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Biofinder: A Remote Sensing Solution for Detecting Life

My prediction that we’re going to find evidence for exo-life around another star before we find it in our own Solar System is being challenged from several directions. Alex Tolley recently looked at the Venus Life Finder mission, a low-cost and near-term way to examine the clouds of the nearest planet for evidence of biology (see Venus Life Finder: Scooping Big Science). Now we learn of advances in a ten-year old project at the University of Hawai‘i at Manoa, where Anupam Misra and team have been working on remote sensing instruments to detect minute biomarkers. This one looks made to order for Mars, but it also by extension speaks to future rovers on a variety of worlds.

Image: This artist’s impression shows how Mars may have looked about four billion years ago. The young planet Mars would have had enough water to cover its entire surface in a liquid layer about 140 m deep, but it is more likely that the liquid would have pooled to form an ocean occupying almost half of Mars’s northern hemisphere, and in some regions reaching depths greater than 1.6 km. How can we best identify markers of early life, assuming they exist? Credit: NOVA Next / UH Manoa.

The challenge is immense, because the lifeforms in question may be tiny, and may have been extinct for millions, if not billions, of years. As Misra’s recent paper notes, organic chemicals formed by biology, or minerals produced by living organisms, are the kind of biomarkers research efforts have targeted. We’re talking about proteins, lipids and fossil residues, the detection of any of which on another planet would lock down the case for life off the Earth. Instruments that can sweep wide areas with sensors and deliver fast detection times are critical for invigorating the biomarker hunt.

Remote sensing is the operative term. Misra’s team have developed what they call a Compact Color Biofinder that, in the words of the paper, “detects trace quantities of organic matter in a large area at video speed.” Moreover, the device can operate from distances of a few centimeters up to five meters. The intent is to move quickly, scanning large areas to locate these biological tracers. The device draws on fluorescence, a short-lived signal that can be found in most biological materials, including amino acids, fossils, clays, sedimentary rocks, plants, microbes, bio-residues, proteins and lipids. According to the authors, fluorescence also figures into polycyclic aromatic hydrocarbon (PAHs) and abiotic organics, such as plastic or amino acids.

Misra, who is lead instrument developer at the Hawai‘i Institute of Geophysics and Planetology at the university, makes the case that these traces are still viable, and that the Compact Color Biofinder can tell the difference between mineral phosphorescence and organic phosphorescence in daylight conditions with measurement times in the realm of one microsecond. It can also distinguish between different organic materials. Says Misra:

“There are some unknowns regarding how quickly bio-residues are replaced by minerals in the fossilization process. However, our findings confirm once more that biological residues can survive millions of years, and that using biofluorescence imaging effectively detects these trace residues in real time.”

Demonstrating the fact is news that the device can detect the bio-residue of fish fossils from the Green River formation, a geological feature resulting from sedimentation in a series of lakes along the Green River in Colorado, Wyoming and Utah. The formation is thought to be between 34 and 56 million years old. The fish in question is Knightia spp, which untangles to several different species within the genus Knightia (spp stands for species pluralis, meaning several different species within the larger genus). The now extinct fish lived in freshwater lakes during the Eocene. The team examined 35 fish fossils, all of which still retained a significant quantity of bio-fluorescence.

Detection is from a distance of several meters and can be achieved over large areas, which should greatly accelerate the process of astrobiological detection on a planetary surface. From the paper:

To further test the detection capability of the Biofinder the camera lens was changed to a long working distance microscope objective, thus turning the instrument into a standoff fluorescence microscope. The same fossil was cut into several pieces to be imaged in cross-section (Fig. 1c). At the microscopic scale, fluorescence images (Fig. 1d) demonstrated the clear presence of organic material in the fossil by the characteristic fluorescence of organic matter detected using a 10× objective at a working distance of 54 mm. The brown color material has been known to paleontologists to be organic matter formed from residues of fish bones along with soft tissues20 and hence, we can say that the organic fluorescence comes from biological origin.

Image: This is Figure 1 from the paper. Caption: Biofinder detection of biological resides in fish fossil. (a) White light image of a Green River formation fish fossil, Knightia sp., from a distance of 50 cm using the Biofinder without laser excitation. (b) Fluorescence image of the fish fossil obtained by the Biofinder using a single laser pulse excitation, 1 µs detection time, and 3.6% gain on the CMOS detector. (c) Close-up white light image of the fish fossil cross-section using a 10× objective with 54 mm working distance showing the fish remains and rock matrix. (d) Fluorescence image with a single laser pulse excitation showing strong bio-fluorescence from the fish remains. Credit: Misra, et al., 2022.

So fluorescence imaging may join our toolkit for future rovers on other worlds, able to detect organisms that have been dead for millions of years by scanning large areas of terrain in short periods of time. The Biofinder detections were corroborated by a wide range of instruments, from laboratory spectroscopy analysis and scanning electron microscopy to fluorescence lifetime imaging microscopy.

Image: This is Figure 3 from the paper. Caption: Confirmation of carbon and short-lived biofluorescence in fish fossil. (a) SEM–EDS analysis of the fish fossil cross-section showing that the fossil contains considerable quantities of carbon in comparison to the rock matrix. The rock matrix is rich in silica and has more oxygen than the fish. (b) FLIM image of the fossil cross-section showing strong bio-fluorescence in the fish (shown as false-coloured green-yellow region) with a lifetime of 2.7 ns. Credit: Misra et al.

The upshot: Biological residues can last for millions of years, and standoff bio-fluorescence imaging as used in the Compact Color Biofinder can detect them. Remote sensing is heating up in astrobiological circles, and I should mention two other ongoing projects: WALI (Wide Angle Laser Imaging enhancement to ExoMars PanCam) and OrganiCam, both based on fluorescence detection. The work of Misra and team indicates the method is sound, and should be capable of being deployed for large landscape surveys on future lander missions. The fact that the technology does not introduce contamination likewise speaks to its utility, says Sonia J. Rowley, a co-author of the paper and the biologist on the project:

“The Biofinder’s capabilities would be critical for NASA’s Planetary Protection program, for the accurate and non-invasive detection of contaminants such as microbes or extraterrestrial biohazards to or from planet Earth.”

The paper is Misra et al, “Biofinder detects biological remains in Green River fish fossils from Eocene epoch at video speed,” Scientific Reports 12, Article number: 10164 (2022). Full text.

{ 19 comments… add one }
  • Alex Tolley June 28, 2022, 11:07

    The BioFinder can distinguish between biological and mineral fluorescence which is important. While the autofluoresce can detect the presence of organic material (mostly due to the aromatic rings), it cannot, as yet, identify the components of organic material. This can perhaps be best done using IR Raman spectroscopy. One can imagine the use of these 2 techniques to survey areas for organic material, locate it, and then characterize it, all without needing to take samples. For planets and moons with solid surfaces and atmospheres – Venus, Titan, one can imagine a drone like Inspiration or Dragonfly doing this type of work. Otherwise rovers crawling over the surface, and perhaps into lava tubes and caves will have to do. (As Inspiration demonstrated than it could fly in Mars’ very thin atmosphere, this might be the easiest way to survey such subsurface cavities for extinct or extant life.

    Organic material has remarkable longevity when preserved under the right conditions. Proteins have been recovered from dinosaur fossils. Organic material has even been detected in 350 my old crinoids.

    Fossils like the Knightia spp. shown in the OP need to be exposed by splitting the surrounding rock. That does require mechanical effort to separate the rock layers to expose the fossil. Finding the right rocks to open up requires an expert eye. Whether that can be done by an AI remains to be seen. What can be done is for the rover/drone to record its journey, transmit the video to Earth (or local crewed station) to be viewed, and the expert to select rocks to be returned to and carefully opened by tools on the vehicle.

    If those dark patches on the scarp faces of craters on Mars are due to subsurface meltwater, then examining the patches for organic material might just help determine is there is extant subsurface life on Mars, without the need to drill down into the regolith.

    • David June 28, 2022, 14:58

      Alex (or Anyone),

      Hydrothermal vents are known to exist on Mars. Mineral associated with such vents, like Quartz, have been found to have inclusions containing organic compounds associated with life. In know that to identify such compounds, the mineral is crushed and Mass Spectroscopy is then used. Has this idea been considered by anyone ? The advantage is that on Earth, evidence for life billions of years old have been found this way. Perhaps the issue is that these regions are too rough to traverse or land on.

      • Alex Tolley June 28, 2022, 17:35

        The quartz found on Mars by teh Spirit rover was inferred to be from an environment like a hot vent. So if Spirit found that rock, samples should be accessible, even if their location was not where the original vent may have been.

        Perseverance rover has the SHERLOC instrument that can detect organics. IDK whether this requires samples to be ground up or not, but it is possible that the dust from drilling for core samples could be used for this type of instrument if needed.

        Here is where autofluorescence might be useful, as the instrument could simply be pointed at the dust or edges of the sample borehole to see if organics can be detected. There is always a risk of contamination from the drill, so ideally observations should be made of undisturbed rocks, or those minimal disturbed by being split with an external strike.

      • Scott June 28, 2022, 19:26

        Yes, it’s been considered, but NASA has routinely ranked Tharsis Uplift landing sites as too risky. Putting a mass spec based biomarker detection system on the surface where it would actually generate some science ain’t gonna happen in the current risk averse environment.


  • Geoffrey Hillend June 28, 2022, 18:06

    I agree with Alex Tolley. Although some primitive life like cyanobacteria does have fluorescence, once it is fossilized, that changes. It becomes rock calcified silica, which needs a trained eye. X ray fluorescence might work, but not a laser unless one uses a laser spectrometer like the one in Curiosity and Perseverance which vaporize rock into sparks of light which can be viewed through the spectrometer and the computer analyzes the spectra by comparing it with a memory of different spectra and shades of light. .

    I don’t think it is going to be easy to find life anywhere. The problem with finding life one Mars, one that not anyone has mentioned or perhaps thought of yet is that our Sun was 27 percent less bright four billion years ago. Consequently, a lot of Mars ocean might be frozen at that time. It depends on the atmospheric pressure. An Earthlike one was possible then based on the amount of loss of CO2 from solar wind stripping. A vapor pressure would keep it warmer.

    Where one looks for life might make a difference. It would be nice to have an analysis of the water from one of the layers areas of the poles which was near the bottom of the layers of ice and dust, the oldest layer. Also at the equator where it was warmest. This idea does not rule out life, but it might be hard to find. It would be interesting to find oxygen in the polar ice samples. It would be a sign of photosynthesis and primitive life.

    The problem with finding life on Venus today is that it has been known over sixty years by the spectra seen through telescopes of Venus atmosphere that there is no free oxygen. This has been confirmed by the probes sent there. Without oxygen, there can be no life there today unless it does not use photosynthesis which is very unlikely which is why I recommend that any mission to search for life on Venus also include a lander. We could look at the oldest regions in Venus where fossils still might be found and certainly and at least evidence of water in it’s distant past. Source Wikipedia. The Geology of Venus, Tectonic Activity. A seismograph would be nice to detect Venus quakes and P and S waves to get an idea of the size of the liquid core since S waves bounce of the core, but P waves go through it, a process that has been recently used to detect the size of the core of Mars.

    I don’t think it will be easy to detect exoplanet life. I am biased against the idea that we will find any false positive of oxygen. I think it might be easy to see water from water vapor, and carbon dioxide.

  • Harold Shaw June 28, 2022, 19:14

    Would biological samples remain fluorescent after pulverization? If we could crack open rocks and find large fossils like the one shown, they wouldn’t need to be tested with the BioFinder. Microscopic and macroscopic fossils could be brought to the surface by drilling into rock. The resulting dust could then be tested or a probe could be lowered into the drilled hole and the sides tested.

  • Geoffrey Hillend June 28, 2022, 21:26

    That’s a good question. Silica and calcite might have fluorescence under ultra violet light. I searched it on google which shows that calcite fluoresces both with laser and UV. So do also fossils. Viewing the rock through a camera might help with identification.

  • Jeff Wright June 29, 2022, 2:54

    On hot-vents: I remember a steam devil one one side of a coke plant’s exhaust tower-and how a MN tornado had two vortices in a double helix. Might Mars lower gravity aid abiogenesis? It seems the geology allows for more delicate shapes-which might also play a role in vortex shedding..surface water coupling.
    Flakes of materials meaning a more refined French cooking approach than Earth molasses could start on its own…weeding out weak chemistries more easily spalled off Mars. This needs computer modeling.

  • Alastair Williams June 29, 2022, 3:55

    Personally I think the focus on Venus and Mars is unlikely to get far – the moons around Jupiter and Saturn are where we will find life, if there is any in the Solar System. The lifeforms there may not even be extinct.

    • FrankH June 29, 2022, 14:46

      Jupiter (Europa in particular) is probably going to be the most likely. The Saturn system shows signs of relatively recent cataclysmic events (Titan’s atmosphere, Enceladus’ energy source, Hyperion, the ring system), so while the environments may look friendly for life, it’s possible that not enough time has passed for life to start.

      I don’t feel that Mars ever had life, or that the conditions for life were sustained for long enough.

  • Geoffrey Hillend June 29, 2022, 16:29

    A spectrometer like x ray, infra red, visible light, laser, etc still gives more information than visible light fluorescence. Photos are also important. Speaking of Mars, I read the NASA article “Help NASA Scientists Find Clouds on Mars,” and one idea that might be overlooked is Jeans escape. Mars atmosphere was mostly lost by solar wind stripping because it does not have a magnetic field to deflect it. Recall Jeans escape takes precedence over the ideal gas law when one of the variables does not remain the same, but changes, so a different planet has a different escape velocity, so it takes more kinetic energy to propel a gas molecule to reach escape velocity with a planet with a larger gravity, than with one with a lower gravity and escape velocity. The brightness of the star matters also since that would also change the average temperature. Our Sun was 27 percent less brighter four billion years ago than it was today. Consequently, the temperature on the surface of Mars has steadily risen over billions of years which increased Jeans escape which becomes significant over time considering escape velocity, is based on the gravity and size of the planet. An Earth sized planet might not matter with 7 miles per second escape velocity, but Mars low gravity with 3.1 miles per second becomes significant. Jeans escape might be a planetary physics principles that was over looked.

    • FrankH June 30, 2022, 15:24

      Jeans escape is THE basic physics that controls atmospheric escape. Magnetic fields (or lack thereof) only reduce or enhance the effect. You can say that a lack of a magnetic field on Mars only enhances Jean’s effect, by letting the solar wind add energy to the upper atmosphere.

  • Geoffrey Hillend June 29, 2022, 16:33

    An increase in average surface temperature is an increase in intensity and the flux of solar radiation on the surface. An increase in temperature is an increase in the kinetic energy of atmospheric atoms and molecules.

  • Geoffrey Hillend June 29, 2022, 16:37

    Greater kinetic energy means that more molecules like water vapor reach escape velocity or at least the turbopause in the Martian atmosphere. There are also exposed to more ultra violet radiation there.

  • Ronald June 30, 2022, 1:05

    This just out: habitable conditions, including liquid water, on non-terrestrial (in particular super-earth, gas dwarf) planets;
    In Science Daily: https://www.sciencedaily.com/releases/2022/06/220627141456.htm

  • wdk June 30, 2022, 11:55

    A few days before this article appeared (28June22) there were some related reports that I have been slow to track down but of significance.
    One was related to the background organic carbon on Mars. Organic
    carbon being defined as bound with an atom or atoms of hydrogen.
    The other was related to the half life of amino acids in the current Martian environment.

    For the first it was noted that organic carbon deposits in target regions for bio exploration compare favorably with the toughest environments on the Earth’s surface ( e.g., Antarctic deserts). But on the other hand, organic compounds such as amino acids would decompose in exposure to the ultraviolet and other surface radiation at zero altitude current martian atmosphere in short periods. 20 million years might even be the half life at 2 meter depth. In such cases, an active vent might be a good target. It could cough up some amino acids from deeper depths, perhaps, but not necessarily any furthr evidence of life.

    Still, amino acids have shown up on carbonaceous meteorites. And if we had them from Mars, we would still have to debate whether they “arrived there” pre-processed or were the result of in situ events. The patterns of methane observation have not been satisfactorily accounted for yet. Maybe locating an active vent would address two birds with one stone.

    Regarding early Mars climate prior to “erosion” of water vapor into space, it might be worth taking into account the effects of CO2 or other gas constituents of the early atmosphere. CO2, if nothing more than molecular weight is considered (44) will have a longer half-life than H2O (18). 7 millibar pressure currently is at least on order of terrrestrial concentrations of CO2 ( 400 ppm, but Mars surface gravity about 38% ). And we already fret about our CO2 as a Greenhouse effect. The polar cap and other reservoirs could greatly increase those concentrations and warm periods of indefinite duration could result.
    Triggers might be rotational axis obliqity chances, precession effecting summer and winter, eccentricity or impacts. As it were a difference between geological or climatic punctuated equilibrium and gradualism.

  • Robin Datta June 30, 2022, 12:51

    Microbial life on earth has become ubiquitous including hard-to-get-at sites such as deep fissures in rock. On other worlds with formerly clement environments, if life or its remains is not readily found in accessible locations, less accessible sites should also be considered.

  • Geoffrey Hillend June 30, 2022, 16:44

    I got the turbopause idea from the National Geographic Magazine, January 1977 issue about Mars, the photos of the Viking Lander from the surface of Mars. I think it was a NASA scientist who wrote in that article that fast moving atmospheric tides can propel a gas molecule to the turbopause, the area where no more turbulence occurs in a couple a days in Mars atmosphere whereas on Earth that process takes a century. I not sure if this is correct since I don’t have that magazine anymore and I am using only my memory, but that is where I got the idea. NASA of course knows all the reasons why Mars lost it’s atmosphere and there is more than one cause. Further evidence will confirm this knowledge and I at sometime in the future a lander or astronauts might take a sample of the polar ice cap’s water ice. Solar wind stripping is the major cause, but Jeans escape also matters since a planet with less gravity has a lower escape velocity, so it is easy for a particular gas to escape. The weight of the gas matters since lighter gases are accelerated easier and faster at the same solar energy, the Jeans escape.

    Also Mars does not have any plate tectonics and has a thicker crust, so it lost it’s volcanism, so it’s atmosphere could not be replenished. Tidal forces on exoplanets in the life belt around red dwarf stars might be volcanically active and still have a an atmosphere since the Earth sized exoplanet has a large gravity.

    The D/H Deuterium/Hydrogen ratio also tells us that Mars has lost a lot of water through the splitting of water into oxygen and hydrogen. The D/H ration in Mars atmosphere is up to six times Earth’s. The heaver DH2O remains behind while the lighter H2O is lost. We also know that Mars had a much thicker atmosphere in the past from the O16/O18 ratio of oxygen isotopes which works on the same principle, the heaver oxygen with more neutrons gets left in the air while the lighter gas escapes. https://www.nasa.gov/feature/goddard/2019/mars-lost-atmosphere

  • stephen July 2, 2022, 10:07

    They could have a video camera with a microscope to detect movement. Inside the sample container it might be in stasis or hibernation so they could change the temperature and pressure to make it wake up, and they could keep watching it for a period of years since the organisms’ changes might be very slow.

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