The most important idea is that of NASA handling effects and causes of microgravity in the book ‘Living without gravity.’ Many problems that arise from living and working in space are resolved. However, psychological effects of weightlessness are still not fully understood. Among these are leaching of certain minerals; atrophy of muscles when not exercised and space adaptation syndrome, a form of motion sickness found in spaceflight. All deleterious effects of living in microgravity disappear after astronaut returns to ground. Some can be encountered while in orbit by special diet and exercises. However, vigorous exercise program does not appear to stop bone loss. NASA is engaged in a long-term program to understand causes underlying these changes, to develop ways to prevent them. This will be important for longer tours of duty on Space Station, where crew members will be in orbit for three months or more.
Microgravity is the condition in which people appear to be weightless. Effects of microgravity can be seen when astronauts float in space. Micro means ‘very small’ so microgravity refers to condition where gravity seems to be very small. In microgravity, astronauts can float in spacecraft or on a spacewalk. Heavy objects move around easily. For example, astronauts can move equipment weighing hundreds of pounds with their fingertips. Gravity causes every object to pull every other object toward it. People think there is no gravity in space. A small amount of gravity can be found in space. Gravity is what holds the moon in orbit around earth. Gravity causes earth to orbit the sun. It keeps the sun in place in Milky Way galaxy. Gravity does become weaker with distance. A person inside a spacecraft may feel very little gravity. But this is not why things float on a spacecraft in orbit. The ISS orbits Earth at altitude between 200 and 250 miles where earth’s gravity is 90% of what it is on earth’s surface. So, if a person who weighed 100 pounds on Earth’s surface could climb a ladder to space station, that person would weigh 90 pounds at top of the ladder.
NASA studies microgravity to learn what happens to people in space. Microgravity affects human body in many ways. For example, muscles and bones become weaker without gravity making them work as hard. Astronauts who live on space station spend months in microgravity. Astronauts who travel to Mars also would spend months in microgravity. NASA must learn about effects of microgravity to keep astronauts safe and healthy. Additionally, things act differently in microgravity. Fire burns differently. Without pull of gravity, flames are more round. Crystals grow better. Without gravity, their shapes are perfect. NASA performs science experiments in microgravity. These experiments help NASA learn things that would be hard to learn on Earth. For same reason, microgravity exists in orbit, it can also be found on Earth. NASA uses airplanes to create microgravity for short periods of time. Airplane does this by flying in up-and-down parabolas. At top of the parabola, people and objects inside airplane are in free fall briefly going over a large hill, like on a roller coaster. Microgravity is experienced in amusement park free-fall rides. NASA also uses drop towers to study microgravity. Objects are dropped using special equipment from top of tall towers, experiencing free fall as they drop.
NASA must succeed in resolving problems created by effects of microgravity.
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