Guys, we all know about gravity which causes every object to pull every other object toward it. But, what about microgravity. Why it is so important in space. Why does NASA study it? There are many questions in your mind but today you will get all the answers.
So, let’s start with what is microgravity? It is the condition in which people or objects appear to be weightless. The effects of microgravity can be seen when astronauts and objects float in space. Microgravity can be experienced in other ways, as well. “Micro-” means “very small,” so microgravity refers to the condition where gravity seems to be very small. In microgravity, astronauts can float in their spacecraft – or outside, on a spacewalk. Heavy objects move around easily. For example, astronauts can move equipment weighing hundreds of pounds with their fingertips. Microgravity is sometimes called “zero gravity,” but this is misleading.
Some people think that there is no gravity in space. In fact, a small amount of gravity can be found everywhere 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 the Milky Way galaxy. Gravity, however, does become weaker with distance. It is possible for a spacecraft to go far enough from Earth that a person inside would feel very little gravity. But this is not why things float on a spacecraft in orbit. The International Space Station orbits Earth at an altitude between 200 and 250 miles. At that altitude, Earth’s gravity is about 90 percent of what it is on the planet’s surface. 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.
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 a vacuum, gravity causes all objects to fall at the same rate. The mass of the object does not matter. If a person drops a hammer and a feather, air will make the feather fall more slowly. But if there were no air, they would fall at the same acceleration. Some amusement parks have free-fall rides, in which a cabin is dropped along a tall tower. 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. Because of that, the object would appear to float in front of the person. That is what happens in a spacecraft. The spacecraft, its crew and any objects aboard are all falling toward but around Earth. Since they are all falling together, the crew and objects appear to float when compared with the spacecraft.
What does it mean to fall around Earth? Earth’s gravity pulls objects downward toward the surface. Gravity pulls on the space station, too. As a result, it is constantly falling toward Earth’s surface. It also is moving at a very fast speed – 17,500 miles per hour. It moves at a speed that matches the way Earth’s surface curves. If a person throws a baseball, gravity will cause it to curve down. It will hit the ground fairly quickly. An orbiting spacecraft moves at the right speed so the curve of its fall matches the curve of Earth. Because of this, the spacecraft keeps falling toward the ground but never hits it. As a result, they fall around the planet. The moon stays in orbit around Earth for this same reason. The moon also is falling around Earth.
NASA studies microgravity to learn what happens to people and equipment in space. Microgravity affects the human body in several ways. For example, muscles and bones can become weaker without gravity making them work as hard. Astronauts who live on the space station spend months in microgravity. Astronauts who travel to Mars also would spend months in microgravity traveling to and from the Red Planet. NASA must learn about the effects of microgravity to keep astronauts safe and healthy. In addition, many things seem to act differently in microgravity. Fire burns differently. Without the pull of gravity, flames are more round. Crystals grow better. Without gravity, their shapes are more perfect. NASA performs science experiments in microgravity. These experiments help NASA learn things that would be hard or perhaps impossible to learn on Earth.
But, how do researchers create microgravity?
Well guys, researchers can create microgravity conditions in two ways. Because gravitational pull diminishes with distance, one way to create a microgravity environment is to travel away from Earth. To reach a point
where Earth’s gravitational pull is reduced to onemillionth cf that at the surface, you would have to travel into space a distance of 6.37 million kilometers from Earth (almost 17 times farther away than the Moon, 1400 times the highway distance between New York City & Los Angeles, or about 70 million football fields). This approach is impractical, except for automated spacecraft, because humans have yet to travel farther away from Earth than the distance to the Moon. However, freefall can be used to create a microgravity environment consistent with our
primary definition of microgravity.
But, are there any other methods? Or can you able to create microgravity on earth?? Yes, you can guys. How? Well, we already explained one above i.e. by using spacecraft. The others are elaborated below.
1) DROP FACILITIES
Researchers use high-tech facilities based on the elevator analogy to create micro-gravity conditions. The NASA Lewis Research Center has
two drop facilities. One provides a 132 meter drop into a hole in the ground similar to a mine shaft. This drop creates a reduced gravity environment for 5.2 seconds. A tower at Lewis allows for 2.2 second drops down a 24 meter structure. The NASA Marshall Space Flight Center has a different type of reduced gravity facility. This 100 meter tube allows for drops of 4.5 second duration. Other NASA Field Centers and other countries have additional drop facilities of varying sizes to serve different purposes. The longest drop time currently available (about 10
seconds) is at a 490 meter deep vertical mine shaft in Japan that has been converted to a drop facility. Sensations similar to those resulting from a drop in these reduced gravity facilities can be experienced on freefall rides in amusement parks
or when stepping off of diving platforms.
Airplanes are used to achieve reduced gravity conditions for periods of about 15 seconds. This environment is created as the plane flies on a parabolic path. A typical flight lasts 2-3 hours allowing experiments and crew members to take advantage of about forty periods of microgravity. To accomplish this, the plane climbs
rapidly at a 45 degree angle (this phase is called pull up), traces a parabola (pushover), and then descends at a 45 degree angle (pull out). During the pull up and pull out segments, crew and experiments experience accelerations of about 2
g. During the parabola, net accelerations drop as low as 1.5×10-² g for about 15 seconds. Due to the experiences of many who have flown on parabolic aircraft, the planes are often referred to as “Vomit Comets.” Reduced gravity conditions created by the same type of parabolic motion described above can be experienced on the series of “floater” hills that are usually located at the end of roller coaster rides and when driving over
swells in the road.
Sounding rockets are used to create reduced gravity conditions for several minutes; they follow suborbital, parabolic paths. Freefall exists during
the rocket’s coast: after burn out and before entering the atmosphere. Acceleration levels are usually around 10-5 g. While most people do not
get the opportunity to experience the
accelerations of a rocket launch and subsequent freefall, springboard divers basically launch themselves into the air when performing dives
and they experience microgravity conditions until they enter the water.