Astrobiology Exam 1 PDF

Module 1 -- Content and Scale of the Universe What is in the Universe? - Earth-Moon System - Solar System - Planets (Jovian + Terrestrial) - Sun - Asteroids (originate in the Asteroid Belt) - Comets (originate in the Oort Cloud + Kuiper Belt) - Stars -...

Module 1 -- Content and Scale of the Universe What is in the Universe? - Earth-Moon System - Solar System - Planets (Jovian + Terrestrial) - Sun - Asteroids (originate in the Asteroid Belt) - Comets (originate in the Oort Cloud + Kuiper Belt) - Stars - Star Clusters (100,00 stars) - Galaxies (100 billion stars) \*10\^22 stars in the universe (possibly)\* AU = astronomical unit = average distance between Earth and the Sun LY = light year = distance light travels in one year Hubble vs. James Webb Telescope Hubble - Orbits Earh just above the atmosphere - At L1 - Able to be serviced through missions - Optimized for UV + visible light - primary mirror is made of one large piece of Ultra-Low Expansion Glass^®^ that is coated with thin layers of aluminum and magnesium fluoride, 7.9 feet Webb - Orbits the Sun - At L2 - No current servicing capability - Optimized for infrared light - 21.3 foot primary mirror Module 2 -- Description and History of the Solar System How did the solar system form? (Solar Nebula Theory) - Gravitational energy of infalling material in the disk becomes thermal energy - Inner disk becomes hotter than the outer disk. - Planet composition is governed by the position of the protoplanet in the disk the disk. - From cloud to planets - Gas motions blow small particles into large particles (accretion) - Clumps approximately 100 m in size - Clumps grow to 1 km in size (Planetesimal) - Gravity pulls planetesimals into protoplanets Evolution of Planets - Protoplanets have primary atmospheres, mini accretion disks form around planets - Moons form from mini accretion disks - Solar wind and low gravity cause small planets to form secondary atmospheres Jovian Planets - Include Neptune, Jupiter, Uranus (tilted on its side), Saturn - large, made mostly of gases and liquids with low densities and found far from the Sun Terrestrial Planets - Earth, Mars, Mercury, Venus - small, made mostly of rock and iron with high densities and found close to the Sun Moon - Keeps the Earth at 23.5 degrees (from vertical) which ultimately maintains a stable climate - Formed by a collision with a protoplanet about half its size more than 4 billion years ago - Largest moon in the inner solar system - Densest side is always facing earth Debris (made up of planetesimals) - Asteroid Belt (between Mars and Jupiter) -- comprised of asteroids, refractory (frozen), includes Ceres (largest asteroid, only dwarf planet in the asteroid belt) - Kuiper Belt (past Neptune) -- comprised of comets, volatile, includes Pluto + Charon The Dwarf Planets - Pluto - Ceres - Haumea, MakeMake Comets - From Kuiper Belt just beyond Neptune (short period comets), Oort Cloud (thought to have originated from planetesimals thrown out of the solar system by Jovian planets) (source of long period comets, \>200 years) - Nucleus is a compact solid body of frozen gases, dust, small rock (usually 10-20 km) - planetesimal - A coma is a halo of dust and gas around the nucleus (can be 100,000 km in diameter) - The tail of the comet is always directed away from the sun - Dark ice + dirt - Coated with fine dust - Ice escapes from jets and gas pockets - Ex: Halley, Hartley Asteroids - Rock that were comets previously? - Rubble piles to dense iron - Ex: Itokawa, Phobos + Deimos Pluto - Red - Darker areas get darker over time (tholins) - Frozen, but it theorized that there is liquid water deep below the surface near the core Module 3 -- Conditions for the Formation of Life, Extremophiles How do we know if something is alive? - Order - Growth and development - Energy utilization - Reproduction - Response to environment - Evolutionary development Evolution - Competition for survival - Individual variation among a population of a species - Natural selection -- individuals whose traits are best suited for survival will have the largest number of offspring and be more populated in succeeding generations Planetary Ingredients for Life - Water - Elements (C, N, O) - Can be found in solid bodies in the solar system (comets + asteroids) - Need liquid or gas to move them about so they can react - Energy - Sunlight -- more available in worlds near the sun - Chemical energy -- requiring worlds where chemicals can be mixed - Time Which kind of atom is able to make the most bonds? - Carbon-based molecules = organic molecules - Can form up to four bonds \*silicon can also form four bonds, but they're much weaker and tend to be single bonds\* \*life only uses left-handed amino acids\* \--\> evidence of common ancestor \* Deinococcus radiodurans can survive high doses of radiation\* Alkalophile - Environments of pH levels of 9+ - Carbonate soils - Soda lakes (found in Egypt, Rift Valley, western USA) - Additives for animal feed - Maintain neutrality in the interior cells Halophile - Common inhabitants of salt lakes, salt evaporation pools, and subsurface salt deposits - Common in saline microenvironments Psychrophile - Capable of thriving at temperatures \ up to 1300 atmospheres Xerophile/ Endoliths - Like dry conditions - Live in rocks