Volume 2, Issue 10
Berkeley's Star Planet Hunter
When most of us gaze up at the sky on a clear night, we marvel at the majesty of the constellations. UC Berkeley professor Geoffrey Marcy sees much more than that though. He's inspired by the fact that the thousands of visible suns could each be the center of a planetary system. Marcy is the world's foremost planet hunter. In the last decade, the team of astronomers that he leads has found more than 100 planets outside our solar system. Some of those planets could even have a rocky surface, ponds, or oceans like our Earth. A few of them may even support life.
Professor Geoff Marcy is consulting with NASA on their SIM PlanetQuest mission. Scheduled for launch in 2011, the unmanned spacecraft will help locate Earth-like planets with temperatures suitable for liquid water and, therefore, the possibility of life.
"Our astrophysicist geekiness makes us want to understand the full family of planets including their masses and chemical compositions," Marcy says. "But it's also true that there's an extraordinary question of habitability. The possibility that these planets may harbor some kind of life brings a twinkle to my eye."
The planet hunt picked up steam in 1995 when Marcy and collaborator Paul Butler, now a staff scientist at the Carnegie Institution of Washington, made their first discovery of a planet orbiting a star. Approximately 70 light years away, the planet's star, 70 Virginis, is visible to the naked eye but the bodies orbiting it are far too small and faint to be seen against the star's glare. Since they couldn't observe the planet directly, the scientists inferred its existence using a technique they devised nearly a decade earlier. Since that Eureka moment, Marcy and his colleagues have found planets as far as 150 light years away from Earth by measuring their parent stars' stellar wobble.
This artist's concept shows a newfound Neptune-size planet — one of the smallest extrasolar planets detected to date — circling the star 55 Cancri. In this depiction, the new planet has a rocky composition, like Earth. In reality, astronomers do not know if the planet is rocky or gaseous, like Jupiter. The planet's temperature is at least a scorching 1,500 Celsius (2,700 Fahrenheit). (Image courtesy NASA)
"There are 2,000 to 3,000 stars that are within 150 light years of us and we're surveying most of them," Marcy says. "That's the equivalent of looking in our galactic backyard."
To spot the planets, the scientists use giant telescopes like the WM Keck Observatory in Hawaii and the University of California's Lick Observatory east of San Jose to measure the change in the color, or wavelength, of light coming from a star over days, months, and years. Known as the Doppler shift, that change in wavelength is caused by the star orbiting a common center of mass with a companion planet tugging on it. For example, in our solar system Jupiter's gravitational pull causes the Sun to wobble in a circle at a velocity of 12 meters per second. The Doppler shift data can be used to infer an unseen planet's approximate mass, orbital size, and the time it takes to make one trip around the star.
Until last year, all of the 120-plus extrasolar planets discovered by Marcy or anyone else have been gaseous giants, much larger than even Jupiter and Saturn, the biggest planets in our solar system with respective masses 318 and 95 times that of the Earth. In August 2004 though, Marcy and Butler's team co-discovered a pair of planets comparable to Neptune, which has 17 times the mass of Earth. The composition of that planet remains a mystery, Marcy says. It could be gaseous, rock and ice, or rock and iron like our own Mercury. Still, the discovery opened a world of possibility of what their pioneering technique might reveal, Marcy says.
This illustration compares the size of the newfound Neptune-size planets to the sizes of Earth and Jupiter. The new planets are only about 20 times the mass of Earth -- much smaller than the majority of Jupiter-size extrasolar planets detected so far. Astronomers don't know if the new planets are rocky or gaseous, but a rocky planet (pink) would have a smaller diameter than a gaseous one (blue) of the same mass. (Image courtesy NASA)
"Finding the Neptunes showed us that we can look farther away for planets even lower in mass, possibly five or 10 times the mass of the Earth," he says. "Planets that size would almost certainly be rocky. So in the next two years or so, we're hoping to discover definitively rocky planets that you could stand on."
While searching for Earth-like planets with chemistry "that could allow life to flourish" is exciting, Marcy says, it's only one of his research goals. The other challenge is to detect "Jupiter clones" that are identical in two ways to our neighbor planet.
"We have not yet found a planet that's as far from its star as our Jupiter is from the sun and maintains a circular orbit," he says. "All of the planets in our solar system have a gorgeous circular orbit like the grooves in a phonograph record."
Marcy's team has discovered one Jupiter-sized planet with the right orbit distance, but it circles its star in an elliptical pattern. A true "Jupiter clone," Marcy says, "would serve as a signpost that there could well be Mars, Venus, or Earth clones between the Jupiter clone and the star in an architecture like our planetary system."
The scientists are keeping a close watch on several dozen "top secret" stars they believe could harbor Jupiter clones. A Jupiter analog would take approximately 12 years to orbit its parent star. So when Marcy and his colleagues notice the velocity of a star's wobble speeding up from year to year, it's a good indicator that a planet is coming around the bend. Within the next few years, the 12 year period will be up and Marcy will run statistical tests he developed to ensure that there's less than a one percent chance they're wrong about their suspected Jupiter clones. Then he'll announce the discoveries to his peers.
Once the data are scientifically confirmed, it'll be up to the International Astronomical Union to name the heavenly bodies. Someday, perhaps the scientists who discover the planets will have that right. And if that day comes, Berkeley's number one planet hunter will be ready. School children from around the world regularly send Marcy funny and poignant suggestions that he proudly keeps in a desk drawer, but he has his own naming scheme in mind.
"My idea is to name the extrasolar planets from words in Earth's languages that mean things like cooperation, harmony, and peace," he says.
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Tiny Test Tubes and Nanoscale Membranes
Professor John Arnold also serves as the Associate Editor for the Americas for the scientific journal Dalton Transactions.
It's no surprise that UC Berkeley chemist John Arnold spends most of his time working with test tubes. What's interesting is that some of Arnold's test tubes are thousands of times smaller than the diameter of a human hair. In collaboration with chemistry professor Peidong Yang, Arnold and his colleagues are using Berkeley's latest innovations in nanoscience to synthesize new materials that could someday lead to longer-lasting batteries and ultra sensitive detectors of poisonous arsenic in drinking water.
One of Arnold's essential nanoscale building blocks is nanowires, single crystals of materials like zinc oxide, carbon, silicon, or other semiconductors grown into rods. In recent years, Yang, a fellow faculty scientist at Lawrence Berkeley National Laboratory, has pioneered several methods to fabricate nanowires out of various materials and with unique characteristics. The ability to precisely control the size and composition of the structures affects the nanowires' properties, enabling them to emit light, for example, or act as transistors.
"The nanowires give us a broad canvas to work with," Arnold says.
Recently, Arnold has used nanowires to synthesize membranes that would improve lithium batteries like those in cell phones and laptop computers. In traditional lithium batteries, current is produced when ions travel through an electrolyte between two terminals. The electrolyte allows just the positive ions to move through the battery, thereby freeing electrons to flow to the device requiring power. The problem is that the electrolyte solution itself is often toxic, corrosive, and flammable. In recent years, engineers have developed lithium-ion batteries with a dry polymer film separating the terminals. Unfortunately, the battery's performance is inhibited because the lithium ions don't travel as freely through these "solid electrolytes."
A porous membrane synthesized using an array of nanowires as a template.
"Fortunately, nature has membrane proteins that are quite good at selectively transporting ions through different environments," Arnold says.
The work is being carried out by graduate students Benjamin Rupert and Marty Mulvihill who were recently joined by postdoctoral researcher Seong Huh. The scientists took a cue from biology and fashioned their own nanomembrane. First, they grew an array of nanowires and coated them with a polymer. Next, they dissolved the wires, leaving polymer tubes behind.
"Essentially, we use the nanowires as a mold, or template, to make the polymer nanotubes," Arnold says. "In a battery, if we were able to control the ion-conduction mechanism inside the tubes, the ions could move between the electrodes through the tubes at incredible rates."
The polymer nanotubes have applications beyond better batteries though. The researchers are also able to grow single nanotubes with different functionality on the inner and outer surfaces. For example, the outside might repel water while the inside of the tube is hydrophilic, literally "water-loving." Someday, these kinds of nanotubes might be even be used as a drug delivery system, ferrying medicine through the body until a specific chemical reaction — an encounter with a tumor, for example — spurs its release.
Scanning electron microscope image of silver nanowires aligned like logs on a river and deposited on a silicon wafer. The thin layer of packed nanowires provides a good surface for chemical sensing with Raman spectroscopy. (Peidong Yang/UC Berkeley
In another project, Arnold and Yang hope to explore how silver nanowires could be the basis of a contamination test for water. In Bangladesh alone, arsenic poisoning from tainted well water is expected to cause 10 percent of all future adult deaths. Ideally, remote villages would have access to inexpensive and highly sensitive detectors for ongoing monitoring of their water supplies.
Nanowires may be just the solution. The researchers are functionalizing an array of silver nanowires so that arsenate ions easily bind to them. If a sample contains arsenate, a sensitive analysis technique called surface-enhanced Raman spectroscopy would detect its chemical signature. The researchers hope to eventually shrink the spectroscopy components so that the entire device can fit on a fingernail-sized silicon chip.
"Chemistry is really the only science where you get to make new things from the bottom up," Arnold says.
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Yosemite Then and Now
A plaque in UC Berkeley's Museum of Vertebrate Zoology is engraved with a prophetic quote from founding director Joseph Grinnell. In 1910, Grinnell said "the value of the museum will not be realized until the lapse of many years, possibly a century." Only after such a long time passed could researchers benefit from hindsight, comparing today's fauna to the snapshot Grinnell and his colleagues took of California's wildlife during a landmark survey launched in 1904. A century later, UC Berkeley scientists are finally taking that look backward as they follow in Grinnell's footsteps through Yosemite National Park.
Jim Patton, project leader and curator of mammals at the UC Berkeley Museum of Vertebrate Zoology, weighs a mouse (Peromyscus maniculatus) live-trapped from the Merced Grove of giant sequoias. (photo copyright Leslie S. Chow.)
The Grinnell Resurvey Project, launched in 2003 by museum director Craig Moritz, is in the process of revisiting more than 200 locations that Grinnell and his team surveyed. Over the next five years leading up to the Museum's centenary, the scientists will document and collect tens of thousands of mammals, birds, amphibians, and reptiles from a range of habitats representing much of California's unparalleled biodiversity. Part of a National Park Service initiative to monitor wildlife in the country's parks, the Grinnell Resurvey Project is the first inventory of this scale in Yosemite since Grinnell traversed the park eighty years ago.
"Comparing the data from then and now will provide knowledge about the dynamics of the species and the related changes in climate and habitat," says former museum director Jim Patton, who retired from the faculty of the Department of Integrative Biology in 2001.
In many ways, Patton's retirement allows him to work even harder. As the director of field research for the Grinnell Resurvey he spends several weeks every few months in the Sierra Nevadas where his team observes animals of all kinds, traps and releases a variety of critters, shoots photographs, and, of course, takes copious notes.
The original Grinnell Survey is legendary in its attention to detail. The collection consists of more than 4,000 specimens, 2001 handwritten pages of field notes, and 1,400 photographs. Grinnell's system for taking field notes informed the museum's current modus operandi. It's the precision and volume of those records that's enabling the researchers to conduct an accurate resurvey. Indeed, a photographer is documenting the vistas as they currently exist, many from the exact same vantage point where Grinnell's photographer snapped the shutter.
Yosemite Redux, a Flash slideshow created by the UC Berkeley NewsCenter.
"This will allow us to do comparative photographic analysis of the habitats," Patton says.
While Yosemite is protected from logging, other kinds of human intervention have had an impact on the terrain, and as a result, the vertebrate fauna. For example, fire management at Merced Grove has increased the amount of brush in the area, resulting in an inviting habitat for an increasing number of birds like MacGillivray's Warblers, Fox Sparrows, and others.
"Sometimes change can be good," Patton says.
On the other hand, pikas and alpine chipmunks were observed at elevations more than 1,000 feet higher than where Grinnell's team spotted them. Why?
"It could be indicative of a climate shift forcing them to move to a higher, cooler elevation," Patton says. "Some might say that's a symptom of global warming. That could be trouble for the species though if they keep moving up into the mountains until they can't go any higher."
Other animals not noted by Grinnell, like the western harvest mouse and the Pinyon mouse, were caught by Patton's team. The latter has expanded its range from an approximate elevation of 8,500 feet on the eastern Sierran slopes up to 10,400 feet into the Park over the course of a century. As more data is gathered, the researchers hope to identify the reason for the shift in the distribution and population. The researchers are employing techniques Grinnell could only have dreamt of, including molecular genetic analyses.
While California is recognized in the conservation community as a megadiversity region, Patton points out, it's also under increasing pressure from population growth, land use changes, fires, and drought. To that end, the "then and now" survey of California's fauna could inform the sustainable development of the state. Meanwhile, he adds, it could also validate models used to predict how myriad variables, from changes in land use to shifts in climate, could affect the state's biodiversity. In that way, looking to the past may help us prevent problems in the future.
"Thanks to Grinnell and his team's rigorous inventory of species, the museum has a historical database that's unparalleled anywhere else in the world," Patton says. "The ability to make such detailed comparisons between today and 80 years ago is just remarkable. It's time to put that database to use."
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Berkeley's Scientific Legacy
Berkeley Nanotechnology Club
The science-fiction fantasy of nanotechnology — building novel structures, devices, and materials at the atomic or molecular scale — is becoming a reality. However for nanoscience and nanotechnology to fully realize its great potential, research efforts must cross many disciplines, from engineering, chemistry, physics, and biology to law and business. At the center of UC Berkeley's cross-disciplinary nano efforts is an organization founded by two passionate students.
In late 2003, MBA student Marcel Roche and mechanical engineering graduate student Ryan Layton launched the Berkeley Nanotechnology Club to foster interest in what they believe is "the next big thing" at the intersection of science, engineering, and business. In less than two years, several hundred students from such diverse disciplines as chemistry, physics, biology, business, engineering, and law have joined the club to explore how interdisciplinary research on small technology could have a huge impact on everything from heavy industry and healthcare to the computer industry and the environment. On April 30, the club will hold its annual Berkeley Nanotechnology Forum, a public conference where leading scientists and entrepreneurs participate with the students in panel discussions, lectures, and old-fashioned networking. This year's keynote speaker will be Steven Chu, director of the Lawrence Berkeley National Laboratory and co-winner of the 1997 Nobel Prize in physics.
Officially, the Nanotechnology Club has three objectives. The first is to disseminate useful information about nanotechnology, the ability to manipulate matter on the nanoscale to build new materials, structures, or devices. (A nanometer is one-billionth of a meter, or one-thousandth the diameter of a human hair.) Another goal is to organize events promoting the Bay Area's leadership in nanotechnology. Finally, its key objective is to spark entrepreneurship and spur technology transfer. According to Roche, "partnerships with interdisciplinary academic departments, particularly the Berkeley Management of Technology Program and the Nanoscience and Nanoengineering Institute, were instrumental in making the club a success."
"The club encourages the formation of teams of science and engineering students with Haas School of Business students to develop business plans around some of the new technologies that will emerge from the new Center of Integrated Nanomechanical Systems on campus," adds Thomas Kalil, Special Assistant to the Chancellor for Science and Technology and a faculty advisor to the club.
Indeed, UC Berkeley has already spun off several top tier nanotechnology companies, including Nanomix, Nanosys, and Quantum Dot Corporation. To help put future nanoscale innovations on the track toward commercialization, the Club launched the Nano Opportunity Challenge. The contest brings together teams of scientists, engineers, and business students who present their plan to commercialize a nanotechnology-enabled device. In the 2005 inaugural contest, the group that won the $2,000 first prize devised new wireless components that could enable the production of smaller, less expensive mobile phones with longer battery life. The $1,500 second prize went to a team whose tiny microfluidic plumbing system could enable the fabrication of a "lab-on-a-chip" for bioscience experiments and assays.
In all of their efforts, the club seeks to leverage and expand the symbiotic relationships that exist between Berkeley, Silicon Valley, and the entire Bay Area. For example, last year's Berkeley Nanotechnology Forum featured chemistry professor Paul Alivisatos, director of the Lawrence Berkeley National Laboratory's Molecular Foundry, along with representatives from IBM Almaden Research Center, NASA Ames Research Center, venture capital firm Draper Fisher Jurvetson, and several of the Berkeley-spawned nano start-ups.
This year, the forum participants will examine how nanotechnology could transform "the triple bottom line of business, society, and the environment." And that's no small matter.