UA Planetary Science Gets Stamps of Approval
By Daniel Stolte
By Daniel Stolte, University Relations - Communications, May 25, 2016
When a University of Arizona planetary scientist persuaded NASA to point the Hubble Space Telescope at Jupiter and Uranus to gather clues about the atmospheres of the two giant gas planets, he had no idea that his images might end up years later in mailboxes across the nation and possibly the world.
On March 28, 2004, three of Jupiter's largest moons - Io, Ganymede and Callisto - came together in a rare alignment, casting their shadows onto the Earth-facing side of the planet to form a triple eclipse.
Erich Karkoschka, a senior staff scientist in the UA's Lunar and Planetary Laboratory, had been waiting for this moment and he was ready. NASA had granted him 40 minutes - the viewing time offered by Hubble orbiting Earth once - to observe how the three moons danced around their host planet.
"Having three shadows and two moons transiting the disk of Jupiter at the same time is very rare," Karkoschka said. "It hadn't happened for 60 years when I made the proposal to use Hubble to observe this event."
Hubble took that image with its "infrared eyes," a camera developed by a team of UA astronomers and engineers, using three different optical filters. Because human eyes can't see infrared light, those wavelengths are translated into false-color renditions of blue, green and red.
"You can make the different features visible that way, and once you are able to see those differences, you can do better science as well," Karkoschka explained. "For this particular color image, the rationale was mostly to get a pretty image of this rare event."
Most images of Uranus, like those taken by the Voyager 2 space probe during its flyby in 1986, revealed a hazy, pale blue disk that looked rather bland and not too exciting, said Karkoschka, who took his image of Uranus in 2003, this time using Hubble's Advanced Camera for Surveys.
Because his image combined three filters, he was able to get a more colorful and revealing rendition of features in Uranus' atmosphere, such as three bright red glowing clouds in the planet's northern hemisphere.
Together with his equally colorful image of Jupiter, Karkoschka's Uranus picture features in a special edition of stamps, "Views of Our Planets," which the U.S. Postal Service officially will release on Tuesday at the World Stamp Show, the world's largest philatelic event, held in the U.S. only once every decade.
"During the modern era of space exploration, the planets of our solar system have been viewed with increasing clarity, thanks to the distant voyages of unmanned spacecraft and the development of ever-more powerful telescopes," according to the design brief. "With this pane of stamps, the Postal Service showcases some of the more visually compelling full-disk images of the planets obtained during this era."
Said Karkoschka: "I was granted one orbit in one specific year, and so I looked for the best occasion in that year, and then I realized if it was going to be on that date, I could get something that really doesn't happen very often. So I was kind of lucky."
Karkoschka has observed the giant planets on telescopes around Tucson and in Chile, and using the Hubble Space Telescope, to understand the structures of their atmospheres. From this work, he determined the vertical and horizontal distribution of hazes, clouds and methane.
"On the gas giants, there is no surface anywhere close to where we can see," he said. "There may be a very small, solid core, perhaps similar in size to Earth, while most of the outer part is hydrogen, helium and other gases including methane."
On all those planets, Karkoschka has been researching the cloud levels and what the clouds are like. Once he had images taken over several years, he could see how the clouds and their altitudes changed.
Jupiter's clouds consist mainly of ammonia crystals, while similar features spotted on Uranus are made up of frozen methane. Because it takes Uranus more than 84 Earth years to complete a trip around the sun, studying seasonal changes takes generations of researchers.
"In the 1990s, we were seeing the southern hemisphere, and it didn't look too interesting," Karkoschka said. "But with the equinox in 2007, more of the northern hemisphere came into view and there were really unique clouds that appeared red in those images. Those clouds were the first really interesting features that we could see on Uranus."
Gradually, atmospheric details first spotted by Voyager 2 became more and more interesting, and tracking them allowed Karkoschka to accurately determine the planet's spin for the first time.
"We really could see activity on Uranus, and that was exciting," he said. "The bluish part is the southern hemisphere, and the three red clouds are in the northern hemisphere, rising above the general haze spreading out below them. In the meantime, we have seen even brighter clouds. You can follow them for a few weeks or months, but after that they change or disappear."
Scientists are still a long way away from understanding the causes of those changes.
"The northern hemisphere of Uranus appears to be much more active now than the southern hemisphere," Karkoschka said. "We don't know why. If we wait for another 40 years for the season to change, and if then only the southern hemisphere is active, we know it's a seasonal effect. But if the activity is still only in the northern hemisphere, then we'll know there really is some intrinsic asymmetry at work."
By then, mailing letters may well be a thing of the past, with the stamps depicting our planets having found their way into stamp collections around the world.
Ed Beshore's Rocket Ride Into the Sunset
By Doug Carroll
By Doug Carroll, University Relations - Communications, September 12, 2016
Unlike the space mission to which he has given the last 4 1/2 years of his life, Ed Beshore's work is nearly done.
Last Thursday's launch of the OSIRIS-REx spacecraft from Cape Canaveral, Florida, was a "bittersweet moment," says Beshore, who will retire as the mission's deputy principal investigator - and also from the University of Arizona - when he turns 62 on Oct. 4.
"I had a big candle for my retirement cake," Beshore says of the blazing Atlas V rocket that launched the UA-led, seven-year mission to return a sample of surface material from the asteroid Bennu.
"I can't think of a better way to do this. I really wanted to get to launch because I knew it was a natural time for me to retire and a good handoff point to the next deputy principal investigator."
Taking over for Beshore as deputy to principal investigator Dante Lauretta on the mission is Heather Enos, who has been with the UA's Lunar and Planetary Laboratory since 1997 and has served most recently as project planning and control officer for OSIRIS-REx. Under Beshore, the position focused on the development of hardware and on launch planning and preparations. Now it shifts in emphasis to mission operations, for which the nerve center will be the Michael J. Drake Building northwest of campus.
"The two-year timeline (of getting to Bennu) will go very quickly," says Enos, who has been on OSIRIS-REx since 2008.
Beshore says Enos has the requisite operations experience and attention to detail.
"She's going to enjoy the job, and people like working with Heather," he says. "She'll bring the necessary insights into what the mission needs and make sure nothing falls between the cracks."
As for Beshore, he plans to ride off into the sunset - literally. As an undergraduate at the UA in the mid-1970s, he had a BMW motorcycle that he rode all over the West. He plans to resume those travels, this time in a new truck, and to do some backpacking "before my knees give out." He will continue tracking the mission closely, perhaps in a consulting role with NASA.
The cutting-edge work of the UA in space science was a big reason he came back to Tucson after a successful engineering career, joining the Catalina Sky Survey in 2002 and becoming its principal investigator in 2009.
"One of the reasons I wanted to come back is that I wanted to hang out with people who were a lot smarter than me," Beshore says. "You'd have a hard time not finding a whole lot of smart people at LPL. They're all doing fascinating things, and the science that comes out of the place is fantastic. It's a joy to be around."
OSIRIS-REx has been a special project from the start, he says.
"This is not just another mission that has been flown before," he says. "We're doing something the United States has never done before, which is going to an asteroid and bringing back a sample - heck, going to another planetary body and bringing back a sample. That represents a turning of the corner for planetary exploration by the United States.
"I think everybody (on the mission team) knows the world is watching. Everybody thinks it's a cool mission and they want it to succeed, so they put in the extra effort they know is needed to make sure the mission gets done right."
Although the OSIRIS-REx launch was not Beshore's first - he saw Apollo 14 lift off as a teenager, and he later watched the Mars Polar Lander and Phoenix Mars Lander launches - it left an impression all its own.
"It was exciting, beautiful, bright and loud," Beshore says. "It was a spectacle, and it was just great. ... (The launch) was a moment of pride, to be able to say, 'The University of Arizona has been doing this for 50 years, and we're really at the top of our game right now.'"
Microscopic Findings, Astronomic Implications
By Rebecca Peiffer
By Rebecca Peiffer, NASA Space Grant Intern, University Relations - Communications, October 16, 2015
Imagine that you could travel back in time four and a half billion years ago, when the solar system was still just a bunch of rocks and dust and gas mixing together. Imagine watching all those billions of years of history re-created in front of you.
Now, imagine that scientists are working to reconstruct this history with objects found here on Earth.
One of the scientists is Tom Zega, an assistant professor in the University of Arizona's Lunar and Planetary Laboratory. He studies "presolar grains," which are the remains of ancient stars preserved in meteorites.
These grains contain clues for scientists looking to build a narrative about the nearby stars before the birth of the solar system. Considering the scale of the undertaking, it is surprising that the evidence found in these presolar grains is microscopic.
Scientists find the grains in chunks of meteorite mostly made up of rocks that formed after the solar system’s creation.
"Those of us that are interested in understanding stardust basically have to find needles in the haystack," Zega says.
To help find the needles, scientists employ some clever techniques.
"We'll take a chunk of a meteorite, we’ll boil it up in these harsh, nasty, aggressive acids, and then we’ll generate a residue," Zega says.
The process eliminates some of the excess meteorite and increases the chances of finding a presolar grain. The grains have endured millions of years of exposure to cosmic rays and maintained their original form, so some will withstand the acid and remain in the residue.
Grains are only a few hundred nanometers wide. For context, a strand of human hair is 100,000 nanometers wide, and one nanometer is about half the width of a strand of DNA. To image the grains, scientists must use microscopes powerful enough to look at individual atoms.
Through this procedure, Zega and a team of researchers discovered the first grain of magnetite with confirmed presolar origins and published their results in the Astrophysical Journal. From a sample only 650 nanometers wide, Zega estimated the size and chemical composition of its parent star, a star that inhabited this part of the galaxy before the solar system came into existence.
Even the discovery of this grain was revealing. The chemical reaction that created the magnetite almost certainly required water vapor. This is one of the first experimental confirmations of water vapor around an ancient star.
With the right approach, Zega says he believes presolar grains could even help construct a timeline for the history of our local part of the galaxy.
"We know the galaxy itself is about 13 billion years old, and we know the solar system is four and a half billion years old, but there’s a lot of billions of years in between there for things to happen," he says.
If we could age-date these grains the way we age-date rocks on Earth, then we could start to document the astrophysical events that took place in this period. That's one way studies of presolar grains can go beyond traditional observations through telescopes.
With meteorites, researchers can do more than observe stardust — they can actually hold it in their hands.
"It's pretty amazing," Zega says. "After 17 years in the field, I'm still fascinated by the fact that I can hold a piece of the solar system in my hand, and I can analyze it in the laboratory at the atomic level."
This excitement and curiosity inspires missions such as OSIRIS-REx, which aims to bring back samples of an asteroid for further study on Earth. For Zega and people in his field, that mission is like a dream come true.
"Everything that didn't go into forming the sun or the planets was left over in the form of asteroids and meteors and dust," he says. "So you can think of that as a time capsule that's just sitting out there, and if we could we'd fly out there and grab samples of it. We'd rewrite the books."
For the next step in his research, Zega would like to collect more samples of presolar grains and look at the trends among them.
That could help answer some of the big questions in planetary science about the origin of the solar system. In particular, the grains offer an estimate for how many stars injected their matter into the early solar system — and what kind of stars they were.
"It just remains to be seen as time progresses whether we can come up with answers to some of these questions," Zega says, smiling. "But we keep asking them."
Michael Drake's Dream Takes Off
By Doug Carroll
By Doug Carroll, University Relations - Communications, September 7, 2016
CAPE CANAVERAL, Fla. - The embodiment of the late Michael Drake's biggest questions about the universe lifted off in coastal Florida's sunshine on Wednesday, September 9, 2016 at 4:05 pm,
A sleek Atlas V 411 rocket, topped by a Lockheed Martin spacecraft, was slowly rolled out in midmorning from United Launch Alliance's Vertical Integration Facility - a space-age hangar - to Space Launch Complex 41 at Cape Canaveral Air Force Station. The OSIRIS-REx mission, conceived by Drake 12 years ago and finally green-lighted by NASA only four months before his death in 2011, is the first U.S. mission to send a robotic spacecraft to retrieve a sample from a primitive carbonaceous asteroid.
In his 38-year tenure at the University of Arizona, the English-born Drake studied lunar rocks, meteors and the moons of Saturn. He helped map the surface of Mars. But nothing captured his imagination quite like an asteroid sample return mission, which he thought would reveal significant clues to the origin of the solar system and the beginnings of life itself.
Drake was "curious about the big questions, the questions like 'How did Earth get its water?' and 'How did it get its organic molecules?'" said Tim Swindle, who succeeded Drake as director of the UA's renowned Lunar and Planetary Laboratory. "This was a mission that could go after at least a chunk of that."
As Swindle and others from LPL - past and present - gathered for a reunion at a Cocoa Beach hotel on the eve of the launch, Drake's profound influence on space science - and on them - was a popular topic of conversation.
"We're a tight-knit group," said Jani Radebaugh, who received her doctorate in planetary science in 2005 from the UA and is now an associate professor of geological sciences at Brigham Young University. "We're realizing that we're here because Mike's vision for OSIRIS-REx came together.
"He was a lab guy, a hands-on geochemist who felt that nothing compared with bringing samples back from a space mission. But that's difficult to achieve. This is a really bold idea, to have the building blocks of the solar system in your hands. It's too bad he's not around to play with those things himself."
In addition to the challenge of carefully plucking at least 60 grams (2 ounces) of surface material from the asteroid Bennu, the mission is risky because of its sheer length. The spacecraft won't get to the asteroid until late in the summer of 2018, and it won't attempt a sample until two years after that. Finally, in September 2023, the sample return capsule is expected to land in the Utah desert, about 80 miles west of Salt Lake City. Over that seven-year period, a certain amount of turnover in personnel is expected - and yet the mission must remain on course.
"Mike was smart enough to figure out that this would be a long, multigenerational mission," Swindle said, adding that training has been essential.
By comparison, the UA-led Phoenix Mars Lander mission launched in August 2007 and reached the Red Planet in less than a year. The mission was considered done in November 2008, its experiments and observations completed. The cost of that mission was less than half of the billion-dollar OSIRIS-REx, which will bring scientists from all over the world to the former Science Operations Center - now the Michael J. Drake Building - north of the UA campus.
Drake's aggressive approach to science may have been matched only by his enthusiastic encouragement of the next generation of scientists. Swindle estimates that more than 100 UA students have been involved in various aspects of OSIRIS-REx to date, and about two dozen UA graduate students are in Florida to watch the launch.
"Mike believed that the best research department should also be the best teaching department," Swindle said. "That was a mantra of his. He had a passion for picking out younger people."
Drake also wasn't averse to doing some recruiting in the hinterlands.
"He cared about kids and wanted them to be in the STEM fields," said Dan Cavanagh, the chair of LPL's external advisory board. "We'd go into the Sahuarita school district and he'd say, 'I want you kids to get scholarships and come to work for me.'"
When they came, so did the success stories. The most notable one would be that of Dante Lauretta, handpicked by Drake to be the deputy principal investigator for OSIRIS-REx. The two men worked side by side on the project for seven years, through two failed proposals, with Lauretta becoming the mission's principal investigator after Drake died of cancer.
"Michael Drake was my friend and mentor and the visionary who brought me into the OSIRIS-REx program," Lauretta said. "We miss him. He's still with us. He's in our hearts and souls and looking down on us today. He'd be having the time of his life here."
Said Swindle: "I think what would excite him the most is the number of people who have pulled together to make this mission possible. Young people have stepped into roles they wouldn't have dreamed of being capable of doing. Older ones who started off the mission have stepped aside to let younger ones take over. The whole thing of it being a team that works so well together, that's the thing he would be proudest of."
Career Map Surprised OSIRIS-REx Scientist
By Doug Carroll
By Doug Carroll, University Relations - Communications, September 6, 2016
CAPE CANAVERAL, Fla. — It's a long, long, l-o-n-g way from El Paso Community College to the asteroid Bennu, but Daniella DellaGiustina has covered the distance.
The University of Arizona alumna, a self-described "military brat" who recalls making Girl Scout trips to the Flandrau Science Center & Planetarium on the UA campus, is the lead image processing scientist for the OSIRIS-REx asteroid sample return mission. As such, she will be involved in mapping the asteroid down to the ability to see an object the size of a penny on its surface. The adventure begins with Thursday's scheduled launch of the spacecraft aboard an Atlas V rocket at Cape Canaveral Air Force Station.
The UA-led mission, 12 years in the making, hopes to collect at least 60 grams (about 2 ounces) of surface material from the carbon-rich Bennu, which is about 150 million miles away and will take two years to reach. When the sample returns to Earth in 2023, it could yield clues to the origins of the solar system and life itself.
DellaGiustina, who graduated from the UA in 2008 with a bachelor's degree in physics, was only slightly less than 150 million miles from a career in planetary science at one point. Headed toward a liberal-arts major, she wasn't even on science's radar until she took a community college class in astronomy simply to get a general-education requirement out of the way.
"It sparked in me a curiosity that's still very much alive," DellaGiustina said after participating on a three-person mission science panel Tuesday at Kennedy Space Center. "I was so amazed and surprised by how abstract the universe is, and how much we don't know, and how science can answer some of these fundamental philosophical questions - Where did we come from? What is our future? - in a way that I did not recognize before.
"After that point, I made the decision that I wanted to study space science, and I transferred to the UA because it's renowned for astronomy, planetary science and optical science."
She remembers looking up at the big Arizona sky in wonderment during the years of her childhood that were spent in the Sierra Vista area.
"I have these memories of how incredibly clear the skies were and how seeing the Milky Way was just a part of my life," DellaGiustina said. "Southern Arizona is a place where you can see the stars."
When DellaGiustina was a UA undergraduate, Dante Lauretta and the late Michael Drake showed her "how to do science within engineering constraints," she said. Drake died in 2011 only four months after the UA had been awarded the OSIRIS-REx mission by NASA, to be succeeded as principal investigator by Lauretta.
DellaGiustina went on to the University of Alaska for a master's degree in computational physics before returning to the UA as a research scientist in 2012. She joined the Lunar and Planetary Laboratory in 2014.
She is one of several women to play key roles in the OSIRIS-REx mission. Others include Sara Knutson, an operations engineer and alumna of the UA College of Engineering; Catherine "Cat" Merrill, formerly deputy project manager for the UA-built OSIRIS-REx Camera Suite, or OCAMS; and Heather Enos, who will succeed Ed Beshore in October as deputy principal investigator for the mission.
Although the field of space science tends to be heavily populated by men, DellaGiustina said she never has felt shortchanged of opportunities.
"As a Hispanic female, I have to say I didn't have a tremendous amount of role models growing up to demonstrate that a career in the physical sciences was a possibility," she said. "But I never felt like doors have been closed for me."
Lauretta said he sees much of himself in DellaGiustina's career arc and work ethic, describing her as "one of my go-to people" on OSIRIS-REx. Both were NASA Space Grant interns at the UA who identified an affinity for meteoric science as undergrads.
"Her life story was very similar to mine," Lauretta said. "My job was to give her opportunity."
The mapping role for OSIRIS-REx presents a unique set of challenges for DellaGiustina.
"Mapping has typically taken place on Earth, Mars and other very large spherical bodies using tools that do everything in 2-D, measuring in latitude and longitude," she said. "But an object like Bennu is not particularly spherical, so when we try to flatten it into two dimensions, the latitude and longitude don't necessarily address points on the surface. ... A lot of software for mapping is not exactly wired to do this work."
Perhaps it takes an avid rock climber, then, to take the full measure of one big space rock.
"It's really common in rock climbing to try to think about lowering the risk of what you're going to do," said DellaGiustina, who has been a director for the Climbing Association of Southern Arizona.
"A lot of what we've done with OSIRIS-REx has been to try to mitigate risk upfront, to think through problems ahead of time so that we're prepared for what's in store for us."
Bradley Williams, another recent UA graduate (2013, College of Engineering), has worked alongside DellaGiustina on OSIRIS-REx and said no one could be better prepared.
"She's always reaching out for more," Williams said. "She'll work more hours than anybody. She's really into it. I like working with people with a passion like hers."
NASA's Surveyor Lander Brought the Moon to the World
By Robin Tricoles
By Robin Tricoles, University Relations - Communications, August 17, 2016
While their colleague Richard F. Gordon was busy orbiting the moon in Apollo 12's command module in late 1969, fellow astronauts Charles Conrad and Alan Bean decided to take a little stroll. They exited Apollo 12's lunar module and moseyed across the lunar surface to Surveyor 3, which was parked right where it had landed two and a half years earlier.
Conrad and Bean snapped photos of the little lander and of each other. Afterward, the two harvested Surveyor 3's camera, some of its cable and tubing, and its trenching scoop and made tracks back to their craft. The astronauts spirited their haul back to Earth, where researchers and technicians would study how the lunar environment had affected the assorted parts.
NASA's Surveyor program, which ran from June 1966 through January 1968, consisted of seven lunar camera-equipped flights in support of the upcoming manned Apollo landings. The intent was to find a way to safely land men on the moon. Five of the spacecraft made it; two didn't.
But of the five craft that did, they transmitted about 92,000 digital images back to Earth via television cameras. In turn, those images were put on film and the digital data forgotten about. After all, back in the 1960s, hardcopy - film in this case - ruled the day.
"When the data came back, it was digital to begin with because it had to be transmitted back to Earth," says Shane Byrne, associate professor in the University of Arizona's Lunar and Planetary Laboratory and lead scientist on the project.
"Once they printed it out and put it on film, they forgot about the digital data, and it got lost over time because why would you need the digital data? That was the thinking at the time. The 1960s was sort of the Wild West of space exploration, and that made it very fun and exciting."
Now the UA's Space Imagery Center in LPL is digitizing the film and putting the final touches on those images. Soon they will be available to researchers and the public throughout the world.
Those final touches include collecting specific data, such as instrument temperature, time of day and camera-pointing angle, to accompany each and every frame. "Alongside each image, there will be printed information about it," Byrne says. "That is valuable information to use later, so you know what you're looking at."
In fact, Ewen Whitaker, a retired LPL research scientist, used those films and others from the Lunar Orbiter program to locate Surveyor 3 so that NASA could land an Apollo spacecraft nearby.
"NASA had no way of knowing where the moon spacecraft were," Byrne says. "Ewen took the pictures from the Surveyor spacecraft so he could pick out mountains and craters and things like that. And then he looked at the overhead images from Lunar Orbiter to try to pick out the same features and figure out where the landers were."
Because the approximately 30 reels of 70-millimeter film were slowly degrading over time, it became increasingly important to convert the film into digital format.
"And the data themselves are important because we've landed on only a handful of locations on the moon," Byrne says. "But if you wanted to see the data, that meant coming here and pulling a spool of film off a shelf.
"We didn't realize the images weren't available digitally online because almost everything is. It certainly was a shock to find that these images weren't available to everybody."
Justin Rennilson, co-investigator on the original Surveyor television experiment, was the one who approached researchers about digitizing the images. Byrne wrote a proposal to get the job done and NASA funded it. Shortly thereafter, in the spring of 2015, John Anderson, a media technician at the Space Imagery Lab, and Maria Schuchardt, the center's program manager, began scanning the film.
There are two main types of terrain on the moon, Byrne says.
"All of the Apollo missions and most of the Surveyor missions went to one type: the lunar mare, the dark areas of the moon," he says. "It's smoother and safer to land there, and that was the motivation for sending the astronauts there. But most of the moon is covered with the bright areas, the lunar highlands, which is most of what you see when you look up. The bright areas are much rougher, much more cratered. So none of the Apollo landings were made there."
Once all the data are archived, scientists will be able to assemble a mosaic of all the images, Byrne says.
"You'll have a full panorama, and you can even watch how it changes as the sun moves across the sky," he says. "I think it's great because the moon is so local. It's right next door."
UA-Led Team Confirms 100+ Exoplanets Via Kepler
By Daniel Stolte
By Daniel Stolte, University Relations - Communications. July 18, 2016
An international team of astronomers led by the University of Arizona has discovered and confirmed a treasure trove of new worlds using NASA's Kepler spacecraft on its K2 mission. Among the findings tallying 197 initial planet candidates, scientists have confirmed 104 planets outside our solar system. Among the confirmed is a planetary system comprising four promising planets that could be rocky.
The planets, all between 20 and 50 percent larger than Earth by diameter, are orbiting the M dwarf star K2-72, found 181 light-years away in the direction of the Aquarius constellation. The star is less than half the size of the sun and less bright. The planets' orbital periods range from five and a half to 24 days, and two of them may experience irradiation levels from their star comparable to those on Earth. Despite their tight orbits - closer than Mercury's orbit around the sun - the possibility that life could arise on a planet around such a star cannot be ruled out, according to lead author Ian Crossfield, a Sagan Fellow at the UA's Lunar and Planetary Laboratory.
The researchers achieved this extraordinary "roundup" of exoplanets by combining data with follow-up observations by Earth-based telescopes including the North Gemini telescope and the W. M. Keck Observatory in Hawaii, the Automated Planet Finder of the University of California Observatories, and the Large Binocular Telescope operated by the UA. The discoveries are published online in the Astrophysical Journal Supplement Series.
Both Kepler and its K2 mission discover new planets by measuring the subtle dip in a star's brightness caused by a planet passing in front of its star. In its initial mission, Kepler surveyed just one patch of sky in the Northern Hemisphere, measuring the frequency of planets whose size and temperature might be similar to Earth orbiting stars similar to our sun. In the spacecraft's extended mission in 2013, it lost its ability to precisely stare at its original target area, but a brilliant fix created a second life for the telescope that is proving scientifically fruitful.
After the fix, Kepler started its K2 mission, which has provided an ecliptic field of view with greater opportunities for Earth-based observatories in both the Northern and Southern hemispheres. Additionally, the K2 mission is entirely community-driven with all targets proposed by the scientific community.
Because it covers more of the sky, the K2 mission is capable of observing a larger fraction of cooler, smaller, red-dwarf type stars, and because such stars are much more common in the Milky Way than sun-like stars, nearby stars will predominantly be red dwarfs.
"An analogy would be to say that Kepler performed a demographic study, while the K2 mission focuses on the bright and nearby stars with different types of planets," Crossfield said. "The K2 mission allows us to increase the number of small, red stars by a factor of 20, significantly increasing the number of astronomical 'movie stars' that make the best systems for further study."
To validate candidate planets identified by K2, the researchers obtained high-resolution images of the planet-hosting stars as well as high-resolution optical spectroscopy data. By dispersing the starlight as through a prism, the spectrographs allowed the researchers to infer the physical properties of a star - such as mass, radius and temperature - from which the properties of any planets orbiting it can be inferred.
These observations represent a natural stepping stone from the K2 mission to NASA's other upcoming exoplanet missions such as the Transiting Exoplanet Survey Satellite and James Webb Space Telescope.
"This bountiful list of validated exoplanets from the K2 mission highlights the fact that the targeted examination of bright stars and nearby stars along the ecliptic is providing many interesting new planets," said Steve Howell, project scientist for Kepler and K2 at NASA's Ames Research Center in Moffett Field, California. "This allows the astronomical community ease of follow-up and characterization, and picks out a few gems for first study by the James Webb Space Telescope, which could perhaps provide information about their atmospheres."
This work was performed in part under contract with the Jet Propulsion Laboratory, or JPL, funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute.
NASA Ames manages the Kepler and K2 missions for NASA's Science Mission Directorate. NASA's Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corporation operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder.
Bennu: How a Little Asteroid Became a Rock Star
By Robin Tricoles
By Robin Tricoles, University Relations - Communications, June 29, 2016
Carl Hergenrother fingers a stack of white, 8 1/2- by 11-inch paper that sits before him on his desk. As he flips through the inch-thick dossier, lines of type are clearly visible.
"This is everything we know about Bennu," says Hergenrother, glancing down at the pile of paper.
Hergenrother is a staff scientist at the University of Arizona's Lunar and Planetary Laboratory. Bennu is an asteroid and a small but distinct resident of our solar system – so distinct that it was chosen as the destination for the OSIRIS-REx mission.
The OSIRIS-REx spacecraft is set to launch in September and in 2020 pick up a sample of the asteroid's regolith, the loose soil and rocky material found on its surface. The sample then will be returned to Earth for analysis.
Scientists discovered Bennu on Sept. 11, 1999, by using electro-optical telescopes operated by the Massachusetts Institute of Technology Lincoln Near-Earth Asteroid Research, or LINEAR, program. The asteroid originally was known as 1999 RQ36.
Hergenrother played a key role in choosing Bennu for the OSIRIS-REx mission. The first time he laid eyes on the asteroid, it was 2005, and 1999 RQ36 was cruising close to the Earth as it does every six years. Through the Kuiper telescope on Mount Bigelow, Bennu appeared as no more than a dot of light, "like a star that moves," Hergenrother says.
After all, an asteroid is simply a "rock in space," he says.
Not Your Average Space Rock
But in many ways, Bennu is a special rock.
It was 2004 when the late Michael Drake, director of the Lunar and Planetary Lab, proposed securing a sample of a near-Earth asteroid. But back then, no one knew much about Bennu. In fact, researchers were considering an assortment of other asteroids, specifically ones rich in carbon.
"We want to go to a particular type of asteroid, a carbonaceous asteroid," Hergenrother says. Researchers also want that asteroid to be rich in volatiles – substances that boil off easily, like water.
"The thinking is that these are the kinds of objects that in the early days of the solar system seeded the Earth with the organics that life formed from, as well as the water needed," says Hergenrother, cautioning that there is still some debate about the matter.
"But we hope that Bennu is what we would call a time capsule, that it hasn't changed much over the history of the solar system and will show what materials looked like in the very early days of solar system."
Hergenrother became Bennu's champion after years of data collection and analysis – and a good deal of deductive reasoning. He served as coordinator for the mission, but much of the observation and deduction fell to other mission scientists.
"We're now approaching a million known asteroids," Hergenrother says. "That wasn't the case when we started doing this 12 years ago. But we were still talking hundreds of thousands of asteroids at that time."
However, the researchers didn't have to analyze nearly so many. Most of them could be quickly eliminated by their stark faults, such as residing too far from Earth. Closer asteroids allow for the completion of a mission within a reasonable amount of time. That criterion alone left only a couple thousand asteroids that remained viable candidates for exploration, Hergenrother says.
And of those, many have orbits that are less than stellar.
"They're too far from the sun or too close to the sun," Hergenrother says. "Or they're at a sharp angle to the Earth, which would take a more powerful rocket to get into that kind of orbit."
Looking for 'Favorable Orbits'
Which, in turn, left only a few hundred objects that have favorable orbits – that is, ones residing near the Earth and remaining a favorable distance from the sun. However, most of those objects are too tiny.
"Some are as small as a desk," Hergenrother says. "The ones smaller than about 200 meters have a habit of rotating very fast. The fastest ones we know about rotate about every 16 seconds."
That's too fast to accommodate a spacecraft looking for a sample of regolith.
But Bennu rotates only once every 4.3 hours, slow enough to sample its regolith.
"So, once you eliminate the small guys, you look at the bigger ones that have very Earth-like orbits," Hergenrother says. "Now you're talking only dozens of candidates, and we wanted to go to one that's carbonaceous.”
Which Bennu seems to be. Its carbonaceous nature sent it to the top of the list of asteroids, says Hergenrother, who emailed Drake and Dante Lauretta, saying, "Guys, this is carbonaceous. It's looking good. And there's radar data."
Lauretta, professor of planetary science and cosmochemistry at the Lunar and Planetary Laboratory, is Drake's successor as the principal investigator for the OSIRIS-REx mission.
The data showed Bennu having a polar diameter of 508 meters, a mean diameter of 492 meters and an orbital velocity of more than 28 km per second. It also showed that the asteroid has a spinning-top shape; that is, it sports a bulge along its equator, a common feature among near-Earth asteroids.
"What we think this means is that this is a rubble-pile object," Lauretta says, meaning that Bennu probably is made out of many boulders tens to hundreds of meters across.
The boulders "are loose, and they’re responding to the forces of the asteroid spinning, and material is migrating from the pole of the asteroid and accumulating at the equator and building up a ridge," Lauretta says.
Life Expectancy: 10 Million More Years
For better or worse, Bennu has an unstable orbit. That means it probably won’t last more than 10 million years before it collides with Earth or another planet, or falls into the sun, according to Lauretta.
This is a concern to scientists. In fact, Bennu is considered a potentially hazardous object and has a relatively high possibility of impacting the Earth. So scientists are interested in understanding how asteroids' orbits evolve.
Key to that evolution is something known as the Yarkovsky effect.
"Which is simply that an asteroid receives energy from the sun, turns that energy into heat, and as it rotates into the afternoon throws that energy back into space as thermal energy, and that acts like a thruster and changes the orbit of the asteroid slowly but surely over time," Lauretta says. "If you want to know where an asteroid is going to be in the future, particularly in our future, then you want to know about the Yarkovsky effect."
Looking back on his quest to help select an asteroid suitable for sampling, Hergenrother says he sometimes thinks about what if there were no Bennu.
"There are only three carbonaceous objects that are easy to get to," he says. "They all seem to be the same shape. They all seem to be relatively safe targets. They're scientifically interesting, and they're easy to get to. But that's only three out of nearly a million."
Skimming the Clouds of Jupiter
Daniel Stolte
Daniel Stolte, University Relations - Communications, July 5, 2016
(An earlier version of this story was published on June 20, 2016)
After cruising through space for five years, NASA's Juno spacecraft, the fastest man-made object, fired its main thrust engine to brake its fall toward Jupiter, the largest planet in our solar system. Its mission: to gather clues shrouded under Jupiter's thick layers of clouds that reveal what the planet is made of on the inside, and to help answer some of the most fundamental questions about how planets form from swirling clouds of gas and dust.
During its critical braking maneuver, carefully calculated to place the Juno probe in a stable orbit around the giant gas planet, UA planetary sciences professor William Hubbard joined a group of about 30 scientists involved with the mission at the Jet Propulsion Laboratory in Pasadena, California, anxiously awaiting confirmation from the windmill-shaped spacecraft that all went well.
"It's a very crucial maneuver," Hubbard said while preparing for the probe's arrival at Jupiter. "The white-knuckle period will be when the spacecraft comes in over the north pole of Jupiter, and then the main engine will fire for about half an hour. If that were to be unsuccessful, the probe would shoot past Jupiter and go off into interplanetary space."
Hubbard has been waiting for that moment for his whole career.
"Having a geophysical orbiter at Jupiter has been a top priority for a number of people in the scientific community for many years," he says. "Our objective is to get at a close range of a giant planet. And when you get that close to Jupiter, you begin to see details of its magnetic field and its gravity field that you can't see at long range. Some of those details will tell us about the interior of Jupiter."
Scientists Vexed by Question
Despite having pointed telescopes at Jupiter for more than 400 years, mankind has much more to learn about the planet that would eclipse 11 Earths lined up in a row. One question, in particular, that has vexed scientists is whether Jupiter hides a solid core of elements heavier than those making up its bulk - hydrogen and helium - or whether those two gases simply become more and more compressed all the way to the center.
"Whether there is evidence for a large, massive core inside Jupiter, as is predicted by various theories about the origins of Jovian planets, is one of the things we hope to learn fairly quickly," Hubbard says.
With more and more exoplanets being discovered far, far away from the reach of space probes, scientists look to our very own gas giant to help them understand how such planets form, how they evolve over time and what they look like inside. Current belief holds that they will not form directly from clouds of hydrogen-rich material that collapses to give birth to stars including our sun, but instead they need a trigger of some form of massive, denser material, Hubbard explains.
As co-investigator on the mission, Hubbard is part of a team that oversees the gravity experiment on the spacecraft, which is expected to reveal clues about Jupiter's hidden interior. Since Jupiter is not a solid, perfectly spherical and homogeneous ball, but rather like a spinning bag filled with a swirling mix of gases, fluids and possibly solid matter, its gravitational field reflects those chaotic conditions in the planet's interior. Its tug on the Juno spacecraft intensifies or lessens by tiny, but measurable, amounts as it travels around the planet.
A highly synchronized, locked loop of radio wave communication between Juno and the antenna array at NASA's Goldstone Deep Space Communications Complex in California’s Mojave Desert will detect Juno moving toward or away from Earth under Jupiter's gravitational pull - shifts on the magnitude of microns.
"Think of how much your weight changes when a mosquito lands on your head," Hubbard says. "Juno's gravity experiment will potentially be capable of measuring signals at the level of one-hundredth of that amount."
After removing the effects of many influences interfering with the gravity measurements - a "terrible job," according to Hubbard - a three-dimensional dataset will emerge, representing Jupiter's gravitational field. Because its shape depends on the planet's interior structure as well as the tugging from its nearest large moons, the gravitational field will allow Hubbard and his collaborators to make inferences about Jupiter's interior.
"We will see terms in Jupiter's gravity field that we can't see from Earth, and some of these terms are related to the interior structure of Jupiter," Hubbard explains. "Others are related to its interior dynamics - for example, how much material is moved around in Jupiter's interior through convection, as opposed to if it were a quiescent planet."
'Money Part of the Orbit'
Unlike any other spacecraft that visited Jupiter before, Juno will enter an orbital trajectory taking it over Jupiter's north and south poles once every 14 days. During what Hubbard calls the "money part of the orbit," the probe will approach Jupiter as close as 5,000 kilometers (about 3,000 miles) above its clouds.
"Most of the time, though, it will be very far away from Jupiter," Hubbard says, "partly to protect it from Jupiter's intense radiation, and partly because you can't carry enough fuel to maintain a real tight orbit around a planet with such a strong gravitational field."
Jupiter's huge magnetic field, which, if it were visible, would appear as big as the full moon when seen from Earth, captures the solar wind and accelerates it into a deathly rain of radiation. Juno's instruments are encased in a titanium vault and its orbit is designed to avoid the peaks of Jupiter's radiation belts as much as possible.
As the first spacecraft to be diving underneath Jupiter's radiation belts, Juno will be able to make observations using microwaves that will provide glimpses into Jupiter's atmosphere to much deeper levels than was possible before.
"Jupiter's powerful radiation belts contain high-energy electrons that emit precisely at those microwave wavelengths," Hubbard says, "so you can't see deep into Jupiter at those wavelengths by looking from the Earth, because there is too much background noise from the radiation belts. But if you can get underneath the radiation belts, which is what Juno will do, then you can probe the atmosphere in those wavelengths."
Potentially, scientists will be able to see several hundred kilometers below the clouds, much deeper than NASA's Galileo entry probe that descended into Jupiter's atmosphere in 1995.
Juno's measurements are expected to also reveal clues about how much water there is in Jupiter's atmosphere, which helps determine which planet formation theory is correct or if new theories are needed. In addition, the data will offer conclusions about whether Jupiter formed at its current location in the solar system or migrated to its present orbit over time.
Because Juno won't be able to stay out of harm's way forever, its instruments and electronic components are expected to deteriorate over the course of the mission - 20 months for a total of 37 orbits. Before the spacecraft becomes uncontrollable, NASA's engineers will set a final course plunging the spacecraft into Jupiter, where it will burn up without leaving a trace, to avoid the risk of it contaminating one of Jupiter's potentially life-friendly moons such as Europa.
Practicing Patience
Hubbard can't wait for the probe to begin streaming data to Earth that he has awaited for years.
"When you work in outer solar system exploration as opposed to inner solar system exploration, you learn a special kind of patience," he says. "The distances are much greater; the orbital periods are much greater; it takes longer to get there; so when you're involved in these projects, you sort of grow old together, you see everybody turn into old men and old women over the course of the whole endeavor."
NASA's Jet Propulsion Laboratory in Pasadena, California, manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. The Juno mission is part of the New Frontiers Program.
UA Engineering Students, Alumni Critical to OSIRIS-REx Mission
By Jill Goetz, UA
By Jill Goetz, UA College of Engineering, September 6, 2016
When NASA's OSIRIS-REx spacecraft lifts off aboard an Atlas V rocket from the John F. Kennedy Space Center in Cape Canaveral, Florida, dozens of UA College of Engineering students and alumni will be on hand to witness their handiwork. Others will be at ground control monitoring and steering the spacecraft.
UA master's student Bradley Williams, a systems engineer for the UA-built OSIRIS-REx Camera Suite, is looking forward to being among the select engineers giving the "All Systems Go" signal on Sept. 8. Williams is equally enthusiastic about what will happen post launch, when he turns his attention to uplinking commands to the cameras and evaluating the data coming down from them.
The UA-led OSIRIS-REx mission is the United States' first attempt to sample an asteroid and return it to Earth, and the first NASA deep-space mission involving a large cohort of engineering students from a public research university.
"OSIRIS-REx has given a young engineer like me a once-in-a-lifetime opportunity to have a hands-on role on a space mission," said Sara Balram Knutson, who earned her UA master's in engineering management in 2012 and is now a senior operations engineer for the OSIRIS-REx mission at the UA.
Knutson oversees day-to-day operations for the spacecraft's scientific instruments to ensure the spacecraft will be able to map the asteroid Bennu, select a sample site and obtain a sample.
So daunting is the task that the spacecraft will spend two years circumnavigating Bennu - 500 meters in diameter - before it extends its retractable arm, releases a burst of nitrogen gas to stir up enough soil to capture a sample, and retracts the arm with the sample securely in tow. OSIRIS-REx will have just three opportunities at only five seconds each to make the grab.
NASA chose the UA to lead OSIRIS-REx in 2011 and appointed Roberto Furfaro, director of the UA College of Engineering's Space Systems Engineering Laboratory, to lead the systems engineering team for the mission's Science Processing and Operations Center, which is responsible for the software that operates the spacecraft.
Furfaro immediately started training undergraduate students in the lab, helping many obtain prestigious NASA Space Grants, hiring them when they became graduate students to work on OSIRIS-REx, and supporting their transitions to UA employees working on the mission.
"The opportunity to work on a NASA-funded mission while obtaining a graduate degree seemed too good to be true," said Kristofer Drozd, a doctoral student studying systems engineering, who connected with Furfaro while finishing his UA bachelor's degree in aerospace engineering.
"I am part of a mission that will directly enhance our knowledge of the solar system - all while still being in school," he exclaimed.
'Holy Grail' of Asteroids
Dante Lauretta, professor of planetary science and cosmochemistry at the UA Lunar and Planetary Laboratory and principal investigator of the OSIRIS-REx project, searched for more than 12 years before determining that Bennu was the most promising candidate for an asteroid sample-return mission.
Researchers have only been able to glean knowledge about asteroids by studying meteorites, pieces of space rock that have fallen to Earth, and by using massive telescopes like that at the Arecibo Observatory in Puerto Rico - one of several around the globe available to researchers at the UA - which have revealed and characterized many of the millions of asteroids in our solar system.
But meteorites become contaminated when they fall to Earth, which makes it hard for researchers to determine their original makeup or the asteroid they came from. And giant telescopes, powerful as they are, can only tell so much about asteroids' behavior and chemical makeup.
Best Still Yet to Come
To help compensate for the uncertainty, aerospace engineering master's student Tanner Campbell worked on software for an optical navigation system that produced the models of Bennu. Engineers will now use the system to navigate the unmanned spacecraft around the asteroid.
"Many of the most interesting aspects of this mission, like the mechanics of operating a spacecraft in close proximity to a small body, don't start until we get to Bennu two years from now," Campbell said.
John Kidd, who received a NASA Space Grant and earned his Bachelor of Science degree in aerospace engineering and a master's in systems engineering from the UA, agrees that the best is yet to come.
"Only when we approach Bennu can we begin a full characterization of the asteroid before we move in to collect the sample," Kidd said. "A large part of my job will be creating new plans and contingency plans as Bennu reveals its secrets to us."
Onward to 2023
Many working on OSIRIS-REx will continue on the mission through 2023, when the SUV-sized spacecraft re-enters Earth's atmosphere and releases a heat-shielded capsule containing its precious cargo - at least 2 ounces of pristine 4.5-billion-year-old carbon-rich regolith, or loose surface soil, snatched from Bennu - that will touch down by parachute at the Utah Test and Training Range.
Daniel Wibben, one of fewer than a dozen systems engineers steering the unmanned spacecraft, will be at mission ground control in Denver when the spacecraft takes off, and will continue piloting it for the next seven years with the Arizona-based deep-space navigation company KinetX Aerospace.
"For the launch, we will be sitting at computers at Lockheed Martin, waiting for the first signals coming back from the aircraft to figure out what trajectory it is on. We have charted a course for the spacecraft, but we don't know exactly what trajectory it will take," Wibben said, adding that "we do have automatic systems in place to help prevent problems in real time, even if we can't see them."
There is no GPS navigation in deep-space systems, and data will be delayed by 20 minutes as it travels from Bennu to Earth.
"Once we get to Bennu, we're going to be ready, agile and on our toes for whatever Bennu throws at us," said Wibben, who earned four UA degrees - bachelor's degrees in aerospace and mechanical engineering and master's and doctoral degrees in systems engineering.
Discoveries from the spinning-top space rock could shed light on the origins of the solar system and life within it and reveal possible sources of natural resources. It will also indicate potential perils from asteroid collisions and influence development of technologies to prevent them.