ASTR2040_HW4_Assignment

M/W/F 10:10-11:00 AM H OMEWORK #4 L IFE IN THE U NIVERSE L IFE IN THE S OLAR S YSTEM ASTR/GEO 2040 D UE 10/27 BY M IDNIGHT N AME _____________________________ 1 I NTRODUCTION This homework assignment focuses on Chapter 7 and the beginning of Chapter 8 in the textbook covering the search for life in the Solar System, especially Mars. Other things to keep in mind – For any question that asks for a quantitative answer, be sure to show all of your work! Lots of partial credit is available for showing work even if the final answer is incorrect. If a question asks for specific units, be sure to put your answer in those units. Finally, many problems have multiple parts or ask for multiple answers – make sure to read all parts of a problem to avoid missing something. ______________________ 1. L IFE IN THE S OLAR S YSTEM The textbook defines a ‘litmus’ test for habitability: ‘A world can be habitable only if it has a liquid medium, probably meaning liquid water.’ (9 points total) (a) What are the three advantages of water that make it seem far more suitable as a liquid medium of life than other liquids? (b) If we decide that the presence of liquid water is required for a world to be habitable, state whether the following Solar System objects are good places to look for life: Solar System Object Habitable? (Yes/No) Mercury Moon Venus Mars Jupiter Saturn Uranus Neptune Pluto Europa Titan Enceladus Genevieve Teller less dense as a solid good solvent wide liquid temp range no no no yes no no no no yes Yes

N AME _____________________________ H OMEWORK #4 2 ______________________ 2. S OLAR S YSTEM E XPLORATION Much of our knowledge about space has come from observations using ground- and space-based telescopes. But, the best way to learn about an object is often to actually send a mission to that object. Given the vast distances involved, we can currently only send missions to other bodies in the Solar System, making our own planetary system the best place to look for life in the Universe. (8 points total) (a) The Huygens mission made the farthest landing from Earth a spacecraft has ever made in 2005. What Solar System body did it land on? If it is a moon, what planet does that moon orbit? (b) Name one Solar System mission that has been launched previously, its target, and its scientific goal. (Hint: Table 7.2 in the textbook provides a table of robotic missions through 2015). (c) If you were in charge of the NASA Planetary Mission Program, what Solar System object would you choose to visit next? Why? (There is no right answer, but make a convincing case!) it landed on the surface of Titan It is saturns largest moon messenger mission its target was mercury and its goal was to understand the planets geogly atmosphere and magnets field I would visit europa even though it has already visited before The radiation around it is intense but the ocean below the surface is very intriguing

N AME _____________________________ H OMEWORK #4 4 (d) Name two potential problems for humans if a planet has concentrations of O 2 that are significantly higher than what is currently found at sea level on Earth. (Hint: See page 490 of the paper to answer this question.) (e) What class of greenhouse gases are considered to be the best candidates to initiate warming of Mars and to sustain a human habitable biosphere? What is an advantage and a disadvantage of this class of greenhouse gases? (Hint: See page 491 of the paper to answer this question.) (f) Extra Credit : Summarize the proposed sequence of events and timeline to turn Mars into a human habitable world. Be specific and complete to get the maximum number of points! Five hazards and toxicity high concern rations of Oz can cause oxidative damage to biological tissues as well as increase flammability of materials Fluorinated gases advantage disadvantage effective at trapping potent greenhouse heat warming atmosphere gas can contribute to climate change First atmospheric pressure must be increased by releasing greenhouse gases into atmosphere This will warm the planet t cause coz in soil to sublimate Process will take centuries Once atmosphere is thick enough plants will grow produce oxygen to further increasure atmospheric pressure Humans can then begin to colonize by building pressurized habitats and terraforming whole process could take several centuries

N AME _____________________________ H OMEWORK #4 5 ___________________ 4. M ULTIPLE C HOICE A few multiple-choice questions to test your understanding of the material covered in lecture. (6 points total) (4.1) Frozen lakes on Earth often have liquid water beneath their icy surfaces because… (A.) Earth’s internal heat keeps the water liquid (B.) ice floats on water and provides insulation to the water below (C.) sunlight penetrates the ice (4.2) On an asteroid that is twice as far as Earth from the Sun, the strength of sunlight would be… (A.) 4x as much (B.) 2x as much (C.) the same (D.) ½ as much (E.) ¼ as much (4.3) Venus is much hotter than Earth because… (A.) it has many more volcanoes (B.) its closer distance to the Sun makes sunlight much stronger (C.) its carbon dioxide atmosphere creates a stronger greenhouse effect (4.4) If life exists in Uranus and Neptune, it will most likely be found… (A.) in the ‘oceans’ of liquid ices in their outer cores (B.) floating on the surface of a layer of liquid metallic hydrogen (C.) high in the atmosphere where it could collect solar radiation (4.5) The New Horizons spacecraft… (A.) flew past Pluto (B.) landed on Mars (C.) orbited Saturn (4.6) We can recognize the oldest surface regions of Mars by the fact that they have… (A.) the most impact craters (B.) the most volcanoes (C.) the most evidence of past water flows o as as as