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Re-entry at a shallow angle turns anything that's not a perfect sphere into a lifting body. It will skip like a stone tossed at a river, and when it's done skipping it will drop like a rock. The Space Shuttle's Orbiter was designed with a lifting body which exacerbated that problem. It could neither enter too shallow nor too steep. Too steep, and air ...


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Going straight down takes a lot more fuel for deceleration. In order for a spacecraft to stay in orbit, it needs a substantial velocity perpendicular to the direction of the vector of gravitational force. This velocity is referred to as your orbital velocity; for a near-Earth orbit about 200 miles up, you need an orbital velocity of 7.79 km/s. In order for ...


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“Bouncing off the atmosphere” is a misleading turn of phrase. When returning to the Earth from the Moon, a spacecraft is on an elliptical orbit with the high end somewhere around the moon’s altitude and the low end just grazing the top of Earth’s atmosphere. The concern around a too-shallow reentry angle is that it won’t slow the spacecraft enough for a ...


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The resistance is proportional to the density of the air. If you come in at a shallow angle you decelerate more gently as you spend more time at a higher altitude.


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Following is a block quote from How to Get an Atmosphere by Peter Tyson Saturn's moon Titan belongs to a very select club within the solar system. It is one of only four "terrestrial" planets or moons—those with solid bodies, as opposed to those made largely of gas, like Jupiter and Saturn—that has a substantial atmosphere. The other three that ...


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While Europa (and Ganymede and Callisto) are indeed not too different in size from Titan, they are too close to the Sun for anything more than a thin atmosphere to form. Jupiter and its moons are far away enough from the Sun to allow for water to condensate and thus form icy moons. At ~5 A.U. there is however still too much sunlight for other volatiles, ...


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