A garage for satellites in Low Earth Orbit?

A “space garage” or garage for satellites in Low Earth Orbit (LEO), at an altitude of roughly two thousand kilometres or less, could, while orbiting the Earth at a speed of about twenty-eight thousand kilometres per hour (almost eight kilometres per second), operate different kinds of services on satellites as well as recycle space debris.

Space debris are useless objects multiplying at an exponential rate, threatening to incapacitate us to access outer space. A team (which wants to reconcile outer space and ecology) from the French Institut Supérieur de l’Aéronautique et de l’Espace or ISAE-SUPAERO, translated as National Higher French Institute of Aeronautics and Space, founded in 1909 and located in Toulouse, is proposing to build a new kind of garage, an in-orbit “space garage” capable to repair, recycle and replace some space debris. This initiative could thus become a new phase in what’s called New Space: a circular space economy.

Outer space could become inaccessible by 2100, even 2050. The reason for this is the exponential increase in the number of space debris: satellites out of use, rocket upper stages, straps or fragments from the explosion of spacecraft… Sometimes called space waste or space garbage, these space objects, traveling at a speed of about eight kilometres per second, are a real threat to the sustainability of outer space activities.

Space debris larger than ten centimetres, large enough to destroy a satellite, increased from twenty-nine thousand in 2017 to thirty-four thousand in 2019. Objects between one and ten centimetres, capable of damaging or deflecting a satellite, also increased from seven hundred and fifty thousand to nine hundred thousand in just two years. And things could get worse. After the United States of America, Russia and China, it was India that, in March, produced thousands of additional space debris by destroying one of its own satellites. The largest in-orbit space debris to date is Envisat (for “Environmental Satellite”), a large inactive Earth-observing satellite which is still in Low Earth Orbit.

Most of the space debris returning to Earth are destroyed by the atmospheric drag. In some rare cases, satellites or rocket reservoirs, capable of withstanding very high temperatures, may reach the Earth’s surface if their trajectory is not controlled. In 2011, the fragment of a Russian satellite in Low Earth Orbit fell on the roof of a house in Siberia.

Let’s recall that space debris affect mainly the Low Earth Orbit or LEO. A LEO is an Earth-centred orbit with an altitude of two thousand kilometres or less (approximately one third of the radius of Earth), or with at least an orbital period of one hundred and twenty-eight minutes or less. Most of the manmade objects in outer space are in LEO. There is a large variety of other sources that define LEO in terms of altitude. The altitude of an object in an elliptic orbit can vary significantly along the orbit. Even for circular orbits, the altitude above ground can vary by as much as thirty kilometres (especially for polar orbits), due to the oblateness of Earth’s spheroid figure and local topography.

The LEO region is defined by some sources as the region in space that LEO orbits occupy. Some highly elliptical orbits may pass through the LEO region near their lowest altitude (or perigee) but are not in an LEO orbit because their highest altitude (or apogee) exceeds two thousand kilometres. Sub-orbital objects can also reach the LEO region but are not in an LEO orbit because they re-enter the atmosphere. The distinction between LEO orbits and the LEO region is especially important for analysis of possible collisions between objects which may not themselves be in LEO but could collide with satellites or debris in LEO orbits. The International Space Station (ISS) conducts operations in LEO. All crewed space stations to date, as well as the majority of satellites, have been in LEO. Apollo 8 was the first mission to carry humans beyond LEO in December 1968.

Another danger is the arrival in outer space of private actors and their projects of satellite constellations (a satellite constellation is a group of artificial satellites working in concert; such a constellation can be considered to be a number of satellites with coordinated ground coverage, operating together under shared control, synchronized so that they overlap well in coverage, the period in which a satellite or other spacecraft is visible above the local horizon). Thousands of tiny low-cost satellites, not necessarily equipped with means of avoidance, will generate probabilities of collision much higher, not to mention their risk of breaking down.

If each collision results in thousands of pieces of debris, which in turn can lead to collisions, the risk is that of triggering a chain reaction, what’s called the “Kessler syndrome”. After a certain threshold, the risks of collisions become too high and the doors of outer space would have to close. This would be disastrous as it would mean the end of Internet and means of communication in many areas, as well as the end of geolocation so important for cars, boats or planes…

We are fortunately not there yet, even if the ISS sometimes has to manoeuvre in order to avoid collision with space debris. Several national space agencies and start-ups are presently starting to tackle the problem by imagining various devices for capturing this space waste.

Rather than collecting space debris or destroying them, a team from the French Institut Supérieur de l’Aéronautique et de l’Espace or ISAE-SUPAERO, researchers wants to minimize their production by repairing and recycling satellites from an in-orbit space garage. An application of circular economy in Low Earth Orbit.

This space garage could, in its cheapest version, be fully autonomous, with the dimensions and mass of about one tenth of those of the International Space Station. Either ten or twenty tons, it could shelter different small spacecraft able to go diagnose the conditions of satellites, repair them or tow them to the garage for recycling.

The project benefits from several prestigious French supports: Airbus, Ariane, the German DLR, and the French CNES. For the partners, the economic interest of the concept is one of the most important arguments. And the potential market is high: five thousand satellites are currently in Low Earth Orbit, including about two thousand functional and three thousand out of use.

Another argument in favour of this space garage is that failures are often not that complicated to fix: satellites often die because they lack of fuel. The service would consist of refuelling them, with terrestrial or even lunar fuel in the longer term, since our natural satellite is home to hydrogen and oxygen, in the form of water, which would be less expensive to use.

For other breakdowns, the in-orbit space garage could provide spare parts to out-of-service satellites, such as solar panels or antennas. Parts could also be produced ex nihilo thanks to 3D printing and debris being crushed in the garage to recover the raw materials. If manufacturers do not engage in this path, they will end up no longer able to launch satellites.

There are still some obstacles to overcome. To effectively recycle and repair satellites, manufacturers should ideally standardize their hardware, they also should favour recyclable materials and repairable parts: solar panels that are not glued to the walls of the satellite, for example. The problem is that there is no “outer space police”, and there will be no international law in this area as long as we do not experience a catastrophic event.

The United States of America, Russia, China and European countries are among the states that have sent the largest number of satellites in outer space. But it is impossible to designate those responsible. France was the first state to legislate on space debris. According to its law, which applied starting in 2011, any French manufacturer that manufactures satellites and any French spaceport which launches satellites must manage their end of life. Once the mission is completed, after ten to fifteen years, the satellite must be turned off and put into a cemetery orbit or destroyed in the atmosphere. Japan is also doing a lot of studies on space debris. Conversely, India does not manage this problem at all.

Space Legal Issues

The status of this potential space object

What are satellites? They are space object. The term Object in reference to outer space was first used in 1961 in General Assembly Resolution 1721 (XVI) titled International cooperation in the peaceful uses of outer space to describe any object launched by States into outer space. Professor Bin Cheng, a world authority on International Air and Space Law, has noted that members of the COPUOS during negotiations over the space treaties treated spacecraft and space vehicles as synonymous terms. The Space Object can be considered as the conventional launcher, the reusable launcher, the satellite, the orbital station, the probe, the impactor, the space telescope…

The term “space object” is not precisely defined by the Onusian space treaties. Let’s note that the five outer space treaties use such phrases as “objects launched into outer space”, object placed “in orbit around the Earth”, “in orbit around or other trajectory to or around the Moon”, or “around other celestial bodies within the solar system, other than the Earth”. Some of the treaties refer also to “spacecraft”, or “landed or constructed on a celestial body”, “man-made space objects”, “space vehicle”, “supplies”, “equipment”, “installations”, “facilities” and “stations”.

Let’s remember that “A treaty shall be interpreted in good faith in accordance with the ordinary meaning to be given to the terms of the treaty in their context and in the light of its object and purpose”, article 31 of the Vienna Convention on the Law of Treaties of 1969. In addition, “Recourse may be had to supplementary means of interpretation, including the preparatory work of the treaty and the circumstances of its conclusion, in order to confirm the meaning resulting from the application of article 31, or to determine the meaning when the interpretation according to article 31: (a) leaves the meaning ambiguous or obscure; or (b) leads to a result which is manifestly absurd or unreasonable”, article 32 of the Vienna Convention on the Law of Treaties of 1969.

Let’s recall that a space object causing damage triggers international third-party liability under the Convention on International Liability for Damage Caused by Space Objects (entered into force in September 1972). Article I (d) of which enounces that “the term space object includes component parts of a space object as well as its launch vehicle and parts thereof”. Its Article II adds that “A launching State shall be absolutely liable to pay compensation for damage caused by its space object on the surface of the Earth or to aircraft in flight”.

A space object requires, thanks to the Convention on Registration of Objects Launched into Outer Space (entered into force in September 1976), registration. Article II of which states that “When a space object is launched into Earth orbit or beyond, the launching State shall register the space object by means of an entry in an appropriate registry which it shall maintain. Each launching State shall inform the Secretary-General of the United Nations of the establishment of such a registry”.

Finally, the term space object effectively triggers application of much of both the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies (entered into force in October 1967) and the Agreement on the Rescue of Astronauts, the Return of Astronauts and the Return of Objects Launched into Outer Space (entered into force in December 1968). Article VII of the first declares that “Each State Party to the Treaty that launches or procures the launching of an object into outer space, including the Moon and other celestial bodies, and each State Party from whose territory or facility an object is launched, is internationally liable for damage to another State Party to the Treaty or to its natural or juridical persons by such object or its component parts on the Earth, in air space or in outer space, including the Moon and other celestial bodies”.

Article 5 of the latter states that “1. Each Contracting Party which receives information or discovers that a space object or its component parts has returned to Earth in territory under its jurisdiction or on the high seas or in any other place not under the jurisdiction of any State, shall notify the launching authority and the Secretary-General of the United Nations. 2. Each Contracting Party having jurisdiction over the territory on which a space object or its component parts has been discovered shall, upon the request of the launching authority and with assistance from that authority if requested, take such steps as it finds practicable to recover the object or component parts. 3. Upon request of the launching authority, objects launched into outer space or their component parts found beyond the territorial limits of the launching authority shall be returned to or held at the disposal of representatives of the launching authority, which shall, upon request, furnish identifying data prior to their return”.

The Outer Space Treaty doesn’t really provide a definition for “object launched into outer space” other than an indication in Article VIII that it includes the “component parts” of the “object launched into outer space”. It states that “A State Party to the Treaty on whose registry an object launched into outer space is carried shall retain jurisdiction and control over such object, and over any personnel thereof, while in outer space or on a celestial body. Ownership of objects launched into outer space, including objects landed or constructed on a celestial body, and of their component parts, is not affected by their presence in outer space or on a celestial body or by their return to the Earth. Such objects or component parts found beyond the limits of the State Party to the Treaty on whose registry they are carried shall be returned to that State Party, which shall, upon request, furnish identifying data prior to their return”.

We can conclude by saying that this “space garage” would be a space object.

The access to Low Earth Orbit (LEO)

An orbit is the curved path through which objects in space move around a planet or a star. The 1967 Treaty’s regime and customary law enshrine the principle of non-appropriation and freedom of access to orbital positions. Space Law and International Telecommunication Laws combined to protect this use against any interference. The majority of space-launched objects are satellites that are launched in Earth’s orbit (a very small part of space objects – scientific objects for space exploration – are launched into outer space beyond terrestrial orbits). It is important to precise that an orbit does not exist: satellites describe orbits by obeying the general laws of universal attraction. Depending on the launching techniques and parameters, the orbital trajectory of a satellite may vary. Sun-synchronous satellites fly over a given location constantly at the same time in local civil time: they are used for remote sensing, meteorology or the study of the atmosphere. Geostationary satellites are placed in a very high orbit; they give an impression of immobility because they remain permanently at the same vertical point of a terrestrial point (they are mainly used for telecommunications and television broadcasting).

Near-Earth space is formed of different orbital layers. Terrestrial orbits are limited common resources and inherently repugnant to any appropriation: they are not property in the sense of law. Orbits and frequencies are res communis (a Latin term derived from Roman law that preceded today’s concepts of the commons and common heritage of mankind; it has relevance in international law and common law). It’s the first-come, first-served principle that applies to orbital positioning, which without any formal acquisition of sovereignty, records a promptness behaviour to which it grants an exclusive grabbing effect of the space concerned. Geostationary orbit is a limited but permanent resource: this de facto appropriation by the first-comers – the developed countries – of the orbit and the frequencies is protected by Space Law and the International Telecommunications Law. The challenge by developing countries of grabbing these resources is therefore unjustified on the basis of existing law. Denying new entrants geostationary-access or making access more difficult does not constitute appropriation; it simply results from the traditional system of distribution of access rights. The practice of developed States is based on free access and priority given to the first satellites placed in geostationary orbit.

However, the influx of newcomers from New Space requires the development of new tools to maintain, repair and ultimately remove all these satellites. This is what’s called Space Traffic Management, which could be described as “the planning, coordination, and on-orbit synchronization of activities to enhance the safety, stability, and sustainability of operations in outer space”. We’ll study the Space Traffic Management question in a future article.