The International Space Station (ISS) is counting down its days, and retirement is looming above the orbiting laboratory in a few years. For more than 20 years, the space station has served as a home for astronauts in low Earth orbit, but it will soon face extinction as it plunges into the atmosphere, leaving behind tiny fragments of an iconic legacy.
NASA is preparing a plan to deorbit its beloved space station in 2030, sending it hurtling through Earth’s atmosphere, where most of it will burn up in the heat of reentry. The space agency, along with its international partners, explored several different options and narrowed them down based on feasibility and cost. After years of effort, NASA has decided to invite private industry to design a spacecraft that will drag the space station to its fiery death.
The ISS is the big boy, holding the record for the largest man-made structure in space. Spanning 357 feet (109 meters) long — about the size of a football field — it will be the largest object ever launched from orbit. Bringing down the ISS will not be easy, and the key challenge is to ensure that its remaining parts land well away from populated areas. Here’s a breakdown of how NASA and its partners plan to bring the legendary space station to its final resting place.
Why is NASA abandoning the ISS?
NASA and its partners began assembling the space station in 1998. The ISS has served as a key platform for scientific research and demonstrations of new microgravity technologies often used on Earth. The space station symbolizes international cooperation and peace and represents cooperation between the space agencies of the US, Russia, Europe, Japan and Canada. It hosted hundreds of astronauts from 18 different countries who completed over 270 spacewalks.
Unfortunately, all good things must come to an end. The ISS is aging and the wear and tear of being in space has taken its toll. Significantly, its termination will make way for commercial exploitation of low Earth orbit, with private companies designing their own space stations to take over once the ISS is gone.
Russia has agreed to continue deploying its cosmonauts to the ISS until 2028 as it builds its own space station in orbit. Since its inception, the ISS has continuously hosted at least one NASA astronaut and one Roskosmos cosmonaut. Over the years, Russian Soyuz and Progress vehicles have carried out numerous crew and cargo missions to the ISS. The Russian space agency will likely take these toys with it when it leaves, meaning NASA won’t have its key ISS partner for the decommissioning task.
The space station will have to be destroyed because it’s just not practical to take it apart. “The station was never designed to be taken apart again,” Marco Langbroek, a lecturer in astrodynamics at Delft Technical University in the Netherlands, told Gizmodo in an email. “I think the current plan is the only option available.”
Initial assembly of the space station took 27 missions using NASA’s now-retired Space Shuttle. Dismantling the ISS piece by piece would require a significant effort by NASA, international space agencies and their astronauts, in addition to having a spacecraft large enough to return the pieces to Earth.
“Any effort to dismantle and safely disconnect and return individual components (such as modules) would face significant logistical and financial challenges requiring at least an equivalent number of [spacewalks] a space station crew, extensive planning for ground support personnel, and a spacecraft with capabilities similar to the Space Shuttle’s large cargo bay that currently does not exist,” NASA wrote in a recent release.
The space agency added that it is in the process of developing a plan to preserve some smaller objects from the ISS. This makes a lot of sense; the station is full of memories and artifacts worth preserving.
Road to destruction
Rather than let the space station return to Earth unchecked, NASA and its partners will have to target a remote uninhabited area in the ocean as a landing spot for the remaining debris. Standard orbital debris mitigation practice accepts a human casualty risk of less than 1 in 10,000.
Before the deorbit process takes place, the ISS will be emptied of all movable goods that can be transported back to Earth. ISS astronauts will also have to evacuate the space station before it deorbits, leaving the orbiting lab empty for the first time in decades. Someone—we obviously don’t know who—will be the last astronaut to soar within its cozy confines.
A controlled reentry always begins with lowering the spacecraft’s orbit. The first step toward reentry will be to cancel the periodic orbital burns that maintain the lab’s position about 250 miles (400 kilometers) above sea level. Eventually, the station’s orbit will drop below 150 miles (250 kilometers), according to Langbroek. This natural decay in orbit, caused by atmospheric drag, will likely take months to gradually topple the ISS, he explained.
The SpaceX factor
As a next step, the space agency commissioned SpaceX to design a new deorbital vehicle. This vehicle will dock with the ISS and perform a series of deorbital burns to lower the space station’s orbit further (NASA has previously proposed using the Russian Progress cargo spacecraft to deorbit the ISS, but that is now off the table). In March, the space agency released its 2024 budget proposal, which included $180 million to develop a deorbit capability for the ISS by the end of 2030. At the time, NASA estimated that its ISS tug would cost about $1 billion in total.
SpaceX’s recently awarded contract is worth $843 million, which will cover the vehicle’s development but not the cost of bringing it to market. The company hasn’t shared details about its space tug design, and it’s unclear whether it could redesign its Dragon spacecraft or build a completely different one. The exorbitantly expensive tug is a disposable spacecraft and will not survive deorbit assignment. While SpaceX “will develop the deorbit spacecraft, NASA will take over the spacecraft after development and operate it for the duration of its mission,” NASA wrote. “Along with the space station, it is expected to break up destructively as part of the re-entry process.”
Safe and controlled return
With the help of its brand new tractor, the ISS will have to perform a major reentry burn to precisely target the reentry site. This will ensure a controlled descent through the atmosphere to manage its debris trail. The thrust maneuver must be strong enough to put the spacecraft into an elliptical or oval-shaped orbit for it to be properly captured by the atmosphere, says Tobias Lips, managing director of the satellite aerodynamics company Hyperschall Technologie Göttingen in Germany.
“If you have a maneuver that is strong enough to bring your perigee. [minimum altitude] essentially to zero, then the uncertainties of the distribution of your fragments on the ground play a smaller role,” Lips told Gizmodo. “If you accept a higher perigee altitude, then the potential splashdown zone, which includes all the uncertainties, gets bigger and bigger.”
A reentry expert estimates that about 40% of the ISS will survive its hot journey through the atmosphere, but that NASA will have sufficient control over the splashdown zone. While a significant amount of material could fall from space, it is unlikely to fall near populated areas.
Destruction icon
The ISS will hit the atmosphere at speeds reaching 17,500 miles per hour (28,000 kilometers per hour). Once the space station descends below 60 miles (100 kilometers), it begins to disintegrate, according to Langbroek. During its fateful nosedive, the famous structure begins to deform, its familiar outline begins to crumble bit by bit and the metal bends under the pressure.
“External elements such as solar panels and antennas will probably break off first, then the main structure of the station will break into fragments,” Langbroek said. “Most of them will burn, but some significant denser and more massive parts, such as docking ports and parts of the lattice structure, will probably survive.”
The parts of the ISS that survive reentry are likely to make up 10% to 20% of its total mass. That’s more than 180,000 pounds (81,646 kilograms) of material, which is why a controlled return is key. It may seem obvious, but the smaller the spacecraft, the fewer fragments will survive reentry. As Lips explained, smaller objects heat up more intensely and are more likely to disintegrate on reentry due to their compact size, while larger objects are less prone to complete disintegration, making it difficult for them to disintegrate completely.
The remaining debris of the ISS will land in an empty area of the South Pacific Ocean known as the spacecraft graveyard, with many dead satellites buried at the bottom (including the Russian space station Mir, which crashed to Earth in 2001). A remote area of the Pacific Ocean, called Point Nemo, lies between New Zealand and South America and is the furthest point from land.
Related article: Skylab, America’s first space station, changed what we thought was possible in orbit
In 1979, America’s first space station, Skylab, disintegrated and disintegrated into Earth’s atmosphere, scattering debris across the Indian Ocean and Western Australia. NASA has calculated that there is a 1 in 152 chance that the remaining debris will hit people on the ground. Fortunately, there were no injuries.
It’s hard to imagine the beloved ISS broken apart and destroyed in the Pacific Ocean, but its legacy will far outlive its charred fragments. The destruction of the space station signals the end of one era and the beginning of a new one that relies more on the commercialization of space. With this new era, the Earth’s orbit is to undergo significant changes.
Repair: A previous version of this article gave an incorrect year for Skylab’s return; it was 1979, not 1973.
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