How and why does Juno curse Echo?

The mostimportant idea is that of NASA handling effects and causes of microgravity inthe book ‘Living without gravity.’ Many problems that arise from living andworking in space are resolved. However, psychological effects of weightlessnessare still not fully understood. Among these are leaching of certain minerals;atrophy of muscles when not exercised and space adaptation syndrome, a form ofmotion sickness found in spaceflight. All deleterious effects of living inmicrogravity disappear after astronaut returns to ground. Some can beencountered while in orbit by special diet and exercises. However, vigorousexercise program does not appear to stop bone loss. NASA is engaged in along-term program to understand causes underlying these changes, to develop waysto prevent them. This will be important for longer tours of duty on SpaceStation, where crew members will be in orbit for three months or more.

Microgravityis the condition in which people appear to be weightless. Effects ofmicrogravity can be seen when astronauts float in space. Micro means ‘verysmall’ so microgravity refers to condition where gravity seems to be verysmall. In microgravity, astronauts can float in spacecraft or on a spacewalk.Heavy objects move around easily. For example, astronauts can move equipmentweighing hundreds of pounds with their fingertips. Gravity causes every objectto pull every other object toward it. People think there is no gravity inspace. A small amount of gravity can be found in space. Gravity is what holdsthe moon in orbit around earth. Gravity causes earth to orbit the sun. It keepsthe 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 whythings float on a spacecraft in orbit. The ISS orbits Earth at altitude between200 and 250 miles where earth’s gravity is 90% of what it is on earth’ssurface. So, if a person who weighed 100 pounds on Earth’s surface could climba ladder to space station, that person would weigh 90 pounds at top of theladder.

NASA studiesmicrogravity to learn what happens to people in space. Microgravity affectshuman body in many ways. For example, muscles and bones become weaker withoutgravity making them work as hard. Astronauts who live on space station spendmonths in microgravity. Astronauts who travel to Mars also would spend monthsin microgravity. NASA must learn about effects of microgravity to keepastronauts safe and healthy. Additionally, things act differently inmicrogravity. Fire burns differently. Without pull of gravity, flames are moreround. Crystals grow better. Without gravity, their shapes are perfect. NASAperforms science experiments in microgravity. These experiments help NASA learnthings that would be hard to learn on Earth. For same reason, microgravityexists in orbit, it can also be found on Earth. NASA uses airplanes to createmicrogravity for short periods of time. Airplane does this by flying inup-and-down parabolas. At top of the parabola, people and objects insideairplane are in free fall briefly going over a large hill, like on a rollercoaster. Microgravity is experienced in amusement park free-fall rides. NASAalso uses drop towers to study microgravity. Objects are dropped using specialequipment from top of tall towers, experiencing free fall as they drop.

NASA mustsucceed in resolving problems created by effects of microgravity.

the correct answer is c.