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HOW BUGS HITCH-HIKE ACROSS THE GALAXY
Mankind’s search for alien life could be jeopardised by ultra-resilient bacteria from Earth. David Derbyshire reports
 
What was the most important discovery of the Apollo programme? Some have argued that it was the rocks that explained how the Moon was formed. Others believe it was the technological spin-offs. But according to Captain Peter Conrad, who led the 1969 Apollo 12 mission, it was life.
 
On the apparently dead lunar surface, a colony of bacteria was thriving. The organisms were not native to the Moon, but were visitors from Earth who had hitch-hiked a ride on board one of Nasa's five Surveyor probes from the 1960s.To the astonishment of biologists, between 50 and 100 Streptococcus bacteria survived the journey across space, at an average temperature 20 degrees above absolute zero with no source of energy or water, and stayed alive on the Moon in a camera for three years. Captain Conrad, who returned the bacteria to Earth, was later to confess: ‘I always thought the most significant thing we ever found on the whole Moon was the little bacteria that came back and lived.’
 
The ability of life to survive, adapt and evolve never fails to astonish. Over the past three decades, bacteria and archaea have been found in some of the most inhospitable places on Earth. Known as extremophiles, these organisms have coped with life in a vacuum, pressure as high as 70 tons per square inch, depths of four miles beneath the surface and scorching waters around deep-sea volcanic vents. They have also survived 25 million years inside a bee preserved in resin. Their resilience has renewed enthusiasm for the search for alien life - a quest that many had assumed had been banished to fantasy fiction. Mars and the moons Titan, Europa and Callisto are once again plausible candidates for extraterrestrials.
 
As interest in alien life has grown, so have concerns that mankind could spread its own microscopic bugs, contaminating the places we want to explore. In 2003, Nasa ended the Galileo probe’s mission by smashing it into Jupiter. The fear was that it could be carrying bacteria that might contaminate Europa's oceans.
 
The team behind Beagle 2 - the British probe that went to search for life on Mars in 2003 - was forced to take contamination particularly seriously. If Beagle carried to Mars life or dead spores picked up during the manufacture of the spacecraft, its science would be jeopardised. Prof Colin Pillinger, the Open University scientist who headed the Beagle project, said: ‘What we’ve learnt since the Apollo missions and the Viking Mars missions of the 1970s is that bugs are far more tenacious than we ever imagined. They seem to be very tolerant of high temperatures, they lie dormant at low temperatures for long periods, they are immune to salt, acid and alkali, they seem to survive on substrate that are not what people expect. Extremophiles are extremely adapted to hanging on to life.’
 
Beagle had to be assembled in a ‘clean room’ - and one was specially put together in a converted BBC outside broadcast van garage in Milton Keynes. It had enough room to include an enormous set of fans that circulated and filtered the air 500 times an hour. Only a handful of trained researchers were allowed inside. ‘I wasn’t allowed in,’ says Prof Pillinger. ‘There was special training for people going in there and special conditions. There was a ban on beards and a limit of four people at any one time. The team kept samples of everything that could have contaminated the craft and monitored every stage of assembly.'
 
To reduce the workload, the idea was to build as much as possible before sterilising it and banishing it to the difficult working conditions inside the clean room. The easy stuff was heated to 115C for 52 hours, more than enough to kill off bugs. Electronic equipment can’t cope with those sorts of temperatures, so the team used a hydrogen peroxide plasma, created in a microwave, to kill off bugs at low temperatures. Parachutes and gas bags were zapped with gamma radiation. It wasn’t just facial hair that was banned. ‘You’ve heard of the paperless office,’ says Prof Pillinger. ‘We had the paperless assembly line. The guys normally go in armed with loads of papers and diagrams, but we didn't allow any of that. They were given information through a glass wall, over mikes and monitors. And sometimes on a piece of paper stuck to the glass with sticky tape.’
 
Beagle’s heat shield doubled as its biological shield. So once the instruments were encased and sealed, the craft could be brought back into the real world. The shield heated up to 1,700 degrees on its descent through the Martian atmosphere, so bugs on the casing were not a worry. Mars Express - the craft carrying Beagle - did not need sterilising. Its trajectory was designed so that if something went wrong, the craft would not simply crash into the planet. Its course could be corrected en route.
 
Eventually, space scientists hope to return samples of Mars to Earth. While the risks of alien bacteria proving hazardous on Earth may be remote, the rocks will still need to be quarantined. Moon rocks from Apollo were analysed in vacuum glove boxes for the first two missions. Later, researchers stored rocks in nitrogen. Prof Pillinger believed the first Mars rocks should be sterilised before they are studied on Earth. ‘For security purposes it would be the most sensible thing to do. You don’t have to sterilise it all, you can contain some of it and then sterilise the sample you want to look at, but it would lower the risk and make it easier to analyse.’ 

Look at the statements and the list of spacecraft below. Match each statement with the spacecraft it applies to.

1. provided transport from Earth for bacteria
A. Apollo craft
B. Galileo probe
C. Surveyor probe
D. Mars Express
E. Beagle 2
Explain:


2. led to realisation of how tenacious bacteria are
A. Surveyor probe
B. Beagle 2
C. Apollo craft
D. Mars Express
E. Galileo probe
Explain:


3. was created so that there could be no bacteria on the outer structure
A. Apollo craft
B. Beagle 2
C. Surveyor probe
D. Mars Express
E. Galileo probe
Explain:


4. was capable of changing direction in the event of a problem
A. Surveyor probe
B. Apollo craft
C. Beagle 2
D. Mars Express
E. Galileo probe
Explain:


5. brought material which was kept in more than one kind of container
A. Apollo craft
B. Galileo probe
C. Beagle 2
D. Mars Express
E. Surveyor probe
Explain:


6. required action because of the possibility of the introduction of harmful bacteria
A. Apollo craft
B. Galileo probe
C. Beagle 2
D. Surveyor probe
E. Mars Express
Explain:


7. resulted in disagreement as to the relative value of what was found
A. Mars Express
B. Galileo probe
C. Beagle 2
D. Surveyor probe
E. Apollo craft
Explain:

Label the diagram below. Choose NO MORE THAN THREE WORDS from the reading passage for each answer. 
 

1.
fans glass wall clean room electronic equipment beards/facial hair gamma radiation


(1)  
(2)  
(3)  
(4)  
(5)  
(6)  


Total: 65 page(s)
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