To boldly go where no germs will follow: The role of the COSPAR Panel on Planetary Protection

planetary protection, space exploration
© Ales Utouka

The COSPAR Panel on Planetary Protection is working around the clock to ensure that space exploration is safe and sustainable, preventing both forward and backward contamination during missions

As our ventures into the “final frontier” accelerate—this year alone saw three separate missions arriving at Mars—and we land on nearby planets, the challenge is to make sure that we do not bring potentially dangerous material home to Earth (backward contamination) or indeed carry anything from Earth that may jeopardise the scientific exploration of these worlds (forward contamination). Planetary protection against biological contamination is an international concern receiving renewed attention due to new findings and the emergence of commercial actors.

But how can we ensure that space exploration is both safe and sustainable?

Nations with their own space agencies and space exploration missions are responsible for their space activities under the United Nations Outer Space Treaty of 1967, including by governmental and non-governmental actors. The COSPAR Planetary Protection Policy, while not legally binding under international law, is the only internationally agreed planetary protection reference for spacefaring nations in compliance with Article IX of the Outer Space Treaty of 1967.


The Committee on Space Research (COSPAR) is part of the International Science Council, a non-governmental organisation that brings together scientific unions and research councils from around the world. COSPAR was formed at the dawn of the space age to promote international scientific research in space and provide a neutral forum for the discussion of challenges to scientific exploration, unencumbered by geopolitical considerations. One of its core activities is to develop, maintain and promote a Policy on Planetary Protection in the form of implementation guidelines.

The COSPAR Panel on Planetary Protection

The dedicated COSPAR Panel on Planetary Protection (PPP) regularly reviews the latest scientific research to adapt its planetary protection policy. The most recent updates to the Policy were approved in June 2020, and a major one concerning the Moon is coming up. The COSPAR PPP currently has 21 members representing space agencies and experts from the scientific community.

The Panel endeavours, through workshops, meetings and at COSPAR Assemblies, to provide an international forum for the exchange of information on best practices for adhering to the COSPAR planetary protection requirements. Through COSPAR, the Panel informs and interacts with the international community, including holding an active dialogue with the private sector.

COSPAR’s PPP is concerned with possible biological interchange during exploration of the solar system and aims to ensure that the scientific research involved is not compromised through terrestrial  contamination, to safeguard investment in space science and exploration, while also protecting the Earth’s environment from any potential hazards of returning samples by a mission to a solar system object.

Enabling space exploration

The PPP’s primary objective is to develop and promulgate a clearly delineated policy and associated requirements to protect against the harmful effects of such contamination. This policy must be based on the most current, peer-reviewed scientific knowledge, and is intended to enable exploration, not prohibit it. Planetary protection requirements are not cast in stone and evolve over time as new information becomes available (updates to the Policy are published in COSPAR’s journal Space Research Today). The Panel does not specify how to adhere to the COSPAR Planetary Protection Policy—this is for the engineering judgment of the organisation responsible for the planetary mission.

Categorisation for space missions

Space research involves missions driven by private organisations and by national or international space agencies who send a variety of craft into space to enhance our understanding of its origin and evolution. Some will orbit a planetary body and others, such as the lunar, Martian or icy moon missions, will land on their surfaces. They will then analyse the surface or internal environment, searching for traces of life. COSPAR PPP’s main goal is to prevent such missions from carrying terrestrial microorganisms to the target destination (forward contamination) as well as preventing any contamination from extra-terrestrial material returned to Earth for laboratory analysis (backward contamination). Using a categorisation approach, COSPAR PPP determines whether each mission is low risk or high risk. The five Categories of Planetary Protection outline the recommended measures that an agency should apply to each mission.

Low-risk space missions

Missions deemed to be of lowest risk (Category I) are those to a target not of direct interest for research into evolution or the origin of life. These can include flyby, orbiter and lander missions but to destinations where no specific protections are required, e.g., currently the Moon, Venus, gas giants and some satellites. A special categorisation was recently issued by the PPP for an unrestricted Earth return from Mars’ moon Phobos by the JAXA MMX mission, as studies showed that samples would not pose a threat for our biosphere after careful handling.

High-risk missions

Higher categories include bodies that are of interest for scientific research about the origin of life. Category III, IV and V missions include those targeting bodies (such as Mars, Jupiter’s moon Europa and Saturn’s moon Enceladus) which could compromise future missions by causing contamination from Earth microorganisms, and also those that are Earth-return and which may carry extra-terrestrial materials.

For such missions, the highest degree of control is applied to ensure that a minimum level of “bioburden” (the number of bacteria living on an unsterilised surface) is brought along. Planetary protection technologies are constantly being improved for cleaning and sterilising spacecraft and handling soil, rock and atmospheric samples.

Preventing planetary contamination without curbing exploration

The COSPAR Policy on Planetary Protection is vital for safeguarding our exploration of outer space and scientific research without contamination of planetary bodies or risk for the Earth’s biosphere. The COSPAR PPP works through a variety of hypothetical scenarios to ensure future scientific research is not compromised. These include whether, after advanced exploration and research, any signs of life found by a rover on Mars is Martian rather than terrestrial contamination, and whether potential extra-terrestrial life brought to Earth is sufficiently quarantined before scientific analyses. They aim not to stifle space exploration and research, but rather to ensure it continues unimpeded through adequate protections and information imparted to scientists and stakeholders around the world.

Please note: This is a commercial profile

© 2019. This work is licensed under CC-BY-NC-ND.

More About Stakeholder

Contributor Profile

Panel on Planetary Protection of the Committee on Space Research (COSPAR)
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Contributor Profile

Panel on Planetary Protection of the Committee on Space Research (COSPAR)
Website: Visit Website

Contributor Profile

Panel on Planetary Protection of the Committee on Space Research (COSPAR)
Website: Visit Website


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