Although working in space is still not considered routine, it is far more frequent than it once was. One reason is the ongoing construction of the International Space Station (ISS) by the United States, Russia, Canada, Japan and 10 European Space Agency (ESA) Member States.

A total of 168 spacewalks will be needed in the next five years to complete the assembly of the space station; more than seven times the number undertaken in the past 10 years.

The first spacewalk to assemble the ISS took place on December 7, 1998, when two astronauts spent more than seven hours outside their spacecraft connecting the Zarya control module to the Unity connecting module. They also fitted handrails to the outside of Unity to facilitate the work of future astronauts. The last spacewalk -- to put the Centrifuge Accommodation Module into place on the complex -- is scheduled for April 2006. Once accomplished, the ISS will be considered complete.

According to astronauts who have visited the ISS, working around the space station imposes new demands. The main reason is its size -- 328 feet (100 meters) long by 240 feet (73 meters) wide. Whereas smaller spacecraft can be positioned to make the most of the available light from the Sun and Earth, the ISS is more difficult to maneuver, resulting in colder and darker working conditions outside the station.

Its size has also led to changes in the stringent safety rules laid down for working outside spacecraft. Previous regulations specified that there should be at least two astronauts on an EVA (extravehicular activity) at the same time, each attached to the spacecraft by two lifelines and in constant visual contact with companions aboard the craft.

New regulations specify that it is sufficient for astronauts to be either in radio contact with the spacecraft or visible through one of the tele-cameras attached to the external structure, and now only one safety line is used to connect astronauts to the ISS. In the unlikely event of this breaking, a Safer instrument attached to their backpacks enables them to use a joystick to stop rotating and move in any direction at a speed of 1.8 miles (3 kilometers) per hour.

Other changes are the result of the vast variety and number of tasks needed to assemble the ISS. Instead of training to become specialists in a small number of highly skilled jobs, todays astronauts have to be good all-round mechanics, prepared to face any eventuality. Training is given in a greater number of generic tasks, such as how to move around the outpost, how to handle and use various tools and, of course, what to do in an emergency.

One of the more revealing changes is that spacesuits are no longer custom-made. This vital and highly technical piece of equipment now comes in standard sizes, with sleeves and trousers that can be lengthened or shortened to meet individual requirements -- a sure sign that the development of the space complex has led to an increase in the ranks of the astronaut corps.

The first European to visit the International Space Station will be ESA astronaut Umberto Guidoni, who is due to take part in an 11-day shuttle mission, tentatively scheduled for April 19, 2001. ESA astronaut Claudie Andre-Deshays will follow him in October 2001. Claudie has already begun training at Star City, near Moscow, for her voyage aboard a Soyuz spacecraft from the Baikonur Cosmodrome in Kazakhstan.