Category Science

It was Isaac newton who discovered that all falling bodies accelerate at the same rate. His second law of motion states that the greater an object’s mass, the greater the force required accelerating it. A bowling ball weighing 7kg is pulled to Earth by a gravitational force 100 times as strong as a 70g tennis ball. However, because the bowling ball’s mass is 100 times greater to start with, the acceleration of the two balls will be exactly the same.

Most of the time, people ask this question with the idea of a Newtonian “feather vs. bowling ball” concept in mind. Based on those terms, the typical answer is correct: two objects will fall at the same speed in a vacuum, and air resistance can appear to make an object fall slower. However, there is a surprising, but more complicated nuance to this problem.

Every action has an equal and opposite reaction. This means that, just as the Earth is exerting a gravitational force on the objects, the objects are exerting a gravitational force on the Earth. Just as much as the objects fall onto the Earth, the Earth falls onto the objects as well. It’s just the fact that the Earth is so much larger and more massive that we default to viewing things from the first perspective and not the latter. Nevertheless, the gravitational force exerted on the Earth by the objects cannot be ignored. Gravitational force is determined by the Universal Gravitation law:

Where m and M are the two masses involved in the interaction. If we do two separate calculations, one for the mass of the lesser object, and one for the mass of the greater object, we can see that there will actually be a larger gravitational force involved with the more massive object.

This is where most people would interject that, well, yes, the larger mass needs a larger force in order to achieve the same acceleration. But reverse the frame of reference; now let’s consider this from the point of view of the objects doing the pulling, instead of the Earth. Now we can see that the force exerted by the larger mass is doing more.

Working in Space allows scientists to explore how different things are affected by gravity. The European Space Agency’s Spacelab was designed with two pressurized laboratories where microgravity experiments could be carried out. Special racks held hundreds of different kinds of cells and organisms including bacteria, lentil seedlings and shrimp eggs. Tests were run on these organisms, and on human beings, to determine whether they behaved differently in space.

Scientific research on the International Space Station is a collection of experiments that require one or more of the unusual conditions present in low Earth orbit. The primary fields of research include human research, space medicine, life science, physical sciences astronomy, and meteorology. The 2005 NASA Authorization Act designated the American segment of the International Space Station as a national laboratory with the goal of increasing the use of the ISS by other federal agencies and the private sector.

Research on the ISS improves knowledge about the effects of long-term space exposure on the human body. Subjects currently under study include muscle atrophy, bone loss, and fluid shift. The data will be used to determine whether space colonisation and lengthy human spaceflight are feasible. As of 2006, data on bone loss and muscular atrophy suggest that there would be a significant risk of fractures and movement problems if astronauts landed on a planet after a lengthy interplanetary cruise (such as the six-month journey time required to fly to Mars). Large scale medical studies are conducted aboard the ISS via the National Space Biomedical Research Institute (NSBRI). Prominent among these is the Advanced Diagnostic Ultrasound in Microgravity study in which astronauts (including former ISS Commanders Leroy Chiao and Gennady Padalka) perform ultrasound scans under the guidance of remote experts. The study considers the diagnosis and treatment of medical conditions in space. Usually, there is no physician on board the ISS, and diagnosis of medical conditions is a challenge. It is anticipated that remotely guided ultrasound scans will have application on Earth in emergency and rural care situations where access to a trained physician is difficult.

Researchers are investigating the effect of the station’s near-weightless environment on the evolution, development, growth and internal processes of plants and animals. In response to some of this data, NASA wants to investigate Microgravity’s effects on the growth of three-dimensional, human-like tissues, and the unusual protein crystals that can be formed in space.

The investigation of the physics of fluids in microgravity will allow researchers to model the behaviour of fluids better. Because fluids can be almost completely combined in microgravity, physicists investigate fluids that do not mix well on Earth. In addition, an examination of reactions that are slowed by low gravity and temperatures will give scientists a deeper understanding of superconductivity.

The study of materials science is an important ISS research activity, with the objective of reaping economic benefits through the improvement of techniques used on the ground. Other areas of interest include the effect of the low gravity environment on combustion, through the study of the efficiency of burning and control of emissions and pollutants. These findings may improve our knowledge about energy production, and lead to economic and environmental benefits. Future plans are for the researchers aboard the ISS to examine aerosols, ozone, water vapour, and oxides in Earth’s atmosphere, as well as cosmic rays, cosmic dust, antimatter, and dark matter in the universe.

Space stations typically orbit between 192 and 576km (120 and 360 miles) above the Earth’s surface. The Earth’s gravitational pull is still quite strong, even at this altitude. If you were standing on Earth and dropped a ball, it would fall to the ground. If an astronaut on a space station dropped a ball, it would fall, too. However, the ball would appear to float in mid-air because it, the astronaut and the space station are all falling at the same speed. They are not falling towards the Earth, but around it. This condition is called microgravity.

Microgravity 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.

Gravity causes every object to pull every other object toward it. 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.

Every object with mass has a gravitational pull, even you and I. The more material that an object contains, the stronger it’s gravitational pull. Objects such as a football have tiny gravitational pulls that are barely noticeable, whereas much larger things, such as planets and stars, have very strong forces of gravity. Imagine that space is a thin rubber sheet. If you placed a large object such as a bowling ball on the sheet, it would create a dent. Other objects would roll into this dent, towards the bowling ball, if they passed by too closely. In a similar way, stars and planets create deep gravitational wells in space. The more massive object, deeper the gravitational well.

Gravity is the force by which a planet or other body draws objects toward its center. The force of gravity keeps all of the planets in orbit around the sun. Anything that has mass also has gravity. Objects with more mass have more gravity. Gravity also gets weaker with distance. So, the closer objects are to each other, the stronger their gravitational pull is.

Earth’s gravity comes from all its mass. All its mass makes a combined gravitational pull on all the mass in your body. That’s what gives you weight. And if you were on a planet with less mass than Earth, you would weigh less than you do here. You exert the same gravitational force on Earth that it does on you. But because Earth is so much more massive than you, your force doesn’t really have an effect on our planet.

Gravity is what holds the planets in orbit around the sun and what keeps the moon in orbit around Earth. The gravitational pull of the moon pulls the seas towards it, causing the ocean tides. Gravity creates stars and planets by pulling together the material from which they are made. Gravity not only pulls on mass but also on light. Albert Einstein discovered this principle. If you shine a flashlight upwards, the light will grow imperceptibly redder as gravity pulls it. You can’t see the change with your eyes, but scientists can measure it.

Black holes pack so much mass into such a small volume that their gravity is strong enough to keep anything, even light, from escaping. Gravity is very important to us. We could not live on Earth without it. The sun’s gravity keeps Earth in orbit around it, keeping us at a comfortable distance to enjoy the sun’s light and warmth. It holds down our atmosphere and the air we need to breath. Gravity is what holds our world together.

However, gravity isn’t the same everywhere on Earth. Gravity is slightly stronger over places with more mass underground than over places with less mass. NASA uses two spacecraft to measure these variations in Earth’s gravity. These spacecraft are part of the Gravity Recovery and Climate Experiment mission. Grace detects tiny changes in gravity over time. These changes have revealed important details about our planet. For example, GRACE monitors changes in sea level and can detect changes in Earth’s crust brought on by earthquakes.

Space stations have given scientists a unique laboratory that can be found nowhere on Earth —one that is unaffected by gravity. Gravity influences everything on Earth, from the way that the human body works to the growth of crystals used in semiconductors for computers. In orbit, however, a space station’s speed cancels out the Earth’s gravitational pull, so scientists can carry out experiments in weightless conditions.

Space Science is the study and research of issues specifically related to space flight/ travel and space exploration. It comprises of interdisciplinary fields e.g. Stellar, Solar, Galactic and Extragalactic astronomy, Planetary Science and Physical Cosmology, Astrobiology, Astrochemistry, Astrophysics, Space plasma physics, Orbital mechanics/ Astrodynamics, Atmospheric/ Environmental Science, Satellite and Space Communications, Aerospace engineering, Control engineering, Space environment and Space medicine.

Rapidly growing subjects of Space Science in the present era of information technology are in process of evolution from the state of infancy to the advanced levels at academic and research institutions. The significant subjects falling under the umbrella of Space Science comprise Remote Sensing, Satellite Applications, Space Physics, Astrodynamics, Atmospheric Science etc. The courses offered in the department are the main building blocks of Space Science. Emphasis has also been given to research and applications oriented areas such as Flight Dynamics and Control, Space Mission Design and Analysis, Space Data Processing and Geoinformatics. The Space Science uses new space-age technologies like satellite positioning, space data visualizations, analysis tools and space data interpretation to greatly advance scientific understanding of Earth and its systems. With the launch of Earth resources satellites such as micro & Nano satellites in Low Earth Orbit and Communication Satellites in Geostationary orbits around the Earth, the last decade has witnessed a wide spectrum of applications in diverse fields subject to the need and quality of imagery datasets acquired from the Earth orbiting satellites. The advances in computing technology & techniques have also contributed a lot in the development of more sophisticated than ever sensors capable of observing the Earth with specialized and dedicated on-board sensors with the help of satellite constellations.

The Space Science department at IST is a truly multidisciplinary department within a multidisciplinary university. As society looks towards the future, we continue the pursuit of further understanding the Earth system and beyond with our focus on Space Communications, Remote Sensing, Astrodynamics, Atmospheric Science, Meteorology and Earth Sciences. The department also conducts public awareness programs like Sky-watch/ Star-gazing shows and World Space Week (UN) for scientific outreach.

Because the body does not have to fight against gravity in space, there is a serious danger of it losing bone and muscle mass. Astronauts must exercise every day to prevent their muscles wasting away. In the ISS there is a treadmill and a stationary exercise bike, but astronauts must remember to strap themselves on or they will float away.

Exercise is an important part of the daily routine for astronauts aboard the station to prevent bone and muscle loss. On average, astronauts exercise two hours per day. The equipment they use is different than what we use on Earth. Lifting 200 pounds on Earth may be a lot of work. But lifting that same object in space would be much easier. Because of microgravity, it would weigh much less than 200 pounds there. That means exercise equipment needs to be specially designed for use in space so astronauts will receive the workout needed.

The environment of the International Space Station isn’t exactly hospitable to the human body. Thanks to microgravity, astronauts experience a variety of health and physical changes while living in space — some of which they can counteract through daily exercise and other activities. But the space environment also exposes astronauts to other elements that cannot necessarily be mitigated.

Our bodies aren’t built for space; they’re built for a planet a lot like our own. Human beings have evolved here on Earth over millennia, so our bodies have adapted to excel in a gravity environment under the protection of our planet’s atmosphere. In low Earth orbit, however, those ubiquitous elements are taken away, and the body’s various systems adapt accordingly.

Perhaps the biggest change astronauts experience is bone and muscle loss. Humans on Earth work out these systems every day, simply by moving and standing against gravity. But without gravity to work against, the bones lose mineral density and the muscles risk atrophying. It’s something astronauts are consistently trying to prevent from happening. “We try to minimize it as much as possible,” says Bob Tweedy, the countermeasures systems instructor at NASA’s Johnson Space Center. To do that, astronauts on the station work out six out of seven days a week for 2.5 hours each day.

The International Space Station is equipped with three machines designed to give astronauts that full-body workout: a bicycle, a treadmill, and a weightlifting machine called ARED, for Advanced Resistive Exercise Device. Each machine is specially designed for space, since normal gym equipment would be useless in microgravity. Lifting weights, for instance, wouldn’t do much in space since dumbbells wouldn’t weigh anything. So instead, the ARED machine utilizes two canisters that create small vacuums that astronauts can pull against with a long bar. This allows them to do squats, bench presses, dead lifts, and more.

Similarly, the station’s treadmill is no ordinary running machine. Astronauts have to be strapped into it with a harness and bungee chords, otherwise they would float away and never actually get a workout. A stationary bicycle is also available for strengthening astronauts’ legs, though it has no seat (since your butt wouldn’t sit on it anyway). Instead, astronauts grip handles and sit up against a back pad to stay stationary. Practicing with this equipment on Earth, it’s hard to get a full grasp of what they will feel like in space, since gravity is ever present.