The principle of “Harmful Contamination” applied to human missions to Mars

Melissa de Zwart, Stacey Henderson, Rachel Neef

Research output: Contribution to journalArticlepeer-review


This article considers the meaning and application of "harmful contamination" under Article IX of the Outer Space Treaty in the context of the renewed interest in human exploration of the Moon and Mars. It identifies the historical context of the development of the Committee on Space Research Policy on Planetary Protection and considers the legal regime that is applicable to harmful contamination. In particular, it applies the treaty interpretation method set out in the Vienna Convention on the Law of Treaties to understand how Article IX may be interpreted and applied in an era of commercial human habitation in space. This study reflects a unique blend of legal and scientific principles which have evolved side by side since the dawn of space exploration. The article concludes that the principle of harmful contamination remains an appropriate and relevant principle to facilitate the long-term habitation of Mars in a manner that reflects the principle of both forward and backward contamination.
Original languageEnglish
Pages (from-to)276-318
Number of pages43
JournalJournal of Space Law
Issue number2
Publication statusPublished - 2021


  • Space exploration
  • Outer Space Treaty
  • Commercial human habitation in space
  • Contamination


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