Context: The world is witnessing rapid increase in creative business models and new technologies leading to launch of thousands of satellites in Low-Earth Orbit. There is growing risk that Earth’s capacity to accommodate such a large set of new objects safely may be in jeopardy. In this context, Space Sustainability Rating is an initiative that seeks to foster voluntary action by satellite operators to reduce the risk of space debris, on-orbit collisions and unsustainable space operations.
About Space Sustainability Rating
- Space Sustainability Rating is tool developed for a more sustainable use of space by encouraging space actors to design & implement sustainable space missions and operations.
- It seeks foster voluntary and bold action by satellite operators to reduce risk of space debris, on-orbit collisions and unsustainable space operations.
- Members: It has been developed by World Economic Forum (WEF), European Space Agency (ESA), Space Enabled research group at MIT, University of Texas at Austin & BryceTech. It is based at eSpace at Ecole Polytechnique Lausanne in Switzerland.
- Rating methodology:
- It is a tiered scoring system that takes a series of metrics based on models to quantify and measure sustainability decision taken by operators.
- Credits (Points) are awarded for actions leading to positive impact on space environment, actions that result in more sustainable impact receive more points.
- It is formulated as a combined score based on evaluation of individual modules, where different aspects of space sustainability are covered.
- To rate a mission, the operator in charge of it voluntarily reaches out to the SSR to start the process. The SSR team collects relevant information regarding different aspects of the mission’s sustainability efforts and then sends these data to their computation partners. Afterwards, the non-profit gathers it all and computes the rating.
- Tier Score: A rated entity receives a ‘Tier Score’ that will determine the rating between Bronze, Silver, Gold or Platinum. Each of the SSR tiers are achieved after earning a certain combined score between 0 (low) and 1 (high), based on combined evaluation of individual modules.
- Bonus ‘Step’ Indicator: Enables the possibility to earn additional credit towards a bonus ‘step’ indicator, which highlights certain steps a mission can take to ‘go over and beyond’ the baseline rating towards space sustainability. Bonuses are reported separately and do not contribute to baseline rating of a requesting identity.
Indicators used in Space Sustainability Rating
- Mission Index: This module is directly derived from European Space Agency’s (ESA) debris index and quantifies the level of harmful physical interference caused by planned design and mission operation. It measures the impact of a space mission on space environment, using the Environmental Consequences of Orbital Breakups (ECOB) based on mission characteristics, collision avoidance strategy and disposal strategy.
- Detectability, Identification & Trackability: Aims to encourage satellite operators to consider how physical attributes of their satellite design and their operational approach during launch, operations and disposal affect the level of difficulty. Small objects which might be operational but cannot be reliably included in space surveillance and tracking products form a risk to other objects in the space. Also, identification is required for registration and liability purposes.
- Collision Avoidance Capabilities: These are essential capabilities satellite operators should have to improve their ability to identify, respond to and mitigate collisions. This module aims to emphasise the steps which can be taken by operators to reduce the risk of accidental collision with debris and among active operators.
- Data Sharing: Measures the information that satellite and launch vehicle operators should share with peers and stakeholders and contribution of such information sharing to spaceflight safety. Sharing of space situational awareness and other information by operators is critical to space safety.
- Design & operation standards: Adoption of internationally endorsed standards in space domain is essential for ensuring compatibility in understanding between operators among themselves and between an operator and space environment, which is being used. Successfully addressing the problem of space sustainability when it comes to avoiding the creation of space debris and operating in congested environments can only be achieved by means of common understanding and objectives.
- External services: Includes a wide range of activities and identifies classes of action that satellite operators can take to make their mission more amenable to receive External Services (ES) or to increase the probability of successful external services such as fixing, improving and reviving satellites and refers to any work to refuel, repair, replace or augment a satellite in space.
About Space Debris
- According to estimates, there are around 20,000 objects which are drifting through low-earth orbits.
- Kessler Syndrome: It is a phenomenon in which the amount of junk in orbit around Earth reaches a point where it creates more and more space debris.
- Conjunctions: Due to rapid increase in number of low-earth objects, close encounters between these objects known as ‘conjunctions’ are at an all-time high, meaning satellites and other spacecraft or debris fragments are increasingly at risk of colliding with each other.
- Anti-satellite weapons and space warfare are expected to increase space debris by multiple times. For ex. India’s Anti-Satellite Weapon.
Initiatives for Space Debris Sustainability
- Zero Debris Approach: ESA aims to totally stop the generation of debris in valuable orbits by 2030. ESA has also launched Clean Space Initiative for testing various technologies for debris management.
- Grapple Fixtures: They are used on spacecraft or other objects to provide a secure connection for a robotic arm.
- Graveyard Orbits: A graveyard orbit, also called a junk orbit or disposal orbit, is an orbit that lies away from common operational orbits. Satellites are moved into such orbits at the end of their operational life to reduce the probability of colliding with operational spacecraft and generating debris.
- Space Net: Japan’s JAXA launched a test space net satellite to collect space junk.
- E.Deorbit: A planned active space debris removal mission being developed by Europe’s European Space Agency as part of Clean Space Initiative. It aims to take down a derelict satellite.
- ClearSpace-1 will be the first space mission to remove an item of debris from orbit, planned for launch in 2025.
- Remove Debris Mission: Aims to test the efficacy of several ADR technologies on mock targets in low earth orbit. The platform is equipped with a net, a harpoon, a laser ranging instrument, a dragsail and two CubeSats.
- International Guidelines for Space Debris Management: Currently, there is no international treat minimising space debris. However, UN Committee on Peaceful Uses of Outer Space has published voluntary guidelines in 2007 for space debris management.
Suggestions for space debris
- Design rockets and spacecraft to minimise the amount of ‘shedding’ – material becoming detached during launch and operation, due to the harsh conditions of space.
- Prevent explosions by releasing stored energy, ‘passivating’ spacecraft once at the end of their lives.
- Move defunct missions out the way of working satellites – either by de-orbiting them or moving them to a ‘graveyard orbit’.
- Prevent in-space crashes through careful choice of orbits and by performing ‘collision avoidance manoeuvres’.