The International Space Station (ISS) is a remarkable and collaborative achievement in the realm of space exploration. Orbiting Earth at an average altitude of approximately 420 kilometers (260 miles), the ISS serves as a symbol of international cooperation and scientific advancement. It is a space laboratory where astronauts and cosmonauts from various nations conduct experiments in fields such as biology, physics, astronomy, and Earth sciences.
The International Space Station has been continuously inhabited since November 2000 and is a testament to the potential for nations to work together in the peaceful exploration of outer space. It not only advances our understanding of science but also promotes diplomacy and goodwill among countries as they unite in the pursuit of knowledge beyond our planet.
Controlled Decommission Plan Of ISS
Recently, NASA has proposed a significant plan to retire the International Space Station by 2031 due to the strain on its structure over time. This ambitious plan involves a $1 billion effort to safely deorbit the ISS, culminating in a controlled reentry into the Pacific Ocean. To facilitate this mission, NASA is encouraging private companies to develop a “space tug” design capable of safely bringing the ISS out of orbit and guiding it towards Earth’s atmosphere. This space tug, referred to as the US Deorbit Vehicle (USDV), will perform the crucial task of gradually lowering the ISS from its orbit, reducing its altitude from 175 miles above the Earth’s surface to around 75 miles.
Companies interested in submitting proposals for the design of a space tug vehicle to facilitate the deorbiting of the International Space Station have until November 17, 2023, to do so. Following this deadline, NASA will evaluate and select the most suitable proposals as part of its plan to retire the International Space Station. The retirement plan itself is set to commence in 2026, at which point NASA will initiate the process of allowing the ISS to undergo a natural decay.
This has been done before, notably with the Mir space station. Many tons of material will hit the ocean relatively intact, and there will definitely be a warning to clear the airspace (we get about one of these a month for disposal of much smaller spacecraft like ISS cargo ships.) Here’s what’s tricky. You can fly the ISS safely down to an altitude of about 250 km.
After that, you need this special USDV ship to take over the steering – it’s like driving down a motorway with a lot of wind gusts -you need a lot of muscle power to stay on the road. If you ever lose control and the ISS starts tumbling, you’re in trouble because then you can’t reliably point the rocket engines in a particular direction. The first step in NASA’s plan is to let the ship begin to decay and not re-boost it so it stays in orbit.
During this time, the atmospheric drag will reduce the orbit from around 250 miles above the surface to 200 miles. However, this will take a few years to happen. In 2030, the crew on the ISS will make the final descent to Earth and bring any crucial equipment. The ISS will continue to move closer to Earth, reaching the ‘Point of no return’ at 175 miles above the surface. And this is where the $1 billion space tug will swoop in and give the ISS a little push from orbit. The station will begin re-entry between 75 miles and 50 miles above the surface.
The external skin of modules will melt away, and then the exposed hardware will vaporize as the ISS soars 18,000 miles per hour through Earth’s atmosphere. Any of it that survives re-entry will be targeted to fall in Point Nemo, a region of the Pacific Ocean between New Zealand and South America often used as a spacecraft graveyard – at least 260 craft have been laid to rest there. Another trick is that it will take about 8 tons of propellant (fuel and oxidizer) to bring the station down from the lowest controllable height.
But you can’t use a rocket engine that takes six hours to burn that much fuel because, in 30 minutes, you’ll be so low that you lose control and start tumbling. So you need a serious rocket engine that can burn through eight tons in only 15 minutes or so, doing the full deorbit burn in an amount of time shorter than the time taken to get too low to control. So the USDV has to be big (lots of propellant) and have a big engine (so big push in a short time), and none of the existing cargo ships have either of those. Hence the need to develop a new vehicle to dispose of the ISS safely.Jonathan McDowell, an astrophysicist at Harvard University, told DailyMail.com
Before settling on this method of decommissioning the ISS, NASA carefully evaluated various alternatives. Among these options, one was allowing the ISS to naturally decay until it eventually re-entered Earth’s atmosphere, but this approach posed significant safety concerns as it could potentially endanger human life and property on the ground. Another possibility NASA considered was boosting the ISS into higher orbits to extend its operational life, but this would have required substantial resources and posed technical challenges.
Additionally, the notion of dismantling the ISS in space and bringing its components back to Earth was contemplated. However, it became evident that the ISS was not originally designed for easy disassembly in the vacuum of space, making this option impractical and risky.
Ultimately, the decision to utilize a space tug vehicle to deorbit the ISS in a controlled manner, followed by a safe reentry into the Pacific Ocean, was chosen as the most responsible and feasible approach to conclude the ISS’s remarkable mission in space exploration.
The International Space Station is entering its third and most productive decade as a groundbreaking scientific platform in microgravity. This third decade is one of the results, building on our successful global partnership to verify exploration and human research technologies to support deep space exploration, continue to return medical and environmental benefits to humanity, and lay the groundwork for a commercial future in low-Earth orbitRobyn Gatens, director of the International Space Station at NASA Headquarters.
The announcement of the construction of the International Space Station (ISS) dates back to January 25, 1984, when President Ronald Reagan made it public during his State of the Union Address. In that address, President Reagan outlined NASA’s ambitious plan to complete the construction of the ISS within a decade. It took four years for NASA to kickstart the project, with the launch of the first ISS component on December 4, 1998. Official operations began in November 2000, marking the start of a remarkable journey in space exploration.
Since its inception, the ISS has been a hub for numerous space missions and has hosted 250 astronauts from 20 different countries. Originally, NASA’s plan was to retire the ISS by 2015, but the station’s continued relevance and contributions led to an extension of its operational life. However, as the massive space station has started showing signs of wear and tear over the years, NASA has now decided to bid a fond farewell to this faithful and marvalous friend.
The responsibility for the safe deorbit of the ISS is shared among five space agencies: NASA, CSA (Canadian Space Agency), ESA (European Space Agency), JAXA (Japan Aerospace Exploration Agency), and the State Space Corporation Roscosmos. Each country is responsible for overseeing and managing the hardware it has contributed to the station. The space station was conceived with the idea of interdependence in mind and relies on collaborative support from all participating nations. The United States, Japan, Canada, and ESA member nations have committed to keeping the station operational through 2030, while Russia has committed to at least 2028.
Successor Of ISS
NASA is proactively planning for the future of human presence in space, as it seeks to ensure its continued engagement in space exploration beyond the retirement of the ISS. The agency has set in motion a transition plan that involves inviting private companies to participate in the development of a successor to the International Space Station. This forward-thinking approach aims to safeguard NASA’s access to the invaluable benefits of a space station platform even after the ISS concludes its mission. Several notable companies, including Axiom Space, Jeff Bezos’ Blue Origin, and Northrup Grumman, have expressed keen interest in spearheading the establishment and operation of commercial space stations.
In summary, the International Space Station, a symbol of international collaboration and scientific achievement, is preparing to bid farewell as NASA and its partners plan for a controlled retirement. This milestone in space exploration marks the end of an era and the beginning of a new chapter, with private companies stepping up to continue humanity’s journey into the cosmos. As we look to the future, the spirit of exploration remains alive, promising exciting developments and discoveries yet to come.
Source: Daily Mail