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Keeping alien invaders at bay
Technology
Keeping alien invaders at bay
We could get more than we bargained for in samples of rock and soil brought back by planetary probes PAUL MARKS
WHEN the Genesis space capsule began its re-entry into Earth’s atmosphere in September 2004, mission controllers at NASA got ready to celebrate. Genesis had spent three years in deep space collecting particles from the solar wind, so it came as a huge relief to see it back from its long journey, on course for a soft landing. That relief turned out to be premature. The capsule’s parachutes failed to deploy, and it smashed into the Utah desert floor at more than 300 kilometres per hour. The impact shattered Genesis’s casing, exposing its delicate cargo of solar dust to terrestrial contamination. As it turned out, a fair proportion of the probe’s samples remained usable. Nevertheless the rupturing of the Genesis probe is now paraded as an awful warning by those opposed to the idea of bringing samples back from Mars or beyond. They warn that if the same thing were to happen to a craft loaded with Martian soil and rock, possibly contaminated with pathogenic bacteria, the consequences could be dire. This concern is more than just academic. Space agencies are already working on craft to carry out sample return missions over 24 | NewScientist | 28 April 2007
070428_N_Tech_p24_p25.indd 24
the next decade or more. The European Space Agency (ESA) is designing concept spacecraft for a Mars sample return mission in 2013, while NASA is planning a similar operation around 2020. Russia is planning a sample return mission to the Martian moon Phobos for as early as 2009. The Genesis crash-landing has highlighted the need to protect Earth from any nasties in the samples these craft bring back, and engineers are actively investigating how this might be done.
Among the first to raise the alarm was the American space scientist Carl Sagan, in 1983. “Sagan told NASA’s Jet Propulsion Laboratory that if they were so sure they could pull off a perfect Mars sample return mission, then they should load up anthrax bacteria in their prototype sample return container, launch it into space and return it to Earth,” says Barry DiGregorio, who coordinates the International Committee Against Mars Sample Return made up of concerned scientists and engineers. “Of course, the JPL people were horrified at Sagan’s suggestion and called him an alarmist,” says DiGregorio, but he insists that the fate of the Genesis capsule demonstrates that there are no foolproof spacecraft. “Mars samples should not be returned to our planet,” he says. The crashlanding of NASA’s Mars Polar Lander in 1999 makes the same point, the sceptics say. This craft came to grief when it mistakenly sensed it had touched down and cut its motor while still 40 metres above the Martian surface. Instead, DiGregorio suggests using part of NASA’s planned moon base as an off-planet astrobiology lab for receiving and testing samples. “That would guarantee Earth’s biosphere
would not have to suffer any errors due to spacecraft engineering mistakes,” he says. “What could be better? Earth will be kept safe and astrobiologists get to work on the moon.” That might not be possible, however, without prior international agreement. Gerhard Kminek, ESA’s planetary protection officer, says that using the moon in this way would breach the UN’s Outer Space Treaty of 1967, unless special precautions are taken. The treaty chiefly bans the stationing of nuclear weapons or other weapons of mass destruction on other planets, but it also governs protocols for handling returned samples and the sterility levels required of probes sent to other planets or moons.
Biosecurity on the moon The moon lab idea comes unstuck because the treaty regards the moon as part of a combined Earth-moon system, and gives it the same level of protection from contamination as the Earth. “To return samples to the moon for analysis would require the same kind of precautions [on the lunar surface] as returning them to the Earth,” Kminek says. Achieving this level of biosecurity is hard enough on Earth. “It will be extremely difficult and not
STOWAWAYS FROM EARTH ARE ALREADY OUT THERE The long, productive lives of NASA’s Mars rovers Spirit and Opportunity surprised even their designers. There is one area, however, in which their predecessors from 30 years ago performed far better, and the shortcomings of the later rovers could be bad news for the Red Planet. The Viking landers that set down on Mars in 1976 were truly clean machines. “The Outer Space Treaty requires that we do not contaminate [planets] for future science,” says Cassie Conley, planetary protection officer at NASA. “So the Vikings were baked in an oven for four days at above boiling point to make sure there was absolutely nothing alive on them.” Sterilising a whole spacecraft is an expensive business, and it can damage sensitive instruments like cameras. So
when the Viking landers appeared to show that terrestrial life had no chance of surviving on Mars, NASA jumped at the opportunity to cut its costs. “Viking suggested that Mars was just far too dry, far too cold, had too much UV radiation and too much CO2 for Earth organisms to survive,” Conley says. As a result, the rules have been relaxed so that only those parts of a rover that dig into the soil or drill into rock have to be sterilised. The rest of the craft can carry up to 300 spores per square metre. Now that water appears to have been found on Mars, these looser rules no longer seem like such a good idea. Water could rejuvenate any terrestrial spores on the rovers, particularly if they are ultra-hardy extremophiles, leading to
contamination of the planet, so NASA is researching new ways to sterilise rovers. One team at the Jet Propulsion Laboratory in Pasadena, California, is developing a device that uses an electron beam to kill any bugs. Some fear such efforts may already be too late. “Contamination of Mars is most likely already accomplished,” says Barry DiGregorio of the International Committee Against Mars Sample Return. “The early Russian spacecraft which crash-landed, the 1997 Pathfinder and the 2004 rovers were minimally sterilised,” he says, and we can’t be sure that organisms that arrived with them have perished. “The discovery of what looks like flowing water on Mars changes everything.” www.newscientist.com
23/4/07 11:36:00 am
JPL/NASA
–Something nasty could be lurking in Martian dust–
very practicable to do this on the moon,” he says. The high cost of building such a lab on the moon, combined with the difficulty of staffing it with skilled technicians and maintaining containment standards in the hostile lunar environment, would make the idea a non-starter. The current plan for Mars sample containment on Earth, as specified by the UN’s advisory Committee on Space Research, is to use a laboratory conforming to biosafety level 4, the most stringent available. “We will treat a sample as if it were the most dangerous possible material that we know how to handle – the Ebola virus – and then we will give it an additional level of containment on top of that,” says Cassie Conley, planetary protection officer at NASA. Samples could be sterilised before being returned to Earth, Conley suggests, though she concedes this may be difficult www.newscientist.com
070428_N_Tech_p24_p25.indd 25
without knowing in advance what it takes to kill any bugs that might be adapted to the extreme conditions found on Mars. NASA is funding research into the development of tools to detect extremophile bugs, and though they are intended primarily to ensure that no terrestrial organisms hitch a lift on Marsbound craft, they could be adapted to study and identify Martian extremophiles. To provide protection once the Martian soil is on board the spacecraft, space agencies will “make sure that the sample is completely contained so that when it lands there is no possibility of it being released”, Conley says. One of the Mars sample return systems under development at ESA’s research lab in Noordwijk, the Netherlands,
envisages a lander launching its cargo of samples into orbit. From there the cargo would be scooped up by an orbiting spacecraft, where robotic welding systems would be used to wrap it in three layers of containment. Only then would it be returned to Earth. Finally, spacecraft engineers will need to ensure that a returning capsule will not suffer a Genesislike rupturing of its sample container. One option is not to even consider bringing the capsule down gently, and instead plan for a crash-landing. The most recent design for a sample container was developed by JPL engineers for a sample return mission scheduled for 2003, which was cancelled after a clutch of Mars mission failures. A simple 20-centimetre titanium sphere containing about 90 core samples weighing up to
“We don’t know what it takes to kill bugs adapted to extreme extraterrestrial living”
300 grams in total would be sealed on the Martian surface and then wrapped in a shock-absorbing layer of high-density carbon foam. The whole thing would then be placed inside a crash-proof capsule fitted with a reinforced carbon-fibre ablative heat shield. While DiGregorio and his allies will take some convincing that even these steps will be enough to safely return samples to Earth, the engineers know their reputations will be on the line. The consequences of getting it wrong, and allowing extraterrestrial pathogens to escape, could be horrendous. “The worst-case scenarios could be very serious to the well-being of our civilisations,” warns Benton Clark of Lockheed Martin Space Systems in Denver, Colorado, in an article to be published in the journal Acta Astronautica. Not even the most enthusiastic advocates of sampling extraterrestrial soils would want to risk that. ● 28 April 2007 | NewScientist | 25
23/4/07 11:36:07 am
Keeping alien invaders at bay
We could get more than we bargained for in samples of rock and soil brought back by planetary probes PAUL MARKS
WHEN the Genesis space capsule began its re-entry into Earth’s atmosphere in September 2004, mission controllers at NASA got ready to celebrate. Genesis had spent three years in deep space collecting particles from the solar wind, so it came as a huge relief to see it back from its long journey, on course for a soft landing. That relief turned out to be premature. The capsule’s parachutes failed to deploy, and it smashed into the Utah desert floor at more than 300 kilometres per hour. The impact shattered Genesis’s casing, exposing its delicate cargo of solar dust to terrestrial contamination. As it turned out, a fair proportion of the probe’s samples remained usable. Nevertheless the rupturing of the Genesis probe is now paraded as an awful warning by those opposed to the idea of bringing samples back from Mars or beyond. They warn that if the same thing were to happen to a craft loaded with Martian soil and rock, possibly contaminated with pathogenic bacteria, the consequences could be dire. This concern is more than just academic. Space agencies are already working on craft to carry out sample return missions over 24 | NewScientist | 28 April 2007
070428_N_Tech_p24_p25.indd 24
the next decade or more. The European Space Agency (ESA) is designing concept spacecraft for a Mars sample return mission in 2013, while NASA is planning a similar operation around 2020. Russia is planning a sample return mission to the Martian moon Phobos for as early as 2009. The Genesis crash-landing has highlighted the need to protect Earth from any nasties in the samples these craft bring back, and engineers are actively investigating how this might be done.
Among the first to raise the alarm was the American space scientist Carl Sagan, in 1983. “Sagan told NASA’s Jet Propulsion Laboratory that if they were so sure they could pull off a perfect Mars sample return mission, then they should load up anthrax bacteria in their prototype sample return container, launch it into space and return it to Earth,” says Barry DiGregorio, who coordinates the International Committee Against Mars Sample Return made up of concerned scientists and engineers. “Of course, the JPL people were horrified at Sagan’s suggestion and called him an alarmist,” says DiGregorio, but he insists that the fate of the Genesis capsule demonstrates that there are no foolproof spacecraft. “Mars samples should not be returned to our planet,” he says. The crashlanding of NASA’s Mars Polar Lander in 1999 makes the same point, the sceptics say. This craft came to grief when it mistakenly sensed it had touched down and cut its motor while still 40 metres above the Martian surface. Instead, DiGregorio suggests using part of NASA’s planned moon base as an off-planet astrobiology lab for receiving and testing samples. “That would guarantee Earth’s biosphere
would not have to suffer any errors due to spacecraft engineering mistakes,” he says. “What could be better? Earth will be kept safe and astrobiologists get to work on the moon.” That might not be possible, however, without prior international agreement. Gerhard Kminek, ESA’s planetary protection officer, says that using the moon in this way would breach the UN’s Outer Space Treaty of 1967, unless special precautions are taken. The treaty chiefly bans the stationing of nuclear weapons or other weapons of mass destruction on other planets, but it also governs protocols for handling returned samples and the sterility levels required of probes sent to other planets or moons.
Biosecurity on the moon The moon lab idea comes unstuck because the treaty regards the moon as part of a combined Earth-moon system, and gives it the same level of protection from contamination as the Earth. “To return samples to the moon for analysis would require the same kind of precautions [on the lunar surface] as returning them to the Earth,” Kminek says. Achieving this level of biosecurity is hard enough on Earth. “It will be extremely difficult and not
STOWAWAYS FROM EARTH ARE ALREADY OUT THERE The long, productive lives of NASA’s Mars rovers Spirit and Opportunity surprised even their designers. There is one area, however, in which their predecessors from 30 years ago performed far better, and the shortcomings of the later rovers could be bad news for the Red Planet. The Viking landers that set down on Mars in 1976 were truly clean machines. “The Outer Space Treaty requires that we do not contaminate [planets] for future science,” says Cassie Conley, planetary protection officer at NASA. “So the Vikings were baked in an oven for four days at above boiling point to make sure there was absolutely nothing alive on them.” Sterilising a whole spacecraft is an expensive business, and it can damage sensitive instruments like cameras. So
when the Viking landers appeared to show that terrestrial life had no chance of surviving on Mars, NASA jumped at the opportunity to cut its costs. “Viking suggested that Mars was just far too dry, far too cold, had too much UV radiation and too much CO2 for Earth organisms to survive,” Conley says. As a result, the rules have been relaxed so that only those parts of a rover that dig into the soil or drill into rock have to be sterilised. The rest of the craft can carry up to 300 spores per square metre. Now that water appears to have been found on Mars, these looser rules no longer seem like such a good idea. Water could rejuvenate any terrestrial spores on the rovers, particularly if they are ultra-hardy extremophiles, leading to
contamination of the planet, so NASA is researching new ways to sterilise rovers. One team at the Jet Propulsion Laboratory in Pasadena, California, is developing a device that uses an electron beam to kill any bugs. Some fear such efforts may already be too late. “Contamination of Mars is most likely already accomplished,” says Barry DiGregorio of the International Committee Against Mars Sample Return. “The early Russian spacecraft which crash-landed, the 1997 Pathfinder and the 2004 rovers were minimally sterilised,” he says, and we can’t be sure that organisms that arrived with them have perished. “The discovery of what looks like flowing water on Mars changes everything.” www.newscientist.com
23/4/07 11:36:00 am
JPL/NASA
–Something nasty could be lurking in Martian dust–
very practicable to do this on the moon,” he says. The high cost of building such a lab on the moon, combined with the difficulty of staffing it with skilled technicians and maintaining containment standards in the hostile lunar environment, would make the idea a non-starter. The current plan for Mars sample containment on Earth, as specified by the UN’s advisory Committee on Space Research, is to use a laboratory conforming to biosafety level 4, the most stringent available. “We will treat a sample as if it were the most dangerous possible material that we know how to handle – the Ebola virus – and then we will give it an additional level of containment on top of that,” says Cassie Conley, planetary protection officer at NASA. Samples could be sterilised before being returned to Earth, Conley suggests, though she concedes this may be difficult www.newscientist.com
070428_N_Tech_p24_p25.indd 25
without knowing in advance what it takes to kill any bugs that might be adapted to the extreme conditions found on Mars. NASA is funding research into the development of tools to detect extremophile bugs, and though they are intended primarily to ensure that no terrestrial organisms hitch a lift on Marsbound craft, they could be adapted to study and identify Martian extremophiles. To provide protection once the Martian soil is on board the spacecraft, space agencies will “make sure that the sample is completely contained so that when it lands there is no possibility of it being released”, Conley says. One of the Mars sample return systems under development at ESA’s research lab in Noordwijk, the Netherlands,
envisages a lander launching its cargo of samples into orbit. From there the cargo would be scooped up by an orbiting spacecraft, where robotic welding systems would be used to wrap it in three layers of containment. Only then would it be returned to Earth. Finally, spacecraft engineers will need to ensure that a returning capsule will not suffer a Genesislike rupturing of its sample container. One option is not to even consider bringing the capsule down gently, and instead plan for a crash-landing. The most recent design for a sample container was developed by JPL engineers for a sample return mission scheduled for 2003, which was cancelled after a clutch of Mars mission failures. A simple 20-centimetre titanium sphere containing about 90 core samples weighing up to
“We don’t know what it takes to kill bugs adapted to extreme extraterrestrial living”
300 grams in total would be sealed on the Martian surface and then wrapped in a shock-absorbing layer of high-density carbon foam. The whole thing would then be placed inside a crash-proof capsule fitted with a reinforced carbon-fibre ablative heat shield. While DiGregorio and his allies will take some convincing that even these steps will be enough to safely return samples to Earth, the engineers know their reputations will be on the line. The consequences of getting it wrong, and allowing extraterrestrial pathogens to escape, could be horrendous. “The worst-case scenarios could be very serious to the well-being of our civilisations,” warns Benton Clark of Lockheed Martin Space Systems in Denver, Colorado, in an article to be published in the journal Acta Astronautica. Not even the most enthusiastic advocates of sampling extraterrestrial soils would want to risk that. ● 28 April 2007 | NewScientist | 25
23/4/07 11:36:07 am