Exam 4 Study Guide

EAPS 105, The Planets Exam 4 Study Guide Know the following: Unit 10: Exoplanets 1. How the transit detection method works. By measuring the minute dimming of a star as an orbiting planet passes (transits) between it and the Earth. 2. The method the Kepler Spacecraft use to find exoplanets. It used transit method of exoplanet detection Kepler used a photometer that continually monitored the brightness of ~150,000 stars in a fixed field of view , identified planets crossing their stars by the slight dimming of the star’s light 3. What the time between observed exoplanet transits represents. Time it takes to complete one orbit (orbital period) the star 4. What a bigger drop in brightness means for an exoplanet transits. It means bigger planet (larger diameter) 5. The types of planets the transit method detects most easily. Big planets close to their stars 6. How the radial velocity detection method works. The radial velocity (or doppler )detection method relies on the fact that the gravitational pull of an orbiting planet will cause a star to wobble — move slightly toward the Earth (blue Doppler shift) and then slightly away (red Doppler shift) each time the planet orbits 7. What the Doppler Effect is. The apparent change in the frequency of a wave caused by relative motion between the source of the wave and the observer 8. What combining observations from the radial velocity and transit method provides. Enables us to determine the mass of the planet 9. What we can estimate from knowing the mass and size of an exoplanet. It’s density and composition 10. How the gravitational microlensing detection method works. Gravitational microlensing works the same way as a magnifying lens. Instead of glass deflecting light to make a bug look bigger, a closer star warps space to the bend light of a more distant star and it make it look bigger. 11. What the gravitational microlensing method detects better than other methods. The microlensing detection method takes advantage of the way a gravitational field of a star bends the light of a more distant star, magnifying its brightness. A planet orbiting the closer star will cause a deviation in the lensing process Which exoplanets does the gravitational microlensing method often detect better than other methods? Planets around very distant stars 1

12. How the direct imaging detection method works. Blocks the overwhelming glare of stars to reveal the reflected light of orbiting planets 13. The types of planets the direct imaging method detects better than other methods. Planets far from their stars 14. How we infer the chemistry of an exoplanet’s atmosphere. The forefront and future of exoplanet research is understanding the chemistry of exoplanet atmosphere. If passed through spectrum, light spreads out into a spectrum. Missing colors show up as black lines, indicating specific gases are absorbing that part of the spectrum. 15. What the absorption spectrum of sunlight passing through our atmosphere reveals. Aliens would be able to see that we have oxygen (O 2 ), ozone (O 3 ), water (H 2 O), and carbon dioxide (CO 2 ), but not Nitrogen 16. How the James Webb Space Telescope improves over the Hubble Space Telescope. It has 100 times higher resolution and views in the infrared as opposed to visible light Two big advantages of observing in the infrared: Can see through dust and able to see objects moving away who's light has redshifted beyond the visible spectrum. Significantly higher resolution 17. How the Nancy Grace Roman Space Telescope improves over the Hubble Space Telescope Nancy grace telescope (Roman) have a field of view 100 times that of Hubble. It will use a combination of transit, microlensing, and direct imaging to catalog exoplanets . 18. Why so few other solar systems look like ours. Telescopes are not yet sensitive enough 19. The most abundant types of exoplanets found so far. Based on Kepler data, the most common planets in the galaxy have radii between 1.4 and 2.8 that of Earth, sizes for which we have no examples in our own solar system These are known as super-Earths and mini- Neptunes. Though the most common elsewhere, wehave none in our own solar system. Exoplanets discovered so far are generally found to be much closer to their stars than the planets found in our Solar System. 20. What a hot Jupiter is. A hot-Jupiter is a Jupiter-size exoplanet orbiting so close to its star such that its temperature is extremely hot 21. What a lava world is. Lava Worlds are rocky planets that orbit so close to their stars that their surfaces are above melting temperature 22. How super-Earth’s different from our planet. Super-Earths are exoplanets with a 1.5 - 2 times bigger radius than Earth. The terms is only about size and does not imply anything about the surface conditions or habitability. Such planets are considered to be Water Worlds, where water layers might make up > 2

30. Whether a Star Wars double sunset is realistic. True 31. How many stars are estimated to be in our Milky Way galaxy. d. 150,000 times the number of grains of sand on Earth, 100-500 billion stars, average 300 billion stars 32. How many galaxies are estimated to exist. 4 trillion 33. How the number of grains of sand on Earth compares to the number of Earth-like planets. For very grain of sand on earth, there are an estimated 15000 earth like planets 34. What the Drake equation calculates. of The number of civilizations we can expect to find in our galaxy with which communication is possible 35. Possible solutions to the Fermi Paradox. Transmissions from alien civilizations are too weak to pick up because up because of vast distances. • We are not looking in the right places — space is vast, and we can only listen in a few directions at a time. • Alien civilizations do not communicate in the radio spectrum like we do, and thus we do not know how to recognize their signals yet. • Civilizations always die out and thus at any given time there are not enough to be easily detected. We are alone Unit 11: Robotic Spacecraft Missions 36. The first spacecraft to make use of a gravitational assist from another planet. Mariner 10 (1973) was the first interplanetary spacecraft to make use of a gravitational assist from another planet, using Venus to bend its flight path and bring it inwards to fly by mercury 37. How a gravitational assist from a planet works. In a gravitational assist, a spacecraft uses the gravity of a planet to bend its flight path and alter its speed. • If the planet is stationary (which it never is), the final speed of the spacecraft will be unchanged. • If the planet is moving in the same direction as the spacecraft, the spacecraft will speed up. • If the planet is moving in the opposite direction of the spacecraft, the spacecraft will slow down 38. What a spectrometer measures. Spectrometers detect which wavelengths of light are being emitted or absorbed by a surface or atmosphere, revealing composition, temperature, and physical processes 4

39. The first spacecraft to orbit Mercury. Messenger 40. Why Mercury is the most difficult planet to orbit. Mercury is the most difficult planet to orbit because the Sun's gravity accelerates approaching bodies to high speeds. MESSENGER used flybys of Earth, Venus, and Mercury over a 7-year span to slow down sufficiently to become the first spacecraft to orbit mercury 41. Why MESSENGER was inserted into a highly elliptical orbit. The surface of mercury radiates too much heat, and this gives the spacecraft time to cool 42. What a radar return from the surface of a planet tells us. The Magellan spacecraft was the first to orbit Venus, using a radar to map topography and surface roughness In addition to the timing of a radar return providing distance and therefore topography, the strength of a radar re turn describes the texture of the surface 43. The milestones the Soviet Union’s Luna 1 spacecraft achieved. The Soviet Union's Luna 1 (1959) was the first spacecraft to achieve escape velocity from the Earth and the first to reach the Moon. It was intended to crash into the Moon, but missed by 6000 km and is now orbiting the Sun. Luna 1 measured earth’s radiation belt, discovery that the Moon has no magnetic field, and provided the first measurements of the solar wind 44. How many spacecraft comprised GRAIL. 2 45. The cause of high gravity observed in larger impact basins on the Moon. Because of the dense volcanic fill, 46. Why Mars is the most explored planet. It holds the greatest chance of finding evidence of past or present extraterrestrial life 47. The first spacecraft to fly by Mars. Mariner 4 48. The first spacecraft to sample the Martian atmosphere. Viking 1 &2 49. The first spacecraft to provide high resolution photos of the Martian surface. Mars reconnaissance orbiter 50. The spacecraft studying the loss of Mars' atmospheric gases to space. Maven 51. The spacecraft the detected Martian quakes. Insight 52. Why Jezero Crater was chosen as the landing site for the rover Perseverance. The most promising place to look for signs of ancient life It was once filled with water 53. What Ingenuity can do on the Martian surface that no other robot can. First test of powered flight on another planet. • Weighs less than 4 lbs, rotors are 4 ft, can fly 90s on a single charge 5

Experienced a fire during a test on the launch pad. It was concluded that the fire was caused from 71. Why the Apollo capsules did not use a nitrogen/oxygen mixture for air. The practice of using pure oxygen in the capsule as opposed to a nitrogen/oxygen mix (our normal atmosphere) was because the required hardware is lighter and simpler to use 72. What mishap happened during the Apollo 13 mission. An oxygen tank blew up on the service module in route to the Moon, creating a host of problems that had to be solved to get the astronauts home, which they successfully did. 73. Where the Apollo 13 astronauts lived during the return trip to Earth The damage to the service module made the command module inoperable (except for reentry). To survive the return to Earth from the Moon, the Apollo 13 astronauts used the Lunar Module (LM), the part built to land on the moon, as a lifeboat. 74. What killed the Soyuz 11 astronauts. They died from asphyxiation after a ventilation valve broke during reentry, resulting in the loss of cabin pressure 75. Why Jerrie Cobb was denied entry into the Mercury Astronaut Program. Because she was a woman 76. What a field joint is on the Space Shuttle Solid Rocket Boosters. Where two segments of a solid rocket booster need to be attached on the launchpad because the boosters are too big to manufacture and ship in one piece The mating of two solid rocket booster segments. The area where they join is known as a field joint 77. The physical cause of the Space Shuttle Challenger disaster. After the conference call, NASA andMorton-Thiokol management made the decision to launch 7 astronauts into space in conditions for which the solid rocket boosters had never even been tested, with a known flaw in the design that would be exasperated at low temperatures The Challenger pilots were not briefed on nor asked their opinion of the cold weather situation and the fact that engineers did not recommend launch and the 78. How NASA and Thiokol management failed the Challenger astronauts. 79. What killed the Space Shuttle Columbia astronauts. Foam from the external tank broke and damaged tiles on the orbiter ring The space shuttle was hit over 15,000 times by debris from the external tank and solid rocket boosters. Foam debris from the external tank caused more than 100 dents in the orbiter 5 years before the Columbia disintegrated upon reentry due to foam damage 80. The dangers of micrometeoroids to humans and the space station. Numerous zap pits on its surface, 81. What spacesuits are designed to protect astronauts from. Heat/cold,micrometeoroids, 82. What the solar wind is. The solar wind is created by the outward expansion of plasma (a collection of charged particles) from the Sun's corona (outermost atmosphere). This plasma is 7

continually heated to the point that the Sun's gravity can't hold it down. It then travels along the Sun's magnetic field lines that extend radially outward 83. What a solar flare is. S olar flares are sudden, larger energy releases from the Sun that carry especially high doses of radiation. 84. The dangers of a large solar flare. No danger of this because radiation does not ignite fires 85. Where most cosmic rays originate from. Supernovae throughout galaxy 86. The greatest danger to humans wishing to colonize Mars. Radiation 87. Where to live on the Moon or Mars and be protected from radiation. To live underground 88. Why space junk is dangerous to satellites and spacecraft. Collisions from fast moving debris 89. What the Kessler Syndrome is. : Collisions create debris which creates more collisions etc. until the Earth is encased in a shell of orbiting debris, making it impossible for us to keep satellites in orbit (goodbye internet, cell phone service, and GPS) and no leaving the planet – forever 90. The consequences of prolonged weightlessness on the human body. Long periods of weightlessness cause muscles to atrophy, bones to become brittle, and the redistribution of body fluids, which can have effects on balance, blood volume, sight, breathing, brain function, heart function, and other yet unknown long-term effects 91. How one can simulate the force of gravity on a spacecraft or space station. Weightlessness can be countered by rotating a spacecraft, generating a centrifugal force that simula tes gravit 92. That sound cannot travel in space. 93. What would kill you first if you took off your helmet in space. You would suffocate 94. What is the best way to move around on the Moon’s 1/6th gravity astronaunats happed and skipped around because it was easier than walking . 8