Catharine Conley, NASA Planetary Protection Officer


Catharine Conley spends much of her time considering and preparing for scenarios that could be drawn straight from the pages of science fiction novels. A biologist by training, Conley is NASA’s top official responsible for ensuring that Earthly pathogens do not hitch rides on NASA spacecraft to contaminate distant solar system destinations, and that material samples returned to Earth from such missions pose no threat to human life.

Much of Conley’s work is focused on keeping NASA probes and equipment sterile before launch. But President Barack Obama’s new direction for the U.S. civil space program presents technical and regulatory challenges to planetary protection as the agency pursues more missions with international partners while fostering private sector development of spacecraft capable of carrying astronauts to low Earth orbit, and perhaps even beyond.

Since assuming her duties in 2006, Conley has spent roughly half of her time on the road. Between monthly visits with her European Space Agency (ESA) counterpart to discuss joint missions to Mars and other deep-space destinations, she keeps a watchful eye on NASA craft nearing launch, including the Mars Science Laboratory rover and a Jupiter probe dubbed Juno.

She spoke recently with Space News staff writer Amy Klamper.


How did you get into the field of planetary protection?

I had an experiment on the Space Shuttle Columbia, the last flight, and the animals that I had on that flight survived the crash. That got me a call from the NASA planetary protection officer at the time saying, “What’s this about contaminating the Earth with animals?” So I am actually uniquely qualified to be a planetary protection officer because I have actually contaminated the Earth with animals.

These were small nematode worms — C. elegans — which were the first animals that had their genomes sequenced. We were using them to try to understand gene expression in space relating to muscle atrophy. It happens that they get centrifuged up to several-thousand-times-G in the lab all the time as part of our experiments, and so the impact when they were ejected from the shuttle in their little cans of hardware was not significantly greater than what they’re used to.


What does the NASA planetary protection officer do?

The NASA planetary protection officer is responsible for ensuring that the United States complies with the Outer Space Treaty. Article 9 of the Outer Space Treaty states that when exploring outer space, nations party to the treaty will do so in such a way that they will avoid harmful contamination of other locations and will avoid adverse effects from the Earth that result from bringing material back to Earth. We don’t want to make the mistake of going somewhere like Mars or Europa or even a comet looking for life or the signs of life and then accidentally identifying something that somebody brought with them from Earth. And then obviously we don’t want to cause “The Andromeda Strain” if we bring things back from elsewhere to Earth. “The War of the Worlds” is not something we want to emulate in real life.


Is the Moon treated differently than other solar system objects in terms of planetary protection?

If you’re going to the Moon, we have a policy that the Moon and the Earth should be treated as one system. … The Earth and the Moon have been throwing rocks at each other for 4 billion years, so we’ve pretty much contaminated each other already.


Has the discovery of water-ice on the Moon changed anything?

The Moon has recently been upgraded as being of higher concern, specifically because of this discovery of ice and the potential for volatile materials to be deposited in the cold traps. Because if those cold traps have really been cold for 4 billion years on the poles, that means they’ve got all the volatile materials that have been floating out in the solar system condensed onto those cold locations over 4 billion years. So there is a lot we might be able to learn about how Earth materials have the potential to condense there. And there are questions about wanting to understand what is there in terms of contamination from rocket fuel. The Apollo rockets burned a huge amount of fuel and a lot that would have condensed compounds onto the Moon. The exhaust fumes from the Apollo program increased the density of the exosphere significantly.


What does decontaminating a spacecraft entail?

The best way that we know to decontaminate things is to bake them. It’s what NASA did with the Viking mission to Mars. A vacuum oven is a really good way to kill things. Viking spacecraft were baked at 111 degrees Celsius. It’s a little bit above boiling, sitting in the oven for several days. And then we have a number of surface sterilization capabilities that we’re looking at that have not formally been approved, so each application is done on a case-by-case basis, but we’re working together with ESA toward getting a consensus set of requirements for hydrogen peroxide vapor. That actually is very good at killing organisms on surfaces. It reacts with their cell walls, so if you use enough vapor hydrogen peroxide, everything turns to gas and it disappears. This is a method that’s commonly used in other industries — FBI forensics labs, surgical instruments — and we’re working to get it adapted to spacecraft.


How so?

We’re hoping to have a protocol approved by the fall, so there will be a set of standards saying you have to expose your surfaces to this amount of hydrogen peroxide for this amount of time. At the Jet Propulsion Laboratory we have a planetary protection group that actually does experiments, so they’re looking at different exposures, different times, different concentrations of the various modalities we’re looking at, in particular trying to understand how that vapor interacts with materials we might use on spacecraft. NASA is doing those experiments mostly independently from ESA and then we get together and reconcile the results. It can’t completely replace the heat, because the vapor only hits the surfaces of things.


How has the process evolved since the Viking experience?

Viking demonstrated the surface of Mars is much more harsh than people initially thought. Missions subsequent to that one have not been required to bake the whole spacecraft. After Viking we found the surface of Mars had no organic materials, and in fact we found something that actually eats organic materials — perchlorate. So it was decided for missions since Viking that we would let the surface of Mars do the decontamination for us. But now we know that not all of the surface of Mars is like that. So there are now Mars-only restrictions for certain places that might be more hospitable to Earth life. The subsurface of Mars where there might be water is definitely restricted, and places like the gullies, where it looks like there might be water flowing. The Viking mission could go anywhere on Mars today, so it’s possible to do it. It’s just that since then we’ve relaxed the requirements a little bit for missions going to your average place that’s easy to get to.


What does it cost to sterilize a spacecraft to the point that Viking was sterilized?

A lot of the problem is that we really don’t understand exactly what would need to be done on modern spacecraft. So there was an effort done to look at the Mars exploration rovers by the Jet Propulsion Laboratory and evaluate how much would that cost extra. I think in 2003 dollars it came to somewhere between $80 million to $100 million. And when you’re talking about a $400 million to $500 million mission, that’s a large chunk. When you’re talking about a $2 billion mission like MSL, it actually isn’t that much. MSL had started out to be fully sterilized but they decided it’s too hard, we’re not going to do it after having done a relatively limited assessment of what it would take.


What is ESA doing in the realm of planetary protection?

With ESA building the ExoMars rover, because that’s a life-detection mission, that means they have stringent controls on what contamination from Earth might be found on that spacecraft and misinterpreted as life. So they’ve actually been developing systems looking at things like a qualified parts list. And we know all these parts as they were manufactured were baked already at 125 degrees Celsius. So there are a lot of parts already available and once this stuff gets worked out for the first mission it will be relevant to all the subsequent missions.


How might governments deal with a commercial planetary mission?

It actually is a concern right now because we have the Google Lunar X Prize going to the Moon. We don’t have NASA-specific participation, but the Federal Aviation Administration (FAA) has to certify the launch, and within the FAA mandate, there is a requirement that they must consult with NASA on matters of international relevance. Obviously breaking the Outer Space Treaty would be relevant, so as the planetary protection officer at NASA I have an “in” to provide information regarding launch capabilities certified by the FAA. So for the Google Lunar X Prize, if they launch from the U.S., we have a capability of regulating.