On a clear December morning, a team of scientists followed a lead into the remote Australian desert to collect precious material from outer space. The shoebox-sized capsule, part of Japan's Hayabusa2 mission, contained rocks and dust from Ryugu, a carbon-rich asteroid that likely hosts the building blocks of life. To keep the sample pristine, the capsule was brought to the Japan Aerospace Exploration Agency (JAXA) Extraterrestrial Sample Curation Center, a laboratory near Tokyo designed to prevent cosmic material from being contaminated with terrestrial organisms.
For years, planetary protection concerns have focused on preventing Earth from dirtying the solar system, sterilizing spacecraft and keeping astronauts under strict quarantine protocols. But as space agencies around the world prepare to bring back more samples from destinations like asteroids, the moon, and Mars, scientists are once again considering the opposite perspective: What if we bring alien germs to Earth?
At one point, scientists treated all supernatural samples as potential biohazards. NASA once quarantined Apollo astronauts when they returned from walks on the lunar surface. When the agency studied lunar samples and found they contained no life, they removed many of these security protocols.
But as multiple sample return missions move apace, extra caution is once again warranted. In recent years, scientists have found abundant microorganisms that can survive in increasingly inhospitable places. Tiny tardigrades, also known as water bears, can even survive in the vacuum of space.
"Here on Earth, for example in the gold mines of South Africa, when you drill into rock, sometimes you come across a reservoir of water that has been there for hundreds of thousands of years and contains microbes," says J. Andy Spry., Senior Scientist at the Search Institute for Extraterrestrial Intelligence. "If you provide them with heat, light and heat, they will grow."
In addition to the fresh samples from Ryugu, a NASA spacecraft will bring home pieces of the carbon-bearing asteroid Bennu in 2023. And in February, a NASA rover called Perseverance is expected to land in a region of Mars that could have preserved traces of life, if it ever existed on the red planet. Crucially, the rover will collect and store Martian rock samples that will eventually be sent back to Earth, perhaps bringing home fellow aliens.
“Our knowledge of Mars is that there absolutely could have been life in the past,” says Spry. "There may still be viable life in reservoirs below the planet's surface."
So space agencies around the world, including NASA, JAXA, and the European Space Agency (ESA), are working together to create new, highly secure laboratories designed to protect Earth from any microbes or organic debris left behind by missions. future may bring home. These laboratories will combine current cleanroom technology with high-security biosafety equipment and protocols used by infectious disease laboratories to safely manage pests such as Ebola and SARS-CoV-2.
"The Mars sample return campaign, which is currently underway, has gone to elaborate lengths to encapsulate the samples that Perseverance will collect," says Scott Hubbard, former deputy director for research at NASA Ames Research Center in California's Silicon Valley, where he oversaw astrobiology programs and missions to Mars.
"When that boat lands in 2031 in the Utah desert, it will be taken to a facility with the highest level of biosafety protection."
When the astronauts went into quarantine
NASA, at least, can look to its past for inspiration for these lab designs. When the Apollo astronauts returned from the surface of the moon, their space suits were covered in moon dust. NASA had not yet studied the composition of pristine lunar rocks, so the agency treated all particles on the lunar surface as potentially dangerous to human life.
NASA quarantined the crews of the Apollo 11, 12 and 14 missions in a modified AirStream trailer on the deck of the aircraft carrier that lifted them out of the ocean in their floating capsule. Once on the ground, a helicopter took them to the Lunar Receiving Laboratory at the Lyndon B. Johnson Space Center in Houston, Texas, the precursor to facilities currently under development around the world.
At the Lunar Receiving Laboratory, crews would spend their first 21 days on Earth in the Crew Reception Area, which sealed them inside a biological barrier to prevent "return contamination," which NASA called the possible spread of lunar microorganisms on Earth. The facility also included the Sample Operations Area, which housed vacuum glove boxes and equipment for biological analysis.
The most important part of the Lunar Receiving Lab's biosecurity scheme was its complex vacuum system, which had to block outside contaminants from entering, as well as prevent potential Lunar microbes from circulating or leaving. The elaborate design of pumps and valves, altogether the size of a double-decker bus, occupied its own warehouse and included a backup vacuum system in case the first one failed.
This lab would later become part of NASA's Astromaterials Research and Exploration Science Directorate, also at the Johnson Space Center, which maintains samples of stardust, meteorites, and comet particles in addition to rocks Apollo moles. All of this material is housed in positive pressure clean rooms similar to those used in the semiconductor industry. Positive pressure means that air is always blown out of the room, so the interior remains sterile.
However, these systems are less complicated than those needed to receive samples from Mars and other new specimens, because they don't need to contain any potential microbes.
The labs being built "will essentially use containment within containment," says Michael Calaway, a NASA contractor for the Jacobs Engineering Group and sample-curation project leader for ARES. And to do that, the designers seek lessons from the highest biosafety labs on Earth.
Building the World's Safest Laboratory
In Boston, the National Emerging Infectious Diseases Laboratories (NEIDL) has closed. A pathogen spill has put the facility on red alert. Researchers and staff follow their quarantine orders when first responders arrive.
Everyone is calm, of course, not just because they know what they're doing, but because the spill isn't real. It's a drill, part of the protocol that keeps NEIDL safe and helps maintain its distinction as one of the safest labs in the world.
It's Ronald Corely's job to imagine the worst case scenarios. As the director of NEIDL, affectionately pronounced "needle," Corely coordinates teams that establish and execute layers of security protocols. They have a plan for power outages, spills, cyberattacks, basically any risk most outsiders would deem unthinkable, to their tiered biosafety labs.
In their quest to create Earth-safe facilities, NASA designers have visited NEIDL to study both its processes and the physical systems that keep the lab clean and safe. While NASA's current clean rooms rely on positive pressure, pathogen containment requires the opposite: negative pressure rooms that keep air circulating within the room.
Although NASA's original Lunar Receiving Laboratory combined these systems, technology and biosafety protocols have come a long way since the 1960s. The Centers for Disease Control and Prevention (CDC) did not codify its biosafety requirement levels until 1984, although US agencies began discussing such practices in 1955.
At level one, researchers could be handling a substance such as E. coli , a common type of bacteria found in a variety of places, from contaminated food to the human intestine. Scientists at these labs wear basic personal protective equipment and implement standard cleaning practices, such as daily decontamination of all equipment and thorough handwashing, to make sure harmful microbes stay where they're supposed to be. Aside from some biohazard signs and the specialized ventilation systems that keep lab air inside the lab, these spaces would look familiar to any biology student.
Level two laboratories deal with slightly more dangerous agents, such as Staphylococcus aureus, an opportunistic pathogen that is also a common part of the body's microbiome. Safety and decontamination practices are more rigorous at this level, but they are far from extreme.
“At biosecurity level three, you're wearing full Tyvek suits,” says Corely. "You're wearing a respirator." Researchers enter the space through vacuum-sealed double doors. Inside, the lab resembles that of a college biology course, with those hooded lab stations with glass shields and overhead ventilation. But “at level three, you have to be able to clean and decontaminate everything,” he says. SARS-CoV-2 remains at level three.
The highest biosecurity level, four, is reserved for deadlier pestilences, like the Ebola virus. Here, the scientists wear what Corely calls a fully encapsulating suit, attached to hoses that pump air in from outside the room. Scientists and dangerous microbes are completely separated by layers of gloves, goggles, and respirators. They become nesting dolls for safety precautions.
Future alien sample curation centers will do the same thing as a level four lab. Scientists studying Martian rocks will enter the labs in full protective gear. They'll walk through vacuum-sealed doors into workspaces with strict designs specialized to keep microbes in.
Plans to complete such facilities are already underway, though, as with other space exploration efforts, they will take years to come to fruition and design adjustments may still be made.
The Mars Quarantine Facility, which will first house dust and rocks from the Red Planet in Houston, Texas, could house astronauts returning from Mars until the agency deems it safe for them to re-enter society. Areas will be compartmentalized and HEPA filtered. ESA, which is working with NASA to share and curate future Martian samples, is developing its own similar facility in Vienna, Austria. Future NASA facilities may even be mobile and modular, mimicking its old lunar receiving lab, but with streamlined, lightweight designs.
None of these preparations should be cause for concern. The agencies are doing this work out of an abundance of caution, not out of fear that space germs might take over the planet.
"Andromeda Strain is a good thriller," says Hubbard. “But there is very little scientific basis for all of this. The odds of anything coming out of that movie are extremely small."
