Editing Talk:681: Gravity Wells
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In the XKCD strip, the artist states above Earth in the lower right popout that the geosynchronous altitude is well below top of Earth's gravity well. While the rest of his strip is a wonderful representation of the science behind gravity wells, this one bit is not accurate. A geosynchronous altitude for Earth is nearly 36,000 km, not under 6000 km. Kudos for the rest of the strip, though. | In the XKCD strip, the artist states above Earth in the lower right popout that the geosynchronous altitude is well below top of Earth's gravity well. While the rest of his strip is a wonderful representation of the science behind gravity wells, this one bit is not accurate. A geosynchronous altitude for Earth is nearly 36,000 km, not under 6000 km. Kudos for the rest of the strip, though. | ||
: The strip scales the heights of the corresponding wells based on the assumption of constant Earth surface gravity; in other words, it takes the same amount of energy to climb such a well as it does to escape the real gravity well. By contrast, as one ascends from the Earth's surface, gravity decreases, so it requires less energy to climb to an orbital altitude than it does to reach the same height in the hypothetical well. The amount of energy required to put a geostationary satellite in orbit, for example, is equivalent to that used in raising it 5413 km in Earth surface gravity, and thus it is located 5413 km from the bottom of the well. [[User:Arcorann|Arcorann]] ([[User talk:Arcorann|talk]]) 03:42, 8 February 2019 (UTC) | : The strip scales the heights of the corresponding wells based on the assumption of constant Earth surface gravity; in other words, it takes the same amount of energy to climb such a well as it does to escape the real gravity well. By contrast, as one ascends from the Earth's surface, gravity decreases, so it requires less energy to climb to an orbital altitude than it does to reach the same height in the hypothetical well. The amount of energy required to put a geostationary satellite in orbit, for example, is equivalent to that used in raising it 5413 km in Earth surface gravity, and thus it is located 5413 km from the bottom of the well. [[User:Arcorann|Arcorann]] ([[User talk:Arcorann|talk]]) 03:42, 8 February 2019 (UTC) | ||
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== How much gravity can be overcome? == | == How much gravity can be overcome? == | ||
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:What killed it was the issue of what happens when one malfunctions or crashes on launch. You've got Space Shuttle & parts raining down on the Denver metro area; not good. | :What killed it was the issue of what happens when one malfunctions or crashes on launch. You've got Space Shuttle & parts raining down on the Denver metro area; not good. | ||
− | + | Source: My dad worked on the project for the Air Force back in the 70s or thereabouts. [[User:Flug|Flug]] ([[User talk:Flug|talk]]) 21:52, 22 September 2019 (UTC) |