Dear friends,
I just finished writing three observing proposals for the Green Bank Telescope (GBT). Allocation of telescope time is typically a competitive process that includes a review of proposals by a panel of anonymous experts.
My first proposal involves observations of Venus, where one of the primary goals is to expand our high-precision measurements of length-of-day variations. The atmosphere of Venus is so massive that it can affect the spin rate of the planet. These changes are small but detectable when we use the Goldstone Solar System Radar in conjunction with the GBT. Our observations will enable stringent tests of hypotheses related to the superrotation of the atmosphere (approximately 60 times faster than the solid planet) or the existence of distinctive planetary-scale structures in the atmosphere that are stationary with respect to the slowly rotating surface. A second objective is to measure the slow precession of the spin axis, which is similar to the motion of a spinning top. This measurement is expected to yield the first empirical estimate of the size of the core of Venus. It is astonishing that we remain ignorant about such fundamental properties of our sister planet, a planet that may have billions of analogs in the Galaxy.
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I obtained this radar image of our sister planet Venus at the Green Bank Telescope while my thesis advisor, Dr. Donald Campbell, was transmitting with the Arecibo Planetary Radar.
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My second proposal describes observations of Europa and Ganymede, two satellites of Jupiter that were discovered by Galileo in 1610. These bodies are the primary targets of NASA and ESA spacecraft missions that are slated to launch in 2022. The interest in these bodies is considerable, in part because of the presumed existence of global oceans under their icy surfaces. In fact, we now tend to refer to these bodies as "ocean worlds." Our observations with Goldstone and the GBT will refine our preliminary measurements of the spin axis orientations of these bodies, which have never been measured since Galileo's discovery. Our estimates will provide a robust test of the ocean world hypothesis because the orientation of the spin of a solid body is different from that of a body with an outer shell that is decoupled from the interior. Our estimates will also enable tidal heating calculations and tests of models that describe the amazing tectonic features on these icy surfaces, all of which require precise estimates of the spin states.
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The volume of Europa's global ocean is probably a few times larger than the combined volume of all of Earth's oceans.
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My third proposal is the most relevant to this newsletter: it is designed to enable a continuation of our search for technosignatures in Spring 2019 during the fourth offering of the UCLA SETI course. We are proposing to examine 16 planetary systems around Sun-like stars near the plane of the Galaxy.
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Two weeks ago, Paul Pinchuk and I presented the results of our 2016 and 2017 searches during two half-day SETI sessions at the Committee on Space Research (COSPAR) meeting in Pasadena, CA. The meeting was well attended and we had an opportunity to exchange information about search strategies and results with our colleagues.
We are still in the process of analyzing the observations acquired by the students in the Spring 2018 course. The students presented preliminary results during the last week of classes and I was impressed by the depth with which the students described their results. The students also contributed multiple new software modules, including tools to identify signals in the neighborhood of a given candidate signal, machine learning algorithms, and a graphical user interface that facilitates the creation of training sets for machine learning algorithms. During the last week of classes, we also recorded some of the students on video, and we may create another video to assist with our fundraising efforts. We would like to expand our current search to observe hundreds of planetary systems each year, and we are eager to secure stable funding for graduate students who are interested in contributing to the search.
NASA recently issued two documents regarding the search for technosignatures, which is almost certainly the result of a congressional directive. Representative Lamar Smith (R-Texas) authored a bill that encourages NASA to "partner with the private sector and philanthropic organizations" to search for technosignatures. The fate of the bill is uncertain, but the language in the two NASA documents mirrors the language in this bill. The first document describes a technosignatures workshop that will be held in September 2018. The second document is a request for information regarding existing and planned searches for technosignatures. While I am thrilled that technosignatures are finally being discussed at our space agency, I am troubled by the partnership language. In no other context have I seen a federal agency rely on identifying philanthropic or private sector partners to enable a scientific investigation. If the investigation has merit, the logical approach is to enable it by providing a budget for it, not by suggesting a search for funding partners. It looks like we are still far from a standard funding model for SETI. Like many of my colleagues, I aspire to nudge attitudes in a positive direction. In all of my talks, proposals, and publications, I strive to use language that puts the search for technosignatures on at least equal footing with the search for biosignatures.
Warm regards,
Jean-Luc Margot
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