AST101H1 Lecture : 7.3 Spacecraft Exploration of the Solar System
2 Aug 2010
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7.3 Spacecraft Exploration of the Solar System
-robotic spacecraft
-operate primarily with preprogrammed instructions
-robotic missions falls into 4 major categories
-Flyby: a spacecraft on a flyby goes past a world just once and then continues on its way
-Orbiter: an orbiter is a spacecraft that orbits the world it is studying, allowing longer-term study
during its repeated orbits
-Lander or probeWKHVHVSDFHFUDIW DUH GHVLJQHGWRODQG RQDSODQHW·VVXUIDFHRUSUREHDSODQHW·V
atmosphere by flying through it. Some landers carry rovers to explore wider regions
-sample return mission: a sample return mission requires a spacecraft designed to return to Earth
carrying a sample of the world it has studied.8il
-choice of spacecraft depends on scientific objectives and cost
Flyby
-cheaper than other missions because it is less expensive to launch into space
-launch costs depend largely on weight and onboard fuel is a significant part of that weight
-but once a spacecraft is on its way, the lack or friction or air drag in space means that It can maintain
its orbital trajectory through the solar system without using any fuel
-fuel is only needed when changing from one trajectory (orbit) to another
-but this can be made for free by taking advantage of the gravity of other planets (gravitational
slingshot)
-only offers a short period of close up study
-but can provide valuable scientific information
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-the gravitational effects of the planets and their moons on the spacecraft itselt provide information
about object masses and densities
Orbiter
-more expensive than flyby
-primarily because the orbiter must carry extra fuel for it to change from an interplanetary
trajectory to a path that puts it into orbit around another world
-effective for study use for a long period than a flyby
-we have sent orbiters to the Moon, Venus, Mars, Jupiter, Saturn and the asteroid, Eros.
Landers or Probes
-the most up close and personal study of other worlds
-sends probes into the atmospheres or landers to the surfaces
-landers typically require fuel to slow down their descent to a planetary surface
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-measure temperature, pressure, composition, radiation for about an hour but then it was destroyed
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Sample Return Missions
-missions that will scoop up samples from other worlds and return them to Earth for a more detailed
study
-the only one that was done is to the Moon
Combination Spacecraft
-many missions combine more than one type of spacecraft
-Galileo mission
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-Cassini spacecraft
-flybys of Venus, earth and Jupiter
-spacecraft itself is an orbiter studying Saturn and its moons
-also carried the Huygens probe that landed on Titan
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