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.
