What Could Be Salvaged From the ISS Before It Is Brought Down

The narrator says the International Space Station is scheduled to be taken out of orbit when a Super Dragon with 46 Draco thrusters pushes the massive structure into a final descent through a precise corridor over the Pacific Ocean, described as the most remote stretch of open ocean on Earth.

He notes that nearly every part of the station will burn up or end up on the bottom of this spacecraft graveyard, but that there is still an opportunity to save some things first.

Right before the Dragon deorbiting ship arrives, another module will attach to the bottom of the ISS. This is Axiom Space Station's first module, and Axiom is the only private company allowed to dock with the ISS before it de-orbits.

The narrator says this gives a golden opportunity to take some valuable objects from inside the ISS, and poses the central question of what the most valuable objects are that could realistically be saved. To answer it, he went to Axiom's headquarters in Houston and asked people there, and he was told there is an extensive list of things Axiom wants to take, though specifics could not be discussed.

Asked to speculate, the narrator says the first thing that comes to mind is the huge rollout solar arrays. Six of them were installed between 2021 and 2023, so they are not very old, and they provide 120 kW of power, which he describes as a solid amount of power to kickstart a new station.

He then says he asked Axiom's VP of engineering, Aaron Tullos, whether those arrays could be scavenged.

Tullos said Axiom is planning to use the Rosas, which are built by a company called Red Wire. He explained that the ISS's solar array upgrades use what is called the ISS Roll Out Solar Array, or Rosa, and that Axiom will use a similar version on its station to provide power.

Asked whether the current arrays could simply be decoupled and reused, Tullos said that in theory they could, but it would require extra vehicular activities, with astronauts going out onto the boom to work on the hardware. He said EVAs are very expensive and very dangerous, so it would be a trade between Axiom and NASA. He added that the person hours needed to decouple everything on orbit would look like thousands of hours of work.

The narrator added that crew time is one of the most valuable resources on the ISS, so there is a cost to using it versus the cost of launching new hardware. He then asked whether it might make more sense to ship up a whole new module with the arrays pre-attached, with its own logistical flow for installation.

Tullos explained that Axiom's solar arrays launch in place, stowed on the forward end of the module, and are attached to a four degree of freedom robotic arm. Once on orbit, the hold-down and release mechanisms holding them in place can be released, the arrays can be deployed, and the arm provides a wide range of motion to point them so they are always oriented in the way that is most efficient for electricity generation.

The narrator says that unfortunately the iconic solar panels that make the ISS visible from Earth will likely come down with the ship. He then turns to the Canadarm, recalling how astronaut Scott Perzinski described dangling from its end to repair the far corners of the solar panels, and noting that the arm can move itself around the outside of the ISS without a spacewalk.

When he asked Tullos about the arm, the response was cold. He pressed by saying that the Canadarm was too useful to deorbit and that surely there were things Axiom wanted to take, but Tullos again said there is an extensive list of things Axiom wants but he could not talk specifics.

The narrator then speculates that the reasons the Canadarm is so useful are the reasons it is not needed on the new Axiom station. The arm was designed to grab modules and bird them together, while Axiom is making its station more flexible, with modules that have their own propulsion so they can attach and reattach by themselves. The arm was also crucial for spacewalks and repairs, but Axiom has no near-future plan for extra vehicular activities, as its airlock will not arrive for another five years.

The narrator asked Axiom what it wanted to keep, but the space industry is tight-lipped, so he pressed other space company CEOs at a panel at the Astro Awards. He noted that the ISS runs on standardized racks that slot into the side of the station, and that a commercial company will have a very small window to take some of those modules out. He wondered what the most valuable things on the station are, citing semiconductor manufacturing, cancer research, biology and the research flowing through the station as possibilities.

Axiom said that a lot of the equipment is fairly old, with some newer items having gone up recently. Taking old equipment out and installing it in another station can cost more than building an updated version, so for that kind of equipment it is almost always better to rebuild, while still allowing research to flow to new stations. Axiom said it has studied the issue and that perhaps one or two experiments in total would need to be kept because they should not disturb the microgravity environment. The narrator thought the more interesting things to take off might be life support systems, which are extremely expensive but proven and well known.

Axiom's pressurized modules are being built by Selena Space at the same facility that built Raphael, one of the ISS's old Italian-built cargo modules. The narrator visited the site and saw the module, which uses the same common berthing mechanism as the ISS, so it can dock to the bottom of the station. The doorways have limited space for transferring equipment, but all ISS equipment racks are designed to fit through them.

The first module is planned to dock to the station in early 2027 and will arrive ready with eight empty equipment rack slots. Each slot is a metal frame roughly 2 m tall, just under 1 m wide and about 1 m deep. The front opens to expose the experiment inside, and the back plugs straight into the station for water, power or gas.

Aaron Tullos explained that this is an ISS standard payload rack, the form factor in which much of the equipment used on the station is packaged, as seen in the MLM or the current ISS. You can build an entire system in a rack like this, for instance a CO2 scrubber or water processor, pack it into the MLM, and move that whole completed system into the station. This greatly reduces the amount of on-orbit outfitting and work.

Tullos said that a payload can be packaged in a common form factor and slotted in, with power, cooling and data provided. Because Axiom's first module, the PPTM, or power payload thermal module, will go to the ISS, Axiom is using this form factor in the first module. That gives the company the opportunity, while on the ISS, to take any hardware that may not be used in the future as the station starts to deorbit, and give those payloads a second life on the Axiom station.

The narrator says the American side of the ISS splits life support across three racks: one handles oxygen generation and two handle water recovery. He had pictured simply disconnecting them and shipping them over, but Axiom's plan undocks its power and thermal module a full three years before the ISS deorbits, and the oxygen system cannot simply be yanked, since the station cannot be left without air. He also noted that Axiom's power module will not be crewed, so it does not need life support right away.

He suggests a possible workaround. Near the end of the ISS's life, NASA plans to test a new oxygen generation system built on 25 years of lessons from the old one. In the current design, the cell stack, separator, valves and sensors sit inside one tightly packed vacuum dome, so if one component fails the whole dome must be replaced. The new design splits this into two domes, so a failed part can be swapped in orbit. The narrator found in the design requirements that the ISS can revert to its original system in less than two days if something goes wrong, and that the unit is meant to be light, portable and able to sit idle for long stretches, which he said is basically the profile Axiom needs. The catch is timing: NASA wants to run the system for at least three years before handover, and Axiom's undocking schedule leaves little room.

The narrator turns to the ISS reference manual, which lists around 35 racks that carry out the station's science, and picks out experiments that caught his attention. The first is microgravity crystals, with the unique freefall environment as one of the main benefits of a space station, since the only Earth options, vomit comets and drop towers, provide only a few seconds of freefall.

He explains that the cancer drug Keytruda is an immunotherapy medication used to treat over 20 types of cancer. When synthesized on Earth, it forms unevenly sized clumps that make it too viscous to inject, so it is normally given through hour-long IV sessions. In space, the crystals grow much more evenly, and batches of Keytruda made in space have been made into much simpler subcutaneous injections. The narrator says Keytruda is not unique, since there are 16 planned investigations and an active partnership with Eli Lilly, which he calls a great profit opportunity for Axiom. A protein crystal growth rack inside the Japanese module is one of his top choices for a full rack to keep.

The narrator notes that other manufacturing processes benefit from weightlessness. When 3D printing biological tissue on Earth, complex structures collapse under their own weight, so a scaffold is needed to hold the shape, while in microgravity the structures simply float. Red Wire's bioprinter has already produced a human knee meniscus in orbit, and in May 2024 it printed live human heart tissue that survived the trip back to Earth. Red Wire also made the first plastic 3D printer to arrive on the station in 2014, and it has since produced hundreds of parts and tools on demand.

He adds that Axiom and Red Wire are already working together on the station's solar panels, and that the ability to build your own tools in orbit is far too valuable to leave behind. Both printers take up half a rack each.

Axiom wants to start sending humans to space and has already flown a couple of missions to the ISS. The narrator notes that space is not a particularly welcoming environment for the human body, since bones degrade, vision blurs and muscle is lost, so a continuous human presence needs a way to monitor those bodies. The Human Research Facility fills that role, with two full racks holding a mass spectrometer, ultrasound, strength testing rigs and a breathalyzer.

Astronauts measure their mass there to track their health. In weightlessness, mass is measured through inertia rather than weight: an astronaut braces against a spring-loaded arm that pushes with a known calibrated force, while an optical sensor times how fast they accelerate away. The narrator says these racks made the twin study possible at all, and that Axiom's crews will spend longer in orbit than most ISS rotations, so these racks are the perfect tools to monitor them.

In 2015, astronauts ate the first space-grown vegetables, a red romaine lettuce grown under lights in a station chamber. Since then the list has grown to radishes, kale, mustard greens, Chinese cabbage, tomatoes and chili peppers. The current habitat runs fully enclosed, with 180 sensors tracking light, temperature, humidity and CO2, sustaining a growth cycle of up to 135 days. It takes up only half a rack.

The narrator then describes Oh 3, a new habitat going up to the ISS this year and designed to test growing food for deep-space missions such as a journey to Mars. It also fits in the other half of the full rack, which the narrator says completes another full rack, leaving two.

With two slots left, the narrator says he is hoping to see some of the cool science that is only available in the microgravity environment of space, but he finds it hard to pinpoint exact experiments, so he passes the question to viewers: with the final two slots, what do you think is worth saving? He will share the top two most-voted comments in a community post next week.

The narrator lists several candidates. The cold atom lab was made to study Bose-Einstein condensates that could help make atomic clocks. The organ-on-a-chip experiment studies human physiology using models of human organs on plastic chips. The electrostatic levitation furnace is used to study materials at extreme heats. A fiber optic cable manufacturing lab is another option, and he says there are many more.

The video includes a sponsor message for IEEE Spectrum, a magazine released by the Institute of Electrical and Electronics Engineers. The narrator says the print magazine costs $5 a month, that a cheaper digital-only offer exists, and that viewers get 20% off through his link. He says he has been a subscriber for years and trusts the magazine for clear technical science journalism.