20.10 Rio Tinto 1080 MH

NEWS FEATURE NATURE|Vol 437|20 October 2005 Life at the cutting edge

Biologists, planetary scientists and engineers have gathered in southern Spain to test a robotic drill. They hope some day to probe for life beneath the surface of Mars. Jenny Hoganinvestigates.

kay, we’re at the surface,” a voice calls across the tent. “Can someone hit the ‘yes’ “Obutton?” In the centre of a makeshift laboratory, sweltering beneath the Spanish sun, people cluster anxiously around S P A I N a robotic drill. Its silver arm draws up from the Madrid deep hole it has made in the dirt. Hitting the o Nerva ‘yes’ button will trigger the drill to release its t n i Seville cargo, and reveal whether it has managed to T io bore material from metres beneath our feet. R “Have we got a core?” asks Howard Cannon, Gulf of an engineer from NASA’s Ames Research Cen- Cadiz ter in California. Peering into the end of the instrument, he spots a plug of red mud, some 7 centimetres long. This is good news. The drill mining pit that is surrounded by pine trees. A is a prototype for an instrument that might one lake of red-hued water lies below, and groves of day be sent to Mars. It’s Cannon’s job to see if he orange trees stretch out in the distance. Local can get the drill to work here on Earth. authorities recognize the beauty of the place; A team of mission scientists is pretending they erected a sturdy stone picnic bench for that this drill, and the precious core it carries, tourists — right on one of the team’s preferred is located on Mars. The drill is equipped with drilling sites. scientific instruments to search for signs of life in the dirt. So, for the team, extracting this Hostile habitat chunk of red earth could be a step towards But it’s underground, in the rocks from which finding out whether life lurks beneath the the scenery is carved, that the Rio Tinto region sterile surface of Mars. may be most like Mars. A hardy microbial The drilling technologies being tested here, world inhabits the acidic waters of the Tinto or others like it, may one day travel to the river. This is what astrobiologists dream of red planet aboard European Space Agency or finding in the subsurface of other worlds. NASA missions (see box, overleaf). Although Microbiologist Ricardo Amils, of the the martian surface is too cold, dry and Autonomous University of Madrid, a member drenched in radiation for anything to survive of the science team, has studied the area for above ground, past life forms could have taken years and once gave Stoker an enthusiastic refuge underground, some scientists think. tour. Her imagination was fired by the idea of Data from the swarm of spacecraft currently an underground ecosystem. “I’m not sure it roaming over and orbiting Mars have identi- struck him as a really good planetary ana- fied some possible spots where surface life may logue, but it did me,” she says. Thus, the Mars once have thrived. “We do our best to pick the Analog Research and Technology Experiment sweet cherries, the prime candidates for life,” (MARTE) was born. so far out of reach, have long scoured Earth for says James Dohm, a planetary geologist at the In 2004, the project’s second year, it got a otherworldly environments. For years, Mars University of Arizona, Tucson. “But eventually huge boost from data flowing back from researchers have been studying the life forms we have to have subsurface analysis.” NASA’s Mars Exploration Rovers, Spirit and that eke out an existence in the Atacama The Spanish project is headed by planetary Opportunity. The rovers identified minerals Desert of Chile or in the cold, parched Dry scientist Carol Stoker of the Ames Research on the surface of Mars, including the sulphate Valleys of Antarctica. One group is exploringAMES JAMES/NASA E. Center, a veteran of previous Mars missions, jarosite, which suggested that, when it ice-bound communities of bacteria in a frozen and focuses on the unusual geochemical envi- existed, martian water was salty and acidic1. volcano on Svalbard, the arctic archipelago ronment of Spain’s Rio Tinto region. These are just the kind of conditions found off the coast of Norway. Some, in an effort To a visitor, the landscape looks little like at Rio Tinto2. to understand the martian atmosphere, are barren Mars. The drill sits at the edge of an old Planetary scientists, with their study subjects studying the dust devils whipped up in

The analysis of cores extracted by a drill (left) may shed light on the nature of the scum in Rio Tinto’s springs.

sulphide minerals tens of kilometres wide that air-conditioning of the ultra-modern Center runs for about 250 kilometres through south- for Astrobiology building outside Madrid. ern Spain and Portugal. These minerals were Olga Prieto Ballesteros, head of the remote- laid down when the region was under water; at operations team, marks the new core on a the site of a hydrothermal vent, deep-seated whiteboard. volcanism forced hot water, rich with dissolved A satellite dish is relaying data from the drill chemicals, through cracks in Earth’s crust. site at a rate of 50 megabytes per day — roughly equivalent to the speed at which a Bottom dwellers spacecraft on Mars might be able to transmit Although the Tinto river is naturally acidic and information to Earth. The remote science loaded with heavy metals, mining has exacer- team can access data from the drill’s instru- bated these characteristics3. For 5,000 years, ments, including pictures of the core and the locals mined the deposit for heavy metals, output of an imaging spectrograph that helps notably copper. Around Nerva, the Spanish identify the minerals present. town where the MARTE team is based, the This year, the team’s month of drilling nets hills are scarred by open pits and abandoned them a hole just over 6 metres deep. Geolo- mining equipment. The acidity, in turn, led to gists may snicker to call this deep drilling, other metals in the rocks dissolving, including but Stoker calls it an impressive accomplish- the iron that gives the Tinto river its distinctive ment for a robotic drill loaded with science red colour and name. instruments. “Nothing like this has been Amils thinks that some of the river’s heavy done before,” she says. metals are extracted from their ores by bact- If the remote researchers spot an interesting eria living inside the rocks. This unique bio- part of a core, they can get the robotic drill to A robotic drill that might one day be sphere, he reckons, is powered by sulphur and subsample it, and pass the sample through used on Mars is tested out at the iron. He says the river could serve as “an sophisticated life-detection systems. The team edge of an old mining pit in Rio Tinto. exhaust for a giant underground bioreactor”. can also instruct the drill to lower a camera Although Amils and other biologists have into the borehole, to inspect the surrounding quantified the microbial ecosystem at the sur- walls. In this case, the team knows there’s a face4,5, the MARTE project has been their first good chance that life could exist in the bore- Nevada’s Eldorado Valley. Others put rovers opportunity to go underground. hole. But it pretends otherwise. “If we see a through their paces in rock-strewn deserts. While Cannon is operating the robotic drill filament in the rock, we know it’s a root,” says Michael Meyer, NASA’s lead scientist for in the stuffy tent, Stoker and other members Ballesteros. But the root is sampled and tested Mars, says it is important to study as many of of the MARTE science team are enjoying the before they conclude that it is life. these places as possible. “We don’t want to get Of the samples analysed already, “we have too far ahead of ourselves in predicting what detected life in cores three and five”, says a Mars is like and expend all our energy on one “The MARTE project has team biologist. The results come from the site,” he says. But Rio Tinto, he says, is a good advanced the date the technology signs-of-life detector (SOLID) instrument, place to include. might be ready for a drilling which uses a protein microarray to look for The Tinto river gets its unique chemistry molecules that are characteristic of life. from the Iberian Pyrite Belt, a vast deposit of mission on Mars.” — Carol Stoker Astrobiologists routinely cite such techniques

for the instrument to operate properly. Despite such difficulties, the MARTE team remains optimistic. They had not set out to solve every drilling and scientific question in 30 days. The point of the simulation, they say, was to see what works and what needs to be worked on. “We’ve got a lot of work to do, but

this is a first step,” says Cannon.HOGAN StokerJ. AMES; agrees,JAMES/NASA E. and is enthusiastic about what they have learned: “This project has advanced the date the technology might be ready for a drilling mission — there’s no doubt about that.” Still, the project’s US$6-million funding runs out this year, and it’s unclear whether the drilling rig will get another outing. Biologists will be back at the Rio Tinto site, regardless. They may have drilled deep holes, but Amils says they’ve only scratched the surface of understanding how this ecosystem Carol Stoker (left) hopes that the drill technology developed by her team could be adapted for Mars. works. During a tour of some springs near the source of the Tinto, he notes the murky red, when they talk about searching for life on the MARTE by New York-based Honeybee brown and white deposits in the water and on other planets6. Robotics operates dry. the surrounding rocks. Amils labels many of Back at Rio Tinto, the drill is working hard the oozy, lumpy patches ‘scum’, a euphemism to bring up new samples. It is designed to run Lone worker for ‘difficult to identify’. Some are minerals, with minimum human intervention. “Right A screw around the outside of the drill bit is some are life. Most are not yet classified. now, we’re sitting here doing nothing,” says meant to carry the debris to the surface, but it Todd Stevens, his colleague and an expert in Cannon. “But every once in a while something keeps getting encrusted with muck. The team geomicrobiology from Portland State Univer- will fail and we have to step in.” has resorted to vacuuming it clean. Red dust sity in Oregon, sums it up: “We have a lot of Terrestrial drillers would usually select their coats everything, including the laptops run- work to do to understand the interactions of drill bit to suit the rock, and change the speed ning the robot. the rocks and microbes on Earth before we can and power depending on the conditions they As the robot ejects a new core, a researcher do it on other planets.” ■ encounter. In contrast, a robotic drill on Mars lunges inside the rig to catch it on sterilized Jenny Hogan is a reporter with Nature. is stuck on its own with just one drill bit and tin foil. Moments later, she dabs a cotton one technique. bud over the core, swabbing material to 1. Klingelhöfer, G. et al. Science306,1740–1745 (2005). 2. Fernández-Remolar, D. et al. Planet. Space Sci.52,239–248 Another huge challenge is cleaning out the analyse for ATP, the energy-rich molecule (2004). hole, to prevent the drill from clogging. On that acts as fuel for life on Earth. Samples des- 3. Davis, R. A. et al. Environ. Geol.39,1107–1116 (2000). Earth some kind of fluid can be pumped down tined for the SOLID instrument are rushed 4. González-Toril, E. et al. Appl. Environ. Microbiol.69, 4853–4865 (2003). the drill shaft to remove the cuttings. This from the drilling tent to an air-conditioned 5. Amiral Zettler, L. A. et al. Nature417,137 (2002). isn’t feasible on Mars, so the drill built for vehicle next door, because the tent is too hot 6. Whitfield, J. Nature430,288–290 (2004). FIRST DRILL ON MARS The first drill to reach Mars technology to get headed by the and Mars, the agency is more might be launched in 2011 by the underground, Italian Space interested than ever in nurturing ESA European Space Agency (ESA), and its ‘mole’ Agency. The drilling technologies. Drills could on a mission called ExoMars. never got a other, CanaDrill, help astronauts reach natural If approved at a December chance to is being resources, such as underground minister-level meeting, ExoMars burrow. sponsored by the water reservoirs if they exist. would include a small rover ESA already Canadian Space The challenge is making drills carrying a lightweight drill. It has experience Agency. lightweight and energy-efficient would be capable of boring 2 in putting drills CanaDrill could enough to fly, says David Beaty, metres into the martian surface. aboard have the first a former exploration geologist That would be deep enough, spacecraft. Last shot at getting in the oil industry who now scientists hope, for it to get March, it into space, if works for NASA’s Jet Propulsion through the oxidized surface launched the Artist's view of the it is selected Laboratory in Pasadena, layer and into relatively cometary ExoMars descent for NASA’s California. He is organizing a unaltered martian soils. mission Rosetta, module. unmanned lunar ‘drill-off’ that will take place It’s certainly deeper than any which carries a lander, details of next February, when a handful sampling tool has ever gone drill to pierce more than 20 which were announced last of companies developing before. The Viking landers centimetres into Comet month. The mission could robotic drills will test their scratched up some topsoil in the Churyumov-Gerasimenko. launch as early as 2010, to machines at Idaho Falls. 1970s, and today’s Mars rovers For the ExoMars project, ESA search for water in the shadowy Competitors will be charged to grind small holes in surface is considering two possible craters near the Moon’s south build a drill that weighs no more rocks. Only the Beagle probe, designs. One, named DeeDri, is pole. than 40 kilograms, digs 20 presumed to have crashed on being developed by the group With NASA’s new push to metres deep, and runs off the landing in 2003, carried the that provided Rosetta’s drill, send astronauts to the Moon power of a lightbulb.