Extra Vehicular Activity (EVA )The technical name for going outside a spacecraft is Extra-Vehicular Activity (EVA). In 1965 Soviet cosmonaut Alexei Leonov was the first person ever to walk in space.
Space suitsSpace suits protect astronauts when they go outside their spacecraft. The suits are also called EMUs (Extra-vehicular Mobility Units). The outer layers of a space suit protect against harmful radiation from the Sun and bullet-fast particles of space dust called micrometeoroids.
The clear, plastic helmet also protects against radiation and micrometeoroids. Oxygen is circulated around the helmet to stop the visor misting. The middle layers of a space suit are blown up like a balloon to gently hold the astronaut’s body. Small astronauts actually have room to ‘float’ inside their space suits.
The soft inner lining of a space suit has tubes of water in it to cool the astronaut’s body or warm it up. The backpack supplies pure oxygen for the astronaut to breathe, and gets rid of the carbon dioxide he or she gives out.
The oxygen comes from tanks which hold enough for up to seven hours. The gloves have silicone-rubber fingertips which allow the astronaut some sense of touch. Various different gadgets in the suit deal with liquids - including a tube for drinks and another for collecting urine.
Cost of space suit
The full cost of a spacesuit is about $11 million although 70 percent of this is for the backpack and control module.
Space stationsThe first space station was the Soviet Salyut 1, launched in April 1971. Its low orbit meant it stayed up only five months. The first US space station was Skylab.
Three crews spent 171 days in it in 1973-74. The longest serving station was the Soviet Mir - launched in 1986, it made more than 76,000 orbits of the Earth. The last crew left in late 1999. Mir was built in stages. It weighed 125 tonne's and had six docking ports and two living rooms, plus a bathroom and two small individual cabins. There is neither an up nor a down in a space station, but Mir had carpets on the ‘floor’, pictures on the ‘wall’ and lights on the ‘ceiling’.
The US space station Skylab was launched in 1973 and lasted until 1979. Cosmonaut Valery Polyakov spent a record 437 days in a row in space on Mir. The giant International Space Station (ISS) is being built in stages and should be complete in 2010. The first crew went aboard the ISS in November 2000.
The longest spells of EVA were by astronauts working from the Space Shuttle for eight hours and 29 minutes. The first space walkers were tied to their spacecraft by life-support cables. Now a days, most space walkers use a Manned Manoeuvring Unit (MMU)- a huge, rocket-powered backpack that lets them move about freely. In 1984, US astronaut Bruce McCandless was the first person to use an MMU in space.
Damages to the Mir space station and other satellites have been repaired by space-walking astronauts. Russian and US astronauts will perform more than 1700 hours of space walks when building the International Space Station.
The International Space Station (ISS) will be over 100 m long and will weigh 450 tonnes. Space walks will be essential to ensure the station is completed by 2004. The SOHO space observatory is stationed between the Earth and the Sun, monitoring the Sun to find out about changes in solar activity.
Space explorationSpace is explored in two ways - by studying it from Earth using powerful telescopes, and by launching spacecraft to get a closer view. Most space exploration is by unmanned space probes. The first pictures of the far side of the Moon were sent back by the Luna 3 space probe in October 1959.
Manned missions have only reached as far as the Moon, but there may be a manned mission to Mars in 2020. Apollo astronauts took three days to reach the Moon.
No space probe has ever come back from another planet. The Atlas space rocket on the launch pad, ready to propel the highly advanced SOHO observatory into space. This satellite observes the Sun and also environmental changes and weather conditions on Earth Travel to the stars would take hundreds of years, but one idea is that humans might go there inside gigantic spaceships made from hollowed-out asteroids.
Another idea is that spacecraft on long voyages of exploration may be driven along by pulses of laser light. The Pioneer 10 and 11 probes carry metal plaques with messages for aliens telling them about us NASA may fund research on spacecraft that jump to the stars through wormholes .