Machine learning technologies in the search for extra-terrestrial intelligent life


An artificial neural network has identified a square structure within a triangular one in a crater on the dwarf planet Ceres, with several people agreeing on this perception.

The result of this intriguing visual experiment, carried out by a Spanish neuropsychologist, calls into question the application of artificial intelligence to the search for extra-terrestrial intelligence (SETI).

Ceres, although the largest object in the main asteroid belt, is a dwarf planet.

It became famous a few years ago for one of its craters: Occator, where some bright spots were observed, leading to all manner of speculations. The mystery was solved when NASA’s Dawn probe came close enough to discover that these bright spots originated from volcanic ice and salt emissions.

Now researchers from the University of Cadiz (Spain) have looked at one of these spots, called Vinalia Faculae, and have been struck by an area where geometric shapes are ostensibly observable.

This peculiarity has served them to propose a curious experiment: to compare how human beings and machines recognize planetary images.

The ultimate goal was to analyse whether artificial intelligence (AI) can help discover ‘technosignatures’ of possible extra-terrestrial civilizations.

“We weren’t alone in this, some people seemed to discern a square shape in Vinalia Faculae, so we saw it as an opportunity to confront human intelligence with artificial intelligence in a cognitive task of visual perception, not just a routine task, but a challenging one with implications bearing on the search for extraterrestrial life (SETI), no longer based solely on radio waves,” explains Gabriel G. De la Torre.

The team of this neuropsychologist from the University of Cadiz, who has already studied the problem of undetected non terrestrial intelligent signals (the cosmic gorilla effect), now brought together 163 volunteers with no training in astronomy to determine what they saw in the images of Occator.

They then did the same with an artificial vision system based on convolutional neural networks (CNN), previously trained with thousands of images of squares and triangles so as to be able to identify them.

“Both people and artificial intelligence detected a square structure in the images, but the AI also identified a triangle,” notes De la Torre, “and when the triangular option was shown to humans, the percentage of persons claiming to see it also increased significantly.”

The square seemed to be inscribed in the triangle.

These results, published in the Acta Astronautica journal, have allowed researchers to draw several conclusions: “On the one hand, despite being fashionable and having a multitude of applications, artificial intelligence could confuse us and tell us that it has detected impossible or false things,” says De la Torre, “and this therefore compromises its usefulness in tasks such as the search for extra-terrestrial technosignatures in some cases. We must be careful with its implementation and use in SETI.”

This shows the image of Ceres

Picture of the Vinalia Faculae region of Ceres obtained by NASA’s Dawn spacecraft on July 6, 2018 at an altitude of about 58 kilometres. Can a square and/or a triangle be seen? Image is credited to NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

“On the other hand,” he adds, “if AI identifies something our mind cannot understand or accept, could it in the future go beyond our level of consciousness and open doors to reality for which we are not prepared? What if the square and triangle of Vinalia Faculae in Ceres were artificial structures?”

Finally, the neuropsychologist points out that AI systems suffer from the same problems as their creators: “The implications of biases in their development should be further studied while they are being supervised by humans.”

De la Torre concludes by acknowledging that, in reality, “we don’t know what it is, but what artificial intelligence has detected in Vinalia Faculae is most probably just a play of light and shadow.”

In the interdisciplinary fields of geobiology, astrobiology, and NASA missions, one of the most important questions yet to be addressed is: What are the best exploration strategies for finding extraterrestrial life? Biosignatures (e.g., elemental, mineral, textural, or other scientific evidence of life) have mappable distributions at microscopic (<mm) to macroscopic (>km) levels.

These scales of investigation can be linked via probabilistic models, statistical representations that represent dependencies permitting inference and prediction between the scales (Thompson et al., 2018bChan et al., 20182019).

Based on observations of Earth analogs, it is expected that extraterrestrial life also requires habitable environments – places where environmental conditions are conducive to sustain life (Preston and Dartnell, 2014Cockell et al., 2017).

Biosignatures are the records and/or remnants of life that must be preserved (study of taphonomy) in order to be detected (e.g., Westall et al., 2015).

Detection of biosignatures requires tools and technology. The intersection of all these conditions (biosignature, preservation, detection, and technology) leads to the optimum chances for finding extraterrestrial life (Figure 1).

In particular, harnessing the power of information technology (e.g., statistical measures and computer vision in an IT platform) grouped with scientific studies across multiple scales has great potential.

For example, geostatistical modeling of relationships of habitable environments across scales and locations (e.g., Thompson et al., 2011), would help identify quantitatively-determined “sweet spots” to explore for extraterrestrial life (Candela et al., 2017) versus the primarily ad hoc methods in use today.

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Scientific efforts to explore for biosignatures must link themes of habitability, preservation, and detection of biosignatures. The best potential for exploration targets lies at the intersection of science studies, and data-enabled cyberinfrastructure technology that can provide multi-scale data management and visualization.

The relative “sweet spot” for habitability in this context relies on the preservation of biosignatures within minerals that have been in place since their original formation, as minerals are typically more robust to change over geologic time versus organic molecules.

Rocks that were formed or had contact with fluids via ancient aqueous processes can contain biological information that future surface rovers can access. The notion of a habitable zone where records of former biotic activity once existed relies on the probability of defined biological and chemical variables.

Quantification of the relationships among environmental variables (e.g., pH, salinity, permeability, etc.) that promote microbial life existence and preservation of biosignatures over geologic time on Earth, can then be used to quantify the probability of finding evidence of life at analogous sites on Mars.

Thus, this perspective paper proposes three focus strategies to search for extraterrestrial life on Mars where there are well established NASA missions with imagery and analysis data, and lithologic systems similar to Earth:

(1) authigenic minerals (in place or in situ) as surface to near surface minerals;

(2) context of habitable environments across multiple scales with quantification of geospatial relationships; and

(3) use of cybertechnology and computer vision to help map and locate the most promising habitable environments for exploration.

We further address what kinds of tools can be employed to address research in these collective areas.

Over the last few decades, overwhelming orbital evidence has confirmed the abundance of authigenic minerals on Mars. Authigenic minerals present a key location for preserving evidence of past life on other planets (Douglas, 2005).

On Earth, environments where authigenic minerals form in the presence of water, these minerals are commonly associated with evidence of microbial life (e.g., Allen et al., 2004Douglas, 2005Fernández-Remolar and Knoll, 2008Lowenstein et al., 2011Preston et al., 2011Allwood et al., 2013Jahnke et al., 2014Parenteau et al., 2014Williams et al., 2015).

Examples include cementing minerals forming where kinetics are facilitated by the metabolism or activities of microbes at sediment-fluid interfaces, or places where precipitation of minerals is associated with gradients in fluid chemistry where the right conditions exist to preserve the microbes that live in the substrate.

A challenge for astrobiological explorations is that the mismatch between the scales of these observations— from the macroscale satellite mineralogical observations to the microscale microbial observations— limits the applicability of our astrobiological understanding as we search for records of life beyond Earth.

Here we present a concept of how future research might better bridge and link scales of observation by combining interdisciplinary geobiological data-driven analyses with new technologies: computer vision, including algorithms which automate and standardize object detection and quantify scene texture, and information technology more generally, which can combine and visualize disparate datasets in a statistically rigorous manner.

The potential outcomes can generate valuable exploration maps to help narrow the search for extraterrestrial life, particularly relevant to Mars environments and mineralogy.

Key advantages to integrated data management of astrobiology communication are:

(1) the ability to increase, facilitate, and integrate communication and datasets of multiple subdisciplines;

(2) limiting replication of data collection or unfruitful research paths because of shared, centralized data repositories; and

(3) verification of important ideas and trends through data mining and data discovery.

Search for Extraterrestrial Life

The last decade of planetary exploration has marked a new era of unprecedented discoveries that provide multiple lines of evidence for a rich history of water and preservation of sedimentary environments on Mars, and thus the potential for past or present life (e.g., Grotzinger and Milliken, 2012Grotzinger et al., 2014McLennan et al., 2014Freissinet et al., 2015).

Concurrently, there is growing evidence for water on other Earth-like planets orbiting other stars [e.g., from the Hubble Telescope and Kepler Missions (Kasting and Harman, 2013)]. Icy worlds with putative sub-surface liquid layers: Europa, Enceladus, and potentially Ceres also present new targets for astrobiologic investigation.

A subsurface ocean has long been hypothesized for the Jovian satellite Europa and recent observations of possible geysers from Europa’s south pole (Roth et al., 2014) are strong evidence of possible subsurface liquid water. Cassini observed geysers emanating from the Saturnian moon Enceladus (Porco et al., 2006).

Ceres observations from Dawn and Dawn combined with modeling indicate a possible past sub-surface ocean (Ermakov et al., 2017).

Among the most irrefutable proxies for extraterrestrial water are the authigenic minerals that waters leave behind in shallow subsurface critical zones (Brantley et al., 2007Grant and Dietrich, 2017), where interactions between the lithosphere, hydrosphere, atmosphere, and potential biosphere all converge.

It is crucial to understand how the presence of life can be preserved and detected as a biosignature in authigenic minerals in Earth environments so that the astrobiology community can develop detection criteria, and apply this knowledge to our explorations elsewhere in the universe.

Potential Habitats on Mars

Widespread findings of fluid activity on Mars have been recorded through mineralogical, sedimentological, and geochemical evidence (McLennan et al., 2005Bibring et al., 2006McLennan and Grotzinger, 2008Andrews-Hanna et al., 2010), which indicate potentially habitable environments on the planet.

The assessment of past and present habitability on both a local and regional scale requires quantifying geologic features analogous to the resolution being investigated. Remote sensing instruments on orbiters, landers, and rovers sent to Mars have given scientists in-depth access to visual, mineralogical, and geochemical data at varying perspectives— allowing for a relatively complete geologic picture of the planet.

Within the Martian rock record, evidence of biosignatures— if present— may have a low preservation potential due to factors such as surface ultraviolet and gamma radiation, oxidation, and extreme temperature fluctuations (among other issues). However, areas not affected by these issues, due to recent exhumation for example (Farley et al., 2013), can be identified.

It has been proposed that Mars in its beginning stages was a warmer and wetter planet (e.g., Farmer and Des Marais, 1999), when habitable regions may have been more widespread. Much work with the “follow the water” motto has suggested that if life existed on the surface of Mars in any fashion, it would have occurred in the Noachian and Hesperian periods where layered clays and sulfates originally formed (Tosca and Knoll, 2009Hurowitz et al., 2010Michalski et al., 2013).

Should microbes exist or have existed on Mars, given conditions of surface radiation, changes in global temperatures, and stripping of surface layers by eolian processes?

It is likely that microbial life might reside in the subsurface, at a depth and location stable for protection from harsh surface conditions (Perl et al., 2013).

On Earth, the restrictions on the survivability of microbial life give us insight into the possible extent of planetary microbial life (Rothschild, 1990). A wide range of microbial-scale terrestrial life thrives in non-ideal environments and extreme conditions (Nealson, 1997Allen et al., 2004Douglas, 2005Fernández-Remolar and Knoll, 2008Lowenstein et al., 2011Allwood et al., 2013Jahnke et al., 2014).

The ability for microbes to exist and thrive, within an environment, as well as the existence of evidence of their activity in the form of organic matter or other biosignatures, suggests a favorable range of variables (i.e., a habitable environment) in place during the course of specific microorganism lifetimes. For example, the presence of authigenic minerals (e.g., sulfates, clays, etc.) over wide areas (Ehlmann et al., 2009Michalski et al., 2013Arvidson et al., 2014) observed via satellite (e.g., CRISM) on a macroscale provide evidence of widespread ancient aqueous alteration and diagenesis.

This broad scale of observation can identify locations with water-related history that may have created favorable zones for biosignature preservation as well as regions that have experienced extensive diagenesis that may overprint these signatures. Indications of biosignature preservation at the mesoscale can be sought using tools on landers or rovers such as the MER Pancam and MSL Mastcam at an outcrop perspective (Berelson et al., 2011Mata et al., 2012Pepe-Ranney et al., 2012).

Finally, when a rover encounters such authigenic minerals within its path, detection of Martian biosignatures on a microscale [e.g., MER (Mars Exploration Rover) Microscopic Imager (MI), MSL Mars Hand Lens Imager (MAHLI)] is possible. In this nested fashion, cues at the higher levels guide the investigation to the “needle in a haystack” of probable biosignatures.



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