NASA Tech Briefs: What is the Medusa project? Michael Flynn: The Medusa project is focused on understanding the potential for abiotic life forms – life forms that exist devoid of the input of photosynthesis or the decomposition of organic materials. If we could find abiotic life forms on Earth that exist purely off geo-chemical energy and don’t have complex genetic defenses against oxygen or very complex metabolic process, those are bacteria that if deposited on Europa they would thrive, or if deposited in some sub-surface area of Mars also would thrive. The Medusa instrument itself is basically a large venturi meter that can be affixed to subsurface basalt rock that is associated with the hydrothermal vents. What it does is measure the flow of water that is coming out of these subsurface zones and, being a venturi-type device, it increases the velocity and the pressure of these flows so they can be measured with conventional instruments. It also provides the ability to collect both gas-type and non-gas-type samples. So, this instrument is used and has been used in the past to understand the circulation of ocean flows associated with hydrothermal vents. What we are looking for is environments where the bulk ocean is not diffusing in and getting entrained in these hydrothermal vent flows, because that is indicative of a recirculation of ocean water (the biology of ocean water is largely determined by photosynthesis and by the photosynthetic cycles that occur in the ocean). This provides us with the ability to understand the geological context in light of hydraulic flows associated with hydrothermal vents. We’ve used the Medusa instrument both in hydrothermal vents and also at water called boreholes, which are wells that have been drilled into the deep ocean to understand the flow circulation associated with those structures. This is work largely being done by Dr. Adam Schultz from OSU. NASA is interested in expanding this capability to also include in situ biological detection and in situ chemical analysis of these subsurface flows. NTB: Who are NASA’s partners in the Medusa’s development? Flynn: This project conforms to what I think probably most NASA tech projects do where NASA provides the scientific content and program management and then works with a variety of external individuals at universities and private companies to do a type of specific technology development. NASA is responsible for integrating the technologies, and then managing the field deployments, although the field deployments can also conducted through university partners. This project has partners from Oregon State University (OSU), Utah State University, and two companies – Los Gatos Research and Thorleaf Research.
Flynn: NASA has been funding the development of three instruments, the first being a chemical sensor that uses a colorimetric technique – a pretty standard industrial detection technique – that is packaged in an underwater, deep-ocean configuration that allows us to use these technologies at full-ocean depth, which is about 3000 meters. As ocean water comes out of the Medusa system it is passed through a solid bed of a detection (colorimetric) chemical that changes color when it is in the presence of a specific target chemical. We use a fiber-optic spectrometer to analyze the color shift and make determinations about the concentrations of the species. We are primarily interested in magnesium, chloride, and iron-3. On the biological side, there are two instruments that we are currently developing. The first of these is an in situ fluorescence detector, which gives us the ability to look at the intrinsic fluorescent characteristics of cells that might be entrained in these flows that are coming from the deep sub-surface. Almost all bacteria have fluorescent signatures, meaning if you shine a certain wavelength of light on them they will fluoresce in a shifted wavelength of light. If you pick the right chemicals, the right targets, and the right spectrum, filters can be used to hit it with a very narrow band of light and pick up a very narrow band of light that fluoresces. We have primarily been using things like NADH and APP. This work primarily is being done at Utah State University and they have some very innovative algorithms that have been developed to get rid of background noise and to provide the ability to differentiate between signals. The idea, again, is that Medusa will collect samples while on the seafloor bottom and the flow is coming up through the system, and we want to know if there is biology in that flow. If there is biology in the flow, then we want to collect samples using the Medusa gas-type sampling system. In addition, it also gives us some limited ability to look at some metabolic intermediaries, and get some information as to whether these are known organisms or represent potentially new, unclassified organisms. The third instrument is a carbon isotope spectrometer. This unit, currently being developed by Los Gatos Research, gives us the ability to look at carbon 12 and 13 ratios, which are indicative of life. If you have, for instance, volcanic gas (carbon dioxide) coming from deep beneath the subsurface and it’s percolating up through the soil, if there is a zone of biology in the soil it will shift the carbon isotope ratios from what we know comes from geo-chemical sources. Then by analyzing the carbon dioxide in the fluid, we can get an understanding whether there is a deep, subsurface biosphere in that particular spot or whether the carbon dioxide is simply coming from geological sources. In addition, the instrument is highly sensitive and also can give us the ability to look at very narrow shifts in those carbon isotopes, which can be indicative of whether the carbon dioxide is coming from decomposed organic material or if it is in fact coming from geo-chemical sources deep beneath the surface. We can actually even infer some levels of mixing from those two sources. So, it’s a very powerful device. It’s also a spectral device, we use a technology called cavity ring-down spectroscopy, which is a system where you have two mirrors separated by a small distance, you fill it with the gas (de-gas the carbon dioxide out of the fluid) and then shoot a laser into this cavity and it bounces from mirror to mirror and you basically look at the time-dependant adsorption of the laser by the targeted isotopes of carbon. By measuring the decay rate – how many times it bounces back and forth and the decay of intensity during the bounces – one can infer the carbon isotope ratios. Inside the cavity, we see that the adsorption peaks of the carbon isotopes are pretty close together, which is a result of pressure. So, we’ve developed an innovative system (being developed by Thorleaf Research) that gives us the ability to drop down the pressure of gasses that we are degassing out of these ocean fluids from full-ocean depth pressure to one atmosphere (we want to run our sampling system at around one atmosphere). Medusa has
really been redesigned to facilitate the integration of these systems.
We’ve done this by instituting a peer-to-peer network-based system,
similar to a home computer. The reason why we have done this is because
we ultimately see this system as being an underwater observatory, which
is a system that would be deployed on the seafloor bottom and basically
left there for very long periods of time. Ultimately, there is the potential
to connect a whole network of these observatories using a fiber optic
network. This is our vision for the future use of this system. NTB: How is this system relevant to other NASA missions? Flynn: The technology is relevant to NASA is relevant because when we talk about searching for life on other planets it is somewhat analogous to what we’re doing here. For example, if you look at Mars or you look at Europa, it is clear that there is not a lot of energy on either of these planets for life forms to exist. So one should expect that the density of life that might be found is going to be very disperse, i.e. very small amounts of bacteria that grow very slowly because there just isn’t enough energy to support a really vibrant biosphere. The only way those types of systems can be detected is to extend the time duration of the observations. If you really want to look for change, you want to look for the generation of biological gases, carbon isotope shifts, and such. The Medusa system is one of the first in a series of NASA instruments being developed that’s designed with this ability – you can deploy the instrument on Mars and basically leave it there indefinitely to analyze certain locations where you may or may not have gas emanating from the subsurface environment or potentially a system that can be deployed into a Europan ocean and could stay there for decades, if need be, analyzing for change and the presence of biology. NTB: How do you retrieve the data once Medusa collects it? Flynn: The system in its present form, which will call the beta form of the instrument, is actually designed to have the ability to not only collect data but also to interpret the data. Not only do we collect biological samples and make intelligent decisions on what samples to collect, in addition we interpret the data and if the data is indicative of important information we have an automated release system that allows us to release the data set (the hard disk) and potentially the entire instrument with sample collections, which floats to the top of the surface and a radio beacon starts and we can go and retrieve it. Ultimately, we would like to tie this into a big National Science Foundation (NSF) project that is happening in the Juan De Fuca Ridge to put out a fiber optic array. Although the completion of this NSF project is probably decades away, we would be able to leave the Medusa on the seafloor permanently – we would never need to do a release because we would be able to send data back and forth using the array. On Europa,
there is up to 100 km of ice on top of an ocean, on top of a solid rock
core. So, the idea is that this instrument would have the ability to be
deployed in an automated fashion, go to the bottom of Europa, place itself
in relation to a potential hydrothermal system, analyze over years or
decades the samples that are coming out of this flow from the subsurface,
and then if it detects life, would then have the ability to re-deploy
itself to the surface and send a signal back to Earth that it had a positive
data set and then begin to transmit data. NTB: What are the commercial applications for Medusa? Flynn: There are definite commercial relevancies to this device and we have been pursuing some of them. For instance, the carbon isotope system is of particular interest to the petrochemical industry, because it gives them the ability to understand the reserves that they have, for instance reserves of methane. The system allows them to interpret what is going on in those environments, like where the methane is coming from and what the source of the methane is. We have also talked to some oil-field service providers about developing a down-hole system that would be a system that could actually be sent down an oil well, get into the reserve, and then interpret data. The bacterial fluorescent detector is actually an example of a system where we tapped into on going commercial activities. That system was originally developed by the Department of Defense (DoD) and the idea was to use it as a battlefield system where they could look out and scan the battlefield to determine whether or not there was a biological release. Later, it did find commercial success in the food industry as a remote contamination detector for food products. Some of the other systems have a lot of commercialization potential in the oceanographic area. So, there is not only many possibilities for commercializing this instrument, there also already has been a lot of work put into commercializing many of these instruments. Michael Flynn can be contacted at mflynn@mail.arc.nasa.gov
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