NASA’s Plan to Decommission the International Space Station

Context:

The National Aeronautics and Space Administration (NASA) has announced plans to retire and decommission the International Space Station (ISS) by 2031.

Relevance:

GS-III Science and Technology: (Space Technology, Developments in Space technology)

Dimension of the Article:

1. What is a Space Station?
2. International Space Station (ISS)
3. Why is NASA planning to decommission the ISS?

What is a Space Station?

• A Space station is an artificial structure placed in orbit, having the pressurized enclosure, power, supplies, and environmental systems necessary to support human habitation for extended periods.
• In simple words: a space station, also called an orbital station, is a large spacecraft or man-made station in space which can act as a home where astronauts live and/or receive several spacecrafts from the Earth and/or act as a kind of science lab, etc.
• Depending on its configuration, a space station can serve as a base for a variety of activities.
  • These include observations of the Sun and other astronomical objects, study of Earth’s resources and environment, military reconnaissance, and long-term investigations of the behaviour of materials and biological systems—including human physiology and biochemistry—in a state of weightlessness, or microgravity.

How are space stations set up and how do they work?

Small space stations are launched fully assembled, but larger stations are sent up in modules and assembled in orbit. To make the most efficient use of its carrier vehicle’s capacity, a space station is launched vacant, and its crew members—and sometimes additional equipment—follow in separate vehicles. A space station’s operation, therefore, requires a transportation system to ferry crews and hardware and to replenish the propellant, air, water, food, and such other items as are consumed during routine operations. Space stations use large panels of solar cells and banks of storage batteries as their source of electrical power. They also employ geostationary relay satellites for continuous communication with mission controllers on the ground and satellite-based positioning systems for navigation.

How many Space Stations have we launched?

• Since 1971, more than 10 space stations have been launched into a low orbit around Earth and have been occupied for varying lengths of time.
• Important Space stations in chronological order are Salyut 1, Skylab, Salyuts 3, 4, 5, 6, and 7, Mir, the International Space Station, and Tiangong 1 and 2.

International Space Station (ISS)

• The International Space Station (ISS) is a modular space station (habitable artificial satellite) in low Earth orbit.
• The ISS program is a multi-national collaborative project between five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA (Japan), ESA (Europe), and CSA (Canada).
• The ownership and use of the space station is established by intergovernmental treaties and agreements.
• The ISS serves as a microgravity and space environment research laboratory in which scientific experiments are conducted in astrobiology, astronomy, meteorology, physics, and other fields.
• It is the largest artificial object in space and the largest satellite in low Earth orbit, regularly visible to the naked eye from Earth’s surface.
• The ISS is the ninth space station to be inhabited by crews, following the Soviet and later Russian Salyut, Almaz, and Mir stations as well as Skylab from the US.

Why is NASA planning to decommission the ISS?

• The ISS was originally built to operate for 15 years.
• The space station has already surpassed that checkpoint by being active for 21 years, with plans to continue operations till 2030.
•  The ISS goes through 16 rotations of the earth per day, causing extreme temperature changes on the exterior. The side facing the sun can get heated up to 121°C while the temperature on the opposite, darker side can fall to –157°C, causing intense expansion and contraction of the building material.
• This orbital thermal cycling, coupled with dynamic loading, affects the longevity of the primary structure of the space station.
• The technical lifetime is also limited by parts like radiators, modules and truss structures that tend to degrade over time.
• NASA is planning to transition operations in low-earth orbit to private players and focus energies on its missions to explore the moon and Mars.
• NASA plans to remove the ISS from its orbit around the earth and eventually plunge it into the ocean at a point farthest from human civilisation.
• NASA claims that the debris of the ISS that survives the re-entry will settle on the ocean floor and not cause any substantial long-term impact.

-Source: The Hindu