SETI Institute Weekly Colloquium - Upcoming Speakers
It is well known that New Zealand hosts spectacular hot-springs associated with a live super-volcano. Less well known is that these geothermal systems are rapidly mineralizing, entombing within silica a biota adapted to high temperatures, and thus serving as an extreme environment analog in the continuing search for the earliest signs of life on Earth and potentially other planets, such as Mars. This hypothesis stems from the following observations – the deepest roots of today’s “Tree of Life” constitute heat-loving microbes in hot springs; some Precambrian settings for early life were silica-rich and hydrothermally influenced; and siliceous deposits recently found by Martian rover Spirit are interpreted as hot-spring related.
The problem in trying to peer back into “deep time” on Earth is that the very old rocks which may contain the earliest traces of life also tend to be very “beaten up” by later geological events. It can be difficult to prove both biogenicity and original environmental setting in altered rocks billions of years old. Hence, Kathleen Campbell’s research examines siliceous hot-spring deposits to track the integrity of their fossil preservation through time. This method allows us to follow microbes as they “turn to stone” and to examine their history far back into the geological record, thereby fine-tuning studies on the recognition of early terrestrial life. The research has led to discovery of giant, Yellowstone-style, paleo-geothermal systems in the Late Jurassic (150-million-year-old) of Patagonia, Argentina. It also has confirmed hydrothermal signatures in fossil microbe-rich, 3.33 billion-year-old shallow marine rocks of South Africa.
Our understanding of the formation of the solar system has undergone a revolution in recent years, owing to new theoretical insights into the origin of Pluto and the discovery of the Kuiper belt and its complex dynamical structure. The emerging picture is one of dramatic orbital migration of the planets in the early history of the solar system, driven by interaction with the primordial Kuiper belt, which produced the final solar system architecture that we live in today. The evidence is all over the solar system, as close as the Moon and as far away as Pluto and the remnant Kuiper belt. Dr. Malhotra will review this new view of our solar system's history, describe the astronomical evidence, and critically assess current theoretical models.
In 1990, at the request of Carl Sagan, Voyager 1 turned and took a picture of Earth from a distance of 6 billion kilometers. This produced the famous “pale blue dot” image of our planet. Several mission concepts are being studied to obtain similar images of Earth-like exoplanets (exo-Earths) around other stars. It is commonly thought that directly imaging a potentially habitable exoplanet requires telescopes with apertures of at least 1 meter, costing at least $1B, and launching no earlier than the 2020s. A notable exception to this is Alpha Centauri (A and B), which is unusually close for a Sun-like star. A ~30-45cm visible light space telescope equipped with a modern high performance coronagraph is sufficient to resolve the habitable zone at high contrast and directly image any potentially habitable planet that may exist in the system.
Dr. Belikov will describe the challenges involved with direct imaging of Alpha Centauri planetary systems with a small telescope and how new technologies currently being developed can solve them. He will also show examples of small coronagraphic mission concepts currently being developed to take advantage of this opportunity, and in particular a mission concept called “ACESat: Alpha Centauri Exoplanet Sattellite” submitted to NASA’s small Explorer (SMEX) program in December of 2014.