Category The Universe, Exploring the Universe, Solar System, The Moon, Space, Space Travel

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.

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.

Because of the lack of gravity, going to the toilet in space can be a tricky operation. Toilets on board space stations are equipped with restraints to hold an astronaut in place. A powerful vacuum pump is used to create a seal between the body and the seat. Waste products are collected. Some are recycled, while solid waste is disposed of safely.

Each spacecraft comes equipped with a unisex toilet. Although the toilet itself looks like a slightly higher-tech version of its counterparts here on Earth, it’s designed a bit differently. The toilet consists of a commode that holds solid wastes and a urinal for liquid wastes. A funnel that fits over the genital area allows both men and women to urinate standing up, although they also have the option of sitting down.

To prevent the astronauts from floating away in t­h­e weightless environment, the toilet comes equipped with foot restraints (for sitting) and a toe bar to slip the feet under (for standing). The toilet also has a thigh bar similar to the one that pulls down over your lap when you ride a roller coaster and fabric fasteners that go around the thighs.

To ensure that the waste also doesn’t float around, the toilet uses flowing air instead of water to flush the toilet. The air pulls the waste away from the astronaut’s body and flushes it away. After the air is filtered to remove bacteria and odors, it’s returned to the living cabin.

But where does all the waste go? Don’t worry, it’s not going to come hurtling into the Earth’s atmosphere and through your roof. Solid wastes are dried to remove all moisture, compressed and kept in an on-board storage container. They’re removed and disposed of once the spacecraft has landed. The liquid waste is sent into space.

On the International Space Station, liquid wastes are recycled through a special water treatment plant and turned back into drinking water. Solid waste goes into a plastic bag. Each time someone goes to the bathroom, the bag clamps down and seals like a trash compactor. The bags are collected and placed into a special craft that is launched into space.

Going to the bathroom becomes even more challenging when astronauts take a walk outside their spacecraft. Because they can’t simply drop their space suit and go, astronauts typically use a superabsorbent adult diaper. These diapers are able to hold up to a quart of liquid. Astronauts use adult diapers during take-offs and landings as well. After the spacewalk, the astronauts remove the diapers and dispose them in a storage area in the craft.

Conditions on board a Space station can be very strange. There is no gravity, which means that astronauts can float in mid-air and lift heavy objects with ease. In a space station, there is no up or down, which can be very confusing, so the walls, floor and ceiling are painted different colours to help the crew orientate themselves. The lack of gravity means that astronauts can eat or sleep on the walls, or even the ceiling, but it can also prove troublesome. Scientists have to strap themselves to the walls when they are working to stop themselves floating away. The planned ISS habitation module is equipped with everything astronauts need to live normally for long periods in space, including a gym, a galley, medical facilities and a meeting area.

The International Space Station is an orbiting space laboratory, assembled through a decades-long collaboration of countries. The 360-ton space station is larger than a five-bedroom house — just much longer and narrower. It has enough room for six sleeping quarters, a gym, a 360-degree viewing window, and areas to conduct a wide array of science experiments. “We’ve had continuous human presence on the space station for 19 years now,” said NASA spokeswoman Stephanie Schierholz. “It is an unprecedented international collaboration among nations.”

Working in outer space for six months has its challenges. Microgravity means that crew members have many obstacles to their regular routines, such as eating, sleeping and hanging out. The space station has no refrigeration, meaning all food has to be stored carefully and is often vacuum-packed. Some foods come in special forms, such as spaghetti which requires added water or rehydratable scrambled eggs. Even salt and pepper come in liquid form because without gravity the sprinkles would fly away.

At dinner time, crew members have to strap meal trays to their laps or to the wall. And while preparing meals, astronauts tape ingredients to the table so they don’t float away. Morning routines also get shaken up by zero-gravity. In the absence of regular showers and sinks, astronauts and cosmonauts use rinse less soap and shampoo and spit their toothpaste into washcloths. The crew also has to use special toilets which have leg restraints and a vacuum for waste.

Solar technology converts sunlight into electricity. Solar cells are made of special materials called semiconductors, mainly silicon. When light strikes, the cell part of it is absorbed into the silicon, and knocks electrons loose. The cell’s natural electrical field forces the loose electrons to form a flow, which is an electric current.

The electrical system of the International Space Station is a critical resource for the International Space Station (ISS) because it allows the crew to live comfortably, to safely operate the station, and to perform scientific experiments. The ISS electrical system uses solar cells to directly convert sunlight to electricity. Large numbers of cells are assembled in arrays to produce high power levels. This method of harnessing solar power is called photovoltaic.

The process of collecting sunlight, converting it to electricity, and managing and distributing this electricity builds up excess heat that can damage spacecraft equipment. This heat must be eliminated for reliable operation of the space station in orbit. The ISS power system uses radiators to dissipate the heat away from the spacecraft. The radiators are shaded from sunlight and aligned toward the cold void of deep space.

Since the station is often not in direct sunlight, it relies on rechargeable nickel-hydrogen batteries to provide continuous power during the “eclipse” part of the orbit (35 minutes of every 90 minute orbit). The batteries ensure that the station is never without power to sustain life-support systems and experiments. During the sunlight part of the orbit, the batteries are recharged. The nickel-hydrogen batteries have a design life of 6.5 years which means that they must be replaced multiple times during the expected 30-year life of the station. The batteries and the battery charge/discharge units are manufactured by Space Systems/Loral (SS/L), under contract to Boeing. N-H2 batteries on the P6 truss were replaced in 2009 and 2010 with more N-H2 batteries brought by Space Shuttle missions. There are batteries in Trusses P6, S6, P4, and S4.