There are more than 750,000 objects in orbit with a size larger than 1 cm, which are all potentially mission ending. These objects coexist with around 3,000 inactive satellites, out of a total of 4,500 that orbit the Earth, and every year approximately 100 tons of debris re-enter the Earth’s atmosphere in an uncontrolled manner.


Even if all Space launches stopped immediately, the amount of wreckage would continue to rise because of collisions, which lead to more debris, thus causing mote accidents, and so on. The most effective way to put an end to this chain reaction and stabilise the debris population in critical orbits is to remove large items of debris from Space.

Given that the problem will only get worse in the coming years, it is urgent to develop technologies and solutions that enable the controlled and safe removal of debris in Space. To achieve this aim, the European Space Agency has launched a new activity that has received the support of its member States, including Portugal.

In December 2019, the European Space Agency assigned the first ADRIOS mission to ClearSpace, a startup created by a team of researchers from the Ecole Polytechnique Fédérale de Lausanne (EPFL). The project that is being assessed will involve Portuguese companies.

At ESA’s Ministerial Council, named Space19+, a number of member States have decided to approve and contribute to the ADRIOS (Active Debris Removal/ In-Orbit Servicing) with two main goals: the removal of human-made objects in Space as well as developing the competence necessary for in-orbit servicing, which can extend the lifetime of infrastructure in Space. Acquired by ESA and its member States as a service, ADRIOS is an innovative endeavour as it not only tackles the topic of debris but does so from a business perspective, stimulating the commercial development of the field.

Active removal can be an efficient solution in terms of the number of collisions prevented versus objects removed. To maximise the effect of debris removal, the selected objects should have a high mass (as they pose the most significant environmental impact in case of collision). They also need to present high collision probabilities, meaning they should be in densely populated regions (around 800–1000 km altitude at high inclinations) and have a large cross-sectional area. And, at last, the objects should be in high altitudes, meaning the orbital lifetime of the resulting fragments is long.

ESA’s Clean Space initiative began developing the mission in 2013, organised around the not so simple task of capturing and safely deorbiting an abandoned ESA-owned satellite in highly trafficked low-Earth orbit. In 2019, the action took a significant step with all the member states subscribing to the first phase of the mission.

Portugal’s commitment to the first phase of the Adrios Mission is 7.5 Million Euro and through the Clear Space Mission, ESA aims to the safe removal of an inactive ESA-owned object from low-Earth orbit.

The benefits of space debris mitigation and clean space activities are numerous

Social: Unchecked growth in space debris will make specific orbits unusable, such as those used by vital climate, Earth Observation and telecom satellites, thus permanently and catastrophically limiting critical services on which society relies upon. At the same time, collision avoidance warnings will enable satellite operators to take protective measures.

Economic: The destruction of individual satellites or permanent loss of specific orbits due to unchecked debris growth would have devastating global effects. For Europe, this could mean the loss of economic activity in Space which is directly worth over 8000 M€. In addition, global satellite operators today spend 15 M€ annually on debris impact avoidance manoeuvres.

Geopolitical: Space is an enabler for the global economy, and any loss of free and open use of Space due to uncontrolled debris growth would undermine international economic stability, and by extension, endanger international public order.

Scientific: Safeguarding our space assets against the risk of debris requires studying debris causation, as well as developing new statistical models, technologies, techniques and systems. Innovative technological solutions, namely design-for-demise, need to be examined to evolve satellites so that they do not become debris. Furthermore, removing debris requires a step forward in the technical solution for close proximity operations.


Accurate, timely and comprehensive situational awareness are instrumental to the protection and safe operation of all critical European (and indeed global) space infrastructure.

Activities in this area will empower institutional, industrial and governmental users, by supporting sustainable space traffic management including monitoring, risk assessments, in-orbit servicing and debris mitigation. They will also contribute to decrease environmental impacts, reduce the production of space debris and deorbiting large pieces of space debris.

Examples of potential users include

Institutional and governmental users: Both data processing, and cataloguing, as well a automation tools and software enable  a timelier, more actionable information, as such improving the ability of ESA, national space agencies and institutional partners to protect satellite fleets;

Industry: European industry can gain long-term competitive advantage by developing technologies and platforms that are effectively compliant with debris mitigation regulation. Precursors for active debris removal can build new European industrial capabilities needed to perform in-orbit servicing.

During the 12 months prior to the ESA Ministerial Meeting, Space19+, ESA devised a new and innovative approach to tackling debris as a service. At Space19+ Portugal subscribed to ADRIOS – Active Debris Removal and In-Orbit Servicing – committing to contribute to the success of this endeavour. The service will be provided by ClearSpace, a startup created by a team of researchers from the Ecole Polytechnique Fédérale de Lausanne (EPFL). It will see the involvement of Portuguese companies. A presence made possible due to Portugal’s commitment of 7.5 million Euro to the first phase of the service contract.