425°C (day), -170°C (night) The 2nd densest planet at 5.427 g/cm³ Moons: 0 Prominent Features: ○ Caloris Basin (impact basin) Artificial Satellites: ○ Mariner 10 (1974, flyby)  ○ MESSENGER (2011, orbiter) ○ BepiColombo (2022, orbiter) Venus Nomenclature: In Greek Mythology, Venus is named as Aphrodite, and is the daughter of Zeus and Dodona. She is the goddess of beauty and love and the mother of Eros. 0.73 AU from the Sun Earth’s Sister planet/ Twin planet (85% of Earth’s diameter) Highest surface temperature because of Greenhouse effect, 470°C (day and night) Atmosphere is thick and made of mostly carbon dioxide There was a false alarm of a biosignature detection of a chemical (phosphine) in 2020. Venus also has phases, first observed by Galileo Galilei in 1610. Moons: 0 Prominent Features: ○ Maat Mons (tallest volcano) ○ Skadi Mons (tallest mountain) Artificial Satellites: ○ Venera 7 (1970, lander) ○ Venera 8 (1972, lander) ○ Venera 9 and Venera 10 (1975, lander) ○ Venera 11 and Venera 12 (1978, lander) ○ Venera 13 and Venera 14 (1982, lander) ○ Akatsuki (2015, orbiter) Earth Earth is associated with the Greek goddess Gaia, who bears life in the universe. Earth is the only planet in the Universe (so far) to hover over life. It lies in the habitable zone where sufficient energy from the Sun permits life development. It contains water- so much volume of water. It also possesses a magnetosphere and breathable atmosphere. Oasis of life Atmosphere, Lithosphere, Hydrosphere, Biosphere  Surprisingly large moon The densest planet in the Solar System at 5.514 g/cm³ Rotation is the movement of the earth as it rotates from west to east on its axis. ○ Mean solar day is the time interval from one noon to the next noon day, because it is the time when the Sun has reached its highest point in the sky. ○ Sidereal day is the time it takes for the Earth to make one complete rotation with respect to a star other than the sun. In which, in a sidereal measurement. The Earth rotates 360° in 24 hours, or 15° per hour. Revolution is one complete orbit of the earth to the Sun, in about 365.25 days. The direction of revolution is counterclockwise as viewed down from the north. Precession is the reaction of Earth to the gravitational pull of the Moon and the Sun on its equatorial bulge. This results in a slow wobbling of the Earth as it turns on its axis. Solstice is either of the two moments in the year when the Sun's apparent path is farthest north or south from the earth's Equator. ○ In the Northern Hemisphere summer solstice occurs on June 21 or 22 and the winter solstice on December 21 or 22. Equinoxes are the days in which there are exactly 12 hours of daylight and 12 hours of night time everywhere in the world. Around March 20 and September 23. The Moon It is about 3,476 kilometers in diameter, slightly more than ¼ the diameter of Earth. In the Solar System, it is the largest moon relative to its planet size The Moon has no significant atmosphere, just a trace of hydrogen, helium, neon, and argon atoms, along with other traces in even lesser quantities. It is made of solid rock. It has a mass of only 1/81 the mass of Earth, and its density is about 3.3 times the density of water, which is less than the density of Earth. Phases of the Moon Lunar Mare/Maria (Latin for “sea”; the dark areas of the moon) ○ 5 biggest lunar mare:  Oceanus Procellarum (Ocean of Storms) Mare Frigoris (Sea of Cold) Mare Imbrium (Sea of Showers) Mare Fecunditatis (Sea of Fecundity) Mare Tranquillitatis (Sea of Tranquility) The Giant-Impact Hypothesis Mars Nomenclature: Greek god Ares is the counterpart of the planet Mars to Greek mythology. He is the God of War. ○ His sons with the Goddess of Beauty and Love are named as Phobos and Deimos (the gods of fear and terror, respectively) 1.38 AU away from the Sun Looks almost Earth-like, but has thin atmosphere Giant volcanoes, huge canyon, CO2 polar caps, more Water flowed in the distant past. Moons: 2 ○ Phobos (biggest and closest) ○ Deimos Prominent Features: ○ Olympus Mons (tallest volcano in the Solar System) ○ Valles Marineris (largest canyon in the Solar System) Artificial Satellites (milestone summary) ○ Mariner 4 (first flyby, 1965) ○ Mariner 9 (first orbiter, 1971) ○ Viking 1 (first lander, 1976) ○ Sojourner (first rover, 1997) ○ Opportunity (longest-running rover, 2004-2019) ○ Ingenuity Mars Helicopter (2021-2024) Aboard the Perseverance rover; the first flight in another planet Jovian Planets Gaseous planets beyond the asteroid belt Gaseous, larger, farther from the sun Faster rotation Slower period of revolution Jupiter Largest planet in the Solar System 5.20 AU away from the Sun. Much farther from sun than inner planets Mostly H/He; no solid surface 300 times more massive than Earth Has zones (brighter) and belts (darker) In 1994, the comet Shoemaker-Levy 9 collided into Jupiter Trojan Asteroids: group of asteroids that share the planet Jupiter's orbit around the Sun. Moons: 95 (as of Feb 5, 2024) ○ Galilean moons Io : most volcanically active world in the Solar System Europa : possible subsurface ocean Ganymede : largest moon in Solar System Callisto: the oldest and most heavily cratered in the Solar System ○ Shepherd moons (moons that maintain rings) Adrastea and Metis (Main Ring) Amalthea (Amalthea Gossamer Ring) Thebe (Thebe Gossamer Ring) ○ Other moons: Himalia, Elara, Callirrhoe, Ananke, Sinope, Carme, Pasiphae Prominent Features: ○ The Great Red Spot (largest anticyclonic storm in the Solar System) Red Spot Jr. (discovered in 2006 by a Filipino, Christopher Go) ○ Planetary Rings: Halo ring, Main ring, Gossamer rings  Artificial Satellites: ○ Pioneer 10 (flyby, 1973) ○ Voyager 1 and Voyager 2 (flyby, 1979) ○ Galileo (orbiter, 1995) (plunged into Jupiter, 2003) ○ Cassini (flyby, 2000) ○ Juno (orbiter, 2016) Saturn Nomenclature: Saturn, in Greek is the Father of the Olympians. He is named Cronus as the God of Time. He was overthrown by Zeus who became the God of Olympus. 9.58 AU away from the Sun. Giant and gaseous like Jupiter Cassini division ○ The gap between K and B rings Rings are not solid (not solid piece), they are made of small chunks of ice and rock each orbiting like a tiny moon ○ Ring rain: The rings are being pulled into Saturn by gravity as a dusty rain of ice particles under the influence of Saturn's magnetic field. Saturn was the last of the planets known to ancient civilizations. It was known to the Babylonians and Far Eastern observers. Saturn gives off more energy than it receives from the Sun. This unusual quality is believed to be generated from the gravitational compression of the planet combined with the friction from a large amount of helium found within its atmosphere. Moons: 146 (as of June 8, 2023) ○ Titan: Largest moon, Larger than Mercury ○ Enceladus: Has a global ocean underneath a thick, icy shell ○ Shepherd moons (moons that maintain rings): Pan (Encke gap) Daphnis (Keeler gap) Prometheus (F Ring) Janus (A Ring) Epimetheus (A Ring) ○ Other moons: Tethys, Mimas, Dione, Iapetus, Hyperion, Phoebe, Telesto, Calypso, Pandora, Atlas  Prominent Features: ○ Planetary Rings: A ring, B ring, C ring, D ring, E ring, F ring, G ring ○ Hexagonal storm (a cloud pattern around the north pole of the planet) ○ Great White Spot (periodic storms that are large enough to be visible from Earth) Artificial Satellites: ○ Pioneer 11 (flyby, 1979) ○ Voyager 1 (flyby, 1980) ○ Voyager 2 (flyby, 1981) ○ Cassini (orbiter, 2004) Huygens (Titan lander, 2005) Uranus Nomenclature: In Greek Mythology, Uranus is the father of the Titans including Cronos, Rhea, Cyclopes, and others. He is the son of Gaea who, in the later times, became the husband of her own mother. He was overthrown by Cronos. 19.22 AU away from the Sun. The coldest planet in the Solar System at -224°C  Smaller than Jupiter/Saturn but much larger than Earth Made of H/HE gas and hydrogen compounds H2O, NH3 (Ammonia), CH4 (Methane) ○ Methane gives Uranus its bluish hue Discovered in 1781 by William Herschel. The first planet to be discovered in modern history Original name proposed for Uranus is Georgian Sidius after King George. Uranium, discovered in 1789, was named after Uranus. Moons: 28 (13 Inner moons, 5 Major moons, 10 irregular moons) ○ Naming system is derived from Shakespearean characters ○ Major Moons: Miranda Ariel Umbriel Titania (biggest) Oberon ○ Shepherd moons: Opheliaand Cordelia (ε ring) ○ Other moons: Puck, Desdemona, Prospero, Sycorax, Ferdinand, Rosalind, Juliet, Cupid Prominent Features: ○ ~97.77 degree tilt ○ Planetary Rings: ζ, 6, 5, 4, α, β, η, γ, δ, λ, ε, ν, μ Artificial Satellites: ○ Voyager 2 (the only flyby, 1986) Neptune Nomenclature: Due to its appearance, Neptune is associated with the sea- Greek god Poseidon, who rules the sea and its creatures. Poseidon is the father of Triton, Pegasus, Orion, and many others. He took advances to his sister Demeter and Medusa. Athena and Poseidon competed for possession of the City of Athens. 30.10 AU away from the Sun. Discovered by Joseph Le Verrier in 1846 via calculations of the perturbations of Uranus Similar to Uranus (except for axis tilt) Planet with the 2nd strongest gravity 600 m/s winds, fastest in the Solar System Moons: 16 ○ Largest moon: Triton (slightly smaller than Earth’s Moon, and has active volcanoes) ○ Shepherd moon: possibly Despina (Le Verrier ring) ○ Other moons: Nereid, Naiad, Thalassa, Despina, Galatea, Larissa, Proteus Prominent Features: ○ Faint Planetary Ring Inner Rings (Galle ring, Le Verrier ring, Lassell ring) Adams Ring ○ Great Dark Spot Artificial Satellites: ○ Voyager 2 (the only flyby, 1989) Dwarf Planets Much smaller than major planets Icy, comet-like composition Pluto Nomenclature: Pluto got its name from 11-year-old Venetia Burney of Oxford, England, who suggested to her grandfather that the new world get its name from the Roman god of the underworld. The ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest known trans-Neptunian object by volume. Known to have ice mountains, and an atmosphere when nitrogen ice melts as Pluto comes closer to the Sun Pluto and Neptune are locked in a 3:2 orbital resonance From 1979 to 1999, Neptune was actually farther from the sun than Pluto because of its elliptical orbit. Tholins: the material that gives some regions of Pluto and Charon its reddish-brown color. It is also found on many other Trans-Neptunian Objects and Kuiper Belt Objects. Moons: 5 ○ Charon (biggest) ○ Nix ○ Styx ○ Kerberos ○ Hydra Prominent Features: ○ Tombaugh Regio (Heart-shaped region) ○ Tartarus Dorsa (mountain showing snake-skin like appearance) Artificial Satellites: ○ New Horizons (the only flyby, 2015) Ceres The first known asteroid discovered by Giuseppe Piazzi in 1801 The largest object in the Asteroid Belt but the smallest of the five confirmed dwarf planets Artificial Satellites: ○ Dawn (orbiter, 2015-2018) Haumea An oval-shaped Trans-Neptunian Object discovered in 2004 by a team headed by Mike Brown. Its oval shape is due to its high rotational speed Possibly has planetary rings due to a collision Moons: 2 ○ Hi’iaka and Namaka Makemake The second largest “cubewano (classical Kuiper-Belt Objects) Discovered in 2005 by a team headed by Mike Brown. Moons: 1 ○ MK2 Eris The most massive and second-largest known dwarf planet in the Solar System Discovered in 2005 by a team headed by Mike Brown. For a period of time, the object became known to the wider public as Xena Moons: 1 ○ Dysnomia Types of Spacecraft Exploration 1. Flybys - Flies by a planet just once - Advantage: cheaper - Disadvantage: less time to gather data 2. Orbiters - Go into orbit around another world - More time to gather data but cannot obtain detailed information about world’s surface 3. Probes/Landers - Lands on surface of another world - Explores surface in detail 4. Sample Return Mission - Lands on surface of another world - Gathers samples - Spacecraft designed to blast off other world and return to Earth - Apollo missions to the Moon are one example, Hayabusa to an asteroid is another. 5. Combination Spacecraft - Cassini/ Huygens mission - Contains any of the previous Solar System Boundaries Heliosphere - the region of space containing magnetic fields and plasma of solar origin Heliopause - the boundary of the heliosphere Terminal Shock - region just interior to the heliopause is where the solar wind is slowed down. Heliosheath - Region between the termination shock and the heliopause. Bow Shock - forms in front of the Heliosphere as the sun moves through the interstellar medium IAU Resolution 2006: Defining a Planet A planet is a celestial body that: is in orbit around the Sun has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape has cleared the neighborhood around its orbit. Star - Self sustaining fusion is sufficient for thermal pressure to balance gravity (+- 0.075 Solar mass about 80 Jupiter mass) for solar composition; a minimum mass for an object to be a star is often referred to as the hydrogen burning limit Stellar remnent - Dead star - No more fusion (or so little that the object is no longer supported primarily by thermal pressure) - Three types Brown Dwarf - Substellar object with substantial deuterium fusion - More than half of the object’s original inventory of deuterium is ultimately destroyed by fusion Planet - Negligible fusion (≤ 0.012 solar mass about 13 Jupiter mass, with the precise value again depending on initial composition), plus it orbits one or more stars and/or stellar remnants Properties of Planets 1. Orbit Johannes Kepler deduced three “laws” of planetary motion directly from observations: - Law of Ellipse - Law of Equal Areas - Law of Periods  A Keplerian orbit is uniquely specified by six orbital elements: ○ a (semimajor axis) - denoted using AU (Astronomical Unit) ○ e (eccentricity) e = 0 (circle e = between 0 & 1 (ellipse) e = 1 (parabola) e > 1 (hyperbola) ○ i (inclination) - tilt of the orbit ○ 𝛚 (argument of periapsis) or 𝝕 (longitude of periapsis) ○ 𝛀 (longitude of ascending node) ○ f or 𝛎 (true anomaly) ➔ a and e fully define the size and shape of the orbit ➔ i gives the tilt of the orbital plane to some reference plane ➔ the longitude 𝝕 and 𝛀 determine the orientation of the orbit ➔ f tells where the planet is along its orbit at a given time Titius-Bode Rule ○ Generates a series of numbers that appear to match the average distances of the planets from the Sun expressed in astronomical units. ○ Was published in 1772 by two German astronomers named Johann Daniel Titius and Johann Elert Bode. ○ Predicted the existence of Ceres between the orbits of Mars and Jupiter ○ Procedure for generating this series of numbers: Write a string of numbers starting with zero Add 4 to each number and divide by 10 The result is: 0.4, 0.7, 1.0, 1.6, 2.8, 5.2, 10.0, 19.6, 38.8, 77.2 ○ The discrepancies between the actual radii of the orbits of Uranus, Neptune, and Pluto and their radii predicted by the Titius-Bode rule may indicate that the orbits of these planets were altered after their formation.  Ecliptic Plane ○ For observational convenience, inclinations are usually measured relative to the Earth’s orbital plane, which is known as the ecliptic plane. ○ All planets and asteroids revolve around the Sun in the direction of solar rotation. ○ Many smaller objects that orbit the sun and the planets have much larger orbital inclinations ○ Some comets, minor satellites and Neptune’s large moon Triton orbit the sun or planet in a retrograde sense (opposite to the sun’s or planet’s rotation) ○ Observed ‘flatness’ of most of the planetary system is explained by planetary formation models that hypothesize that the planets grew within a disk that was in orbit around the sun 2. Mass Ways to Determine Mass: Newton’s Generalization of Kepler’s Third Law ○ Orbits of moons: the orbital periods of natural satellites, with Newton's generalization of Kepler’s third law, can be used to solve for mass. Effective when the difference between masses is very small.  Perturbations ○ Gravitational disturbances from other celestial bodies ○ Usually used for large asteroids ○ Short-term: mass can be determined from close encounters with asteroids ○ Long-term: Periodic variations of the motion of the moons Spacecraft Tracking Data ○ Best means of determining masses of planets using robotic spacecraft such as flybys and orbiters ○ The doppler shift and periodicity of the transmitted radio signal can be measured very precisely. Spiral Wave Density ○ If the moon is close to the ring it affects the ring particles, causing ripples or wave-like motions ○ Used to estimate the masses of some of Saturn’s small inner moons Asymmetric escape of released gasses and dust ○ For comets Gas tail (Interaction with solar winds) Dust tail (only affected by the Sun’s radiation pressure) 3. Size Ways to Determine Size: Angular Size ○ To solve for the diameter of a body ○ Has large uncertainties in angular size because of limited resolution from Earth Occultation ○ Geometry of an asteroid occultation ○ Diameter of a solar system body can be deduced by observing a star as it is occulted by the body ○ Calculate the amount of time it takes for an object to pass a certain point Radar Echoes ○ Can be used to determine radii and shapes for relatively nearby objects that may be studied with radar (similar to echolocation) Radar is especially useful for studying solid planets, asteroids and cometary nuclei  Triangulation ○ Triangulation using landers and orbiters to more accurately measure the radius of an object Photometric Observations ○ Use of photometric observations at visible and infrared wavelengths ○ Can estimate the size and albedo of a body With size and mass we can get: 1. Mass density - quantity per unit 2. Escape velocity - lowest velocity which a body must have in order to escape the gravitational attraction of a particular planet or other object. 4. Rotation a vector quantity related to spin angular momentum Obliquity (axial tilt) ○ Angle between its spin angular momentum and its orbital angular momentum ○ < 90 degrees obliquity = prograde rotation ○ > 90 degrees obliquity = retrograde rotation Ways to Determine Rotation: Marking ○ Only applicable with solid surface not covered by the atmosphere and is inaccurate with gas giants Radio Signals ○ Planets with sufficient magnetic fields trap charged particles in their magnetospheres ○ Particles are accelerated by electromagnetic forces and emit radio waves which have periodicity equal to the planets rotation speed Light Curve ○ Gives the total disk brightness as a function of time Doppler Shift ○ Crude estimate of the rotation axis, provided the body’s radius is known ○ Can be done passively by visible light or radar 5. Shape Self-gravity tends to produce bodies of spherical shape, a minimum for gravitational potential energy. Material strength maintains shape irregularities, which may be produced by accretion, impacts or internal geological processes. Self-gravity increases with the size of an object, larger bodies tend to be rounder Rotation introduces a centrifugal pseudo-force that causes a planet to bulge out at the equator. Polar flattening is greatest for planets that have a low density and rapid rotation ○ Saturn - most oblate planet in our solar system ○ Faster spinning - more oblate shape ○ Slower spinning - more spherical shape Ways to Determine Shape: Direct Imaging ○ Can be done from either the ground or spacecraft Length of Chords ○ Observed by stellar occultation experiments at various sites Analysis of Radar Echoes ○ Can be used to determine radii and shapes for relatively nearby objects that may be studied with radar (similar to echolocation) Radar is especially useful for studying solid planets, asteroids and cometary nuclei Analysis of Light Curves ○ Several light curves obtained from different viewing angles are required for accurate measurements Central Flash ○ Sudden brightening at the minimum of a light curve ○ Central flash results from the focusing of light rays refracted by the atmosphere 6. Temperature Can be calculated from the energy balance between solar insolation and reradiation outward ○ In situ measurements with a thermometer Can provide an accurate estimate of the temperature of the accessible (outer) parts of a body ○ Thermal infrared spectrum Good indicator of the temperature of its surface or cloud tops 7. Magnetic Field Generated by dynamo process or remnant ferromagnetism Examples ○ Ganymede - magnetic field comes from the core ○ Venus and comets - magnetic field produced by solar wind and particles in atmosphere ○ Mars and The Moon - localized crustal magnetic field Ways to Determine Magnetic Fields: Magnetometer ○ carried by landers with an instrument for measuring the strength and sometimes the direction of magnetic fields Radio Emissions ○ from accelerating charges 8. Surface Composition Refers to the chemical and physical components of an object's surface Ways to Determine Surface Composition: Spectral Reflectance Data ○ May be observed from earth ○ Spectra at ultraviolet wavelengths can only be obtained above the Earth’s atmosphere Thermal Infrared Spectra and Thermal Radio Data ○ These measurements contain information about a body’s composition Radar Reflectivity ○ can be carried out from earth or spacecrafts that are near the body X-ray and Gamma Ray Fluorescence ○ Measurements conducted from spacecraft in orbit around the planet if the body lacks a substantial atmosphere  Chemical Analysis of Surface Samples ○ can be performed on samples brought to Earth by natural processes (meteorites) or sample return spacecraft 9. Surface Structure Varies greatly from one planet or moon to another Ways to Determine Surface Structure Imaging ○ Can detect large structures ○ Either passively in the visible/infrared/radio or actively using radar imaging techniques Radar Echo Brightness and Variation of Reflectivity ○ Used to find small scale structures (grain size) ○ Related to radar echoes and albedo 10. Atmosphere Composition and structure of an atmosphere can be determined from: ○ Spectral reflectance data ○ Thermal spectra and photometry ○ Stellar occultation profiles ○ Attenuation of radio signals 11. Interior Not directly accessible to observation Can be derived from mass and size or gravitational field and rotation rate Detailed information on the internal structure of a planet with a solid surface may be obtained if seismometers can be placed on its surface Photometry - light curve Attenuation - reduction in strength Spectroscopy - to obtain the composition of a planet and to detect biosignatures Planetary Geology Processes That Shape Surfaces: 1. Impact Cratering ○ Happens when an object (e.g. asteroid, comets) crash in to the planet and leave bowl-shaped depressions (craters) ○ Most cratering happened in the first billion years after the solar system formed A surface with many craters has not changed much in 3 billion years The moon’s mare are younger regions of the surface due to them not having a lot of craters ○ Craters are about 10 times wider than the object that made them ○ There are more small craters than large ones  2. Volcanism ○ Happens in planets with thin lithospheres when molten rock (magma) finds path through lithosphere to the surface through volcanoes; at that point magma is called lava Runny lava makes flat lava plains Slightly thicker lava makes Shield Volcanoes Thick lava makes steep Stratovolcanoes ○ Kinds of Lava: Pahoehoe - smooth lava; Aa - rough lava ○ Kinds of Volcanoes: Cinder Cone, Stratovolcanoes, Shield, Lava Dome ○ Outgassing - the release of gasses (H2O, CO2, SO2) from Earth’s interior into the atmosphere 3. Tectonics ○ The deformation of the rocks that make up the Earth’s crust and the forces that produce such deformation ○ Tectonic Forces - stresses in the crust created by the convection of the mantle ○ Types of Plate Tectonics: Convergent, Divergent, Transform 4. Erosion ○ Related terms: Weathering, Breakage ○ A blanket term for weather-driven processes that break down or transport rock ○ Erosion can be caused by: water, ice, wind, gravity (depositing debris) History of Spaceflight PART 1: ROCKETRY Wooden bird ○ One of the first devices to successfully employ the principles essential to rocket flight Archytas ○ Lived in the city of tarentum mystified and amused the citizens by flying a pigeon made of wood (400 BC) Hero of Alexandria ○ Invented a similar rocket-like device called an aeolipile  First true rockets were accidents (1st century A.D.) ○ The Chinese reportedly had a simple form of gunpowder made from saltpeter, sulfur, and charcoal dust. and began experimenting with the gunpowder-filed tubes. First use of true rockets was in 1232 (Battle of Kai-Keng). ○ Chinese repelled Mongol invaders by a barrage of “arrows of flying fire” ○ Fire-arrows were a simple form of a solid-propellant rocket. Roger Bacon (England) ○ A monk who worked on improved forms of gunpowder that greatly increased the range of rockets Jean Froissart (France) ○ achieved more accurate flights by launching rockets through tubes. ○ This idea was the forerunner of the modern bazooka. Joanes de Fontana (Italy) ○ designed a surface-running rocket-powered torpedo for setting enemy ships on fire 16th Century ○ Rockets fell into a time of disuse as weapons of war, though they were still used for fireworks displays. Johann Schmidlap ○ German who invented the “step rocket,” a multi-staged vehicle for lifting fireworks to higher altitudes. ○ This idea is basic to all rockets today that go into outer space. Lesser-known Chinese official named “Wan-Hu” ○ He had two large kites attached to the chair and fixed to the kites were forty-seven fire-arrow rockets 17th Century ○ Sir Isaac Newton laid the scientific foundations for modern rocketry.  1720 ○ Willem Gravesande (Netherlands) built cars propelled by jets of steam End of 18th Century and early into the 19th Century ○ Rockets experienced a brief revival as a weapon of war Colonel William Congreve ○ Set out to design rockets for use by the British military William Hale (England) ○ developed a technique called spin stabilization 1898 ○ Konstantin Tsiolkovsky, a Russian school teacher, proposed the idea of space exploration by rocket ○ He is the Father of Modern Astronautics Early 20th Century ○ Robert H. Goddard (USA) ○ Conducted practical experiments on rocketry and achieved the first successful flight with a liquid propellant rocket on March 16, 1926. ○ Father of Modern Rocketry Hermann Oberth (Germany) ○ The third great space pioneer that published about rocket travel into outer space in 1923 Verein für Raumschiffahrt (Society for Space Travel) ○ Led to the development of the V-2 rocket, which the Germans used against London during WW2 Wernher von Braun ○ Key figure in the production of the first guided ballistic missile, the V-2, during the war October 4, 1957 ○ Soviet Union stunned the world by launching an Earth-orbiting artificial satellite called Sputnik 1  1958 ○ US launched their own satellite Explorer 1 PART 2: BASIC ROCKET PRINCIPLES A rocket in its simplest form is a chamber enclosing a gas under pressure Small opening at one end of the chamber allows the gas to escape, and in doing so provides a thrust that propels the rocket in the opposite direction. Balloon ○ Air inside a balloon is compressed by the balloon’s rubber walls ○ Air pushed back so that the inward and outward pressing forces balance ○ When the nozzle is released, air escapes through it and the balloon is propelled in the opposite direction. The difference between a balloon and a rocket is the way the pressurized gas is produced. For rockets, the gas is produced by burning propellants that can be solid or liquid in form or a combination of the two Rockets and rocket-powered devices have been in use for more than 2,000 years but rocket experiments only had a scientific basis for understanding how they work in the last 300 years. Science of Rocketry Philosophiae Naturalis Principia Mathematica (1687) ○ In the principia, Sir Isaac Newton stated three important scientific principles that govern the motion of all objects, whether on Earth or in space. (Newton’s Laws of Motion) ○ An unbalanced force must be exerted for a rocket to lift off from a launch pad or for a craft in space to change speed or direction (FIRST LAW). ○ The amount of thrust (force) produced by a rocket engine will be determined by the rate at which the mass of the rocket fuel burns and the speed of the gas escaping the rocket (SECOND LAW). ○ The reaction, or motion, of the rocket is equal to and in the opposite direction of the action, or thrust, from the engine (THIRD LAW). PART 3: HUMAN SPACEFLIGHT HISTORY Almost a century before the first human space flight occurred ○ Jules Verne’s fictional characters planned and set of on a trip to the Moon in his novel De la Terre a la Lune, published in 1865 Verne was followed by H.G. Wells, who published The First Men in the Moon in 1901 Pilatre de Roziers and Marquis Arlandes ○ Made the first balloon flight from Paris in 1783 Gliders were developed in the 1800s, and towards the end of that century serious efforts were made to construct powered serious aircraft. 1903 - Orville and Wilbur Wright ○ Made the first successful flight in the “Wright Flyer” near Kitty Hawk, North Carolina, U.S.A. High-altitude balloons were used in the United States during the period 1955-1958 for a project called Project Man High to study cosmic rays and human flight at high altitudes. Project Excelsior ○ Parachute jumps were made from balloons to simulate parachuting from high-flying aircraft or space capsules. Missile technology ○ Invented during the Second World War in Germany, served as the basis for the rockets utilized to launch humans into space in the 1960s Sergei Korolev ○ Ukrainian, leading player in the early Soviet space program ○ Often referred to as the Soviet Chief Designer Russians had a series of successes beginning with the launch of the world’s first artificial satellite, Sputnik 1, on October 4, 1957, Using an intercontinental ballistic missile (R-7) inspired by the German V-2 rocket ○ The launch was linked to the International Geophysical Year, which lasted from July 1957 to December 1958. After the surprise launch of Sputnik 1, the Soviets launched Sputnik 2 on November 3, 1957. It was much larger and carried a living passenger, the dog Laika Followed by the scientific spacecraft Sputnik 3 on May 15, 1958 that used to investigate the space environment near the Earth.  In 1959, it was decided that only operational Air Force pilots would be considered for the first orbital space missions of the Soviet Union. Chief Designer Korolev specified the requirements for the candidates: + Men + Age range 25-30 + No taller than 1.70 m + No heavier than 72 kg Star City: Center for cosmonaut training was established in a Moscow suburb, 30 km from the capital Vanguard Six ○ Yuri Gagarin ○ Valerij Bykovskiy ○ Grigory Nelyubov ○ Andriyan Nikolayev ○ Pavel Popovich ○ Gherman Titov On April 12, 1961, human space travel became a reality when Lieutenant Yuri Gagarin flew into space on Vostok 1.  Gherman Titov ○ Age 25, made 17 orbits around the Earth on Vostok 2 after Gagarin’s historic flight Valentina Tereshkova ○ First woman to fly in space, on aboard the final Vostok mission in 1963 Svetlana Savitskaya ○ Flew twice and on her second flight became the first woman to make a space walk. Vostok was upgraded to create Voskhod Development of the Soyuz spacecraft started in the early 1960s, initially to support a manned circumlunar mission. The United States of America successfully launched a number of satellites into space in the years 1958 to 1960 On April 1, 1959, NASA selected seven test pilots for its first manned spaceflight program, Project Mercury. ○ Mercury Seven Walter (Wally) Schirra Alan Shepard Donald (Deke) Slayton Virgil (Gus) Grissom John Glenn Gordon (Gordo) Cooper Scott Carpenter  President John F. Kennedy ○ Gave his historic speech to Congress (May 25, 1961) about plans for space exploration The Mercury program in the United States was followed by the Gemini Program. ○ The Gemini spacecraft resembled its predecessor but was bigger and could carry two people. In the early 1960s some efforts were made to initiate a “Girl Astronaut Program” The Apollo program was operational from 1968 to 1972. ○ 24 astronauts left Earth orbit on Apollo spacecraft ○ 12 astronauts walked on the Moon. No one has gone back since. ○ 80 Hours were spent working on the lunar surface ○ Crew assigned to the Apollo 1 mission were killed in a fire during a rehearsal on the pad a month before their scheduled launch. ○ Apollo 2 to 6 were unmanned tests in preparation for the manned flights