Future astronauts may return to Earth with fragments from the depths of deep space to unlock secrets of our solar system—samples of asteroids, Mars or its moons, or other destinations beyond. What precautions should be taken to maintain the scientific integrity of celestial samples and to ensure that we don’t inadvertently contaminate distant bodies with Earth-based organisms?
It’s a daunting two-part question that NASA has addressed in a report titled, “Planetary Protection Knowledge Gaps for Human Extraterrestrial Missions.” The report summarizes the proceedings of a three-day workshop in 2015 that convened global experts who investigated the top considerations for preventing biological cross-contamination of Earth and other worlds during human missions to different celestial bodies.
Planetary protection is required by the Outer Space Treaty and has far-reaching implications on human spacecraft design, operational procedures and overall mission structure.
Read the full workshop report on the NASA Technical Reports Server: https://hdl.handle.net/2060/20160012793
Together with industry and international partners, NASA is developing the key technologies and capabilities to take humans farther from Earth than ever before, to advance science and technology, and to enhance our knowledge of the universe around us. For example, astronauts on the Asteroid Redirect Mission will return from cislunar space with asteroid samples that could answer questions about the formation of our solar system and our planet. Crews returning from Mars are expected to deliver samples that could tell us if Mars ever harbored microbial life, and could possibly teach us about our own planet’s past, present and future.
These extraterrestrial samples may be able to answer some of humanity’s fundamental questions, but only if they remain free of contaminants that humans or human spacecraft could potentially introduce, and don’t pose a threat on their own.
“We already have samples of Mars, and some comets and asteroids, here on Earth,” says Bette Siegel, program executive and planetary protection expert in NASA’s Human Exploration and Operations Mission Directorate. “Some comet and asteroid samples were collected by spacecraft and returned directly to Earth, but many others that have spent millions of years in space regularly fall to Earth. These are quickly contaminated by Earth organisms once they hit the ground.” Siegel noted that carefully selected samples that humans collect on Mars and return directly to Earth in special containment will be far younger and more pristine than any Mars materials analyzed in laboratories thus far.
Planetary protection experts focus on two main areas of study. “Forward contamination” refers to the transport of Earth-based microbes to other celestial bodies, a disrupting concept for scientists who are searching for signs of life in an extraterrestrial sample. “Backward contamination” refers to the possibility that extraterrestrial microbial life returned by a space mission could propagate on Earth.
The Planetary Protection Workshop report identified 25 gaps in knowledge about human-rated hardware systems, technologies and procedures for collecting samples and establishing decontamination procedures and acceptable contamination generation rates. Critical to closing these gaps in knowledge is cooperation between the science, planetary protection and engineering communities contributing to future human missions.
The Committee on Space Research (COSPAR), an organization which is part of the International Council on Science, and which comprises national scientific unions, hosted the follow-on workshop Oct. 25-27, 2016, in Houston. After many years of successful planetary protection implementation for robotic missions, COSPAR established the first post-Apollo list of qualitative principles and guidelines in 2008 for forward and backward contamination on human missions. These guidelines, together with NASA’s own policies on planetary protection requirements, served as guiding bases for identifying the 25 knowledge gaps.
According to NASA Planetary Protection Officer Catharine Conley, the collaborative goal of planetary protection experts is to inform spacecraft design and mission protocols compliant with the qualitative and eventual quantitative requirements. NASA plans to pursue development of a NASA Procedural Requirements (NPR) document that will ensure future spacecraft are designed to those requirements.
“Effective requirements, which NASA describes in NPRs, are essential to ensuring that planetary protection protocols are included in mission design from the start,” says Conley. “It’s critical to establish the quantitative requirements now, that engineers need to follow while designing human-rated systems for travel beyond Earth orbit.”
Outcomes of the recent COSPAR meeting could potentially have significant influence on global contributors to human spaceflight. Gerhard Kminek, the European Space Agency’s Planetary Protection Officer and the Chair of COSPAR’s Panel on Planetary Protection acknowledged the strong role that NASA will play in the global collaboration, “NASA and COSPAR hope that by closing the knowledge gaps outlined in the report of the previous workshop, we will be able to establish clear quantitative guidelines on planetary protection that will lead to eventual international consensus standards for human missions beyond Earth orbit and particularly in support of a collaborative journey to Mars.”