When an away team returns to Jean-Luc Picard's Enterprise, the biofilters within the transporter system eliminate most potential alien "hitchhikers."

If only it were that easy today.

When the crew of Jonathan Archer's Enterprise comes back from a planet where they may have been exposed to alien lifeforms, it's a little messier. With Dr. Phlox looking on, the crewmembers spend hours in the isolation chamber smearing decontamination gel over their bodies. This is much closer to what we will soon have to face as we walk on other worlds.

NASA and other space agencies have been sending spacecraft across the solar system for 40 years. For the most part, care has been given to make sure that these objects don't infect other worlds with Terran lifeforms. Indeed, the Galileo spacecraft will be purposefully crashed into Jupiter to avoid any possible contamination of its moon Europa — a world thought to have an ice-covered ocean that may harbor life.

NASA, in coordination with other space agencies around the world, has been planning future missions in accordance with a series of recommendations made by COSPAR (Committee on Space Research, an international organization) regarding the risk of terrestrial contamination of other worlds — and the extraterrestrial contamination of our own. This field is referred to as "Planetary Protection." (Photo courtesy NASA JSC)

To illustrate the importance of these activities, NASA's Planetary Protection Officer, John Rummel, often hands out bumper stickers at meetings that say "Planetary protection: All of the planets – all of the time." Rummel and other NASA scientists recently made a number of presentations at the Spring meeting of the American Geophysical Union in Washington DC.

Participating in a press conference with Rummel was Michael Meyer, Astrobiology Discipline Scientist at NASA Headquarters. I asked Meyer what affect an unequivocal discovery of life on present-day Mars would have upon NASA's Mars exploration plans. Meyer replied, "If we found life there, I think we'd have to pause for a while and think about how we should study this life." I then asked Meyer specifically if a "Prime Directive" of sorts would need to be put in place to guide the exploration of Mars. He agreed that something like that should be considered, and that there are ethical considerations that will come into play.

Mars is one of the places in our solar system where we think life may once have existed. With a recent flurry of announcements, it is becoming increasingly clear that there may be conditions on present-day Mars which could support life "as we know it."

As predicted in a story which first broke on SpaceRef.com last week, NASA has announced that the Mars Odyssey spacecraft has detected significant amounts of water ice within centimeters of the surface of Mars. The full extent of the water ice is not known, however one thing is clear: it is all over the planet and there is a lot of it. This announcement followed upon much more preliminary results released earlier this year (see related Science Brief). Given that water is one of the prime requirements for life, these discoveries continue to raise the hope among astrobiologists that we may soon discover that another world bears life.

Before we send humans to Mars we need to learn much more about the planet. We not only need to make certain that human activity does not contaminate the planet (making it harder to see what is uniquely Martian), we also need to make sure that we understand the risk to humans from Mars — both on the planet and coming back home.

While most astrobiologists and space medical experts agree that the risk to humans, and Earth life, from putative Martian life is low, it is certainly not zero. As such, all samples returned to Earth will be handled as if they were the most hazardous biological agents known on Earth — something we're actually rather good at.

The exact date for a sample return from Mars is still in flux. The earliest date would be near the end of this decade. The missions currently underway and in the planning process will all help to characterize the planet so as to allow the best sample return sites to be chosen.

The rationale for bringing samples to Earth is simple: the instrumentation required to fully examine these samples and ascertain their biological inventory exists only on Earth. Trying to cram all of the gear into a spacecraft that we could send to Mars would be prohibitively expensive. Even studying these samples on the International Space Station would be similarly problematic — with the added factor that microgravity's effects of living systems are still a bit of a mystery and would complicate the study of any possible Martian lifeforms. The best place to study these samples is here on Earth. (Photo courtesy NASA JSC)

These samples will be handled in biocontainment facilities not unlike those used to handle Earth's most lethal lifeforms: Ebola. Samples will only be released for study outside this facility once they have been deemed perfectly safe. If any lifeforms are found, samples will only be released once the samples have been thoroughly sterilized.

As suggested by NASA's Michael Meyer, there is an ethical component to decisions we make as we move outward from our planet to explore other worlds. As such, NASA's Planetary Protection Advisory Committee has a bioethicist on it. The first cases of interaction between life from two worlds could happen as we explore Mars, or perhaps Europa. This will likely be limited to simple lifeforms. At some point we'll have to deal with more complex issues.

In the Enterprise episode "Dear Doctor," Dr. Phlox and Captain Archer butt heads over whether to interfere with the evolutionary friction between two intelligent races on the planet Valakis. As Archer makes a difficult decision, he says "we need some sort of directive" to guide Starfleet crews as they encounter situations such as this.

Some thought has already gone into one aspect of our own interaction with an alien society and is embodied in a set of procedures adopted by SETI researchers in case a signal is detected. These procedures are designed more to guide how we inform our own species of the discovery.

As for the procedures whereby we do, or do not, interfere with alien life on other worlds, some regulations are already in place. Meanwhile the first draft of the regulations that will serve as the foundation for the Prime Directive are already being reviewed by committees on Earth today.

What kind of language should a first-draft "prime directive" have? Discuss it at the Science & Technology message board!