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Our mission is to encourage space actors to design and implement sustainable space missions and operations to contribute to the long-term sustainability of the space environment

The Space Sustainability Rating (SSR) provides a rating system informed by transparent, data-based assessments of the level of sustainability of space missions and operations - without disclosing confidential mission data and proprietary information. 

The SSR also offers practical recommendations to space operators on how to improve their sustainability performance, with the goal of helping to address the challenges raised by the proliferation of space debris.

All space actors can engage with our platform for action-focused collaboration centered on the rating system to support research and leverage best practices

A new way to incentivize safer conditions for space operations

The opportunities offered by the flourishing space economy can only be harnessed if we keep the space environment sustainable and safe.

image of a satellite above earth

Space infrastructure & services are essential to
life on earth

Satellites provide crucial services such as weather forecasting, climate and natural resources monitoring, global positioning, and communications.

The sustainability of the space environment is vital to maintain and develop scientific and commercial use of space in the future.

earth surrounded by a web of network

A growing number of objects
launched in already congested orbits

Thousands of spacecraft are expected to be launched in the coming years by the commercial sector alone, driven by declining costs, and the proliferation of related technology. They will add to approximately 5400 already active satellites.

These trends inevitably increase the risk of collisions and spur debates on the safe and sustainable use of vital near-Earth orbits.

nations flags in the wind

Quantify, measure and verify
international guidelines pose significant challenges

Existing international guidelines steer space actors’ activities in our globally shared orbital environment. However, the fundamental shifts in space traffic will affect their potential to curtail the proliferation of new debris in the coming years.


An opportunity for space actors to demonstrate sustainability commitment & scorecard

The Space Sustainability Rating will enable spacecraft operators and satellite manufacturers to enhance the sustainability and safety of their missions through offering an incentive:

To design missions compatible with sustainable and responsible operations

To operate missions considering impact to the orbital environment & on other operators

To communicate transparently on space sustainability & debris mitigation efforts

By voluntary engaging in the SSR, they will go through a transparent rating process supported by a comprehensive, transparent and data-based assessment of their mission’s current level of sustainability.

Actionable guidance will complement the ratings to identify where improvements can be made, and support space debris mitigation efforts to drive sustainability in outer space.

The rating methodology, tested by operators in an advanced development phase, has been designed to enable a straightforward and  transparent assessment process.

The SSR is designed as a composite indicator, aggregating and weighing six modules encompassing the various aspects of the mission design. Each module consists of an individual point system based on key criteria and information.

  • mission index

    Mission Index

  • DIT

  • Collision Avoidance Capabilities

  • data sharing

    Data Sharing

  • Application of Design Operations Standards

    Design & Operations Standards

  • External Services

Mission Index

Any mission and object associated therewith leaves a trace in orbit. In the best case, it is just using a portion of the space environment sustainably. In the worst case, it will cause harmful interference with other objects in the environment. This module quantifies the level of harmful physical interference caused by the planned design and mission operations considering mission characteristics, collision avoidance strategy, and post mission disposal strategy.


Detectability, Identification & Trackability

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 environment. Moreover, identification is required for registration and liability purposes. This module aims to cover these aspects. As space surveillance and tracking capabilities improve and become more accurate in tracking satellites, this module is expected to undergo updates with each SSR version.

Collision Avoidance Capabilities

In absence of a perfect space surveillance capability and depending on the operators’ capabilities, there are various ways a mission can choose to operate in a congested environment. 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

Sharing of space situational awareness and other information by operators is critical to space safety. At the same time, some operators have sensitivities about sharing certain kinds of information. In other cases, operators simply do not share certain information, but have no particular objection to potentially doing so. This module quantifies the amount of relevant information an operator shares with various communities and the contribution of this information to spaceflight safety.

Design & Operations Standards

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. As such, a part of the SSR emphasis is placed on the adoption of standardisation concepts in design and operations where possible. Standardization is a continuous process based on the availability of technologies and understanding of the environment. As such, changes in the standards need to be included when releasing a new SSR version and the implementation is considered relevant for bonus ratings where they are not mandatory.

External Services

Innovations taking place in the area of close proximity operations have the potential to improve space sustainability and as such are of interest. However, their application can be widely different for individual mission concepts. As such, they are considered relevant for bonus ratings. As external services develop and are successfully proven and utilized, the External Services module of the SSR will be updated accordingly.


Space operators demonstrating a strong sustainability performance through the assessment process are awarded a recognised “bronze”, “silver”, “gold” or “platinum” rating badge. This will aim to serve in the future as an independent certification which can be shared publicly, increasing transparency on debris mitigation efforts.

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silver badge
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get in touch!

Contact us to learn more about the SSR, explore how you can get involved and apply for a rating.


The SSR is an initiative hosted by eSpace - EPFL Space Center seeking to foster voluntary and bold action by satellite operators to reduce the risk of space debris, on-orbit collisions, and unsustainable space operations.

It provides an incentive for satellite operators to design and implement sustainable missions design and operations in outer space, through an innovative and inclusive approach consisting of:

  • a rating system informed by transparent, data-based assessments of the level of sustainability of space missions – without disclosing confidential mission data and proprietary information; and
  • practical guidance on how to improve sustainability performance and responsible practices.

The rating system is the result of a five-year development process initiated in 2016 by the World Economic Forum’s Global Future Council (GFC) on Space Technologies, and the metrics used are widely recognized by scientific communities, regulators, and industry as efficient space sustainability assessment criteria.

Space debris pose significant challenges to the safety of current and future operations in space. In 2022, around 5400 active satellites are sharing orbits around Earth with more than one million objects larger than 1cm - increasing the risk of collisions and the loss or disruption of space-based infrastructure. As thousands of spacecrafts are planned to be launched in the coming decade, and without internationally binding guidelines, implementing tools to incentivize space actors and foster responsible behaviour will be key to ensure long-term sustainability of the space environment. 

The SSR offers an innovative and practical solution to addressing the orbital challenge by rewarding sustainable design and responsible behaviour, as well as increasing the transparency of organisations’ debris mitigation efforts.

It evaluates the implementation and efficiency of collision avoidance and post-mission disposal strategies, assesses the ability to detect and track a spacecraft, promotes compliance to existing space debris mitigation guidelines and rewards operators sharing data contributing to space situational awareness.

Operators going through a rating will be evaluated but will also benefit from the support of the SSR team to identify the actions that can be taken in order to increase the mission’s sustainability.

The Space Sustainability Rating is a non-profit association recognized by EPFL and hosted within eSpace – EPFL Space Center. The rating system is independent, neutral and transparent: its methodology is available online and the team is available to address any question which may arise. 

The rating methodology was developed by a multi-disciplinary consortium composed of BryceTech, the Space Enabled research group at Massachusetts Institute of Technology, the European Space Agency Space debris office and the University of Texas at Austin and the World Economic Forum.

The development process of the rating methodology spans two years (between 2019 to 2021) and was also supported by satellite operators through alpha and beta testing phases to ensure its robustness and relevancy.

Read More about the SSR’s origin:

The rating process is managed by the SSR team within eSpace who is responsible for gathering the inputs, giving guidance on the completion of a rating, and providing results and recommendations to the operators.

The final score resulting from the assessment is computed from the evaluation of six individual modules and from the verification level of the information provided to the SSR issuer. The score is jointly computed by eSpace, MIT (Detectability, Identification and Trackability module), and ESA (Mission index module).

The SSR also draws from the principles outlined in the UN Guidelines and considers specific decisions about design, operations and post mission disposal that reduce risk of collisions, shorten orbital time for debris and increase space situational awareness.

The rating methodology is detailed on The Rating webpage.

The SSR provides an assessment of the sustainability level of a space mission. A mission is defined as a functional unit of spacecraft, launch vehicle, and mission related objects aimed at providing a specific service, by means of design and operations, for which they need to access and use part of the space environment.

A mission can consist of a single satellite, a satellite and a launch vehicle, or combinations of these elements. The rating is computed considering the contribution from all the objects.

Satellite operators can engage with the SSR by taking an annual subscription comprising up to 10 ratings. Each rating pertains to one mission but can be recomputed in case parameters change or if recommendations from the initial rating report are implemented. The yearly subscription allows operators to benefit from the support of the SSR team throughout the year in order to better understand how to improve their mission sustainability.

A flat fee applies for the rating subscription and will remain valid for 12 months from the subscription date. In order to enable academic projects and startups with limited financial resources to apply for a rating, a special discount on the subscription fee is offered to these entities. 

In addition, any organisation can join the SSR as an association member to get involved in the work of the SSR, provide input on the rating system, and support communications and policy efforts.

The SSR is designed as a guiding instrument for space operators in their sustainability journey. It is a unique tool providing an accurate assessment of the current sustainability performance, and helping to identify where improvements can be made along the way - contributing to establishing best practices for the space sector.  By voluntarily taking part in the rating, spacecraft operators, launch service providers and satellite manufacturers will share a single point of reference externally describing their mission’s level of sustainability.

The Space Sustainability Rating can be applied to any type of mission, at any mission phase. The rating however only remains valid for a given mission phase, as significant changes can occur from a mission phase to another. As the SSR issuer needs to be able to certify that a mission complies to the SSR criteria, the rating is only valid for subscribed operators. On demand re-evaluation of the rating can be requested at any time if recommendations are implemented in the mission.

There are three ways to support SSR’s activities:

  • Satellite operators can request to be rated by subscribing and benefit from the SSR’s recommendations to implement sustainable design and operation practises in their mission and showcase their efforts towards space sustainability.
  • Any organisation can join the SSR as an association member in order to be involved in the discussions about the rating and participate in shaping its evolution. The SSR Association’s goal is to federate satellite operators and any entity having an interest in space sustainability such as insurers, policy-makers, and researchers to facilitate discussions about the evolution of the rating system. Visit the Get engaged page for more information.

our partners

The Space Sustainability Rating is an initiative developed in the last three years by a consortium including the World Economic Forum, the European Space Agency, the Massachusetts Institute of Technology, BryceTech and the University of Texas at Austin, and hosted by eSpace - EPFL Space Center.

All space actors are welcomed to join the SSR and constribute to the space sustainability discussion, through two different levels of participation.

Stellar and the Nihon University, Japan have joined the SSR as founding members, and the Secure World Foundation as an association member. To learn more about opportunities for involvement in the SSR, please contact the team.