The Federal Aviation Administration (FAA) on Wednesday, September 20, 2023, published a proposal that aims at reducing the rising number of space debris cluttering useful orbits around Earth, such as Low Earth Orbit and Geostationary.
The proposal comes at a critical period, with more and more private companies launching probes, satellites, and spacecraft of diverse use, while constellations are a widespread solution adopted by various corporations.
All these factors are prone to becoming a troublesome burden for everyone to share. The collision of multiple debris could impact satellites in use, and in the worst case, render whole regions of Earth orbits unusable.
A piece of titanium the size of a grain of rice traveling in space can easily do more damage than a bullet. Of course, being unable to guarantee the removal of such dimensioned objects, will compel the companies to prevent their release from the spacecraft. One example could be staging or payload adapters’ explosive bolts being forced to extinction.
The Administration is in fact particularly concerned with spent upper stages of launch vehicles. They alone account for over 95% of the total mass of debris in orbit today. Some of them, for example, are left on a Geostationary Transfer Orbit, after delivering payloads. Fragmentation of a highly durable structure such as that could create a high number of dangerous debris. It is then of utmost importance that upper stages and high-mass objects in particular are removed from potential situations of collision as soon as possible.
The FAA proposal and its predecessors
The agency is aiming to amend and modify some of its mandatory requirements that companies have to address to launch payloads to space. The goal is to establish new rules that will tie together launch requirements within a specified time frame.
The goal is to “dispose” of space debris larger than 5 mm within 25 years at most, from their assigned end of mission. The FAA also specifies exhaustively which procedures launch operators can enact to reach this requirement. The options are various, with each one calling for simulations and probability calculations in order to be considered and approved, and being monitored until the completion of disposal. Collision and explosion mitigation options will also be evaluated.
The FAA is building its set of requirements over a preexisting regulation, that to this day has addressed space debris concerning only the safe separation of payloads from the upper stages of rockets. However, in the span of forty years, regulations have also been put in place by other entities or agencies.
The Inter-Agency Space Debris Coordination Committee (IADC, 1993) is another fundamental member of the equation, providing swift communication and information exchange to avoid collisions. The IADC also first published a set of internationally recognized space debris mitigation guidelines in 2002.
Another example, that is often referred to in the FAA proposal, is the United States Government (USG) Orbital Debris Mitigation Standard Practices (ODMSP), established in 2001. While some regulations are not mandatory, they are now serving as the backbone of the FAA Amendment.
Five very different options
The FAA is proposing 5 different methods companies can choose to use. The choice will be influenced by the type of orbit, propellant availability, cost, and other factors. Each method has a specific time requirement if chosen:
- Controlled Atmospheric Disposal is the safest option both in terms of debris and people on Earth. Companies would have to demonstrate viable reentry corridors on isolated patches of ocean, or engineering components to be incinerated during reentry. Time frame: 30 days.
- Earth Escape Disposal requires higher propellant quantities and costs to inject the object in an heliocentric orbit. Will probably be applied for debris deriving from inter-planetary missions. Time frame: 30 days.
- Direct Retrieval is the most challenging option of sending another probe to catch and bring back the debris. Even if unfeasible at current times, it’s projected to become a viable option in the next few years. Time frame: 5 years, due to the complexity of such missions.
- Uncontrolled Atmospheric Disposal with demonstrations of low impact on land after reentry, as for option 1. Time frame: 25 years, taking into consideration the predicted influence of solar wind and atmospheric drag on orbital decay. The gravitational forces of Earth, Moon, and Sun in highly elliptical orbits such as Molniya orbits are also considered.
- Manuever to a Disposal Orbit where the satellite population is scarce and solar activity is not relevant. While it fails to remove debris from orbit, it can be useful to reduce the chances of collisions. Some storage orbits may be needed for future missions. Time frame: 30 days.
These proposed regulations would be another fundamental step toward a safer and more sustainable management of space, that can be a great benefit in the long run.