Several capsules returned to Earth uncontrolled one, which came down in the Arctic near Svalbard, was never found. If your package is the size of a golf ball, you can try that delivery method. A golfer floating next to the ISS could conceivably hit a golf ball out of orbit in a single stroke. Golf balls, on the other hand, travel fast enough. Even the fastest pitchers don’t break 50 m/s. Unfortunately, throwing something at 100 m/s is difficult. Shaving off just 100 meters per second from the orbital speed at the ISS’s altitude is enough to deliver your package to the atmosphere. The ISS is traveling at almost 8 kilometers per second, but luckily, you don’t need to throw your package that fast. The faster you throw the package, the more precise its landing. If you throw it downward, it will still have enough forward speed to stay in orbit-it will just be a slightly different orbit. Surprisingly, the way to do this isn’t to throw the package downward, toward Earth. A fast throw can get the package down into the atmosphere more directly, without a long delay as atmospheric drag causes its orbit to slowly decay in a hard-to-predict way. You can improve the precision of your package delivery by throwing the package really hard. 4 Spacecraft undergoing uncontrolled reentry-like your package-can miss their intended landing site by hundreds or thousands of miles. SpaceX’s spent rocket boosters can guide themselves precisely enough to land directly on a target on the deck of a boat, while the older Apollo and Soyuz spacecraft have generally missed their targets by a few miles. Some do this with more precision than others. Returning spacecraft generally try to control where they land. Controlling where the package will land is much harder than simply delivering it to Earth. They designed the planes to survive the heat and pressure of reentry, but, sadly, the project never went through.Ī package tossed by hand from the ISS will descend gradually over the course of many orbits, with little control over the eventual landing point. In fact, a team of Japanese researchers planned to try this by launching paper airplanes from the ISS. As long as it’s shaped right, it could make it to the ground intact. If you print your message on a sheet of baking parchment paper, aluminum foil, or some other thin and lightweight material that can survive being warmed up, you might just be able to toss it out the door as is. There are impact “craters” a few feet across-barely larger than the objects that made them-and impact craters a few thousand feet across, but nothing in between. This is why all impact craters on Earth are large: only large, heavy objects keep their orbital kinetic energy all the way to the ground. If they land in soft dirt or mud, they can splash a little, but they don’t leave much of a crater. These surviving bits of debris hit the ground at relatively low speeds. After the brief pulse of heat during breakup, this free fall through the cold upper atmosphere takes several minutes, which is why meteorites are often very cold when they’re found. But when they do, they lose their orbital speed and then fall at terminal velocity straight down to the ground. Sometimes, pieces of these objects survive entry into the atmosphere, either because other pieces absorb the heat and shield them or because they’re made of a material that can withstand the reentry conditions. When they hit it, they heat up until they break apart, evaporate, or both. Small objects-anything from pebble-sized to car-sized-are too small to smash through the atmosphere. These are the objects that leave craters in the ground. Very large objects-house-sized or larger-have enough inertia to punch through the atmosphere and hit the ground without losing much speed.
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