NASA duct tape may confuse life sensors on Mars rover

In January 2009, astrobiologists found evidence of methane, an organic molecule usually produced by life on Earth, flowing from three distinct regions on Mars’s surface. While the findings were a promising sign of life beneath the surface of Mars, the methane could also have been generated by geological processes.

The methane-release points were thought to be likely indicators of life due to their proximity to suspected ancient waterbeds and the observation that one of the sites released methane on a seasonal basis. These findings prompted NASA to give Curiosity, the next Mars rover, the task of pinpointing the source of the methane. Scheduled to launch in late 2011, the rover will be equipped with sensors capable of detecting trace amounts of methane.

However, researchers recently found that the materials in Curiosity itself could also release methane and confuse the sensors. A team led by microbiologist and veteran Mars simulator Andrew Schuerger of the University of Florida showed that the kapton tape, NASA’s equivalent of duct tape, used to hold the rover’s joints together could release enough methane to create a false positive.

Adam Johnson of Indiana University agrees that this is a valid concern, as the tape is capable of producing concentrations of methane that are orders of magnitude above the sensors’ detection limits. Johnson found in November 2010 that microbial hitchhikers on Mars rovers could potentially create false alarms for or even wipe out Martian life.

To test the effects of the tape on Curiosity’s sensors, Schuerger and his team placed a variety of biological materials, including amino acids, DNA and soil bacterium spores, as well as some of the materials used to build the rover, into the Mars Simulation Chamber. The chamber consisted of a stainless steel cylinder that mimicks environmental conditions on the Mars surface, including pressure, temperature and amount of sunlight.

When the materials were removed after eight hours in the chamber, the organic materials were found to emit some amount of methane, but not enough to cause a problem. However, the bacterial spores leaked significant amounts of methane even after they were killed by ultraviolet radiation. The research team believes that this will not be a problem as the rover will be cleaned exhaustively prior to launching.

Due to its size, Curiosity requires more kapton tape than the previous rovers, Spirit and Opportunity. As the use of kapton tape is unavoidable, the researchers believe that the tape will pose the biggest problem. Schuerger’s team found that Curiosity’s methane-detecting sensors could pick up as much as several orders of magnitude of methane molecules in the first few days of the mission.

Fortunately, the rover team has a few solutions in mind. As methane release is encouraged by ultraviolet radiation, the rover could take measurements at night to eliminate the possibility of detecting non-Martian methane. The rover could also rotate its sensors towards the Martian wind, receiving a cleaner picture of the planet’s atmosphere.

Schuerger suggests that models detailing the quantity of methane the tape will produce, as well as where it is likely to appear on the rover, should be made. His team also notes that kapton tape emits less methane with time, making measurements made later in the mission more reliable.

NASA planetary scientist Paul Mahaffy says the study will help sample analysts differentiate between Martian materials and those brought from Earth and can potentially reduce the chances of accepting a false positive.