A Tool for Finding Life in Outer Space
A new robotic device to map the ecosystem of one of Earth’s ice-bound lakes could be used to search for life on other planets.
Interest in the possibility of extraterrestrial life is leading scientists to design methods to study the most extreme regions of Earth, with the hope that such research will result not only in a better understanding of how life might sustain itself on Mars or Jupiter, but also in equipment that might one day be used in space. Such is the case at the University of Illinois at Chicago (UIC), where scientists have collaborated with NASA researchers to design an autonomous underwater vehicle (AUV) that will probe the icy waters of Antarctica. The robotic device, called endurance, will map the biological and geochemical composition of the ice-bound Lake Bonney in three dimensions using tools that scientists think will one day be employed in space.
The concept for the explorer is derived from a project being led by NASA’s Astrobiology, Science, and Technology for Exploring Planets program (ASTEP). The group, in search of microbial life, is using an AUV called depthx to map underwater caves in Mexico. Once the project is complete, the vehicle will be reengineered by its makers, Stone Aerospace, a Texas-based company, for Lake Bonney.
“While the propulsion and navigation systems between [endurance and depthx] will be similar, the science package will be completely different,” says Peter Doran, an associate professor of earth and environmental sciences at UIC and the project’s lead investigator, who formulated the initial proposal. “We are building an entirely new vehicle to discover how to best map a large water body covered in ice.” Both systems are being funded by NASA and engineered by Stone Aerospace. Endurance will also become part of ASTEP.
Unlike depthx, which swims through the warm water at various depths using visualization systems and which takes water samples to gather data, endurance will be dropped into the water through a drill or a melt hole in the ice and will swim at the top of the water. Tethered to it will be a deployable package that includes a new set of sensors designed to detect organic molecules and characterize life forms. By lowering the package into certain study areas, scientists will help preserve Antarctica’s pristine environment. An onboard flash drive will gather the data to be relayed back to a visualization laboratory in Chicago that will generate 3-D images, maps, and graphics of the lake.
The newest of the sensors already in development for endurance uses a Raman spectrometry to measure the composition of ice. This sensor differs from other spectroscopy spectrometers such as an infrared emission spectrometry by its use of laser beam to actively excite objects of study. By detecting property changes in the light bouncing back from target objects, the sensor can determine the chemical composition of a given object at any depth of the lake it chooses to study. Studying different depths of the lake will allow the scientists to create a profile of the chemical compositions of its many levels.
“It is a very sensitive sensing technique that can measure organic small molecules like carbon dioxide, lipids, and different fragmentations that makes it a very good biomarker detector,” says Bin Chen, a senior scientist at NASA Ames Research Center (ARC), who’s leading the development of the spectrometer.
The NASA scientists are working to increase the sensitivity of the spectrometer even further by coating the probe–a fiber bundle that the light goes through to illuminate the target and that also receives the signal bouncing back–in gold and silver nanomaterials. This will enhance the electromagnetic and plasmonic properties of the probe on a device, says Chen. NASA scientists had originally planned to deploy a form of the Raman spectrometer on Spirit, the Mars rover, but because they worried about the durability of the device, they removed the spectrometer at the last minute.
The scientists working on endurance are planning to meet in Mexico in a month to further discuss the technological reconstructions of depthx with lead engineer William Stone, of Stone Aerospace. They will be addressing how to make it smaller and more power-efficient, as well as how to increase the durability of the sensors so that they can withstand the temperatures of the arctic waters. Once depthx is reconstructed, the scientists plan to do a small test of the device in an ice-bound lake in Wisconsin next spring before deploying the robotic probe to the Antarctic waters in November 2008. There the device will be tested for a month; scientists will be spending eight hours a day taking measurements.
“Determining the biogeography of the Antarctica lake could be a model for life on early Mars, so if you imagine how life survived on Mars, like, three billion years ago, it may be like the dry valley of lakes in Antarctica,” says Chris McKay, a planetary scientist at NASA and a project coinvestigator. Mapping an ecosystem under the lake will help scientists better understand how life might be able to survive on ice-covered oceans on moons such as Jupiter’s Europa.