Space exploration archive
The International Space Station
In January 1998 fifteen nations signed an international treaty agreeing to the construction of the International Space Station (ISS). Later that year the first two modules were placed in orbit.
Once completed, the ISS will be used for major scientific and medical research. It is the single largest and most ambitious space project ever undertaken.
One of the most important European projects is the Columbus laboratory, which will aid in the research of such subjects as fluid mechanics and materials science. Other projects include a European robotic arm and an Automated Transfer Vehicle (ATV). The Italian Space Agency (ISA) is building two of the station’s docking nodes.
On 2 November 2000, the first crew of two Russians and one American started to live on the ISS. Shortly afterwards the main solar panels were attached and unfurled. These provide the electrical power to the station. In early 2001 the space shuttle Atlantis carried the Destiny science module to the ISS. This was the largest ever payload carried into space in a single launch. After a long spacewalk it was successfully attached to the space station. It is the ISS's first science laboratory where the residents will carry out the bulk of the scientific research. As each module is attached to the station, it reflects more sunlight and hence becomes more visible from the ground, even to the unaided eye.
Size
When fully assembled, the outpost will weigh approximately 470 tons, and will house a crew of six, down from the seven originally proposed. About the size of a football pitch (109 m wide; 88 m long; 44 m tall), the station will orbit 350 km above the surface of the Earth. It is already easily visible in the night sky.
Research
As well as the habitat modules (each 8.5m long and 4.2m in diameter) there will be several state of the art laboratories that will carry out major research in:
- biotechnology
- biomedicine
- gravitational biology
- materials science
- fluid physics
- combustion research
- space science
- earth science
- engineering research
Scientists will also be looking at the effects of weightlessness and space sickness on the crew members who experience long-duration stays on the ISS. This work is vital for any future expeditions to planets like Mars.
Launches
The first two modules of the ISS were launched late in 1998. The Russian built ZARYA control module was launched onboard a Russian proton rocket, on 20th November 1998, shortly followed by the space shuttle Endeavour containing the US connecting module, UNITY, on 3rd December 1998. In July 2000, after a long delay, the Russian Space Agency launched the ISS's living quarters.
Cost
One of the most talked about problems of the ISS is the cost. When the agreements were signed in 1988 the estimated cost was put at $20 billion. Its final cost is now estimated to be at least $96 billion. This has delayed progress on the project, for example the Russian service module (the living quarters) was deployed a year late because of budget difficulties.
Other problems
Even in the late 1990s, some of the unmanned rockets carrying ISS components failed to reach orbit. But the biggest setback was the destruction of the Columbia shuttle in February 2003. Large ISS components are carried in the ISS cargo bay and connected together by astronauts in orbit. The grounding of the shuttle fleet brought ISS construction to a halt. After the repairs to the shuttles, construction was to have resumed in 2006. But the renewed problems with foam damage on Discovery's flight in July 2005 has set back this work and the next ISS mission will not take place until at least July 2006. The station is not expected to be complete until 2010.
Apart from the construction problems, there have also been many debates on human manned space stations and flights. Some scientists prefer the use of robots, arguing that these are cheaper
Although controversy has surrounded the ISS since it was first proposed, supporters believe that it will help future space programs (as Mir has done), promote better international relations and also aid scientific and medical research.
Viewing the ISS
The ISS is on an orbit inclined to the Earth's axis of rotation, which means it never comes more than 51.6° north or south of the equator. It orbits the Earth every 90 minutes at a height of 385 km, but can rarely be seen from the ground. In order to see it, the ISS must be in sunlight while the observer must be in darkness. This condition only prevails for an hour or so after sunset or before sunrise. As a result, there are typically 15 days when the ISS is seen in the evening sky, followed by about 15 days when it is not seen and then another 15 when it is only seen in the morning sky, after a further 15 days of invisibility the pattern repeats itself.
The ISS can be distinguished from a distant aircraft by its steady motion, its tendency to brighten steadily as it rises above the horizon, lack of any flicker due to navigation lights and its tendency to suddenly fade and disappear while high in the sky, as it enters the Earth's shadow.
If you live in the UK and want to see the ISS, click on the link on the right-hand column of the page. The site is updated daily and offers predictions over a few days. Accurate predictions can not be made far ahead as the station's orbit will change slightly while under construction.
