News this Week

Science  30 Mar 2007:
Vol. 315, Issue 5820, pp. 1776
  1. GENDER EQUITY

    U.S. Agencies Quiz Universities on the Status of Women in Science

    1. Yudhijit Bhattacharjee

    The U.S. government has begun questioning research universities to determine whether their treatment of women students in science and engineering violates federal law. Science has learned that officials from the National Science Foundation (NSF), the Department of Energy (DOE), and NASA have visited four academic departments on three campuses in the past 14 months to monitor their compliance with a 1972 law that prohibits sex discrimination in educational programs and activities receiving federal funds. The law's Title IX has traditionally been used to broaden women's participation in high school and college athletics; educators say it's the first time the government has applied it to long-standing gender imbalances in fields such as physical sciences and engineering.

    “I'm delighted that a start has been made,” says Debra Rolison, a chemist at the Naval Research Laboratory in Washington, D.C., and longtime advocate for the enforcement of Title IX in academics. “This will push science and engineering departments to work harder to recruit and retain female students and faculty.”

    Women are underrepresented in several areas of U.S. science: For example, only 22% of graduate students in engineering, and fewer than 10% of engineering professors, are women. Although some argue that such imbalances merely reflect personal preferences, others blame a male-oriented culture within many science and engineering departments. A 2004 report by the Government Accountability Office, which scolded NSF, DOE, and NASA for not checking to see whether their grantees are complying with Title IX, prompted the current round of reviews. In 2005, Congress also ordered NASA to do two such reviews a year.

    In spring of last year, DOE officials visited Columbia University's physics department to conduct the agency's first-ever onsite Title IX compliance review. NSF officials did the same thing around the same time at Columbia's electrical engineering department. And NASA officials looked at the aerospace engineering departments at the University of Michigan, Ann Arbor, and the University of Maryland, College Park. In addition to examining grievance procedures, reviewers interviewed dozens of female students and faculty members about access to laboratory facilities and the general climate of their departments, as well as gathering data on enrollment and faculty composition. NASA's David Chambers says his team deliberately asked “who was in a leadership position and who was doing the note-taking” as well as whether male and female graduate students were equally likely to get research assistantships. NSF has reported its findings to Columbia, whereas DOE and NASA plan to share reports with the universities this spring.

    The nature of those interviews was annoying to some. At Columbia, cosmology professor Amber Miller described her DOE interview as “a complete waste of time.” The reviewers “made us write down every piece of equipment in the lab,” she says, and whether women were permitted to use each item on the list. She says the interviewer responded to her generic complaint about a shortage of lab space to press her on whether she felt discriminated against as a woman. “I wanted to say, ‘Leave me alone, and let me get my work done,’” says Miller.

    Team players.

    Amber Miller's experimental cosmology lab at Columbia University.

    CREDIT: DAVID TAM/COLUMBIA UNIVERSITY

    Columbia's Department of Physics Chair Andrew Millis thinks that the reviewers' concern about access to equipment suggests that they don't really understand basic academic science. “For God's sake, everybody is so desperate for good graduate students that gender is the last thing that faculty members are looking at when considering applicants,” he says. “Frankly, the process has been a little tedious.”

    But other academics say that questions about climate are appropriate. “To understand if women face barriers, you have to look at the experiences of individuals in the department,” says psychologist Abigail Stewart, head of Michigan's Institute for Research on Women and Gender, who was interviewed during the NASA review. Jocelyn Samuels of the National Women's Law Center, a Washington, D.C., nonprofit that has pushed for compliance reviews, applauds the government for looking beyond obvious metrics such as the number of women students and faculty members in a particular department. “Sex discrimination in labs ranges from outright harassment and sexual overtures to expressions of doubt about women's capabilities and exclusion of women from social gatherings where lab matters may be discussed,” Samuels says.

    Agency officials did not explain the basis for determining compliance and have not said what would happen if they uncover evidence of discrimination. But one DOE official noted that “this is not a ‘Gotcha!’ exercise. It is just a matter of ensuring that everybody gets equal opportunity.”

    Whereas DOE and NASA plan to continue their reviews, NSF's Ronald Branch says that an interagency group within the White House Office of Science and Technology Policy (OSTP) is now leading the Administration's effort to monitor compliance. OSTP did not return calls seeking comment.

  2. GENETICS

    Selfish Genes Could Help Disease-Free Mosquitoes Spread

    1. Martin Enserink

    “Inspired by a true story”—that could have been the subtitle for a new study that brings the idea of disease-fighting mosquitoes a step closer. Researchers borrowed an idea from real life and, like Hollywood screenwriters, adapted it to suit a different plot.

    The paper, published online by Science this week (www.sciencemag.org/cgi/content/abstract/1138595), addresses a crucial but often overlooked question: Even if you can make mosquitoes unable to transmit disease, how do you enable them to “replace,” or outcompete, the natural population? The study team, led by molecular biologist Bruce Hay and postdoc Chun-Hong Chen at the California Institute of Technology in Pasadena, answered it by producing a set of “selfish” genes in Drosophila fruit flies. The same principle could be applied in mosquitoes as well, they say. “This the most exciting thing I have seen [in this area] for a very long time,” says Jason Rasgon, an insect geneticist at Johns Hopkins University in Baltimore, Maryland.

    The plan to battle disease using transgenic insects has been around for years. Scientists have already spliced into mosquitoes genes that make them unable to transmit dengue, a painful viral disease, and the rodent form of malaria. A malaria-resistant version of Anopheles gambiae, the mosquito whose bite kills more than 1 million people a year, is expected to arrive soon. Almost $40 million from the Bill and Melinda Gates Foundation has given the field a big push and may help pay for trials in giant greenhouses within a few years.

    Leg up.

    A new study suggests a way to make transgenic insects—such as this malaria-resistant mosquito, created by a team at Johns Hopkins University—spread rapidly.

    CREDIT: M. T. MARRELLI ET AL., PNAS 104, 13 (2007)

    Yet one big question remains: Nobody quite knows how to give an introduced resistance gene an evolutionary leg up so that it becomes widespread. Natural selection alone probably won't do it. It's true that having a virus or parasite reproducing in its body does reduce a mosquito's fitness, and a lab study published in the Proceedings of the National Academy of Sciences (PNAS) last week showed that malaria-resistant mosquitoes beat out their nonresistant rivals in the struggle for survival—if both were feeding on malaria-infected mice. In real life, however, only a small proportion of mosquito hosts are infected, says Rasgon, one of the PNAS paper's authors, so resistance doesn't offer a big enough benefit to make it race through a population. Some sort of active “driver” is needed.

    Hay found inspiration for such a mechanism in a bizarre selfish genetic element first described in 1992 in a beetle called Tribolium castaneum. When female beetles carry even a single copy of this element, all their viable offspring have it, too; those that don't simply die. As a result, the element, called Medea, spreads through populations rapidly.

    Researchers have proposed that Medea produces a toxin during egg development, just before meiosis. That way, even if female beetles have only one copy of the element, the toxin ends up in all of their egg cells. After fertilization, the toxin kills the zygote—unless it has inherited the Medea element from either its mother or father. In that case, Medea produces a special antidote just in time to neutralize the toxin.

    All of this is just a hypothesis to explain Medea's inheritance pattern, says Richard Beeman of Kansas State University in Manhattan, one of Medea's discoverers, who is still trying to nail down the mechanism. But Hay and Chen decided they didn't need to wait for the answer to build the proposed system, toxin and antidote included, from scratch in fruit flies.

    The team spent years engineering flies to produce several kinds of toxins, such as ricin, in their egg cells, along with their respective antidotes. But making the insects produce exactly the right amount of toxin proved difficult. The team was luckier after it realized that the “toxin” didn't need to be a protein at all: It could also be the absence of one. They produced flies whose egg cells contain microRNAs that silence a gene called Myd88, whose protein product is crucial to pattern formation in the early embryo. Embryos resulting from these egg cells died. But if the embryos carried the team's Medea element, the “antidote”—in the form of an extra copy of the Myd88 gene, switched on after fertilization—came to the rescue, and development was normal. “To create a synthetic Medea—what an amazing idea!” says Beeman.

    And it worked. In cage experiments where Medea-carrying flies were mated with wild-type counterparts, Medea-carrying flies took over in 10 generations or fewer. By stitching a resistance gene into the genetic element—right between the genes for the toxin and the antidote—it should be easy to make that spread through a population as well, Hay says, although that experiment still needs to be done.

    Applying the same strategy in mosquitoes will be quite a bit of work, says Anthony James of the University of California, Irvine. Also, researchers have no idea whether the public will endorse the release of genetically engineered insects. But, says Kenneth Olson of North Carolina State University in Raleigh, the new study is a big step forward in making the notion of transgenic mosquitoes fly.

  3. PROFESSIONAL SOCIETIES

    ACS Drops Iranian Members, Citing Embargo

    1. Yudhijit Bhattacharjee

    The American Chemical Society (ACS) has reluctantly rescinded the membership of some 36 Iranian scientists after the society determined that having members in Iran violates U.S. law. The society hopes to reinstate them after obtaining a government license, a step that could set a precedent for other U.S. societies with Iranian members.

    U.S. organizations are prohibited from doing business with individuals in Iran, Cuba, and North Korea, but an exemption permits the trade of informational materials. That provision allows U.S. scholarly societies, whose journals are a major benefit to its overseas members, to retain ties to members in those countries.

    But ACS's stance changed after Assistant General Counsel David Smorodin reread the embargo rules and concluded that selling publications to members at discount rates, a common practice, represents a service above and beyond the trade of informational materials. He also believes that membership benefits such as “insurance, career counseling, invitation to meetings, and educational opportunities” are not exempt under the rules, although he acknowledges that overseas members typically do not use those privileges. “We had no choice as a federally chartered organization but to comply with the law,” says Smorodin, adding that his interpretation of the regulations did not “win [me] any friends within the ACS.”

    In January, ACS's membership off ice informed the society's 36 Iranian members that their memberships were being discontinued, although they could still purchase materials from the society at the full rate. The move angered David Rahni, an Iranian-American chemist at Pace University in Pleasantville, New York, and an ACS member, who says ACS should “refrain from allowing politics” to get in the way of scientific openness. Smorodin says the society will soon apply for a license from the Department of Commerce's Office of Foreign Assets Control allowing it to serve its Iranian members.

    Other associations are troubled by ACS's proposed solution. “We have no plans to do anything similar,” says Judy Franz of the American Physical Society in College Park, Maryland, which also has members in Iran. “We would resist having to obtain a license to the extent we can.”

  4. CLINICAL RESEARCH

    Testing a Novel Strategy Against Parkinson's Disease

    1. Jennifer Couzin*
    1. With reporting by Eliot Marshall.

    One of the largest clinical trials ever for Parkinson's disease, announced last week by the National Institute of Neurological Disorders and Stroke (NINDS) in Bethesda, Maryland, is experimental in more ways than one, officials say. It will use a novel approach to test a nutritional supplement against a disease, with a goal of recruiting 1720 participants (half to receive a placebo). And the method of selecting the test agent, a supposed energy booster called creatine, was unorthodox as well.

    In 2000, the institute began canvassing the community for compounds worth testing against Parkinson's disease and whittled a list of dozens down to a handful of candidates for so-called futility trials. Rather than show whether the compounds work, these small studies suggest whether a drug is futile in combating the disease.

    Creatine is the only compound of four examined so far to pass. NINDS is beginning to recruit early-stage patients for a large, phase III trial to see whether a purified medicinal version can slow the disease's progress. In another twist, the institute may add more compounds to the trial if they pass futility studies. “The whole thing is unusual,” agrees Debra Babcock of NINDS of the creatine trial, for which she is the scientific director. “It's a very new clinical trial for us and a new approach for disease intervention.”

    Babcock declined to give precise numbers on how much the trial will cost. But the entire venture, including futility trials of other potential Parkinson's compounds, is now expected to cost about $60 million, $20 million above the initial estimate, Babcock says. These estimates are “fuzzy,” she explained, because NINDS doesn't know how many futility trials it will run or how the creatine trial will evolve in the 7 years it's expected to last.

    Top candidate.

    A medicinal version of creatine, a popular nutritional supplement, will be tested as an anti-Parkinson's agent.

    CREDIT: NAJLAH FEANNY/CORBIS

    Creatine, which is available over the counter in health food stores, is thought to help boost ATP levels in cells, giving them more energy and protecting mitochondria, which in Parkinson's patients seem to malfunction, leading to cell death. Whether creatine is promising enough to justify a massive, long-term clinical trial in a time of tight budgets is up for debate. “To be honest, I think the evidence is not tremendously strong” that creatine can help, says J. Timothy Greenamyre, director of the Pittsburgh Institute for Neurodegenerative Diseases at the University of Pittsburgh in Pennsylvania.

    Another question is whether enough patients will sign up, because volunteers risk receiving a placebo. Recruiting may be “a major logistical challenge,” says Joel Perlmutter, a neurologist at Washington University School of Medicine in St. Louis, Missouri, whose center is one of the 51 participating. Babcock hopes the offer of pure creatine will attract volunteers.

    Although Perlmutter considers creatine promising, he's uncertain about its mechanism and how it might work against Parkinson's disease. Still, “even if creatine completely bombs,” says Perlmutter, the trial may still help teach researchers how to run largescale Parkinson's trials and identify new biomarkers.

  5. RESEARCH FUNDING

    Canadian Institutes Get Windfall Without the Bother of Competition

    1. Wayne Kondro*
    1. Wayne Kondro writes from Ottawa.

    OTTAWA, CANADA—Several Canadian research institutes will receive multimillion-dollar grants from the government this year without having even asked for the money.

    The government's unprecedented decision to dispense with peer review in awarding the grants—or even solicit advice on which programs to fund—comes as a huge surprise to the science community, which has questioned the process even as it welcomes the windfall. “I feel like I've been adopted by a rich grandmother,” says David Colman, director of the Montreal Neurological Institute and Hospital, which will get nearly $13 million.

    The gifts were wrapped in a 2007–08 budget, unveiled last week by Finance Minister James Flaherty, that boosts federal spending overall by nearly 5%. But the biggest twist in a budget that also hikes science and technology spending by a government-projected 5%, to $7.8 billion (ScienceNOW, 20 March, sciencenow.sciencemag.org/cgi/content/full/2007/320/1), is the proposed Centers of Excellence for Commercialization and Research. Finance and Industry ministry officials have already allocated some $130 million to eight institutions deemed best in class in fields that include brain research, stroke recovery, sustainable energy, and optics. The money is designed to help them compete next year for a new $165 million pot of money to support work in areas in which Canada hopes to become a world leader. “It's sort of proof-of-concept stuff,” says one ministry official.

    Colman says the money will expand fledgling research programs on neural engineering—using engineering techniques to understand and manipulate the behavior of the central and peripheral nervous systems—and neuropalliative care. He also applauds the government's willingness to reward the country's elite researchers with additional resources rather than trying to spread its wealth around. “This is what I like about this government. They're willing to say, ‘These things are outstanding. And because they're outstanding, let's give them a little more, not a little less.’”

    Brain food.

    David Colman's Montreal Neurological Institute and Hospital is one of several getting more government funding.

    CREDIT: MONTREAL NEUROLOGICAL INSTITUTE AND HOSPITAL, MCGILL UNIVERSITY

    For one recipient, however, the government's current largess is already more than adequate. Howard Burton is director of the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, which receives $42 million in the new budget. BlackBerry mogul Michael Lazaridis helped create the institute in 2000 with an $85 million endowment (Science, 5 December 2003, p. 1650), and the federal government chipped in $21 million. Ministry officials said that favorable reviews from an international panel evaluating that initial 5-year award persuaded them to pony up more money.

    “I'm very happy that we're held as an exemplar in terms of the research and the outreach that we do,” says Burton about the institute's ongoing work in foundational theoretical physics, including string theory, quantum gravity, quantum information theory, cosmology, and particle physics. But he says it's “not our intention” to apply for a centers grant because federal and provincial funding is “sufficient” for the next 5 years.

    The biggest complaint from scientists is that national politicians and bureaucrats identified and targeted disciplines for investment, and then picked individual winners, without benefit of scientific input and peer review. “It's a dangerous precedent,” says Ronald Worton, chair of Research Canada: An Alliance for Health Discovery, a new advocacy group for the research community. “I have no problem with governments prioritizing and saying we're going to support [one discipline or another],” adds Worton, who is CEO and scientific director of the University of Ottawa Health Research Institute. “But there has to be a process to arrive at this that is robust and arrives at conclusions that are logical and transparent.”

    Worton is also upset with the size of the outlays at a time when the Canadian Institutes of Health Research (CIHR), Canada's leading funder of biomedical research, has seen success rates for competitive grant proposals plummet from 32% to 16% in the past 5 years. “That amount of money added to the CIHR would have solved the whole problem,” he avows. The government announced it would raise CIHR's budget by 5%, to $627 million.

    Canadian Association of University Teachers Executive Director James Turk says the new initiative not only sets a bad precedent but is also further evidence of the government's preference for strategic initiatives over basic research, both within and outside the granting councils. “Sprinkled through all their discussions on research is a greater focus on targeting,” he says, “and the federal government choosing the targets.” But Claire Morris, president of the Association of Universities and Colleges of Canada, says that “good things can happen [through] partnerships between the private sector, the public sector, and academia.”

    Details of the new program are sparse. The winning institutes will have to come up with some outside funding, although the amount will be higher for centers focused on commercialization than for those doing basic research.

  6. GENETICS

    Sequencers of a Famous Genome Confront Privacy Issues

    1. Eliot Marshall

    A U.S. company has begun to trickle out information on a unique DNA study it calls “Project Jim,” a crash effort to sequence the entire genome of a single individual. The results are likely to be made public this summer. Anonymity is out of the question: It has already been announced that the genome belongs to James D. Watson, winner of the Nobel Prize and co-discoverer of DNA's structure.

    Watson won't be alone: Harvard Medical School has approved a plan by computational geneticist George Church to sequence and make public the genomes of well-informed volunteers—including his own. And J. Craig Venter says his nonprofit institute will soon release a complete version of his genome. (Venter contributed the largest share of otherwise anonymous DNA in the human genome sequenced by Celera Genomics in 2000.) These projects are adding urgency to an old issue: What constitutes sensitive genome data, and how should those data be safeguarded? As sequencing costs plummet, more and more individuals will be facing those questions.

    Watson, 79, says he agreed to have his genome sequenced when he gave a blood specimen 2 years ago to 454 Life Sciences in Branford, Connecticut. His reason was simple: “curiosity about my life.” He figures that, “On the whole, I will gain more from people looking at [the genome]” than not.

    The company has a new “resequencing” technique that uses public data as a template and relies on massive DNA replication and computerized sorting to lower costs. It would like to show off its prowess. Michael Egholm, 454's vice president of research and development, said in a telephone interview that the company's “fundamental vision” is to make “routine human sequencing” affordable. 454 is one of several firms in a race to claim this territory (Science, 17 March 2006, p. 1544). Company staff debated “who should be the first” person to be sequenced, Egholm says. After a dinner with scientific advisers, including DNA sequencer Richard Gibbs, according to Egholm, they decided that “It had to be Watson.” Watson not only accepted but also talked about it to the press.

    Know thyself.

    Nobelist James Watson is planning to receive—and possibly share—a complete copy of his own genome sequence this year.

    CREDIT: MARKUS SCHREIBER/AP PHOTO

    When the project began, 454's equipment wasn't up to the task, Egholm says. But improved technology made it possible to sequence 10 billion bases in multiple overlapping fragments of Watson's DNA “in a space of a few weeks” early this year. Egholm and 454's academic partners discussed preliminary findings at a meeting of sequencers in Marco Island, Florida, in February. For example, according to Egholm, a comparison between the new data and the reference human genome in public databases suggests that the reference genome is “about 97% complete.” He adds that Watson's genome has now been sequenced in triplicate, and company leaders and Gibbs—who heads the sequencing center at Baylor College of Medicine in Houston, Texas—estimate that a few weeks'more work would achieve sixfold coverage, enough for a “very high quality diploid genome.” The projected cost is “about $1 million.”

    Still undetermined, however, is precisely what the project will release. Watson agreed that his DNA sequence should be added to public databases. But he requested at the outset that his ApoE gene status—which can indicate a risk for Alzheimer's disease—be blanked out. Company staff then realized, Egholm says, that more might need to be blocked—perhaps all genetic loci currently known to be associated with disease risk. Opting to block only high-risk DNA variants would signal that Watson has those variants. Another problem: Some spots now considered innocuous may be linked to disease in the future—a consideration for Watson's sons.

    As Baylor scientists got involved, Gibbs and ethicist Amy McGuire of Baylor's Center for Medical Ethics and Health Policy presented the project (without identifying Watson) to the college's Institutional Review Board (IRB). The first step was to obtain a more rigorous consent. That was done, and the IRB gave its approval on 19 March. But public agencies have given “very little guidance,” McGuire says, on how to handle privacy and consent issues involving relatives.

    Baylor and 454 settled on a “data release pathway,” McGuire and Egholm say. The company will put the completed genome on a DVD and hand it over to Watson—perhaps, Egholm says, with a small ceremony. Watson will accept responsibility for discussing the risks of its release with his family, decide what should be blocked, and determine how and when to make the sequence public. Watson declines to say more until the company is ready to publish an article—by July, he expects.

    As for Venter, he says he plans simply to release his genome without restrictions.

  7. METAGENOMICS

    Massive Microbial Sequence Project Proposed

    1. Elizabeth Pennisi

    Taking stock of the microbial world is like trying to count the stars. But a report* released this week by the U.S. National Academies' National Research Council (NRC) outlines an ambitious program to decipher the incredible diversity of Earth's invisible life. The Global Metagenomics Initiative would be on par with the Human Genome Project in size and relevance. “Understanding the microbiome—human, animal, and ‘environmental'—is as important as the human genome,” says Michael Ashburner, a geneticist at the University of Cambridge, U.K., and a co-author of the report.

    A decade ago, researchers were limited to studying only the microbes they could isolate and grow in the lab—less than 0.1% of Earth's estimated microbial life. Now, they can sequence all the DNA from millions of different microbes in a sample and use powerful computers to pick out the genes. This technology—metagenomics—has enabled them to identify genes from the full complement of microbes in a particular environment, be it the ocean, sewage sludge, or the human colon (Science, 16 March 2007, p. 1486; 2 June 2006, p. 1355).

    Already, these approaches are revealing that microbes play a far bigger role in human health, agriculture, and the environment than previously realized. “Every process and event on Earth and in its inhabitants is directly or indirectly influenced by microorganisms,” says Jo Handelsman, a plant pathologist at the University of Wisconsin, Madison, and co-chair of the NRC panel. Microbial proteins may hold the key to cleaning up toxic wastes; developing “green” fuel sources; catalyzing the production of industrial products, food, and drugs; and protecting against bioterrorism, the report says.

    Soaring interest in these possibilities prompted the National Science Foundation (NSF) and other U.S. federal agencies to ask the National Academies to help define the field, establish standards for metagenomics research, and come up with goals for this emerging discipline. The NRC panel calls for a three-pronged approach: single-investigator studies, medium-sized projects, and three large-scale examinations of the microbes that live in particular habitats. The experts suggested that one project cover a natural environment, one look at microbes that live in human or other hosts, and a third focus on a community created by people—such as a sewage treatment plant.

    Researchers are already headed in that direction. Last year, NSF awarded the new Center for Microbial Oceanography: Research and Education, based in Hawaii, $19 million over the next 5 years. A human microbiome initiative is under consideration as a priority for the National Institutes of Health in 2008. Researchers from eight European countries have banded together to seek support for a €16 million effort on human gut microbes, and a joint French-Chinese metagenomics project is being planned.

    The NRC panel also recommends increased funding to improve the collection, storage, and analysis of the massive amounts of genomic and environmental data involved. “Extracting information from the [sequence] data, that's a hard problem,” says Daniel Drell, who coordinates metagenomics projects for the Department of Energy.

    Microbial genes revealed.

    Researchers can now study many different microbes (in different colors) in a sample at once.

    CREDIT: VINCENT DENEF/UC BERKELEY

    As for comparisons with that earlier sequencing effort: “This is not like the human genome project, where you know when you are at the end,” says James Anderson, a microbiologist at the National Institute of General Medical Sciences in Bethesda, Maryland. “How big this project might be is anyone's guess.”

  8. URANIUM ENRICHMENT

    Spinning a Nuclear Comeback

    1. Dan Charles*
    1. Dan Charles is a freelance science writer in Washington, D.C.

    A U.S. company is banking on the world's biggest and fastest centrifuges to restore the country's capacity to produce enriched uranium for nuclear power plants at home and abroad

    PIKETON, OHIO—It's not easy to get a glimpse of the “American Centrifuge.” A visitor must first clear a checkpoint at the edge of the Department of Energy's (DOE's) 1500-hectare Portsmouth reservation in southern Ohio, then pass through several sets of locked and guarded gates. Finally, one reaches the gargantuan, dimly lit centrifuge hall holding the centrifuges themselves—four-story-tall white ghosts, just a few of them so far, looming in the twilight.

    Inside each one is a cylinder, called a rotor, that spins faster than the speed of sound. By separating one isotope of uranium from the other, the cylinder slowly increases the concentration of uranium-235. Hooking together thousands of these devices in a cascade yields a fuel rich enough to sustain a nuclear chain reaction.

    This technology, a key to acquiring nuclear weapons, is one of the most tightly guarded in the world. In the desert south of Tehran, Iranian engineers are also trying to master the intricacies of the centrifuge. If they succeed, Iran could become one of a handful of nations with a full-scale centrifuge enrichment plant (see map). The United States, currently, is not among that select group. Its membership expired in 1985 when DOE abandoned the centrifuge facility here.

    Building capacity.

    Several new centrifuge facilities are under development in anticipation of increased demand.

    SOURCE: ISIS, NUCLEAR ENERGY DATA (2003) OECD, WORLD NUCLEAR HANDBOOK (2003), AND COMPANY STATEMENTS

    Now the U.S. Enrichment Corporation (USEC), a private company that took over the government's uranium-enrichment operations in 1993, is trying to bring both the building and the technology back to life. The $2.3 billion project would employ thousands of centrifuges and turn the Piketon facility into a source of enriched uranium for nuclear power plants in the United States and around the world. The facility would replace USEC's aging and unprofitable enrichment plant in Paducah, Kentucky, which uses a less efficient technology called gaseous diffusion.

    USEC's engineers have retrieved drawings from locked vaults and rediscovered long-forgotten technical skills. “It's like reliving your youth,” says Dean Waters, one of the project's leaders. “You almost have to pinch yourself: ‘How can I be doing this again?’”

    Global demand for enriched uranium is rising, and prices are soaring. Yet the future of the project remains uncertain. A small-scale demonstration of USEC's technology that was due to begin last autumn has fallen nearly a year behind schedule. Even if the technology works, some observers doubt that USEC has the financial muscle to build a full-scale plant. The company also faces increased competition from abroad.

    Born in the USSR

    The modern gas centrifuge was born in a Soviet camp for captured German and Austrian scientists after World War II. Ordered by Stalin's government to help build an atomic bomb, they took on the job of acquiring uranium-235, an isotope that comprises less than 1% of natural uranium mined from the earth. Low-enriched uranium, with up to 5% uranium-235, is used in power plants. Nuclear weapons contain highly enriched uranium, in which the concentration of U-235 exceeds 90%.

    The imprisoned scientists came up with a solution that employs a simple and light tube, balanced on a needle and spinning more than 1000 times each second inside a vacuum chamber. When they fed uranium hexafluoride gas into the cylinder, centrifugal forces pushed the gas outward, against the spinning wall. Atoms of uranium-238, being heavier, concentrated against the wall and also moved toward one end of the rotor. The lighter U-235 moved toward the other end.

    The Austrian mechanical engineer Gernot Zippe, one of the leaders of the team, carried this design—in his head, of course—to the West when the Soviets released him in 1956. “At first, I did not want to have anything to do with this highly secret [technology] anymore,” said Zippe in a 1992 interview with this reporter. But he soon changed his mind: “I saw that the West was far behind what we did in Russia, and I decided that it would be wrong to leave this to the Russians.” Zippe, who lives near Munich, shared his secrets first with the U.S. government, then with an industrial consortium in Europe called Urenco. The longer a centrifuge's rotor is, and the faster it spins, the more effectively it can separate two isotopes. But this creates huge engineering challenges. Velocities around 600 meters per second, now typical for spinning rotors, test the limits of even the strongest materials. As rotors accelerate, they pass through unstable phases called “critical speeds,” where the rotor's shape shifts slightly. The slightest imbalance can cause a rotor to crash catastrophically, and minor stresses will cause bearings to fail.

    Cylinder of secrets.

    USEC's Jennifer Slater and Bob Lykowski inspect a centrifuge in Piketon, Ohio. USEC digitally erased some sensitive features from this image.

    CREDIT: USEC

    Each heir to Zippe's invention developed a different version of it. Soviet engineers filled enrichment plants with millions of centrifuges, each one less than 1 meter tall. For many years, they made only small changes to Zippe's original, tried-and-true design. In contrast, Urenco created more powerful machines by increasing both the length and the speed of the rotors. And the U.S. effort, which began in 1960 at Oak Ridge National Laboratory (ORNL) in Tennessee, created the world's largest and most powerful centrifuge. “We started with the original Zippe machine” and improved it, says Waters, who was among the first scientists to work on the centrifuge at ORNL. “Then, within about 6 years, we discovered how to build the kind of machine that we're building today.”

    That machine, developed during the 1970s and early 1980s, stood about 14 meters tall and could enrich uranium five times faster than any Urenco centrifuge of its time. In the early 1980s, DOE began building a home for it on the Portsmouth reservation, right next to an existing gaseous diffusion enrichment plant. By 1985, more than 1300 machines had been installed in the new facility.

    That buildup, however, coincided with the tanking of the U.S. nuclear industry. Faced with plunging estimates of future demand for enriched uranium, DOE officials pulled the plug on the project. For 20 years, the mothballed centrifuges stood idle in silent rows, a mausoleum of secret technology. “We had the feeling that someday those buildings would be like Stonehenge,” says Houston Wood III, a centrifuge expert at the University of Virginia in Charlottesville who worked on the project. “People would come and wonder, ‘What were they thinking?’”

    Recovered memories

    There is, in fact, a Stonehengian quality to the Piketon plant. Its scale is massive—the buildings cover 160,000 square meters—and its peculiar architectural features reflect the unique demands of its very tall and very fragile tenants: doors five stories high, for instance, and concrete floors that float on a vibration-absorbing foundation.

    From 1985 until last year, these buildings were used only to store containers of waste from the nearby gaseous diffusion plant. Now they are coming back to life. Over the past 2 years, the centrifuges were dismantled, shipped to a classified landfill at the Nevada Test Site, and buried. The first of a new generation of centrifuges, identical-looking but quite different inside, are now arriving.

    Expired.

    The 1300 centrifuges at the Piketon facility in 1985 were never used; they are buried in a classified Nevada landfill.

    CREDIT: USEC

    The revival began in 1999, when USEC decided to bet its future on centrifuges after the rising cost of electricity made USEC's 50-year-old gaseous diffusion plant ruinously expensive to operate. The company went looking for people who knew something about the technology. “A surprising number were still at Oak Ridge,” says Waters, one of many nearing retirement. “Frankly, I don't think we would have resurrected this had that not been the case.”

    USEC signed up ORNL as a partner. Waters helped retrieve piles of old technical reports, computer programs, and centrifuge-related equipment from a laboratory vault. The know-how stored in human brains was even more valuable. “You can never put precisely into a document everything that you know,” says Waters.

    The team set about recreating its earlier centrifuge, with one crucial difference. The new machine features a rotor made from woven carbon fiber rather than fiberglass. This stronger rotor can spin faster—how much faster, USEC officials won't say. But it has made the world's most powerful centrifuge even more so.

    A centrifuge's ability to enrich uranium is measured in “separative work units” (SWU). According to Daniel Rogers, director of the plant in Piketon, each new centrifuge can perform 350 SWU per year. By contrast, the machines that sat unused in the Piketon plant for 20 years were rated at about 200 SWU per year. Julian Steyn, president of the consulting firm Energy Resources International in Washington, D.C., says the latest Urenco centrifuges, which have carbon-fiber rotors about 6 meters long, can run at 70 to 80 SWU per year.

    Is tall and fast a winner?

    USEC officials like to compare their machine to a Mercedes. In contrast, says one, Urenco's resembles a Volkswagen. A company slide show states it bluntly: “Taller and Faster is Better.”

    USEC will need only one-fifth the number of centrifuges as Urenco to produce the same amount of enriched uranium. But USEC's large centrifuges may be more costly to manufacture and to maintain. And reliability is even more important, says Steyn. USEC's centrifuges will have to operate flawlessly for decades to hold their own against Urenco's stable of centrifuges.

    Waters believes that his new centrifuge will prove the doubters wrong. In the 1970s and 1980s, he says, “we achieved reliability that was on the same order of magnitude as Urenco's. We have several examples of extremely reliable cascades. The people who did that are working on this program today.”

    USEC is also facing a financial pinch. In U.S. Securities and Exchange Commission filings last month, USEC estimated that a full-scale centrifuge facility will cost $2.3 billion. The company admitted that it will need “some form of investment or other participation by a third party and/or the U.S. government” to get a new plant running.

    Most observers don't think Uncle Sam is likely to help out. Once a tightly held government monopoly, the business of uranium enrichment is now—at least in the United States and Europe—dominated by commercial priorities. Failing companies face bankruptcy rather than a government bailout.

    For the first time, USEC also faces possible competition on its own turf. With its eye on the U.S. market, Urenco has acquired preliminary approval for a full-scale centrifuge plant and has broken ground near the town of Eunice, in southeastern New Mexico. Production is scheduled to begin in 2009. Meanwhile, GE Energy is testing another approach to uranium enrichment in Wilmington, Delaware, using lasers that are tuned to excite particular isotopes. GE Energy licensed this technology from an Australian company. “There's not enough enrichment capacity in the West,” explains Steyn. Many U.S. power plants currently use fuel that originally came from the Russian stockpile of highly enriched uranium. But the deal that makes this possible will expire in 2013.

    Some nuclear proliferation experts worry that the Piketon facility could be a tempting target for nations trying to develop nuclear capabilities. Urenco, the first of the commercial enrichment companies, was the source of centrifuge technology that aided nuclear efforts in Pakistan and other countries. In particular, A. Q. Khan, a Pakistani metallurgist who worked for a Urenco contractor in the Netherlands in the early 1970s, obtained details of centrifuge design before returning to Pakistan, where he led that nation's successful efforts to create a nuclear bomb.

    Noting that USEC, like Urenco, plans to rely on contractors to manufacture most of the centrifuge components, Harvard University proliferation researcher Matthew Bunn says that “the more different sets of people have their eyes on parts of the centrifuge, the more chance there is for that technology to leak.” Rogers, however, says that USEC has tightened security in recent years to address growing proliferation concerns.

    USEC's next step is construction of a small pilot cascade, with up to 240 centrifuges, inside the Piketon plant. The pilot will persuade potential investors that the American Centrifuge is both technically and economically viable, says Rogers. It's running slightly behind schedule: The “lead cascade” was expected to start up last fall, but USEC is now aiming for the end of this summer.

    Virginia's Wood hopes that it succeeds, putting the United States back into the big leagues of uranium enrichment. “USEC has a tough road, but I'm pulling for them,” he says. “I would hate [for us] to be the only country in the world that doesn't have a centrifuge plant.”

  9. PHIL BARAN PROFILE

    Chemical High-Flyer's Strategy: Take Away the Safety Net

    1. Robert F. Service

    Synthetic chemists take great pains to ward off unwanted reactions. A young researcher says they can save time—and learn new science—by dropping their defenses

    Gentle giant.

    Baran (center) is pioneering an effort to streamline the synthesis of natural products.

    CREDIT: COURTESY OF THE SCRIPPS RESEARCH INSTITUTE

    The way synthetic chemists tell it, three things in life are unavoidable: death, taxes, and protecting groups. Phil Baran can't do much about death or taxes. But the 29-year-old chemist at the Scripps Research Institute in San Diego, California, is making considerable headway on the third item: a class of molecular stoppers that chemists append to key sites on their molecules to keep unwanted reactions from creating chemical garbage. Among the scientific artisans who craft big, unwieldy molecules—the sort that biology has spent eons perfecting—protecting groups are a must. But they carry a high price tag. Tacking them on and later stripping them off adds so many steps to a typical synthesis that they make the work maddeningly hard and the final yield of the desired compound vanishingly small.

    In his young career, Baran has set out to find an alternative to waging this synthetic battle. His solution has been to develop a sort of molecular judo that takes advantage of a molecule's reactive propensities rather than trying to fight them head on. This “gentle way,” as a judo master might call it, is beginning to show its strength. Last week, Baran and his students unveiled the latest displays of their technique in papers in Nature and the Journal of the American Chemical Society, which showed that they could make a variety of highly complex, naturally occurring molecules while either minimizing the number of protecting groups or doing away with them altogether. Earlier this week, such feats also helped Baran reel in this year's National Fresenius Award, which the American Chemical Society gives to a promising chemist under 35.

    Baran isn't the first chemist to try to do more with less. But doing away with protecting groups for synthesizing complex natural products is rare. That's because large organic compounds are studded with sites known as functional groups that are difficult to control, says Jie Jack Li, a medicinal chemist at Pfizer in Ann Arbor, Michigan. “For large molecules, there are so many functional groups, it's hard to touch one and not the others,” Li says. The typical solution: protecting all but one to avoid the problem.

    Baran's gentler display of control is flooring many of his colleagues. “This guy is an off-the-scale youngster who towers above everyone else in his age group,” says Elias J. Corey, a chemist at Harvard University who won the 1990 Nobel Prize in chemistry for developing the logical foundations of synthesizing complex molecules. As Baran's former postdoctoral adviser, Corey might have reason to be biased. But other synthetic chemists are equally laudatory, calling Baran “exciting,” “impressive,” even “a superstar.” “Phil is going to be a big name in organic chemistry for a long time to come,” concludes Tom Stevenson, a synthetic organic chemist at DuPont in Newark, Delaware.

    He's certainly off to a fast start. After blitzing through his undergraduate degree at New York University in 2 years, Baran spent the next 6 years honing his skills with two of the world's leading synthetic organic chemists—earning his Ph.D. at Scripps in the lab of K. C. Nicolaou before settling in with Corey for his postdoc. When Scripps then offered him a position, Baran says he was both excited and concerned about how to focus his research.

    After working with Nicolaou and Corey, Baran says he was enamored of synthesizing large, complex molecules. But few young faculty members start out with such complex synthetic projects. “Young people typically start out on [developing novel reaction methods] and move towards synthesis,” Baran says. But he recalled a quotation from Corey in a chemistry textbook that said there is still plenty of room for discovering new ways to plan syntheses of complex molecules. That inspired him to see whether he could craft such a plan without protecting groups.

    The problem is a tricky one. Take a marine natural product called hapalindole U, one of the molecules Baran and his students reported synthesizing in their Nature paper. The compound had been synthesized before. But that approach required 20 steps, half of which involved either putting on or taking off protecting groups on five different sites around the molecule. At one point in the synthesis, for example, the growing molecule sports an indole group, a five-member ring containing a nitrogen atom that's just begging to react with any electron-hungry compound. The conventional approach caps that nitrogen with a short, chainlike compound called a Boc group to stymie its reactivity.

    Baran and his students, however, opted to put the nitrogen's reactivity to use. They reacted the indole with a highly basic compound called LHMDS, which ripped a proton off the nitrogen. They carried out related preparation of another molecular fragment called a terpene. With those groups primed, they then linked two fragments using a specially invented reaction designed to target only the linkage site. By continuing with the strategy, Baran's team cut the synthesis of hapalindole U down to eight steps. Using the same approach, the group turned out another compound in 10 steps that had previously required 25. “This really challenges the rest of us to think that way,” Stevenson says.

    In addition to making for more efficient syntheses, Baran says he's found that the biggest advantage of using molecular judo is that it forces him to invent new chemistry along the way. Adding protecting groups, Baran says, gives researchers the illusion that they can control the chemistry they are working on. But in reality, protecting groups are added precisely because researchers have not managed to emulate the exquisite knack biological enzymes have for operating on just one bond on a molecule. Removing that safety net forces researchers to find ways to match biology's control. “The point is not to say you should blindly throw away all protecting groups,” Baran says. However, he adds, doing so in select cases “is a vehicle for discovery and adventure.”

    It has a practical upside as well. Fewer synthetic steps mean more of a desired compound at the end, because each added step produces some loss. A 20- to 25-step synthesis typically yields just milligrams of a compound, too little for extensive studies of its biological activity. Baran's approach, by contrast, typically produces final compounds by the gram. Naturally derived compounds, Li points out, remain at least the starting point for about 50% of all new drugs today, excluding small changes to existing compounds. But in many cases, such as with compounds harvested from marine organisms that are difficult to collect, researchers can't get their hands on enough of the naturally occurring compounds for biological tests. Having grams or more of a compound to work with could change things dramatically. “This could potentially revolutionize both [drug] discovery and development,” Li says.

    Baran, Corey, and others caution that synthetic chemistry's gentle way can't be used in every case. But Baran has already shown that it works with a wide range of complex molecules. That's an achievement in itself and likely a harbinger of many to come.

  10. PLANT PATHOLOGY

    Deadly Wheat Fungus Threatens World's Breadbaskets

    1. Erik Stokstad

    New mutations have put an old killer back on the map. As it spreads, breeders are racing to develop resistant plants

    Against the grain.

    A new race of stem rust, Ug99, could wipe out wheat fields that were once resistant.

    CREDIT: DAVID MOWBRAY/CIMMYT

    Scientists thought they had beaten Puccinia graminis a long time ago, and for good. Before the late 1950s, the fungus was notorious for causing black stem rust, one of the most devastating diseases of wheat. Every few years, outbreaks would lay waste to entire fields somewhere in the world, sometimes sweeping across great swaths of continents in a matter of months.

    Salvation came with the development of wheat varieties that resisted the disease, which are widely credited with helping to usher in the green revolution in the 1960s. The new cultivars caught on rapidly, helping ensure bumper crops not just in the United States but in developing countries as well. “Stem rust was something we felt we had solved,” says Miriam Kinyua, a plant breeder at the Kenya Agricultural Research Institute (KARI) in Njoro.

    But stem rust is back, and it's more dangerous than ever before. In 1999, a new race of the fungus was discovered in Uganda that can defeat the resistance of most varieties of wheat. The fungus spread in northeast Africa for several years while researchers scrambled for funds to study it. In January, pathologists announced that it had jumped the Red Sea into the Arabian Peninsula—on a path to the major wheat-growing regions of Asia. Compounding matters, a new mutation turned up late last year that enables the fungus to infect even more kinds of wheat. “This is the most virulent strain we've seen in 50 years,” says Kay Simmons, the national program leader for plant genetics and grain crops at the U.S. Department of Agriculture (USDA).

    While pathologists nervously track the spread of the disease, breeders have ramped up their search for varieties that can survive it. Already, they've had initial success with two that might help Ethiopian farmers. But it can take years to complete field-testing and generate enough seed to distribute to farmers. With much of the world in need of resistant varieties, the challenge is enormous, says wheat breeder Rick Ward, who coordinates the Global Rust Initiative.

    Stem rust is the worst of three rusts that afflict wheat plants. The fungus grows primarily in the stems, plugging the vascular system so carbohydrates can't get from the leaves to the grain, which shrivels. In the 1950s, when the last major outbreak destroyed 40% of the spring wheat crop in North America, governments started a major effort to breed resistant wheat plants. Led by Norman Borlaug of the Rockefeller Foundation and others, researchers succeeded by bundling several genes that conferred powerful resistance in new varieties. One gene, Sr31—added later on a large chunk of a rye chromosome—also boosted yield and became widespread in wheat varieties by 1980. Puccinia, in contrast, became ever more rare, and fewer new races arose. Researchers turned their attention to the two less devastating wheat rusts, leaf rust and yellow rust, that still cause trouble.

    Two decades later, pathologists and breeders were caught off-guard when the new race of stem rust turned up in Uganda. It was first detected in 1999 at a research station, where many varieties of wheat were being studied. Ravi Singh, chief wheat breeder and pathologist at the International Maize and Wheat Improvement Center (CIMMYT) in El Batán, Mexico, recalls being alarmed when he heard how many kinds of wheat were susceptible. Most worrying was that this new race—dubbed Ug99—could even kill wheat plants outfitted with the resistance gene Sr31. Still, he says, a few new races had turned up in the past decades without causing epidemics. And Ug99 didn't come back the next year. “If it shows up just for 1 year, you can't make any major commitment. It's hard to justify,” Singh says.

    In 2001, however, Ug99 started infecting wheat cultivars at a research station in Kenya. It was noticed in Ethiopia 2 years later. Still, the response was minimal; CIMMYT was in a budget crunch, and it had little core funding that it could switch to the problem, Singh says. Enter Borlaug, then 90 years old. He and Christopher Doswell of the Consultative Group on International Agricultural Research wrote a memo in 2004 urging CIMMYT leadership to make Ug99 a priority. “We knew the dangers, and we blew the whistle,” Borlaug says.

    Shortly thereafter, CIMMYT and a sister institute—the International Center for Agriculture Research in the Dry Areas (ICARDA)—started the Global Rust Initiative (GRI) to coordinate efforts to track and study Ug99 and develop resistant varieties of wheat. With funds that Borlaug helped raise from international donors, CIMMYT and ICARDA began to send more seeds from their collections to be evaluated in Kenya, where the pathogen is now endemic—so many seeds that the seven breeders and pathologists at KARI's Njoro research station are increasingly overwhelmed. “Ug99 is so threatening that other problems have almost been overlooked,” says Kinyua.

    So far, about 90% of the 12,000 lines tested are susceptible to Ug99. That includes all the major wheat cultivars of the Middle East and west Asia. At least 80% of the 200 varieties sent from the United States can't cope with infection. The situation is even more dire for Egypt, Iran, and other countries in immediate peril.

    More bad news arrived last December. Tests on sentinel plots by GRI-funded researchers revealed that Ug99 had mutated. Testing at a USDA laboratory in St. Paul, Minnesota, showed that the new race can now also defeat Sr24, another key source of genetic resistance. “That was the worst case scenario,” says USDA plant pathologist Yue Jin, who did the work. “It's increased the worldwide vulnerability incredibly.” Right now, this identification may only be done in midwinter in Minnesota, so that any spores that might escape will be killed by the temperatures. Researchers are hopeful, however, that the recent sequencing of the Puccinia genome will speed development of diagnostic tools that can be easily used in Africa.

    Out of Africa.

    Blown by winds, stem rust spores (inset) are projected to follow the path a related disease took in the 1990s.

    CREDITS (TOP TO BOTTOM): T. ELAM AND Y. ANIKSTER; SOURCE: BASED ON SINGH ET AL., PERSPECTIVES IN AGRICULTURE, VETERINARY SCIENCE, NUTRITION AND NATURAL RESOURCES, 1 (54), 2006

    Meanwhile, Ug99 continues its march. In January, Jin's Minnesota lab confirmed that Ug99 had reached Yemen. The fear is that the spores will quickly spread via winds north through the Middle East and then head to the bread baskets of India and Pakistan, as an epidemic of yellow rust did in the 1990s. That epidemic caused some $1 billion in damage, and stem rust could easily triple those losses, CIMMYT has estimated.

    Fungicides can help control the damage from Puccinia, and GRI will begin trials in June to figure out the best way to use them. But chemical treatments are too expensive for many farmers in the developing world, Singh says, so plant breeding is the primary strategy.

    Two new kinds of wheat have shown promise in Ethiopia. “The yields are very favorable, comparable to the commercial varieties,” says Tsedeke Abate, director general of the Ethiopian Institute of Agricultural Research in Addis Ababa, where a half-dozen scientists are working full-time on Ug99. The immediate challenge is to grow enough seed from these resistant strains to distribute to Ethiopian farmers. Last year, researchers harvested 15 kilograms of precious seed. Then, in a painstaking effort, they hand-planted this wheat to maximize seed production. Spread over 4 hectares, the seedlings had extra room to grow and were carefully watered and weeded by hand. The resulting yield was nearly 4 tons of seed of each variety. “They went to extraordinary efforts,” Ward says.

    Now, that success must be replicated for other regions. Singh says it's important to come up with resistant varieties for countries that aren't yet infected. Planting those before an epidemic strikes could help slow the spread of the disease. Egypt, for example, has vast tracts of wheat. If stem rust infects those crops, they will send enormous quantities of spores throughout the Middle East and toward west Asia. It's a tight race, as several observers suspect that Ug99 could start reaching Egypt later this year.

    Despite the world's initial slow response, Borlaug, who turned 93 last week and is battling lymphoma, says he is optimistic that the fungus will be beaten again.

  11. LUNAR AND PLANETARY SCIENCE CONFERENCE

    Bringing Martian Streaks and Gullies Down to Earth

    1. Richard A. Kerr

    LUNAR AND PLANETARY SCIENCE CONFERENCE, 12–16 MARCH 2007, LEAGUE CITY, TEXAS

    Nice vantage point.

    In the Dry Valleys of Antarctica, snowmelt makes Mars-like dark streaks by seeping in and flowing downhill to dampen and darken the surface.

    CREDIT: JAMES HEAD, BROWN UNIVERSITY

    For all their dramatic visual appeal, the gullies of Mars are proving mighty enigmatic. They look as if they were cut the other day by rivulets of water seeping from crater walls and cliff faces. But in geology, looks aren't everything. Seven years after discovering gullies, planetary geologists still disagree about where the water comes from and even whether water was involved at all. Add in the even more contentious dark streaks that mark other martian slopes, and you've got no end of debate over the recent history of water on the Red Planet.

    At the meeting, planetary geologist James Head of Brown University and colleagues offered a down-to-earth resolution of the gully-and-streak conundrum. If a cold, dry Mars works the way the hyperarid and perennially frigid Dry Valleys of Antarctica do, they said, streaks and gullies are both shaped by flowing water, the one from below and the other above and below.

    During a 3-month field season this past austral summer, Head and colleagues took a close look at Dry Valley dark streaks that from orbit and from a helicopter appear “very, very comparable to things seen on Mars,” Head said. Like martian streaks, these are dark, stretch down steep slopes, and show no sign of relief across a streak. On Mars, researchers have typically invoked some sort of surface flow: an avalanche of dry dust that unveils a darker substrate, a cascade of wet debris, or the flow of an erosive spring.

    Twins?

    Streaks in Antarctica (top) and on Mars (bottom) bear a strong family resemblance.

    CREDITS: IKONOS IMAGE COURTESY OF JAMES GARVIN, NASA/GSFC; MSSS/JPL/NASA

    In Antarctica, nothing whatsoever flows on the surface to form a streak. Scarce, windblown snow accumulates in pockets near the tops of slopes, melts in the warmest and sunniest part of the summer, seeps down a few tens of centimeters into the loose rocky debris that passes for soil, and runs downhill on top of a layer of ice-encased rock. When the unseen water encounters less-porous, finer-grained soil, it wicks upward to dampen the surface and darken it.

    In the next talk, Joseph Levy of Brown spoke for the same group about Dry Valley gullies. A gully works much as a streak does, he said, but with water supplied so fast that it flows both through the soil and on the ground's surface. On higher, steeper slopes, the greater flow cuts a channel, and lower down it deposits fans of sediment.

    The Antarctic Dry Valley examples are “the best analogs I've seen,” said planetary scientist Oded Aharonson of the California Institute of Technology in Pasadena. And Head's streak presentation was “a great talk,” says planetary scientist Robert Sullivan of Cornell University. Still, no one considers the case closed. Sullivan, for one, finds a dearth of snow and ice on the slopes above the martian streaks; he wonders how there would be enough water to even dampen the soil. And Aharonson asks how dark streaks could stay damp for decades on Mars. As Sullivan notes, “We don't have things entirely figured out.”

  12. LUNAR AND PLANETARY SCIENCE CONFERENCE

    Warped Shorelines on a Rolling Mars

    1. Richard A. Kerr

    LUNAR AND PLANETARY SCIENCE CONFERENCE, 12–16 MARCH 2007, LEAGUE CITY, TEXAS

    Some planetary scientists see remnants of shorelines where oceans lapped onto land early in Mars's history, but the putative shorelines wander over martian hill and dale. They diverge by a kilometer and more from the single sea-level elevation that an ocean would have traced out. But a group of geophysicists reported at the meeting that they have found a plausible explanation for warped ancient shorelines: Mars rolled on its side, twice, in response to a huge ocean basin emptying.

    The new view relies on the ready mutability of vast spinning objects. Tape a penny to the top of a ball floating in water, and the ball will roll over until the penny is at the bottom, the weighted ball's most stable position. Do the same thing to a ball spinning in space, and the ball—while still spinning as before—will roll until the penny is at the ball's rotational “equator,” the most stable position for a spinning, weighted ball. Now imagine your spinning ball is a chunk of rock the size of Mars and the added weight is an ocean's worth of water. Because rock is not entirely rigid, the roll that takes the ocean toward the equator will also raise rock into an equatorial bulge, warping the ocean's shorelines in the process. Geophysicist Taylor Perron of Harvard University and colleagues described how they investigated whether such rolling could explain two warped apparent shorelines of different ages that partially enclose the northern lowlands of Mars. They calculated how much Mars would have had to roll, and in which direction, to deform the once-level shoreline of an ancient ocean into the putative shorelines. Working backward in their model, they found that the shorelines become releveled when the lowlands roll in two steps from their present pole-centered position to more equatorial positions. Throughout both steps, Mars's massive Tharsis volcano stayed near the equator—where it is today. If the releveling had moved the dominant Tharsis mass, the calculation would have been obviously erroneous. Keeping Tharsis in place by chance would have been a “pretty incredible” coincidence (about a 0.01% probability), they calculated. The group also calculated that the mass of water in the lowlands would have been great enough to drive such planetary rolling.

    A roller?

    Northern lowlands (blues) may once have been equatorial and water-filled.

    CREDIT: GSFC/NASA

    “The idea is really interesting and refreshing,” says geophysicist Shijie Zhong of the University of Colorado, Boulder. “If the story is true, we can probably make sense of these shorelines.” One possible snag, he adds, is the mass of ocean water. It may have been too small to overcome the forces besides Tharsis—such as the thickened crust of southern Mars—that influence the planet's orientation.

  13. LUNAR AND PLANETARY SCIENCE CONFERENCE

    Cold, Cold Bodies, Warm Hearts

    1. Richard A. Kerr

    LUNAR AND PLANETARY SCIENCE CONFERENCE, 12–16 MARCH 2007, LEAGUE CITY, TEXAS

    What would erupting volcanoes, even icy ones, be doing on the coldest bodies in the solar system? Temperatures hover around 50 kelvin on Kuiper belt objects (KBOs), which circle on the frigid dark fringes of the solar system for eons on end. But astronomers recently have seen signs that fresh ice has formed on KBOs in the geologically recent past. Now, researchers have calculated how a KBO, at least a larger one, might husband its primordial allotment of heat until the present day.

    At the meeting, theoretical astrophysicist Steven Desch and colleagues at Arizona State University (ASU) in Tempe explained the problem researchers have with some KBOs. Astronomers, including members of the ASU group, have detected the spectroscopic signature of crystalline water ice on KBOs such as 1260-kilometer-diameter Quaoar and 1500-kilometer 2003 EL61. But both cosmic rays and ultraviolet light destroy ice's crystallinity within a few hundred thousand years.

    Somehow, relatively warm crystalline ice has formed of late on the largest KBOs, but scientists have had trouble explaining where the necessary heat came from. KBOs have been cooling inside for billions of years, and unlike satellites such as Io or Enceladus, they do not orbit a huge planet that can spare a trickle of tidal energy to heat the smaller body's interior. So the ASU group constructed a mathematical model to simulate the temperature history of a 1200-kilometer KBO, beginning as a cold ball of ice and rock. They included the heat produced by radioactive elements such as potassium-40 as well as the ability of rock and water to separate if the heating goes far enough, a process called differentiation.

    The trick to staying warm proved to be differentiating. The test KBO—modeled after Pluto's moon Charon, which is a KBO-type body like Pluto—differentiated within 70 million years of formation, from the inside out. It differentiated just enough to include half the body's mass in a hot, rocky core overlain by a liquid ocean. A thick, cold outer crust remained unchanged while central temperatures rose to 1300 kelvin for 2 billion years. Modelers added a dollop of ammonia “antifreeze” inferred from spectroscopic detections of ammonium dihydrate on the surfaces of large KBOs. Even today, a liquid ammonia-water ocean a few tens of kilometers thick remains in the model KBO, thanks to the antifreeze. Ammonia-water “magma” could still be oozing to the surface of real KBOs, the group calculates, as ongoing freezing and expansion of water initiates cracks that propagate to the surface.

    “I'm surprised it stays so hot,” commented planetary physicist William McKinnon of Washington University in St. Louis, Missouri. Desch had two explanations. One was the insulating effect of the rock in the undifferentiated outer shell. The other was the large heat stores in the rocky core.

    If the real Charon works anything like the model version, there's hope of seeing some lively geology—frozen “lava” flows and flooded plains—when the New Horizons spacecraft reaches Pluto-Charon in 2015. Then on into the Kuiper belt.

  14. LUNAR AND PLANETARY SCIENCE CONFERENCE

    Snapshots From the Meeting

    1. Richard A. Kerr

    LUNAR AND PLANETARY SCIENCE CONFERENCE, 12–16 MARCH 2007, LEAGUE CITY, TEXAS

    Springtime on Mars. The Red Planet may be colorful to the eye, but for decades it had been a drab, wintertime landscape to spectroscopists as they searched for new colors denoting new minerals and thus new geology. Now colors are bursting out all over. “Revelation number one is not just a handful of water-related sites but hundreds,” Scott Murchie of the Applied Physics Laboratory in Laurel, Maryland, said at the meeting. Murchie is principal investigator of the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) orbiting on Mars Reconnaissance Orbiter. The most powerful spectrometer ever flown to Mars, CRISM is revealing the intimate details of highly weathered sulfates, clays, and iron minerals deposited in early martian environments where conditions varied dramatically over time. That should give mission planners no end of options when they put the next rover on Mars in 2010.

    Big sploshes. Mojave impact crater on Mars is worn beyond its years. Formed in the cold, dry times of later martian history, Mojave looks as if torrential rains stripped its flanks and dumped the debris in great fans (Science, 9 April 2004, p. 196). But new images from the HiRISE camera aboard the Mars Reconnaissance Orbiter reveal other drenched-looking craters of about the same age. Planetary geologist Livio Tornabene of the University of Arizona, Tucson, and colleagues reported heavy erosion and fan deposition in and around Tooting, Zunil, and Zumba craters in low northern latitudes. Did four recent icy comets dump their water on Mars? Statistically improbable, the researchers say. Instead, they suggest, the impacts may have unleashed water stored deep beneath the surface. That beats a divining rod on Mars.

    Deep flood.

    Water to erode young martian craters may have welled up from below.

    CREDIT: TORNABENE ET AL., LUNAR AND PLANETARY SCIENCE CONFERENCE XXXVIII (2007)

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