The second talk in the science lecture series, “Are We Alone?” took place on Thursday, Jan. 12 at the University Theatre. The series, which aims to educate the public on recent astronomical discoveries and the methods being used to search for alien life, continued with a talk entitled, “Alternative Earths: How Earth’s Past Guides NASA’s Search for Life.” Attendees were welcomed with refreshments and raffle tickets at the event sponsored by UCR’s College of Natural and Agricultural Sciences and Alternative Earth’s Astrobiology Center.
Chancellor Kim A. Wilcox greeted audience members before the night’s program began. “Tonight we have one of the best faculty members on campus coming to talk to us about what we know, but as importantly, what we don’t know,” Wilcox said, before lecturer Timothy Lyons, professor of biogeochemistry and director of UCR’s Astrobiology Center, was introduced. Lyons is also the principal investigator of the UCR-led Alternative Earths Team of the NASA Astrobiology Institute.
He began by discussing the importance of studying Earth in the search for life on exoplanets. Extra-solar planets, or exoplanets, are planets beyond our solar system. “What’s so striking about them is the diversity and the sheer numbers,” Lyons said. The Kepler telescope has discovered over 1,000 exoplanets in the past year and there are now 4,696 exoplanet candidates, with 3,439 being confirmed. “The technology is so sophisticated that we can now detect things the size of Earth or even smaller,” Lyons explained.
Planets are now being detected that have the potential to be Earth-like and possibly habitable. “The combination of an Earth-like planet at the right distance around a star like our own sun is a great place to look,” Lyons said. The right distance that Lyons is speaking of would be in the habitable or “Goldilocks” zone, which is where our Earth resides. While liquid water is a possible indication of life, scientists are also searching for biosignatures that can further heighten that possibility. A biosignature is any detectable archive such as an element, isotope, molecule or fossil that could provide evidence of life. “As we explore exoplanets, what we’re really doing is trying to characterize their atmospheres, understand the composition of those atmospheres,” Lyons explained.
Lyons went on to discuss how exoplanets are discovered by NASA’s Kepler telescope, using a process in which the spacecraft watches for the dimming of starlight in order to account for the possibility of an exoplanet. However, the search for exoplanets may become a lot easier with a device called starshade that would provide direct imaging. “(It’s) the ability to look specifically at a planet and not have to filter out all of that energy coming from the star itself,” Lyons described.
The lecture then transitioned into a discussion about the origins of Earth and the types of atmospheres that could sustain life. Zircons, zirconium silicate minerals, are useful in determining these atmospheres. “These zircons are incredibly resilient so they can form billions of years ago and capture a chemical environment at that time and be found billions of years later and yield message of what was going on all those years before,” Lyons said. Zircons suggest that Earth may have had a protective magnetic field, a characteristic that Mars may not have had and resulted in the depletion of it’s atmosphere, as well as loss of water.
Much of this information is important when searching for life on other planets. “Now we’re thinking like exoplanet scientists. We’re looking at these model atmospheres of Earth through this period of time that I’m talking about,” Lyons said. Lyons ended the talk by suggesting that telescopes should be constructed to monitor lower levels of gases like methane and oxygen. “It’s likely that the first headline you’re going to see is that scientists detect methane and oxygen on a distant exoplanet and after much discussion suggested could be life, and so, that’s the way it’s going to go. And our good, old, home the Earth is the template for much of our understanding,” Lyons explained.
The lecture ended with a Q-and-A session and raffle giveaway. The next talk in the series, “Ocean Worlds: Missions to Icy Moons and Dwarf Planets,” will be given by Deputy Project Scientist Kevin Hand. The lecture will be held at the University Theatre on Wednesday, Feb. 1 at 6 p.m.