Prime Directive: How NASA's Planetary Protection Officer Keeps Our Germs from Contaminating Other Planets (& Vice Versa)

How NASA's Planetary Protection Officer Keeps Our Germs from Contaminating Other Planets (& Vice Versa)

On July 20, 1969, humans set foot on the moon for the first time. But some say our microbes beat us there. With the Space Age came new questions about microscopic invaders from outer space and concern about where we are leaving our microbial footprints. The questions are even more relevant today.

In the US, the place to find answers is the Office of Planetary Protection. With the goal to protect "all of the planets, all of the time," the office has a straightforward mandate to protect life on Earth, and prevent contamination of other celestial neighbors from our germs. With the unbeatable job title of "Planetary Protection Officer," Catherine A. Conley is our national go-to authority on where Earth and alien microbes do, and don't, belong.

For Conley, microbes — in all their forms — are a lifelong interest. Her father worked as a consultant to NASA, and when young, antibiotics saved her from a common, but life-threatening, infection. At the same time, she also understood bacteria were part of her favorite yogurt and the cause of recurring infections in her pet cat. Given the job of cleaning out abscesses on her cat, Conley remembers thinking that yogurt and pus have a similar consistency — and that yogurt was a whole lot more pleasant. Years later, suffering a chronic bacterial infection reminds her of her role to protect outer space against the invasive nature of microbes, since, as she says, "planets don't have immune systems at all."

Conley became better acquainted with the space program when the space shuttle Columbia disintegrated in the atmosphere on re-entry, in February 2003. As a research biologist with the Ames Research Center, Conley had an experiment returning on Columbia that contained tiny worms called nematodes.

Weeks after the disaster, her recovery crews discovered her experiment in the shuttle wreckage. When they opened the canisters in late April, the worms were still alive in their petri dishes, having survived the catastrophic disintegration of the spacecraft in which they flew. Conley joined NASA in 2006. And for anyone who wonders? Yes, reminiscent of the movie, "Men in Black," Conley was given a pair of Ray-ban sunglasses her first day on the job.

And if you wish to be a planetary protection officer, too, you're in luck, as NASA recently posted job ad for the three-year term job, as they relocate the position to the Office of Safety and Mission Assurance, an independent unit within NASA. Conley has not yet indicated if she intends to apply for an extension of her now-completed three-year term.

Debris from the main fuselage of the Columbia space shuttle. Image via NASA

"Planetary protection is a very simple concept, which is derived from the full history of human experience on Earth," Conley told Invisiverse. "We know that introducing organisms into new places can cause problems, so we're trying to avoid doing that in space — at least until we have a better handle on possible unintended consequences."

And it's not just the United States. In January 1967, in recognition of many issues involving the exploration of space, the Outer Space Treaty was developed to offer firm guidelines for international space law. Currently, 105 countries have signed the Treaty.

As private companies race to provide commercial space travel and launch vehicle services, others are hustling to get back to the moon in response to the lure of winning Google's Lunar XPrize — with a total of $30 million in prize money. With a deadline for successful launch and deployment of December 2017, look for action on the Lunar XPrize this year.

As we enter the next Space Age, the Outer Space Treaty, signed decades ago, holds significant relevance. Just some of its rules include:

  • Outer space belongs to everybody. The moon and other celestial bodies, are open to exploration and use by all, collaborative exploration is encouraged. "Celestial bodies" are moons, comets, asteroids, planets, and basically any natural body that exists outside of Earth's atmosphere.
  • Planet grabs are prohibited. No country can appropriate a celestial body as sovereign territory, and all countries are responsible for damage caused by any of their launched objects.
  • Peace is a priority. Exploration is to be conducted with "international peace and security" in mind. All celestial spaces are to be used for "exclusively peaceful purposes."
  • No nukes. The treaty nulls the militarization of celestial bodies by preventing parties from orbiting the Earth, or elsewhere with weapons of mass destruction, like nuclear weapons. This means no Death Stars, or military stations armed with weapons of devastating impact.
  • We come in peace: Astronauts, as "envoys of mankind," are to be rendered all possible assistance on Earth, or elsewhere. Parties to the Treaty agree to share discoveries that could impact the health of astronauts in space.
  • This means private enterprise too: Private or non-governmental entities in the aerospace industry are governed by the Treaty through their sovereign country. This means SpaceX and Blue Origin, private companies aiming at providing key space services, are under the authority of the US government to comply with the Treaty, and to ensure their launch and other vehicles and activities conform to microbial contamination standards. On private parties, Conley said, "The US government is responsible for ensuring that all US entities comply with US treaty obligations — but how this will be accomplished for US commercial missions is still in the works."
  • Prime Directive, sorta: Article IX of the Treaty requires exploration of space to be done in a way that avoids "harmful contamination" of celestial objects and "adverse changes in the environment of Earth."

Researchers classify this unintentional hitchhiking of microbes as either forward or backward contamination. Forward contamination involves the transfer of Earth microbes to another celestial body. We want to avoid contaminating the otherworldy places we explore and investigate. Otherwise, we are only discovering human microorganisms, and what we could have learned about their native bacterial communities is lost.

Backward contamination is the return of foreign microbes to the Earth ecosystem. The potential exists for irreversible environmental impact if an unmanageable pathogen dangerous to human or other life is let loose on our planet.

Some experts support the theory of panspermia, the idea that life on Earth, and perhaps other places in the Universe, results from the distribution of organic, bacterial, and other material traveling in and on asteroids, comets, meteorites, and the tons of cosmic dust that float out of the sky every day. For these scientists, strict planetary protection mechanisms are overrated, because organic material is constantly hitchhiking through the galaxy. And it is true, some of that dull dust on your roof, sidewalk, or car parked outside is star dust.

Despite this, as Conley points out in an interview with Inverse, "it's very difficult to put a microbe back in the box," so we need to keep trying to stop contamination through planetary protection.

While the Outer Space Treaty offers global groundwork for the use of space, it is the Committee on Space Research (COSPAR), an interdisciplinary scientific panel formed in 1958, that created the Planetary Protection Policy.

COSPAR decides how much contamination we can deposit on celestial bodies. The policy doubles down on protection for different types of missions, like flybys and orbiters, landers and rovers — and human space flight.

The astronauts of Apollo 11, Buzz Aldrin, Neil Armstrong, and Michael Collins, step onto the U.S.S. Hornet on their way to quarantine, after the first walk on the moon. Image by NASA/Marshall Space Flight Center

Where Our Microbes Have Been and Where They Are Going

Between 1966 and 1968, NASA launched a series of seven probes to the moon, to gather landing data in anticipation of a manned moonshot later in the decade. Five of the spacecraft successfully touched down, but NASA lost contact with two others. Surveyor 3, launched in April 1967, transmitted more than 6,000 photographs back to Earth in addition to conducting soil tests at the site.

All of the probes remain on the Moon. Surveyor 3 is the only probe that was later visited by Apollo astronauts. Apollo 12, launched in November 1969, landed close to Surveyor 3. During their extravehicular activity (EVA), astronauts Pete Conrad and Alan Bean made two visits to Surveyor 3 to evaluate the probe and retrieve parts — parts exposed to harsh lunar conditions, including severe temperature fluctuations and radiation, for about 2.5 years.

Apollo 12 astronaut Pete Conrad next to Surveyor 3. Image via

After their return to Earth, NASA evaluated the recovered parts, including a camera, at the new $16 million Lunar Receiving Laboratory at the Johnson Space Center in Houston, Texas. The lab is modeled on the ultra-high bio hazard containment facility at Fort Detrick, Maryland, and should have been a spotless room with little ability for techs to contaminate the returned items. They were stunned to find an isolated a small colony of five to 100 Streptococcus mitis, on a piece of foam from the innermost part of the returned camera from Surveyor 3. S. mitis is a bacteria that lives in the human mouth and throat.

The finding that a terrestrial microorganism survived such extreme conditions ignited a controversy that lingers to this day. The incident potentially illustrates both the forward and backward movement of microbes in space. In the years following, two studies suggest the bacteria resulted from germs in the clean room. In other words, that the camera was contaminated after retrieval from the Moon.

Also, Conley notes that in the mid-2000s, NASA digitized Apollo era footage that demonstrates clean room conditions that could have led to contamination of the camera. She said: "We're pretty sure the S. mitis contamination happened after the Surveyor camera was brought back to Earth."

Surveyor 3 camera on display at the Smithsonian Institution. Image by Air and Space Museum/Smithsonian Institution

On the other hand, the original study disclosing the findings of S. mitis carefully evaluates the handling conditions of the camera before it went to the Moon, and after, and leaves doubt about post-Moon contamination. Here are a couple of interesting points:

  • The bacterium was found only on foam in an inaccessible part of the camera. If contaminated by in-gassing, through vapor, breath, or handling of the camera on its return to Earth, the bacterium would have likely been on external parts of the camera, the collar, or other pieces leading into the center of the camera. Though tested thoroughly, researchers didn't find a trail of bacteria indicating the colony came from outside.
  • Upon culturing, the bacteria took longer than expected to grow, almost four days. Study authors suggest the delay resulted from dormant, freeze-dried, or damaged, bacteria. Fresh human microbes from a clean room setting could be expected to grow quickly.
  • Fresh contamination would not likely have resulted in the growth of only a few individuals of one species of bacteria, which was the case with the camera.
  • Like the other Surveyor probes, Surveyor 3 was not sterilized before launch. The study quotes findings from the Hughes Aircraft Company, which tested the camera before launch, noting that "there were opportunities for contaminates to deposit on the camera prior to launch" — potentially when the camera was removed from the spacecraft, repaired, and reassembled before its journey to the moon on Surveyor 3.

Years later, Apollo 12 mission commander Pete Conrad remarked, "I always thought the most significant thing we found on the whole ... Moon was that little bacteria who came back and lived and nobody ever said (anything) ... about it."

Clean room and biohazard protocols have advanced since the 1960's, but one way or the other, the incident remains as a cautionary tale about the ease of microbial contamination. Even if that caution is just... "you never know."

Tougher Than Space

In recent years, laboratory, space shuttle, and International Space Station experiments reveal some microbes and their biofilm communities can not only survive but thrive in space with only minimal protection, casting doubts on claims that microbes cannot survive space travel and conditions on other planets.

Some extremophile bacteria, microbes that thrive in environments previously considered uninhabitable, show resiliency in conditions like those found on Mars including high radiation, temperature swings, minimal moisture, and low pressure.

With the end of the Apollo space program, humans continued exploration through missions flown on the space shuttle, and currently on the International Space Station.

"The main difference in planetary protection objectives since the Apollo program is that we have not sent humans to places where planetary protection applies — humans haven't gone to another planetary object since then," Conley said.

Instead, Earth set its sights on the Red Planet.

Selfie taken by the rover Curiosity on the surface of Mars in September, 2016. Image via NASA

It Came from Planet Earth... Or, How We Put Life on Mars

Although humans have never set foot on Mars, our microbes are already there.

With the success of the Mars rover program, some may have forgotten that the first spacecraft to land on Mars were the twin Viking spacecraft, which each orbited Mars, and landed an instrument pack on the surface to collect and relay information to Earth.

Launched in 1975 and 1976 respectively, both Viking 1 and Viking 2 accomplished their mission. Data returned by the Viking landers did not paint a picture that suggested microbial life on Mars.

Although the Viking landers underwent a baking sterilization before launch, our latest launches, the rovers, did not — based on the assumption that Mars was less hospitable to life than it turned out to be. Sterilizing usually means treating spacecraft and components with high heat, which is expensive and has a tendency to fry electrical components.

After culturing samples taken from the rover Curiosity before it launched, researchers found the US sent about 377 strains of 65 different bacterial species to Mars on Curiosity. Two years into its mission, in 2014, Curiosity measured a spike in methane, a discovery that started conversations about current chemical activity on Mars and may point to conditions that may have once favored microbial life on Mars.

In 2015, the Mars Reconnaissance Orbiter, launched in 2005 and currently orbiting the Red Planet, located long dark patches in the Martian soil that come and go. These recurring slope lineae (RSLs), were first thought to be evidence of soil damp with seasonal water runs, but NASA has since stepped back that theory. If we do find water on Mars, it could mean we'd have to reclassify parts of the planet's surface as "special regions" — which the International Planetary Protection Policy defines as areas of space in which foreign or terrestrial microbes life could grow or proliferate.

Nonetheless, the discovery raised flags about the path of the rover Curiosity. Known to be contaminated with Earth microbes, there are problems with Curiosity moving toward or into an RSL. Asked if NASA is going to be diverting Curiosity away from these spots, Conley said: "This is still in work — the constraints relate to the probability of organisms from the rover being introduced into RSL, which are considered possible Mars Special Regions."

"The idea was that we need to be the most vigilant on the early missions when we don't have any knowledge of Mars, and we can relax when we know," Conley told The New Yorker. "But it turns out maybe we relaxed too much."

To the extent that some of those stowaway bacteria have tough outer coats called endospores, those bacteria could survive, drop off Curiosity into the Martian soil, and remain dormant — or not.

A 2015 experiment called E-MIST lofted bacteria-laden plates attached to a balloon into Earth's stratosphere, to simulate how germs would react to exposure to conditions similar to Mars — radiation, no moisture or nutrients, and very cold. The bacteria aboard was Bacillus pumilus, a microbe commonly found in the soil that is exceptionally tough. Resistant to successive treatments with disinfectant, the bug infiltrated even the most rigorously cleaned labs at NASA's Jet Propulsion Laboratory.

NASA balloon used to carry bacteria to Earth's stratosphere. Image by NASA/David J. Smith

Irradiation by sunlight killed more than 99.9% of B. pumilus on the plates within eight hours. Yet, bacteria on the underside of the equipment, or those shaded during exposure, did not suffer the same fate. On Mars-bound spacecraft or Earthbound medical devices, it is the nooks and crannies, seams, and creases where bacteria and other pathogens are most likely to find safe harbor.

Interestingly, the bacterial survivors, when compared with relatives on the ground, already showed genetic changes in areas related to environmental adaptation. Harsh conditions in the upper atmosphere, and perhaps on the trip to Mars, could result in bacterial mutations that produce microbes already adapted to extreme conditions by the time the rover lands there. Knowledge of the disinfecting power of sunlight in thin air is important but does not resolve contamination issues.

With the Earth and Mars set to take favorable orbital positions in July and August of 2020, the US has ambitious plans to make use of that launch window with the Mars 2020 rover mission. In addition to other tasks to explore the habitability of Mars, Mars 2020 may be the first rover to gather and cache Martian soil samples for eventual return to Earth.

Artist's rendering of landing of Mars 2020 rover on the Red planet. Image via NASA

A Mars Sample Return (MSR) mission is controversial. Scientists concerned about contamination of Earth's ecosystem and those interested in examining Martian samples first-hand do not currently agree on how NASA could do that safely, or effectively.

Planning for an MSR mission has been ongoing since the 1970's, Conley said. With discussions ongoing, basic considerations include handling samples with the assumption they may contain life, and the need to balance the aims of science with the need for planetary protection.

A group of over 100 scientists, engineers, policy makers and others met in 2015 to list knowledge gaps that currently exist in plans for exploration and human travel to Mars. The report, released in late 2016, lays out a framework for mission plans and processes to maintain containment, and avoid forward or backward contamination.

With any luck, we'll be seeing the results of their hard work — and learn more about the life and conditions on Mars — in 2020.

Alien Life Could Be Microbial

With a universe full of coalescing and disintegrating organic and inert materials, the odds for combinations that create chemical life are good.

Despite Hollywood's affection for frightening or lovable extraterrestrials, the likelihood is that any new life forms we meet are going to be microbial. On our spacecraft, satellites, and astronauts, we have already sent our first microbial emissaries into space.

The point of planetary protection is to plan and prevent accidental release or acquisition of harmful pathogens on Earth, or other planets.

"It's rather like brushing one's teeth, or not using someone else's dirty spoon, or not drinking out of a communal milk carton," Conley said. "A sensible precaution to reduce the chance that introduced organisms could cause problems."

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Cover image via NASA

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