Interview with Beagle 2 Scientist
From 200 million miles away on Mars, the European Beagle 2 lander was intended to send back a faint 5-watt signal. To acquire that miniscule signal could be compared to picking up a cellphone call if broadcast from Mars to Earth. That phone call was intended to as a Christmas greeting to scientists listening in after Beagle 2's expected December 25th touchdown.
Interview with Colin Pillinger, Beagle 2 Chief Scientist, European Space Agency
Astrobiology Magazine (AM): Beagle carried an experiment that could look for signs of life by measuring the fractionation of carbon in martian rocks. Recently Opportunity discovered a high concentration of sulfur in rocks in the bedrock outcrop at its landing site. During the press conference that announced the finding, the possibility of using sulfur fractionation as a biomarker was mentioned. Do you agree that this could be a good way to look for life signs? If so, what are the challenges to adapting the Beagle technology to measure sulfur fractionation, in addition to carbon? Does ESA have any plans along these lines?
Colin Pillinger (CP):Sulphur isotopes can be used to recognize biological action. It's a tricky measurement on Earth and may not be possible on a robotic spacecraft.
AM: NASA indicated that isotope experiments would require a sample return from Mars. But Beagle was going to do isotopes in situ, so what gives?
CP:NASA doesn't have an isotope Mass Spectrometer. We do. I have been building isotope machines all my career.
AM: Given what has been learned so far with Spirit and Opportunity, have you revised any thoughts about whether Beagle 2 would have found positive life detection at the Isidis landing site?
CP:Neither MER rover has found anything to change our view. The Beagle 2 project was based on martian meteorite studies. Sulphates were found in martian meteorites in the 1980's.
AM: Are there any caveats about testing for life by baking the soil? Such as high temperature degradation of biologicals?
CP:We don't heat, we combust to convert all carbon to CO2 for isotope study.
AM: It has been reported that when Beagle's airbag system was tested once before launch in Ohio, that it failed the certification but flew anyway without another test. Could you clear up this as true or false?
CP: Not true. it was tested extensively at JSC [NASA Johnson Space Center], Houston.
AM: Beagle didn't have mobility but did have a mole-like sample retriever. Does this bias life detection to microbes in the soil, compared to rocks?
CP:No. Beagle was intended looking at rocks using the PAW.
AM: What kind of subsurface sampling could have been done?
CP:Down to 1.5 meters and under boulders.
AM: When considering Beagle 3, what would you change about the Beagle 2 design?
CP: In a reflight landing has to be a priority.
AM: It has been reported that a transponder was hoped for prior to flight, that it would have greatly helped the landing search, but couldn't be put on Beagle 2 in time. Could you clear up the importance of this kind of tracking beacon if this reporting was true?
CP: We looked at this, but we had no satellites in position around Mars to monitor Beagle 2 during its descent.
When the signal did not at first appear, early indications might be that the lander had been shadowed by the lip of a crater. The fortuitous crater-landing of the Mars Opportunity rover later in January showed that missing a crater might require more luck than landing in one.
After entering orbit around Christmas, the parent spacecraft, Mars Express, began its multi-year mapping with its unique focus on ancient volcanoes and the mystery of what happened to Martian water. For the lost Beagle 2 probe, the orbiting of Mars Express held out the chance that a direct communication link could be established to a beacon distress signal from the surface. The beacon never could be heard.
Another chance presented itself to try to image the landing site of Beagle. The comprehensive, stereo-view maps from Mars Express features 10 meter resolution, while some particularly interesting regions can get a close-up view to 2 meters [about the size of small car, as seen from orbit]. Although hundreds of thousands of images have been part of previous mapping missions, as much as ninety-seven percent of Mars remains unexplored at high resolution.
Neither the Beagle surface beacon nor an image could ever be acquired--not using orbiters, the Deep Space Network or the Jodrell Bank Telescope in England--and the surface mission was concluded.
In England, the Astrobiology Magazine recently had the opportunity to revisit the goals and remarkable mission plans for the Beagle 2 with Chief Scientist, Professor Colin Pillinger. The interview had two main questions, how does a robotic spacecraft look for life on another planet?, and secondly, what can be learned from Beagle 2's long journey from conception to somewhere unknown on the surface of Mars?
Beagle 2 was something of an afterthought to Europe's overall Mars exploration, said Pillinger. "Mars Express was originally going to be a rescue mission. It was going to relaunch instruments that had been lost on the Russian Mars 96 mission," Pillinger explained. But the discoveries related to signs of life in Martian meteorites and the 1996 scientific revelation that ALH84001 might contain a fossil sparked a new idea, Pillinger said. "I suggested to ESA that if they were going to have a mission to Mars that they really needed to have a lander and address some of these new issues."
The Beagle lander was small - a mere 30 kg (66 pounds) - and was never intended to move from its landing spot. But at its core sat a miniaturized version of a sophisticated chemical laboratory.
The lander's Gas Analysis Package, or GAP, was central to its mission to discover signs of past or present life on Mars. The only previous life-detection experiments on Mars were carried out by NASA's Viking 1 and 2 landers in 1976. "It wasn't that Viking didn't find life," said Beagle 2 Chief Scientist, Professor Colin Pillinger, "it was that they thought the conditions were just so horrid, so harsh, nobody anticipated that life could exist there."
"The Beagle 2 project was based on martian meteorite studies," said Pillinger. "I think the real thing that is driving us back to wanting to look at whether there is life on Mars is something that Viking did that nobody anticipated, nobody planned. It was that they were able to show that we have martian meteorites on Earth."
"The discovery of water in martian meteorites was made just after Viking. Of course, we didn't know then they were martian meteorites," said Pillinger. "But we found evidence of water trickling through martian meteorites, we found carbonates in martian meteorites that was definitely indigenous. And we found organic matter. I believe that the organic matter is there in an amount that can't just be explained by contamination. However, I can't prove it. And if I can't prove something, I just simply say, right, what are we going to do next? Go find another experiment."
So where is the Beagle 2 lander now? The detailed postflight analysis of the Beagle 2 mission includes an assessment of the landing site ellipse from orbital images, reanalysis of atmospheric conditions during the entry into the Martian atmosphere on Chirstmas day, examination of the separation from Mars Express and of the cruise phase preceding arrival at Mars.
One extremely useful piece of evidence could be provided by an image of the lander. The team is hoping that the High Resolution Stereo Camera on Mars Express or the camera on board Mars Global Surveyor (MGS) may eventually be able to capture an image that reveals its location on the Martian surface. In addition to the European mission, two NASA orbiters--the Mars Odyssey and Mars Global Surveyor--are part of the constellation of satellites that help mapping and communication tasks independently.
|"..the way in which I plan to detect organic matter is to burn it."-- Colin Pillinger, principal scientist, with Beagle Credit: ESA/Beagle
It would be extremely difficult to find a lander for which the location is uncertain. The large size of the Beagle 2 landing ellipse makes its identification from orbital imagery a vast survey task. The same caveat applies to previous minute search efforts, such as Viking 2 or Mars Polar Lander (in fact, for Mars Polar Lander, it would take over 60 years to map out the entire landing ellipse in which the spacecraft was lost).
Close scientific coordination between Mars Express and the surface Mars Exploration Rovers (MER) continues. Scientists participating on both NASA and ESA missions joined forces recently to design a novel imaging experiment. While "in the works for over a year," said MER's Deputy Principal Investigator, Dr. Ray Arvidson, "the schedule was firmed up only [in January 2004], science team to science team." One reason for the serendipitous opportunity was uncertainties about the fate of the Beagle lander and when exactly the timing might be right for an overpass view of the Spirit rover for Mars Express. "The overpass will happen when it is nice and hot on Mars, in the mid-afternoon. The rocks will be cooking by then, and so infrared imagery will show up well in infrared (0.35-0.5 microns)."
Arvidson said that simultaneous mapping from above and below is key, if scientists want to remove the strong infrared properties of atmospheric dust and distortion from what future panoramic infrared images may provide for distant objects, like the eastern hills in Gusev two to three kilometers away.
Arvidson recalled that the overpass experiment "began as an informal conversation in a Paris cafe, in early summer ."
As for the future, the Beagle 2 team is already considering what might be possible with a Beagle 3 mission. "Viking did a very noble job," said Pillinger. "They had three experiments, which were configured to see whether there were any actively metabolizing organisms on the planet. [Beagle 2] was not doing a metabolism experiment. The thing which is crucial as far as I'm concerned is we need to see whether we can detect any organic [biologically produced] matter.
Pillinger concluded, "I think there were a lot of failures of missions designed to go to Mars. And we don't necessarily know what experiments were on some of those Russian missions. But all of them had to get down before they could do any experiments."
Related Web Pages
Five Year Retrospective: Mars Pathfinder
Open University: Beagle
Space Research Centre: Leicester
Mars Express PPARC
ESA's Beagle: Sniffing Out Life on Mars
Call from the Red Phone
Isidis, Martian Impact Basin