How SpaceX Will Flood the ISS

NASA has measured the lifespan of the International Space Station. The most expensive man-made object in the world will exist for no more than 32 years and will be deorbited in 2031. The contractor for this operation has been selected, and the appearance of the ship that will sink the ISS has recently become clear.

The International Space Station is currently the record-holder satellite for the longest continuous human habitation. The previous record was held by the Mir station, which had a little over 12.5 years between the first crew moving in and the last crew leaving. The ISS began as an international merger of the Soviet-era Mir-2 project and the American Reagan-era plans.Freedom“, but later the space agencies of Japan, Europe and Canada joined the project. At present, the station has spent more than 25 years in orbit, of which more than 23 people were on it and working.

In the script of the film “Valerian and the City of a Thousand Planets“It is assumed that the International Space Station has been in operation for centuries and is only growing in size. The real ISS is subject to wear and tear, and no one plans to leave it in orbit even as a monument. Many modules have already exceeded their design service life, so in recent years they have begun to show their age with a series of malfunctions and even leaks of the internal atmosphere.

For example, the key module of the ISS, Zvezda, has been leaking for several years. The problem is the rate of air loss noticed back in 2019, and in 2020 the leak location localized and at the end of the year tried to eliminate her. However, the pressure drop did not stop. Over the next few years, astronauts continued to try to solve the problem, but leaks continue to this day and only are getting stronger in intensity.

The thickness of the walls of the “Zvezda” is measured in millimeters and varies. For example, in the transition section this thickness makes up 4 mm. The module has been in orbit since 2000, and the welding of the aluminum-magnesium alloy body finished back in 1985. However, Roscosmos believes that the problem is not metal fatigue, but a welder's error.

Even if we forget about the aging equipment, mechanical wear of the station is inevitable. Connected this is with sharp temperature changes of 240 ° and dynamic loads during any docking/undocking.

Options

The ISS's service life has been extended several times. At the moment expectedthat the station can operate until the end of 2030, after which it will be disposed of. Any other options are simply unrealistic:

If you simply leave such a large object in space, it will be slowed by the upper atmosphere for years until it finally enters its denser layers. This process will be uncontrollable. As the recent incident with the old ISS battery showed, the danger of falling space debris is quite real and threatens property and people's lives.

Since the ISS orbital inclination is 51.6°, it is at risk 90% the territory of the Earth inhabited by people.

Any attempts to keep the entire ISS in orbit, or even just parts of it, are pointless and impossible. The station's modules are most often non-independent parts of a large structure, requiring interfaces and auxiliary systems created 30 years ago. It is cheaper and easier to create a new station from scratch than to use modules from an existing one that have been in operation for at least 15 years.

The ISS orbit is about 400 km high. Taking an object weighing about 420 tons to a disposal orbit (36,000 km high) would require a truly astronomically huge amount of fuel.

It would be expensive to even delay the fall for a couple of centuries. For the curious NASA leads a table of how large a tug's fuel capacity should be.

For comparison: the Progress of modern modifications, the main cargo ship for supplying the ISS and correcting its orbit, carries about two tons of fuel on board. All of the options considered require the development and construction of a fundamentally new spacecraft of enormous size. If advanced ships like SpaceX's Starship are used, many engineering problems will have to be solved for docking such large objects and subsequent operation of the engines without destroying the ISS.

NASA also considered using an electric rocket engine. To reach an orbit that would last 1,000 years, it would take three years of continuous operation of an expensive propulsion system and 15 tons of working gas. During these three years, maneuvers to avoid space debris are impossible, but there are still requirements to supply the station with fuel for the orientation systems. At the same time, the station will spend a significant amount of time in the Earth's inner radiation belt during the transition to the desired orbit. Because of all this and the lack of a crew on board, the ISS is at risk of completely failing.

Finally, the very idea of ​​leaving a “gift” for future generations in the form of 420 tons of garbage falling from the sky is unethical.

The station was assembled module by module, the majority of which were sent into space over 13 years on American space shuttles and heavy-class Proton rockets. Assembly of the ISS required 27 shuttle flights and 161 spacewalks. At the same time, dismantling was not provided for in the design of the equipment, and the shuttle fleet has been permanently moored since 2011. There is no technical possibility of returning the modules back.

Several years of ISS assembly in two minutes

As originally planned, the station is subject to irreversible destruction. This cannot be done even in parts: dismantling is logistically difficult, expensive, labor-intensive, and will require a huge number of spacewalks.

The only acceptable option is a controlled deorbit of the station.

Usually, the ISS flight trajectory is adjusted (raised to a higher altitude, moved away from space debris, or changed to a more convenient orbit for the arrival of a new ship) by a cargo ship docked to the aft docking port of Zvezda. To deorbit, a ship is needed in a similar way, which will give the station a braking impulse and lower the perigee of the orbit below the so-called point of no return.

Early plans

The service of Mir ended in a similar way: due to the braking impulse of Progress M1-5, the station entered the dense layers of the atmosphere, and the unburned debris fell in a special non-drifting region of the Pacific Ocean – the so-called spaceship graveyard. But the US so far has only had the unfortunate experience of deorbiting a long-term orbital station.

When the orbit of the first and only all-American station “Skylab” began to descend to the dense layers of the atmosphere, the operators tried to divert it to fall on the Indian Ocean. The maneuver did not work completely. Even the historical joke: The Australian county of Esperance jokingly issued a $400 fine to the American space agency after unburned Skylab debris fell from space into the outback of Western Australia in 1979.

The earliest project to flood the ISS is dated back in 2010. Within its framework, it was proposed to rely on the Russian side: Roscosmos would provide a modified version of the Progress spacecraft, which would use fuel from its own tanks, as well as from the Zvezda and Zarya modules. NASA has been publishing plans for abandoning the ISS on a regular basis (every two years) since December 2017 — these are the so-called transition reports.

Sometimes Russian political statements make the American side nervous. For example, in April 2021, Deputy Prime Minister Yuri Borisov reported about plans to withdraw from the ISS project as early as 2025. In early August of that year, NASA thought about itwhat to do next. Probably, a signal was received from the media: in the second half of the month, the head of Roscosmos Dmitry Rogozin calmed downthat Russia is not abandoning its obligations to sink the station.

So when the next one Transition Report January 2022 extended the work of the ISS until 2030, the report planned the ISS convergence in January 2031 exclusively by Russian efforts. The document states: calculations have shown that three Progress will be needed. The potential to attract the already proven Cygnus space truck of the American company Northrop Grumman for supplying the ISS is mentioned only in passing and is not seriously considered.

Also in January, the American side appealed to Russia with a request to develop a scenario for sinking the ISS. As the head of the Russian segment flight, Vladimir Solovyov, claimed, the Americans “threw themselves at his feet” and wanted to work under Russia’s leadership.

Selected project

The political situation heated up in the following months. No one is voicing the reasons for the further developments, but it is likely that NASA decided to play it safe. As early as August 19, 2022 NASA sent a request from US industry to assess the possibility of building an ISS-killing ship. The requirements for the device hinted that the American side is seriously preparing that Russia will not participate in the sinking at all.

The satellite's life cycle: dock with the Harmony module and have the capacity to exist like that for a year. At the same time, the braking impulse must not be issued immediately, but only when the station reaches the final orbit at an altitude of 270 km. The requirements of August 2022 proposed to descend to 270 km either with the participation of the Russian side, or due to natural braking (for which it is necessary to remain operational in orbit for at least a year).

The gears of the bureaucratic machine of state contracts began to turn. The first request was followed by a second and a third, and a Contract. Judging by the documents, no later than the meeting with company representatives in December 2022, the ship was given the name USDV (US Deorbit Vehicle or, in other spellings, United States Deorbit Vehicle). Call for applications for the technical proposal competition opened in September 2023 and lasted until March 4, 2024.

At one of these stages, the mention of the Russian side disappeared. Now it was expected that the ISS would drift to its final orbit on its own for a year.

In the final stage of technical proposals of the competition participants left There are only two: Northrop Grumman and Space Exploration Technologies Corporation, also known as SpaceX.

• Northrop Grumman has a moderately successful track record in the ISS project, building the Cygnus cargo ship and the Antares rocket that launches it.

  However, the cost of the presented NG project exceeded $680 million. Also, the first contractor scored less points in a specially developed system of assessment of requirements. The description of the results of the competition describes some questions to the company's report.

• SpaceX is known for its high success rate. As part of the Commercial Resupply Services program, Elon Musk's company set up resupply of the ISS with Dragon cargo trucks, and later, under the contract for private delivery of the Commercial Crew Program, began launching people on Dragon 2.

  SpaceX scored significantly higher in the rating system and promised to meet the required amount. However, the documentation also mentions questions for SpaceX.

June 26, 2024 NASA named the winner of the technical competition – the company SpaceX.

The contract assumes that SpaceX will create the US Deorbit Vehicle to deorbit the ISS after 2030. As NASA points out, the Russian side will withdraw from the ISS project as early as 2028.

NASA's June press release did not reveal what exactly would be built. On June 28, an agency spokesman only addedthat SpaceX will use a significantly modified design for the Dragon capsule. More details were given out yesterday on NASA TV and in SpaceX tweets.

The planned USDV looks like an overgrown “Dragon”. tweet It is stated that the ship will have 6 times more fuel (16 tons) and a 4 times more powerful propulsion system. The $843 million contract does not include the cost of launching the device.

The final plan is slightly is different from the initial requirements. USDV will launch 1–1.5 years before the planned deorbit of the ISS. The station's crew will remain on board while it gradually drifts and loses orbital altitude. The Russian side is not expected to participate in this process.

Six months before the destruction date, people will leave the ISS forever. They will take only small souvenirs and museum exhibits with them. The return capsules of the Soyuz and Dragon 2 will not hold much cargo.

To save as much fuel as possible, the natural braking effect of the upper atmosphere will be used to the fullest. Upon reaching the final orbit at an altitude of 220 km, the modified Dragon will slow down the station so that it will fall in a controlled manner at the desired location on Earth. The station will be destroyed, some of the fragments will burn up, the rest will fall in a given corridor and settle on the bottom of the Pacific Ocean.

The International Space Station began partly as a political project between two former rivals. Twenty-five years later, the project's main participants can't even agree on how to deorbit the station together.

Unfortunately, the countries' paths diverge in the future: NASA plans to create a station in orbit around the Moon Lunar Gatewayand Russia will continue its presence in Earth orbit ROSNASA will no longer have mandatory Russian language courses, and astronauts will not have to learn English.