Can Microgravity Be Found on Earth?įor the same reason microgravity exists in orbit, it can also be found on Earth. These experiments help NASA learn things that would be hard or perhaps impossible to learn on Earth. NASA performs science experiments in microgravity. Without gravity, their shapes are more perfect. Without the pull of gravity, flames are more round. In addition, many things seem to act differently in microgravity. NASA must learn about the effects of microgravity to keep astronauts safe and healthy. Astronauts who travel to Mars also would spend months in microgravity traveling to and from the Red Planet. Astronauts who live on the space station spend months in microgravity. For example, muscles and bones can become weaker without gravity making them work as hard. Microgravity affects the human body in several ways. NASA studies microgravity to learn what happens to people and equipment in space. The moon stays in orbit around Earth for this same reason. As a result, they fall around the planet. Because of this, the spacecraft keeps falling toward the ground but never hits it. An orbiting spacecraft moves at the right speed so the curve of its fall matches the curve of Earth. If a person throws a baseball, gravity will cause it to curve down. It moves at a speed that matches the way Earth’s surface curves. It also is moving at a very fast speed – 17,500 miles per hour. As a result, it is constantly falling toward Earth’s surface. What does it mean to fall around Earth? Earth’s gravity pulls objects downward toward the surface. Since they are all falling together, the crew and objects appear to float when compared with the spacecraft. The spacecraft, its crew and any objects aboard are all falling toward but around Earth. Because of that, the object would appear to float in front of the person. If a person let go of an object at the beginning of the fall, the person and the object would fall at the same acceleration. Some amusement parks have free-fall rides, in which a cabin is dropped along a tall tower. But if there were no air, they would fall at the same acceleration. If a person drops a hammer and a feather, air will make the feather fall more slowly. In a vacuum, gravity causes all objects to fall at the same rate. If 90 percent of Earth’s gravity reaches the space station, then why do astronauts float there? The answer is because they are in free fall. In other words, if a person who weighed 100 pounds on Earth’s surface could climb a ladder all the way to the space station, that person would weigh 90 pounds at the top of the ladder. At that altitude, Earth’s gravity is about 90 percent of what it is on the planet’s surface. The International Space Station orbits Earth at an altitude between 200 and 250 miles. But this is not why things float on a spacecraft in orbit. It is possible for a spacecraft to go far enough from Earth that a person inside would feel very little gravity. Gravity, however, does become weaker with distance. It keeps the sun in place in the Milky Way galaxy. Gravity is what holds the moon in orbit around Earth. In fact, a small amount of gravity can be found everywhere in space. Some people think that there is no gravity in space. Gravity causes every object to pull every other object toward it. Microgravity is sometimes called “zero gravity,” but this is misleading. For example, astronauts can move equipment weighing hundreds of pounds with their fingertips. In microgravity, astronauts can float in their spacecraft – or outside, on a spacewalk. “Micro-” means “very small,” so microgravity refers to the condition where gravity seems to be very small. Microgravity can be experienced in other ways, as well. The effects of microgravity can be seen when astronauts and objects float in space. Microgravity is the condition in which people or objects appear to be weightless.
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