From UPSC perspective, the following things are important :
Prelims level : International Space Station
Mains level : Space research
The National Aeronautics and Space Administration (NASA) has announced plans to retire and decommission the International Space Station (ISS) by 2031.
What is the ISS?
- The ISS was launched in 1998 as part of joint efforts by the U.S., Russia, Japan, Canada and Europe.
- The idea of a space station originated in the 1984 State of the Union address by former U.S. President Ronald Reagan.
- The space station was assembled over many years, and it operates in low-earth orbit.
- Since its inception, it has served as a laboratory suspended in space and has aided multiple scientific and technological developments.
- The ISS was originally built to operate for 15 years.
Why was ISS launched?
- A space station permits quantum leaps in research in science, communications, and in metals and lifesaving medicines which could be manufactured only in space.
- ISS has consistently maintained human presence for the past 21 years, providing astronauts with sophisticated technologies for scientific research.
Why is NASA planning to decommission the ISS?
- 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.
What is the procedure to de-orbit the ISS?
- 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.
- The space agency will use the dual method of natural orbit decay and a re-entry manoeuvre to bring an end to the ISS as we know it.
- According to the plan, the earth’s natural atmospheric drag will be used in lowering the altitude of the ISS while setting up the de-orbit.
- The space station operators will then provide the final push to it to lower the structure to the maximum possible height and ensure safe re-entry into the earth’s atmosphere.
- It would then lead to Point Nemo over the South Pacific Oceanic Uninhabited Area (SPOUA).
- Dissembling process would have posed huge logistical and financial challenges.
How big is it?
- The ISS is a huge structure — almost the size of a football field — and it was not designed to be disassembled easily in space.
- The station currently operates in low-earth orbit above 400 km in altitude, at a point where it still experiences atmospheric drag and requires re-boosts to continue in its orbit.
- The station also has a mass of over 4,30,000 kg.
- Existing propulsion systems do not have the capacity to raise the station’s altitude to a high target and escape low-earth orbit.
- The random re-entry method was discarded since it carries a huge risk for the human population on the ground.
What is the future of space stations?
- As the ISS plans to end operations in space, new players are already lining up to replace it.
- In January 2022, China announced that its space station will be ready for operations this year.
- Blue Origin, the aerospace company founded by Jeff Bezos, has also announced its plans to build Orbital Reef, a commercially developed, owned, and operated space station in low-earth orbit.
- Blue Origin is working alongside Sierra Space on the project.