A cosmic perspective with Jill Tarter of SETI

Jill Tarter thinks that Craig Venter and Daniel Cohen may not have been bold enough when they declared in 2004 that the 21st Century would be the century of biology.

Jill Tarter

The SETI Institute’s Jill Tarter spoke recently at the Rose City Astronomers in Portland, Oregon. (Photo: Greg Scheiderer)

“I think the 21st Century is going to be the century of biology on Earth—and beyond,” Tarter declared during a talk at last month’s meeting of the Rose City Astronomers in Portland, Oregon. Tarter, the Bernard M. Oliver Chair for SETI at the SETI Institute and former director of the Center for SETI Research, thinks there are many ways we might find extraterrestrial intelligence. We might discover it through biomarkers or even artifacts in our own solar system. We could assay the atmospheres of exoplanets looking for biosignatures. We could spot alien “work product” such as structures or signs of engineering. We might even export it, traveling to the Moon, Mars, or even other star systems.

“I think life beyond Earth is a good bet in this 21st Century,” Tarter said, “and when you begin to think about that kind of thing, you really have to reorient your point of view, your perspective. You have to start talking about here and now in a different way, a much bigger point of view, a cosmic perspective.”

Tarter feels that our perspective has changed much since the advent of the space age. Photographs like the Apollo 8 Earthrise or “selfies” by Voyager and Cassini have helped make that happen. We’ve also looked far into the past in viewing distant galaxies.

In the time we’ve been involved in SETI, Tarter says there have been two gamechangers: extremeophiles and exoplanets.

Earthrise

Photos from Space, such as Earthrise by astronaut Willam Anders from Apollo 8, have changed our global perspective. (Photo: NASA)

“Extremeophiles are life as we did not know it until a just few decades ago,” she said, “thriving in places that we once thought completely hostile to life, and they are now illuminating the amazing possibilities for life on our own planet by suggesting more potentially habitable real estate within our solar system and out into the cosmos.”

Similarly, this discovery of thousands of exoplanets has given us more places to look for life.

“Today we know that there are more planets than stars in the Milky Way, and that’s a fundamental change in our perspective,” Tarter said. “When I was a student we knew of nine planets—then lost one!—and didn’t know whether planets would be plentiful around other stars.”

“There is more potentially habitable real estate out there than we ever imagined,” she added, stressing the potential. “We have no idea whether any of it is, in fact, inhabited, but that’s what this century is going to tell us.”

Tarter noted that a big assumption of SETI is that since our technology is visible from a distance, that alien technology might be as well. So we’re looking for something engineered, not a natural occurrence of astrophysics.

“Whether or not SETI succeeds with its optical, infrared, radio searches for signals is going to depend on the longevity of technologies,” Tarter explained, “because unless technologies, on average, last for a long time, there are never going to be two technologies close enough in space to detect one another and coeval in time—lined up at the same time in this ten billion year history of the Milky Way galaxy.”

Tarter said that, in 50 years of SETI, we’ve searched an amount of the cosmos that compares to a 12-ounce glass of water out of the total of Earth’s oceans, so it’s not so surprising that we haven’t yet caught a fish. She adds we’ve been limited by our technology.

“We are beginning to build tools that are commensurate with the vast size of this search, and we understand that the ocean is vast and we are still very, very motivated to go and find what might be out there,” Tarter said. The Allen Telescope Array is a big part of that; you can follow the search at setiquest. There are dozens of other instruments that may provide data to help with SETI, and more than a half-dozen on the drawing boards for the next decade or so.

“This is a hard job,” Tarter said. “This is a lot of very difficult technology to get this job done.”

“Whether or not SETI succeeds in the near term, it has another job to do,” Tarter concluded. “Whether or not it ever finds a signal, it has another job to do. And that is holding up a mirror to all of us on this planet and showing us that in that mirror, when compared to something else out there, we are all the same. Talking about SETI, thinking about SETI, listening to talks about SETI, helps to transfer and to encourage this cosmic perspective. It helps to trivialize the differences among us.”

Tarter encouraged everyone to go home and set their discriptions on their social media profiles to “Earthling,” and to start thinking and acting from that perspective.

“SETI is a very good exercise at working globally to solve a problem,” she said, “and there are many problems that we are going to have to solve quickly in the near term, and do so as a global community.”

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Celebrating three years of Astronomy on Tap Seattle

Astronomy on Tap Seattle observed its third anniversary last month, and celebrated by breaking format, with updates on talks from the past year and some new tidbits of information.

One of the fun new items was a story by Dr. James Davenport about how he helped convince NASA to use the Kepler space telescope to take a selfie of Earth.

“This is a personal story,” Davenport explained. “This is a story about an image that we asked NASA to take, and they were kind enough to take it.”

It took more than a year of cajoling, using the usual bureaucratic channels and also social media campaigns to get the shot.

Selfie from space

Selfie from space: Earth as observed by Kepler in December. (Image: NASA)

“We guilted them into taking this picture that we wanted for no other value than just to have this amazing image,” Davenport said. He noted that NASA has a long tradition of taking photos of the home planet, starting with the “Earthrise” photo from Apollo 8 and going through the “Pale Blue Dot” image from Voyager and the more recent pic of Earth from Cassini at Saturn.

The Kepler telescope usually points away from Earth, but sometimes NASA moves the aim to look at a different part of the sky, and that’s when Earth can move through the scope’s field of view. This happened on December 10, 2017, and that’s when Kepler got this shot. Now, Kepler usually looks a dim objects that are far away—a typical exposure is about 30 minutes. This isn’t the best setup for taking a photo of Earth from about 94 million miles.

“We expected it to look like a bright mess,” Davenport said. “We were not disappointed.”

It’s a personal story for Davenport because he was doing an entirely different thesis project for his Ph.D. program when Kepler came on line. He was so excited about the hunt for exoplanets that he ditched his other thesis and started working with Kepler.

“It represented a huge turning point in my career,” he said.

Polarimetry

Back in September Kim Bott gave a talk about how she and other astronomers are using polarimetry to try to figure out if exoplanets are habitable or inhabited. Since then she’s done some actual modeling of Venus at various phases to see if polarimetry can tell us what we need to know.

The short answer appears to be no, at least for right now. The instruments simply aren’t senstive enough to detect the changes in light wiggle that might reveal a variety of indicators.

“It’s just a couple orders of magnitude,” Bott explained, “so something that we might be able to obtain within the next decade” as the technology improves.

Trappist 1

The planets around the star Trappist 1 have attracted a lot of interest since they were discovered beginning in 2015. There are seven planets in all orbiting this red dwarf star; they’re all roughly the size of Earth, and three of them orbit within the star’s habitable zone.

Trappist-1 system“These are planets that could be a lot like Earth, that could potentially support life,” said Dr. Rodrigo Luger, adding that this is an active area of research. Luger said it’s interesting that all seven planets are in orbital resonance.

“There’s a very distinct pattern linking the orbital periods of all seven planets,” he said. Interestingly enough, this resonance and the gravitational influence the planets have on each other makes the transit times of the planets change from orbit to orbit.

“It’s just like when you’re at the bus stop here in Seattle,” he explained. “Sometimes the bus comes early, sometimes it’s on time, sometimes it’s late. Transits are the same way.”

This gives astronomers a lot of information about the system.

“By studying the transit time variations you can actually get the mass of the planets because you know how strong their gravity is,” Luger said. “Because of the geometry of the system we can get the radius of the planets—the size when it transits the star—and by doing some clever numerology and math we can figure out their mass. If you have the radius and the mass you actually have the density, so you have an idea what these planets are made of.”

It turns out that the Trappist planets mostly appear to be of lower density than Earth and Venus. This could mean that the planets have large amounts of water or large hydrogen atmospheres.

“These planets are going to be studied a ton in the next decade to figure out if in fact they are habitable,” Luger said.

Astronomy on Tap Seattle co-founder Brett Morris noted that much future study of exoplanets was to have been done by the James Webb Space Telescope, but the recent decision to delay the launch of that instrument has been disappointing to many.

“That affected some people a lot,” Morris said. “Some of those people were me!”

When the announcement that the launch would be pushed out to 2020 was made last month, Morris and others were coming up on what was an April 6 deadline to propose observing targets for the Webb.

“We were all working really hard because this telescope is super cool and it’s going to be the one that’s going to tell us if these planets are actually habitable and what’s going on in their atmospheres,” Morris noted. “Then the rug got pulled out from under us.”

R-process is better than your process

Back in July Trevor Dorn-Wallenstein told the AoT crowd how the universe makes beer for us. Last month he explained how heavier elements are made, and how we now know that theory to be true.

Dorn-Wallenstein explained how elements are made within stars. Typically, when neutrons collide with protons, they are captured. Nature stabilizes this through a process known as beta decay; the neutron just turns into a proton. This causes the release of an electron and a neutrino, or maybe an anti-neutrino.

“The jury is still out on whether neutrinos are the same as anti-neutrinos,” Dorn-Wallenstein observed. In any case these particles just go away.

“What we’ve really done here is we’ve converted one of those neutrons into a proton, and in doing so we’ve made a whole new element,” Dorn-Wallenstein said. “We’ve gone from hydrogen to helium, though both are unstable and have oddball numbers of neutrons.”

This happens slowly—that’s why it’s called the s-process. It occurs in low-mass stars, which can make strontium, barium, and lead.

Then there’s the r-process, which is rapid. In this process neutrons get bombarded onto atomic nuclei so quickly that beta decay can’t happen, and you get ridiculously unstable nuclei. Eventually neutron capture either slows, or it becomes so unstable that beta decay happens all at once, and BAM, you’re making silver, gold, platinum, and other heavier elements.

Essentially to do this you need three big explosions. First you need two supernovae to leave behind a pair of neutron stars. Then the neutron stars need to merge. Their collision is called a kilonova.

“There’s a lot of free neutrons around, and maybe those free neutrons are created rapidly enough that the r-process occurs,” Dorn-Wallenstein said. To confirm this you’d need to see evidence of a neutron star collision, a gamma-ray burst from the event, and follow up to make sure r-process elements were actually being formed. That’s exactly what happened when LIGO detected gravitational waves from a neutron star merger back in August.

“We found evidence that r-process elements were being formed and it confirmed that neutron star mergers were the dominant sites of the r-process,” Dorn-Wallenstein concluded.

Exoplanet instruments

Back in August Lupita Tovar did a talk about LUVOIR and SAMURAI and how they will help us map exoplanets. Her latest interest is the Transiting Exoplanet Survey Satellite—TESS—which launched April 18. Its primary mission is to search for Earths and super-Earths. While Kepler looked at a relatively small swath of sky, TESS will scan about 80 percent of the sky and observe some 200,000 stars.

“You can imagine how many more things we’re going to be finding,” Tovar marveled. TESS will look at brighter stars than Kepler was able to observe, and will be a constant source of data. It will send back full-frame images every half hour or so, and about 200,000 smaller “postage stamp” images every two minutes.

“What that translates to is a whole lot of data that’s going to be coming down from this telescope,” Tovar said. “You’re going to get a lot of planets—planets everywhere!”

There could be as many as 20,000 new ones; Tovar said many will likely be gas giants, which are easier to spot.

SPAMS a lot

UW student Aislynn Wallach is involved in a project called The Search for Planets Around post-Main Sequence Stars—SPAMSS.

The question is what becomes of planets like Earth when their host stars become red giants.

“They blow up to a larger size, much like a marshmallow in a microwave,” Wallach said. After that the stars become white dwarfs. The prospects for the close-in planets aren’t good.

“Anything inside (the expanded red giant) will probably be disintegrated,” Wallach noted. “That’s what we’re looking for we’re trying to find—these broken up planets around stars like the Sun.”

The approach is to look at the spectra of white dwarf stars. If we spot heavier elements in those spectra, the elements will have come from ripped-up planets. If those materials were part of the star, they would sink quickly from its surface.

For her search Wallach has been using the ARCSAT (Astrophysical Research Consortium Small Aperture Telescope) at the Apache Point observatory in New Mexico. Results of her search so far: nothing.

“Nothing is still a result!” She laughs. The search continues.

The beautiful music of the universe

An interesting new approach to data is to turn it into sound. Locke Patton is doing this with the brightness of supernovae. Brighter data points are assigned higher musical pitches. The process is called sonification.

“We don’t just look at it, we listen to it,” said Patton of the data.

Sadly, his recording of a supernova sound didn’t play—a rare technical glitch at Astronomy on Tap Seattle. He sang it. Sort of! You can hear a recording here.

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Calendar: Yuri’s Night, SETI, and club events on the horizon

It was 57 years ago this Thursday that Yuri Gagarin became the first human in space. Celebrate with a dance party this week, and check in on some interesting club meetings, too.

Yuri’s Night

While Yuri’s Night is officially April 12, many organizations celebrate at a more convenient time. The Museum of Flight will be throwing a 21+ dance party beginning at 7 p.m. Saturday, April 14. The evening will feature live music from the band Noise Complaint, a costume contest, food trucks, a cash bar, and a mixed-reality experience. You’ll also get to mingle with a list of “aerospace guest stars, including Chris Lewicki of Planetary Resources; Erik Lindbergh, co-founder of XPRIZE; Scott Schoneman, chief engineer at Spaceflight; So-yeon Yi, the first South Korean and 49th woman to fly in space; and Marilyn Ferguson, a software engineer at Blue Origin.

Tickets to the event are $35, or $30 for museum members. They’re available online.

The museum’s weekly aerospace update on Saturday will feature a special tribute to Gagarin. That will be at 1 p.m.

Jill Tarter in Portland

Jill TarterThe Rose City Astronomers in Portland will have an outstanding guest speaker next week when Jill Tarter of the SETI Institute gives a talk at their monthly meeting at 7:30 p.m. Monday, April 16. The meeting will occur at the Oregon Museum of Science and Industry in Portland. Tarter has long been involved in the search for extraterrestrial intelligence, and will explore what’s coming up in our effort to answer that fundamental question: Are we alone? Tarter’s work is the basis for the Jodie Foster character in the 1997 film Contact.

This is the sort of event Seattle Astronomy would like to be able to cover more often. Won’t you please consider a subscription through Patreon to help defer our costs? Even a dollar a month is a big help!

Club events

Several astronomy clubs have meetings this week:

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Astro Biz: Lake Champlain Five Star Bars

Lake Champlain ChocolatesMany businesses, products, and places have names rooted in space and astronomy. We’re featuring one every Tuesday on Seattle Astronomy.

This week’s Astro Biz is the collection of Five Star Bars from Lake Champlain Chocolates based in Burlington, Vermont. We spotted these in our local supermarket the other day—one of those checkout-line tricks!—and, since they were an Astro Biz couldn’t resist picking up a couple.

They’re pretty good! The bars come in six flavors in all, and are just part of a varied line of products from the company.

More info:

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The search for Earth 2.0

Astronomers have to date discovered more than 3,700 exoplanets—planets in orbit around stars other than our Sun. With each discovery, someone wants to know if the newly discovered planet is like Earth.

Elizabeth Tasker

Elizabeth Tasker at Astronomy on Tap Seattle.

Elizabeth Tasker thinks that’s not a very good question. Tasker, associate professor at the Japan Aerospace Exploration Agency, Institute of Space and Aeronautical Science and author of The Planet Factory: Exoplanets and the Search for a Second Earth (Bloomsbury Sigma, 2017) gave a talk at the most recent edition of Astronomy on Tap Seattle. She said that some of the exoplanets confirmed so far have at least a little resemblance to Earth.

“Roughly one third of those are approximately Earth-sized, by which I mean their physical radius is less than twice ours,” Tasker said. News media often wish to leap from that to describing a planet as Earth-LIKE, but Tasker said we don’t have nearly enough information to make that sort of call. Our current methods of detecting an exoplanet can give us either its radius or its minimum mass, and a pretty good read of its distance from its host star.

“The problem is neither of those directly relates to what’s going on on the surface,” Tasker noted. Part of the challenge is what Tasker feels is the somewhat oversimplified notion of the “habitable zone” around a star, a band of distance in which liquid water—a key to life as we know it—could exist on a planet’s surface.

“Like all real-estate contracts, there is small print,” Tasker said. “Just because you’re inside the habitable zone doesn’t mean you’re an Earth-like planet. Indeed, of all the planets we’ve found in the habitable zone around their stars, there are five times as many planets that are very likely to be gas giants like Jupiter than have any kind of solid surface.”

Another misleading metric that has been used is something called the “Earth similarity index.” This method compared exoplanets to Earth on the basis of properties such as density, radius, escape velocity, and surface temperature.

“None of these four conditions actually measure surface conditions at all,” Tasker said, pointing out that the index didn’t take into account such features as plate tectonics, a planet’s seasons, it’s magnetic fields, greenhouse gases, or existence of water. We can’t observe any of those things about exoplanets yet. As an example of the flaws of the index, Venus came out at 0.9, pretty similar to Earth, which is at 1.0 on the zero-to-one scale. While Venus is about the size of Earth and is around the inner edge of the Sun’s habitable zone, its surface temperature could melt lead. Not very Earth-like, or habitable. It’s one of the reasons that the index is seldom used these days. So we don’t have much of a clue about conditions on any of the known exoplanets.

“Our next generation of telescopes is going to change that,” Tasker said. She noted that NASA’s James Webb Space Telescope is scheduled to launch next year, the ESA’s Ariel in 2026, and the UK’s Twinkle in the next year or so.

“All of these are aiming at looking at atmospheres, and these may be able to tell us what is going on on the surface, and may even give us the first sniff of life on another planet,” Tasker said. “Maybe then we’ll be able to talk seriously about Earth 2.0.”

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Astronomy on Tap and a blue moon this week

It’s a light calendar of astronomy events for Easter week, but you can celebrate Astronomy on Tap Seattle’s third birthday and enjoy our second blue moon of the year!

Happy three to AOT

AOT March 28It’s hard to believe it’s been three years since a group of graduate students in astronomy started up the Astronomy on Tap Seattle lecture series, but this week’s edition will mark the 36th consecutive month that they’ve offered interesting talks, astronomy trivia, fun prizes, and great beer. Head to Peddler Brewing Company in Ballard at 7 p.m. Wednesday, March 28 for updates on the astronomy AOT has covered in the last year, and a look at the exciting new science that has come out recently—neutron star mergers, new planets, and more!

It’s free, but buy some beer. Bring your own chair to create premium, front-row seating.

Blue moon

It turns out “once in a blue moon” isn’t all that rare! Saturday’s full moon will already be the second one this year, at least by the definition that a blue moon is the second full moon in a calendar month. We had a blue moon in January, too; see the video below of Seattle Astronomy’s Greg Scheiderer talking on KING-TV’s New Day Northwest about the super blue blood moon.

The next blue moon after this week will be on Halloween in 2020.

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Museum of Flight launches podcast

Flight Deck PodcastThe Museum of Flight has launched a new podcast, titled Flight Deck.

Two of four episodes published so far have space or astronomy themes. One is a look at the mix tape that Pete Conrad listed to while on SkyLab; the tape is part of the Apollo exhibit opened at the museum last year. The other is an interview with astronaut Scott Parazynski.

There’s also an interesting look at The History of Legroom on airliners. It gives me cramps just thinking about it!

The museum plans to publish a new episode every other Tuesday. You can find episodes at this link, on SoundCloud, or you can subscribe using your favorite podcast app. Don’t forget to subscribe to the Seattle Astronomy Podcast while you’re at it!

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