Over sixty years ago, the first search for extraterrestrial intelligence (SETI), known as Project Ozma, was conducted. This campaign was led by legendary astronomer Frank Drake, which relied on the Robert C. Byrd Green Bank Telescope (GBT) in West Virginia to listen to Tau Ceti and Epsilon Eridani for any signs of radio transmissions. Since then, the field of SETI has become more sophisticated thanks to more advanced radio telescopes, improved data analysis, and international collaboration. In the coming years, SETI will also benefit from advances in exoplanet studies and next-generation instruments and surveys.
In addition to examining exoplanets for signs of technological activity (aka. “technosignatures”), there are also those who recommend that we look for them here at home. Examples include the Galileo Project, which is dedicated to studying interstellar objects (ISOs) and unidentified aerial phenomena (UAP). There’s also the Penn State Extraterrestrial Intelligence Center, a research group dedicated to advancing SETI through the search for technosignatures. In a recent paper, they explain how future SETI efforts should consider looking for extraterrestrial technology in our Solar System.
The PSETI Center consists of researchers from Penn State University, the Blue Marble Space Institute of Science (BMSIS), the SETI Institute, the Planetary Science Institute (PSI), NASA’s Goddard Space Flight Center, Jet Propulsion Laboratory (JPL), and multiple universities . The paper they recently authored was the subject of a report titled “Opportunities for Technosignature Science in the Planetary Science and Astrobiology Decadal Survey,” presented at the First Penn State SETI Symposium – which took place from June 27th-30th.
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For the entirety of its history, the field SETI has been predominantly focused on observing distant star systems and galaxies for signs of technological activity. These surveys have all searched for signs of radio transmissions since it is the most effective communication method grounded in well-known physics (by our standards). But in the coming years, SETI researchers hope to cast a wider net and search for other means of communication – such as directed energy, neutrinos, and even gravitational waves. These and other possibilities were outlined in NASA’s Technosignature Report, released in 2019.
In addition, there is a growing movement among SETI researchers that want to expand the search for extraterrestrial intelligence (ETI) here at home. Dr. Jacob Haqq-Misra, the Senior Research Investigator at the Blue Marble Space Institute of Science and the report’s lead author, is one such person. Haqq-Misra’s research is focused on the conditions that allow life to emerge and thrive in the universe and the possibility of detecting life on other planets through signs of biological (“biosignatures”) or technological activity. As he told Universe Today via email:
“Most SETI searches have focused on looking for technosignatures in other star systems, [while] Only a handful have looked for technosignatures in our own Solar System. We cannot yet rule out the possibility of technosignatures in the Solar System, so it would be worthwhile to look.”
For years, Haqq-Misra’s work has also focused on the types of technosignatures we should be looking for. This included a NASA-funded study he conducted in 2020 alongside Prof. Adam Frank of the University of Rochester, Avi Loeb and Manasvi Lingam from the Harvard & Smithsonian Center for Astrophysics, and Jason Wright from Pennsylvania State University. This study was aimed at looking for traces of chlorofluorocarbons (CFS) – specifically tetrafluoromethane (CF)4) and trichlorofluoromethane (CCl3F) – in exoplanet atmospheres and large arrays of solar panels.
Earlier this year, Haqq-Misra teamed up again with Frank, Wright, Lingam, and other colleagues to author a study about how the James Webb Space Telescope (JWST) could search for extraterrestrial civilizations by looking for signs of atmospheric pollution. But as Haqq-Misra expressed, SETI research also needs to expand to consider technological activity and objects that could be here in our Solar System. Such efforts have received a boost in recent years, thanks to the interstellar objects (ISOs) like ‘Oumuamua (which flew by Earth in 2017) and 2I/Borisov, detected two years later.
The detection of these objects confirmed what astronomers had suspected for some time, which is that ISOs enter the Solar System on a regular basis. Other research showed that some of these visitors are periodically captured by the Solar System and even suggested where some of them could be found today. Last, but not least, multiple proposals have been made since 2017 for missions that could rendezvous with ‘Oumuamua or intercept future ISOs and retrieve samples from them. If even one of these ISOs were artificial in origin, the scientific returns would be immeasurable.
If there are any Von Neumann probes in the Solar System – especially in the Main Asteroid Belt, the Kuiper Belt, and the Oort Cloud, where they would be hardest to detect – then relatively low-cost missions to search for them could provide similar returns . Haqq-Misra described what form these missions could take and how they might look for possible technosignatures:
“Orbiters, rovers, and probes that explore planetary bodies would be well-suited to constrain the presence of technosignatures on surfaces. Missions that observe small bodies such as asteroids and Kuiper Belt Objects would be ideal for looking for free-floating or orbiting artifacts in space. Ground- and space-based observatories might also be able to help with the search.”
These goals are consistent with the Planetary Science and Astrobiology Decadal Survey (2023-2032) drafted by the National Research Council (NRC) and released on April 19th, 2022. The Survey recommends several missions for the coming decade, like a Uranus Orbiter and Probe (UOP), an Enceladus orbiter and lander, and the crewed exploration of the Moon and Mars. An ISO intercept mission is also recommended, like the Comet Interceptor mission the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) are developing. As is indicated in the Survey:
“It is expected that in the coming decade, the rate of ISOs will increase speed. By discovering and characterizing additional ISOs, we will be able to compare them to the small body populations in the Solar System, and potentially constrain their birthplace.” Haqq-Misra and his colleagues note in their report that such a mission would also provide opportunities to constrain the presence of technosignatures on ISOs. As he explained, this would require no changes in the mission architecture or instrumentation:
“We are encouraging scientists and mission planners to consider the kind of technosignature science they can already do with their existing Solar System exploration program. Our report highlights a number of ways in which the recommendations of the Decadal Survey could advance technosignature science without needing to add any new instrumentation. For example, the ongoing Mars Exploration Program can place constraints on technosignatures on the surface of Mars by analyzing the high-resolution images that arise from other science on Mars.”
The goals of the PSETI report are also consistent with those of the Galileo Project, which will rely on astronomical, atmospheric, and space-based observations (combined with machine learning algorithms) to characterize ISOs and UAFs. The Project will rely on instruments like the Vera C. Rubin Observatory (VRO), which will detect ISOs as they enter our Solar System (at a rate of a couple per month) once it begins its Legacy Survey of Space and Time (LSST) . Alongside the many next-generation observatories that will be operational soon, the number of known ISOs is expected to increase exponentially.
In the meantime, Haqq-Misra and his team hope that their paper will inspire aspiring SETI researchers and veterans in the field to look beyond traditional boundaries. With some simple modifications, missions destined for locations throughout the Solar System in the coming years could also become frontline SETI missions. As Haqq-Misra summarized:
“We hope that our report will encourage scientists, mission planners, and administrators to consider the relevance of technosignature science to their existing and planned missions. We have many capabilities for constraining the prevalence of technosignatures in the solar system, and so it is worth considering the possibility as we continue to explore the Solar System.”
Throughout our Solar System, there are countless places where defunct extraterrestrial spacecraft might be lingering. According to recent research, ISOs captured by the Solar System are most likely to be found between the orbits of Jupiter and Neptune. As for functioning probes and Von Neumann machines, the smart money says they would be beyond the orbit of Neptune, residing in the Kuiper Belt and the Oort Cloud. For all we know, there could be dozens of probes in our Solar System that are looking for biosignatures and technosignatures themselves!
Further reading: arXiv