Category Archives: research

The search for ET at Pacific Science Center

They’re thinking a lot about extraterrestrial life these days over at the Pacific Science Center, where two new exhibits explore how scientists are working to identify far-away planets that may harbor life, and how we’re going to feed ourselves while we’re on our way to pay a visit.

Mission: Find Life!The exhibit Mission: Find Life! opened up last month in the science center’s Portal to Current Research space. Erika Harnett, a University of Washington professor of Earth and Space Sciences who serves as the education and outreach lead for the UW’s Virtual Planetary Laboratory (VPL), was one of the key players in developing the content for the exhibit.

“We really wanted to connect the research being done by the Virtual Planetary Laboratory and some of the more cutting-edge science,” Harnett said.

It’s all in the biosignature

They decided to focus on examining the biosignatures of exoplanets. Harnett noted that we actually have the technology to take images of planets orbiting other stars, even though the images only amount to a pixel or two.

“From that single pixel you can actually glean quite a bit of information,” Harnett noted. “Scientists are trying to figure out if, from that, you can actually start to see if there are signatures of life on a planet, and really the initial work that they’re doing now is defining what are the signatures of life on Earth.”

The color of the light might tell you if you’re looking at ocean or continents. You might even identify the chemical components of a planet’s atmosphere or the types of molecules that are there.

Promotional material for the exhibit notes that, for finding life, “the color purple may be the key.” Harnett explained that that’s because red dwarf stars are plentiful in the universe, and they last a long time—long enough to give life plenty of time to develop. Whatever life appears would be faced with much redder light than we have here on Earth.

“Life will want to make use of it as much as possible, so it’s going to be either purple or black vegetation, instead of green, to be able to absorb as much electromagnetic radiation in the visible as possible,” Harnett said. She noted that, for the exhibit, they wanted to convey the speed of discovery—scientists verify new exoplanet discoveries practically every day. She also wanted to set expectations about what sorts of life might be found. Spoiler alert: it won’t likely be little green men like the ones on the socks Harnett wore when we spoke.

“It’s more likely that it’s going to be something like microbes or bacteria, because that’s actually what most of the life on Earth is. It’s not the most visible, but it’s the most plentiful,” she said.

Watch an exoplanet transit

One of the cool, hands-on features of the exhibit gives visitors a look at how scientists using the Kepler Space Telescope actually find exoplanets. A lighted globe represents a star, and you can spin a couple of planets around it.

“Then they have a sensor off to the side,” Harnett said—it’s actually inside a model of Kepler. “On a screen you can see the light from the star, and then as the planet transits you can see the dip” in the amount of light that arrives at the sensor.

“You get to actually play with that and explore what the change in signal associated with a planetary transit looks like,” she added.

Another interactive feature of the exhibit is a large touch screen that uses the NASA Eyes on Exoplanets program to let visitors explore planets.

Communicating science

The Mission: Find Life! exhibit is part of the VPL’s work funded by the NASA Astrobiology Institute, which requires that a portion of funds be reserved for education and public outreach. VPL has created several science-on-a-sphere shows and trained numerous graduate students to be science communication fellows.

“The Portal to Current Research project is the culminating part of our work,” Harnett said. She has been involved with the Pacific Science Center’s communication fellows program for about a decade and said she feels effective communication about science is important.

“If scientists do a better job of communicating their science there would not be quite as much mistrust of science,” she said. “Everybody needs to get out more into the community and be doing more communication and writing for the general public, as opposed to just writing the peer-reviewed articles that will go into a journal and ten people will see.”

Harnett said they’re working to line up astrobiologists to offer talks during the exhibit’s run, especially during Astrono-May at the science center. Mission: Find Life! runs through September 4, 2017 at the Pacific Science Center.

What’s for lunch?

Feeding Future AstronautsAnother new exhibit called Feeding Future Astronauts is just across the gallery from the Portal to Current Research space. Growing food in space will take a lot less energy than carrying a bunch of it along, and the exhibit highlights some of the things NASA is trying. In the test garden of the exhibit they’re growing “outredgeous” lettuce, “Tokyo bekana” cabbage, and “Red Robin” cherry tomatoes. The latter will be a challenge because tomatoes require pollination, and as far as we know there are no bees in space. ISS astronauts are experimenting with hand pollination and how it will work in microgravity. The Red Robin might be a good variety of tomato to try in your Seattle garden; the ones in the exhibit were doing great for early April with only artificial light.


Podcast of our interview with Erika Harnett:

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White spots on Ceres may be salt

The first big surprise as the Dawn spacecraft was approaching the dwarf planet Ceres earlier this year were bright white spots on its surface. Now that Dawn has been orbiting Ceres for six weeks, a theory has emerged about what the spots are: salt.

Dr. Tom McCord, a planetary physicist who is co-investigator on the Dawn mission, spoke about the exploration of Ceres Saturday during an astronomy day event at the Pacific Science Center in Seattle. Photo: Greg Scheiderer.

Dr. Tom McCord, a planetary physicist who is co-investigator on the Dawn mission, spoke about the exploration of Ceres Saturday during an Astronomy Day event at the Pacific Science Center in Seattle. Photo: Greg Scheiderer.

Dr. Tom McCord, a co-investigator on the Dawn mission and director of the Bear Fight Institute, a research organization based in Winthrop, Wash., spoke at an Astronomy Day event Saturday at the Pacific Science Center in Seattle. Here’s why he thinks the spots could be salt.

McCord explained that Ceres is differentiated: it has a rocky core, a water-ice mantle layer, and a dirty crust. He noted that they’ve learned a lot from the early photographs.

“There’s a lot of evidence of activity; many craters, an older surface, but not as old as the object, so something obliterated the craters from early on,” McCord said. “Distorted features, so the surface had to have been warped.”

“There are domes, things pushing out from the inside,” he continued, “and bright spots that suggest that material from inside has come to the surface in some sort of volcanism.”

In addition, McCord explained that ground-based telescopes have detected water vapor that comes and goes in the area of Ceres. Liquid water from the interior of Ceres may be being ejected to the surface, where it wouldn’t last long.

Ceres

This image was taken by NASA’s Dawn spacecraft of dwarf planet Ceres on Feb. 19 from a distance of nearly 29,000 miles (46,000 kilometers). It shows that the brightest spot on Ceres has a dimmer companion, which apparently lies in the same basin. Photo: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

“What that would do is leave a residual salt deposit, so these bright spots could be salt deposits that accumulated around vents—volcanos—where the water is coming through,” McCord speculated.

He stresses that the work on data from Ceres is still in its early phases, joking that, “We scientists don’t know entirely what we are seeing.”

McCord said the evidence of geological activity has been the most interesting finding so far at Ceres.

“It has been active and may well still be active today,” he said. “That’s exciting to a physicist because you really want to know whether these processes that you conjure up in your models really have happened and, we hope to learn, to what extent and over what time scale.”

Ceres is a great target for study because it may hold clues to how planets form. It is the only dwarf planet in the inner solar system and is the largest object in the asteroid belt. With a diameter of 590 miles, it’s about as big as Texas.

“This is a very large small planet,” McCord said. Ceres comprises about a third of the mass of all objects in the asteroid belt.

The Dawn spacecraft is unique, according to McCord.

“It is the only interplanetary spacecraft that uses ion propulsion, and that is the only reason we are able to orbit two different objects in the outer solar system and still have enough fuel to go on,” he said. Dawn launched in 2007 and studied the asteroid Vesta for 14 months in 2011 and 2012 before heading to Ceres.

“Dawn is really a pathfinder for this kind of multiple-object extended exploration,” McCord said.

Dawn will be collecting data at Ceres for another year to 18 months. McCord said the spacecraft has four momentum wheels and needs three of them to hold itself in stable position. However two of the wheels have failed, so mission scientists are using the craft’s thrusters as a substitute. The hydrazine fuel will eventually run out, and Dawn will tumble about in a stable orbit around Ceres for a long, long time.

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Gamma ray bursts, galaxies, exoplanets, and beer

Back in 1979 when I was an undergraduate at the University of Washington I took an introductory course in astronomy to fulfill some science credit requirements. The two Voyager spacecraft had just visited Jupiter and the faculty in the astronomy department seemed practically giddy about all of the new data received and textbook re-writing to come. These days, given the number of exciting missions returning information from the near and far reaches of the solar system, it seems we’re learning something new about the cosmos almost every day.

Case in point: earlier this week a trio of UW astronomy graduate students put on the first Astronomy on Tap event in Seattle, each giving a mini-lecture about their current research. Two of them had news fresh out of the headlines.

Zapped by gamma rays

Kristen Garofali was first up with a talk titled “To GRB or Not to GRB.” The GRB in this case stands for gamma ray burst.

Astronomy on Tap

There was a full house Wednesday at Bad Jimmy’s in Ballard for the first Seattle Astronomy on Tap event. Photo by @AoTSeattle.

“Gamma ray bursts are cosmic lighthouses,” directional beams that Garofali explained result from the formation of a black hole. “When the black hole forms there are two jets of energy emitted that are really high-energy.”

Last week, for the second time in less than a year, scientists thought they had detected a GRB from our closest galactic neighbor, M31, the Andromeda galaxy. This would have been a first; we’ve never detected a GRB so nearby before. The nearest have been billions of light years distant, while M31 is a mere 2.5 million light years away from Earth.

Both the event last May and the one last week turned out not to be GRBs. Garofali noted that there are other objects out there that emit gamma rays, but these don’t look at all like whatever was detected coming from the neighborhood of M31 last week.

“It’s too bright to be a transient or an ultraluminous x-ray source,” she said. “It’s too faint, however, to be a gamma ray burst.” Even so, Garofali finds the discovery and the mystery exciting. “It could open our eyes to some new process that we haven’t thought about before,” she said.

Garofali said the reason we should care about this is that gamma rays are nasty things. At the very least, one would foul up your cell phone reception, and a strong burst could cause mass extinction on Earth. In fact, there is some scientific speculation that a GRB may well be responsible for at least one of the mass extinctions that have hit our planet. However, to do that the GRB would have to come from relatively close by and be aimed right at us. The odds of that happening are extremely long, but not zero.

Astronomy porn

Talk number two by Nell Byler was titled “Andromeda, So Fly, So PHAT.” She wasn’t using dated slang, but rather was talking about the Panchromatic Hubble Andromeda Treasury, a key tool for her work studying stellar populations. PHAT has taken up a lot of the Hubble Space Telescope’s time; the treasury was created from some 7,400 Hubble images involving 936 exposure hours. The collected data has resolved more than 117 million stars in our neighboring galaxy. The UW’s Julianne Dalcanton is the principal investigator for PHAT.

PHAT M31

This PHAT portrait of M31 is a mosaic of more than 7,000 Hubble Space Telescope images. Photo: NASA; ESA; J. DALCANTON, B.F. WILLIAMS, AND L.C. JOHNSON/UNIV. OF WASHINGTON; THE PHAT TEAM; R. GENDLER.

Byler showed a great deal of “astronomy porn”—stunning Hubble images from the project. They’re more than just pretty pictures; Byler said PHAT has the potential to reveal much about star formation, stellar evolution, and a host of other questions about how galaxies work.

“Even though we’re looking at stars within another galaxy it provides a lot of insight for galaxies that we can’t resolve and for our own galaxy, which we think is pretty similar to Andromeda itself,” Byler said. “And there’s lots more science to be done.”

Little green men

Brett Morris closed the evening with a talk titled “Dear Grandpa.” Morris is an astrobiologist, which his grandfather thinks is a pretty fishy undertaking involving the cover-up of the existence of extraterrestrials. Morris is hoping to find ETs, though, and on the very day of Astronomy on Tap the news wires were abuzz with new information about subsurface oceans on Jupiter’s moon Ganymede and on Saturn’s moon Enceladus, both of which could be havens for life. Kenneth Chang’s article in the New York Times provides excellent coverage.

Enceladus geysers

Water vapor geysers erupt from the south pole area of Saturn’s moon Enceladus. Photo: NASA/JPL.

“Enceladus has what we call cryovolcanoes; they’re volcanos that shoot out water,” Morris said.

“I personally think that this is the best chance to look for life elsewhere in our solar system because we can send a spacecraft that just orbits this moon and picks up the water as it shoots out of the moon,” he said. “Could it get more convenient? We don’t need to dig at all!”

Morris explained how the Kepler Space Telescope hunted for planets around other stars, though he bristled a little at the fact that when one is discovered similar in size to our home world it is invariably called “Earthlike.”

“Those have very broad, flimsy definitions,” he said, noting that Venus, which is practically our twin in size and mass, could be called Earthlike, but it would not be a nice place to visit. Morris is excited for scientific advances that will help us get a better idea of what exoplanets are truly like, and to identify which ones might harbor life like us.

The Astronomy on Tap event was well attended, with more than 60 people jamming into Bad Jimmy’s Brewing Company in Ballard (which pours a lovely IPA, by the way). The talks were well received and games were enjoyed, even though our team, nicknamed “Hubble Trouble,” did not win any cupcakes donated by Trophy Cupcakes. The organizers plan to be back with more events. Follow them on Twitter at @AOTSeattle. Also watch Facebook, where they hope to set up a page soon.

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SDSS delivers a new look at the sky

Astronomers are crunching enormous amounts of data and amassing more all the time. It’s almost enough to make one think that there’s more data in the universe than the universe can hold, but that would be something of a paradox.

Another 100-terabyte chunk of data was delivered to the astronomical community Jan. 6. The Sloan Digital Sky Survey (SDSS) made the final release of the third epoch of its survey (SDSS-III) in Seattle at the 225th meeting of the American Astronomical Society. Data Release 12 (DR12) contains measurements of the properties of nearly half a billion stars and galaxies, making it one of the largest and richest databases in the history of astronomy. SDSS-III spent six years collecting that data using the 2.5-meter Sloan Foundation Telescope at Apache Point Observatory in New Mexico.

A still photo from an animated flythrough of the universe using SDSS data. This image shows our Milky Way Galaxy. The galaxy shape is an artist’s conception, and each of the small white dots is one of the hundreds of thousands of stars as seen by the SDSS. Image credit: Dana Berry / SkyWorks Digital, Inc. and Jonathan Bird (Vanderbilt University)

A still photo from an animated flythrough of the universe using SDSS data. This image shows our Milky Way Galaxy. The galaxy shape is an artist’s conception, and each of the small white dots is one of the hundreds of thousands of stars as seen by the SDSS. Image credit:
Dana Berry / SkyWorks Digital, Inc. and Jonathan Bird (Vanderbilt University).

“The most astonishing feature of the SDSS is the breadth of ground-breaking research it enables,” said Daniel Eisenstein of the Harvard-Smithsonian Center for Astrophysics and director of SDSS-III. “We’ve searched nearby stars for planets, probed the history of our Milky Way, and measured nine billion years of our universe’s accelerated expansion.”

DR12 includes data from several different surveys.

APOGEE (the Apache Point Observatory Galactic Evolution Experiment) looked in near-infrared wavelengths to see through obscuring dust clouds and mapped the distribution of 15 separate chemical elements in more than 100,000 stars, probing all regions of the Milky Way.

“That’s a huge amount of information,” said Steve Majewski of the University of Virginia, APOGEE’s principal investigator, “and each element reveals a different subplot in this galactic screenplay. Sometimes the interactions between the characters are quite surprising!”

MARVELS (the Multi-Object APO Radial Velocity Exoplanet Large-Area Survey) made repeated measurements of 3,000 stars to detect the back-and-forth motions that could reveal unseen orbiting planets.

“MARVELS is the first large-scale survey to measure these tiny motions for dozens of stars simultaneously,” said principal investigator Jian Ge of the University of Florida, “which means we can probe and characterize the full population of giant planets in ways that weren’t possible before.”

SDSS conference

Scientists involved with the Sloan Digital Sky Survey talk about their latest data release during a news conference Jan. 6 at the meeting of the American Astronomical Society in Seattle. L-R: Connie Rockosi, Daniel Eisenstein, Jian Ge, Steven Majewski, and Michael Wood-Vasey.

BOSS (the Baryon Oscillation Spectroscopic Survey) maps the fossil imprints of sound waves that filled the universe during the first half-million years after the Big Bang. The BOSS team is using those imprints to trace the expansion of the universe across nine billion years of cosmic history, with unprecedented precision.

SEGUE (the Sloan Extension for Galactic Understanding and Exploration) measured visible-light spectra of a quarter-million Milky Way stars.

“Data release 12 is the largest SDSS data release so far, it contains data that make more precise measurements than before, new kinds of data in new wavelength ranges for the survey facility, and new techniques for making those measurements,” said Connie Rockosi of U.C. Santa Cruz, the lead scientist for the Sloan telescope. Rockosi added that more science is certain to come now that all of that data has been released to the public.

And there’s more data to come. SDSS-III may be finished, but SDSS-IV began began a six-year mission last July to study cosmology, galaxies, and the Milky Way.

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