Now that plans are afoot to return astronauts to the Moon and send others to Mars, it is time to revise our collective understanding of the space environment and devise an international policy for sustainable exploration and development. Why? Because history shows that without ‘environmental protection policies,’ we tend to explore and exploit an environment with insufficient regard to the long-term impact.

We are all familiar with the impact this ‘lack of care’ has had on our terrestrial environment, as well as the fact that it has taken decades of international conferences to address the issues and promote the concept of sustainable development.

However, although space is now firmly part of our business environment, it is generally not recogniz ed as an environment worth protecting. This is partly because space is such a challenging environment to explore and utiliz e, but it is also due to ignorance. Even seasoned space professionals tend to view the space environment (including the planetary bodies) in the same way the early explorers viewed the American West: wild, untamed and ripe for exploitation. Moreover, with missions planned largely on a one-off basis, the concept of sustainable development has yet to enter the space vernacular.

This is incredibly short-sighted. Even discounting the opinion that the space environment has a value in its own right — because it is strange, unique and beautiful –anyone running a business that depends on that environment should recogni ze its “asset value.” The asset might be a geostationary orbital position for communications, a sun-synchronous orbit for Earth imaging or, perhaps in future, a lunar orbit for tourism.

Thankfully, the value of Earth orbits and the need to keep them free from debris has now been recogniz ed, and policies and mitigation measures have been agreed to at international level. But what about spacecraft debris in orbit around the Moon or Mars? With governments intent on sending astronauts to these destinations and private companies planning tourist flights around the Moon, it is time to think about protecting the orbits round the planetary bodies.

As for surface environments, they too have an undeniable value depending on the user. While scientists characteri ze chemical compositions or search for traces of life, prospective developers might wish to strip-mine a surface or build a leisure resort. But since the Moon has no self-repair capability, and any change to its barren surface is irreversible, the lunar environment is far more fragile than the Earth’s.

It is common knowledge that, with no wind or rain to erode them, the Apollo astronauts’ footprints could remain for millennia as they are today, but consider the fragility of the tenuous lunar atmosphere. Though it may comprise only a few tons of carbon dioxide, carbon monoxide, methane and other trace gases, to a planetary scientist all atmospheres are unique and worthy of study. Considering the estimate that a single Apollo mission temporarily doubled the total atmospheric mass of the Moon, it takes little imagination to predict the environmental impact of sustained lunar exploration and development. This is not an argument for somehow banning future exploration, simply a call for recognition that our actions have an effect — sometimes an irreversible impact — on the space environment.

And what about Mars? Are planned missions in danger of damaging the environment they seek to explore, contaminating the surface before potential life-forms have been discovered? It was reali zed as early as 1964 that planetary spacecraft should be sterili zed as part of a “planetary protection” regime, but requirements were relaxed in the late 1970s, effectively eliminating the need for any decontamination of spacecraft destined for the outer planets. Although the situation has improved since then, estimates suggest that the Mars Exploration Rovers each carried some 200,000 bacterial spores to the planet’s surface.

As life-detecting payloads become more sensitive, this so-called bioload becomes more critical, since the last thing scientists want to detect on Mars is something deposited in the Jet Propulsion Laboratory cleanroom. Indeed, false positives planted by poor sterili zation techniques could damage the course of scientific exploration, as indicated by the streptococcus mitis bacteria found in a camera from the Surveyor 3 probe returned to Earth in 1969 by the Apollo 12 crew.

It was difficult to argue in the 1960s that crashing spacecraft onto the lunar surface was detrimental to the local environment, especially one that exhibits a history of meteor impacts. But surely some 80 impacts and 100 tons of spacecraft debris deposited on the Moon in the name of science is enough. The impact that excited the most criticism was that of Lunar Prospector, which was targeted at the Moon’s south pole in 1999, in an attempt to create a plume of water molecules from suspected polar ice deposits. Not only was it not sterili zed or actively decontaminated, it carried within it the cremated remains of lunar geologist Eugene Shoemaker — hardly consistent, one might argue, with the search for potable water.

If research bases, astronomical observatories and lunar hotels are built, it seems likely that this ‘sledgehammer’ policy of lunar exploration will be shelved for safety reasons, but the coloni zation of the Moon will bring its own problems. If tourism opens the space frontier for a new class of traveler, what is to stop those adventure tourists from destroying the environment that attracted them in the first place? The Apollo 11 landing site will be a key attraction, but how long will it be before trophy hunters remove the science equipment for sale to private collectors? How long before the first lunar tourists place their own, clumsy boots in the historic footprints of Neil Armstrong and Buzz Aldrin, erasing them forever?

We are used to protecting and preserving our culture here on Earth, but what about the important cultural heritage represented by our exploration of the space environment. At the very least, the landing sites should be preserved as historic international monuments or sites of special scientific interest.

Whether you subscribe to the asset-value argument, the protection of a unique environment scenario or the cultural preservation stance, it should be clear that time is not on our side. Aspects of the space environment exhibit a fragility that makes damage irreversible. If we are serious about the exploration and development of the space environment, the space community needs to address the sustainability issue now. Attempting to answer the ‘what if’ questions after the second generation of lunar explorers make footprints on the surface will be too late.

Mark Williamson is a U.K.-based space writer/consultant and the author of Space: The Fragile Frontier and The Cambridge Dictionary of Space Technology.