My Science School

A spacesuit is all that stands between an astronaut on a space walk and the emptiness of space. It must supply all his or her needs. There is no breathable atmosphere in space, so a spacesuit supplies oxygen to the astronaut.

Most spacesuits have very specific purposes. First and foremost, they must keep the wearer alive. They serve—in actuality—as individual custom spaceships of a sort, designed for considerably differing environments.

Today, the United States “sports” two specific space suits. One, the Assured Crew Escape System (ACES) suit, is the bright orange contraption familiar to many through viewing shuttle launches on television. Visible during the crew’s “waving walkout” to the Astros Van and their subsequent trip to the launch pad, they are no longer needed with the ending of the space shuttle program (boo hiss!). The suits are now being evaluated for use with future programs—including NASA ’s Orion capsule development—and modified capability to perform spacewalks in the event of a capsule emergency need (e.g., a solar panel that won’t deploy).

Designed to protect the crew only during the ascent (liftoff) and entry (coming back to earth) phases of flight, the ACES suit’s essence was to provide an oxygen source (although a brief one of about 10 minutes) and helmet-suited pressurization for a relatively short period of time, in hopes of enabling the crew to parachute to safety in the event of a bailout emergency. Note that this very purpose went unfulfilled during the Columbia (2003) tragedy and was not even available during Challenger (1986). In fact, the Challenger disaster was one of the key reasons for the original development of this type of spacesuit.

The spacewalking suit, also known as the Extra-Vehicular Activity (EVA) suit, is easily recognizable to even the most casual space buff. Bright white, with identifying stripes of solid, dashed, and angled/hashed red and white, this suit truly was an astronaut’s spaceship. Worn outside of a vehicle while working in the vacuum of outer space, this suit’s design was a bit more extravagant than that of the ACES.

Within the helmet, headphones and a microphone enable the astronaut to communicate with crew members and mission control. All the joins in the spacesuit must be absolutely airtight. Inside, the spacesuit is pressurized, like a deep-sea diver’s suit. A specially treated dark visor protects the astronaut’s eyes from the glare of the Sun, while lights can illuminate dark areas.

A camera may be fixed to the astronaut’s shoulder, so that other crew members and the ground crew can watch what is being done. The temperature, pressure and oxygen levels inside the suit are monitored by a control pack on the astronaut’s front or back. Under the outer suit, a body suit contains pipes through which cool liquid flows to protect the astronaut from the heat of the Sun. The visor and outer layer of the spacesuit must be tough enough not to be torn or cracked by tiny meteorites that may bounce off the astronaut.

Suits are made of artificial materials that offer maximum protection, such as nylon, Kevlar and Dacron. The astronaut is completely sealed within his or her suit, so urine is collected inside for disposal later! On Earth, a spacesuit can be as difficult to walk in as a suit of armour, but in the weightlessness of space, the pull of gravity is not a consideration.

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The space shuttle has many uses and, because it is reusable, has made it possible to pursue some space activities that would otherwise have been too expensive. It is used to launch satellites and to make repairs to existing satellites. The shuttle can also be used as a laboratory, in which to carry out experiments that are only possible in zero gravity.

The space shuttle was NASA’s space transportation system. It carried astronauts and cargo to and from Earth orbit. The first space shuttle flight took place April 12, 1981. The shuttle made its final landing July 21, 2011. During those 30 years, the space shuttle launched on 135 missions.

The space shuttle carried as many as seven astronauts at a time to and from space. In all, 355 people flew on the shuttle. Some of them flew more than one time. During its history, the space shuttle flew many different types of missions. It launched satellites and served as an orbiting science laboratory. Its crews repaired and improved other spacecraft, such as the Hubble Space Telescope. The shuttle also flew missions for the military. On its later missions, the space shuttle was mostly used to work on the International Space Station.

The space shuttle had three main parts. The first part was the orbiter. The orbiter was the large, white space plane where the crew lived and worked. It was the only part of the shuttle that flew into orbit. The orbiter also had a payload bay for carrying cargo into orbit. Five different orbiters took turns flying into space. The second part of the shuttle was the external tank. This was the large orange fuel tank that was attached to the bottom of the orbiter for launch. The third part was actually two pieces. A pair of white solid rocket boosters provided most of the thrust for the first two minutes of a shuttle launch. The solid rocket boosters were long and thin.

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Astronauts outside the shuttle are encumbered by a heavy spacesuit, but this is not really a problem in weightless conditions. Controlled movement is more difficult, however. Astronauts wear a unit called a manned maneuvering unit (MMU) on their backs. This is fuelled by nitrogen and is rechargeable in the shuttle. Several small thrusters allow the astronaut to move in all directions.

The process leading up to a spacewalk takes almost an entire day, and it's not because of the many items that make up an astronaut’s suit. The main reason for this is because astronauts need time to go through decompression, the same procedure cave divers use when returning from the depths of the ocean to the surface of the water.

To allow maximum mobility and maximum protection from the lack of pressure in space, a spacesuit is pressurized at 29.6 kilopascals during a spacewalk, about one third of the pressure experienced by the crew inside the spacecraft. Astronauts also have to breathe in pure oxygen, because the amount of oxygen in air at such a low pressure isn't enough.

Now, if an astronaut simply donned a space suit in 15 minutes and promptly exited an airlock, he or she would go through decompression sickness, or "the bends" -- the same thing scuba divers experience if they're exposed to a rapid drop in external pressure by ascending too quickly. The bends causes expanded nitrogen gas bubbles in the bloodstream to escape too quickly, and joint pain, dizziness, cramps, paralysis and even death can follow.

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The Great Wall, which stretches for over 3640km (2150 miles) across China, is the only human structure that can be seen from space.

It has become a space-based myth. The Great Wall of China, frequently billed as the only man-made object visible from space, generally isn't, at least to the unaided eye in low Earth orbit. It certainly isn't visible from the Moon. You can, though, see a lot of other results of human activity.

Expedition 10 photo showing Great Wall of ChinaThe visible wall theory was shaken after China's own astronaut, Yang Liwei, said he couldn’t see the historic structure. There was even talk about rewriting textbooks that espouse the theory, a formidable task in the Earth’s most populous nation. The issue surfaced again after photos taken by Leroy Chiao from the International Space Station were determined to show small sections of the wall in Inner Mongolia about 200 miles north of Beijing.

Taken with a 180mm lens and a digital camera last Nov. 24, it was the first confirmed photo of the wall. A subsequent Chiao photo, taken Feb. 20 with a 400mm lens, may also show the wall.

The photos by Chiao, commander and NASA ISS science officer of the 10th Station crew, were greeted with relief and rejoicing by the Chinese. One was displayed prominently in the nation's newspapers.

At lift-off, the space shuttle has two rocket boosters. These are jettisoned when the shuttle reaches a height of 43km (27 miles). The shuttle usually remains in orbit around the Earth for about seven days, although it can continue for 30 days. When it returns to Earth, the shuttle lands on a runway, in a similar way to an ordinary aircraft. The rocket boosters are reattached to it, so that it is ready for another mission.

Space shuttle, also called Space Transportation System, partially reusable rocket-launched vehicle designed to go into orbit around Earth, to transport people and cargo to and from orbiting spacecraft, and to glide to a runway landing on its return to Earth’s surface that was developed by the U.S. National Aeronautics and Space Administration (NASA). Formally called the Space Transportation System (STS), it lifted off into space for the first time on April 12, 1981, and made 135 flights until the program ended in 2011.

The U.S. space shuttle consisted of three major components: a winged orbiter that carried both crew and cargo; an external tank containing liquid hydrogen (fuel) and liquid oxygen (oxidizer) for the orbiter’s three main rocket engines; and a pair of large, solid-propellant, strap-on booster rockets. At liftoff the entire system weighed 2 million kilograms (4.4 million pounds) and stood 56 metres (184 feet) high. During launch the boosters and the orbiter’s main engines fired together, producing about 31,000 kilonewtons (7 million pounds) of thrust. The boosters were jettisoned about two minutes after liftoff and were returned to Earth by parachute for reuse. After attaining 99 percent of its orbital velocity, the orbiter had exhausted the propellants in the external tank. It released the tank, which disintegrated on reentering the atmosphere. Although the orbiter lifted off vertically like an expendable rocket launcher, it made an unpowered descent and landing similar to a glider.

The space shuttle could transport satellites and other craft in the orbiter’s cargo bay for deployment in space. It also could rendezvous with orbiting spacecraft to allow astronauts to service, resupply, or board them or to retrieve them for return to Earth. Moreover, the orbiter could serve as a space platform for conducting experiments and making observations of Earth and cosmic objects for as long as about two weeks. On some missions it carried a European-built pressurized facility called Spacelab, in which shuttle crew members conducted biological and physical research in weightless conditions.

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