The Top 10 Science Stories of 2009 [Slide Show]

A hominid ancestor, swine flu, the world's biggest laser system and other highlights that defined this year in science

Stimulus Funds for Science The most prosaic event of 2009 may have the biggest impact. To deal with the pain of the deep recession, the U.S. committed $787 billion to jump-start the economy. Formally called the American Recovery and Reinvestment Act, the stimulus package sets aside a good chunk for science—some $21.5 billion for federal research and development and billions more in related infrastructure and administration. States are seeing hundreds of new grants. (Details can be seen at ScienceWorksForUS, a consortium of academic research institutions tracking stimulus spending.) Other targets for stimulus funds include various technology projects, such as boosting broadband access in the U.S. and creating a high-speed rail.

Renewable energy research is a major part of the stimulus funds, as well. And at least one benefit goes directly to individuals installing solar panels, wind turbines or other alternative-energy technology: Thanks to those funds, the federal tax credit of 30 percent of the cost of installation is no longer capped (the previous limit was $1,500). © ISTOCKPHOTO/MARKGABRENYA
The National Ignition Facility On May 29, the world's largest laser system was officially dedicated. Located at the Lawrence Livermore National Laboratory, the stadium-size National Ignition Facility (NIF) required $3.5 billion and 12 years to build. Beams from 192 lasers will go past several energy-boosting "control points" over a total distance of one kilometer before converging, all within 30 trillionths of one second of one another, onto a pencil eraser–size pellet containing frozen hydrogen. The beams will heat the hydrogen to millions of degrees and trigger nuclear fusion with a net gain in energy. Actual ignition experiments begin next year.

The main mission of the NIF is to generate technical data necessary to maintain the U.S. nuclear arsenal without the actual detonation of nuclear warheads. But NIF designers also think that astrophysics studies will benefit because the system creates conditions similar to those in supernovae, black hole event horizons and the centers of gas-giant planets. And, of course, the NIF represents an enormous advance in inertial confinement fusion that could pave the way for a practical fusion reactor. LAWRENCE LIVERMORE NATIONAL SECURITY, LLC
Water on the Moon Forty years after Apollo 11 first delivered humankind to the moon's surface, NASA again made headlines with a lunar mission, finally confirming the long-suspected presence of water ice deposits on the moon. The LCROSS mission slammed a spent rocket booster into a permanently shadowed polar crater in October, trailed by a shepherding spacecraft that observed the debris plume from the crash up close before plunging into the crater minutes later. Preliminary data from the spacecraft indicated roughly 95 liters of water ice in the plume. The month before LCROSS's lunar bombardment, researchers announced that they had found a much less concentrated water resource on the moon: molecular water, possibly coalescing from the solar wind, distributed across much of the lunar surface.

Astronomers are also poised to discover liquid water well beyond the solar system as they continue to discover Earthlike exoplanets. JPL/NASA
Epigenetics and the Passing of Acquired Traits to Offspring The same year that celebrated Charles Darwin witnessed numerous reports that give a measure of credence to a scientist historically viewed as his competitor: French biologist John-Baptiste Lamarck. In the early 19th century Lamarck asserted that acquired characteristics can be transmitted to offspring. In this tradition, the science of epigenetics, which studies the ways genes are switched on through environmental influences (and can remain in that state over multiple generations) experienced a banner year.

In February researchers reported in The Journal of Neuroscience that exercise, social interactions and other forms of stimulation enhanced brain activity that promotes learning and memory in mice genetically engineered to have memory deficits. Offspring of these mice, moreover, experienced improved cognition through early adolescence.
A November report in the journal Endocrinology showed that the pups of pregnant mice fed a high-fat diet during pregnancy were longer than normal and insensitive to the effects of insulin, a trait that persisted into a subsequent generation.

Such persistent epigenetic changes are likely to apply to humans. Researchers have been studying how chemicals in the environment can alter epigenetic switches in our bodies and leave us vulnerable to diseases ranging from diabetes to cancer. © ISTOCKPHOTO/NOEL POWELL
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Hubble Servicing Mission The Hubble Space Telescope, one of the most productive astronomical observatories ever built, passed its 19th anniversary of reaching orbit in April, and the next month received a makeover that left the telescope looking sprightlier than ever. In the course of five spacewalks from space shuttle Atlantis, the astronauts of the STS-125 mission repaired or replaced key scientific instruments as well as batteries and other mundane hardware on Hubble, leaving behind a tuned-up and enhanced observatory that NASA hopes will continue to work for five to 10 more years.

An early threat to the astronauts' safety thankfully failed to materialize: Three months before the launch of STS-125 a collision between two satellites littered Hubble's orbital path with dangerous debris, but the mission passed without incident. NASA
AIDS Vaccine Results Disappointment and hope were ironically the two main reactions to the results of an AIDS vaccine trial in Thailand, announced this fall. Costing $105 million and enrolling some 16,000 subjects, the trial was the largest AIDS vaccine test to date. But what little protection the injections conferred, scientists have concluded, could have been statistically the result of chance.

Nevertheless, the trial has generated data that point to new avenues of investigation, and scientists have begun several experiments to put the Thai findings to work. For instance, researchers will examine trial volunteers for their immune responses and test whether subsequent booster shots can sustain any protective immune activity. Many authorities think that a vaccine is the best long-term solution to stop HIV, which infects some 7,000 people worldwide every day and 66,000 in the U.S. every year. © ISTOCKPHOTO/ATNOYDUR
Copenhagen Climate Conference Leaders from 193 nations gathered in the Danish capital this month to haggle over strategies to slow the warming of the planet. Despite a pre-conference release of stolen e-mails that seemed to be an attempt to derail negotiations, delegates agreed to a nonbinding accord developed by a core group of nations—including the U.S., China, India and South Africa—that, for the first time, extracts commitments from both developed and developing countries to reduce emissions of greenhouse gases. Goals include cutting emissions to 50 percent of 1990 levels by 2050 and an establishment of a "climate fund" to help poorer nations, all aimed at keeping the average global temperature from rising more than 2 degrees Celsius.

Climate scientists and environmentalists say that the "Copenhagen Accord," which so far leaves out large parts of the world, falls far short of what's needed to tame climate change—a point not lost on some leaders. "Ultimately this issue is going to be dictated by the science," President Barack Obama said at a December 18 press conference. "The science indicates we are going to have to take more aggressive steps in future."

For complete coverage, see the In-Depth Report: "Copenhagen and Climate Change" Copenhagen (& climategate emails)
Ardipithecus, Our Last Common Link with Chimps After some 4.4 million years in the ground—and another 15 years sequestered for close scientific scrutiny—the early human relative Ardipithecus ramidus was formally unveiled to the public and outside researchers in October. Described within a colossal 11 papers in Science, the in-depth analysis found "Ardi" to be an able upright walker and to have hands quite different from modern chimpanzees, solidifying the notion that the last common ancestor between humans and chimps looked little like either species does today.

Other paleoanthropologists question Ardipithecus's propensity for bipedalism, especially given the specimen's missing knee joints, primitive pelvis and its crushed, fragile bones. But most in the field applaud the researchers' epic work and look forward to years of analysis to come. J. H. MATTERNES
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The H1N1 Pandemic In April news about a novel "swine flu" that was killing people by the dozens in Mexico swept around the globe, sparking anxious debate about the 1918 pandemic, the 1976 swine flu vaccine fiasco, and possible antiviral shortages. Although H1N1 itself is not a novel combination, this strain of the virus appeared highly contagious and, unsettlingly, was felling the young rather than the elderly. Indeed, by June the virus had spread worldwide, prompting the World Health Organization to declare a global pandemic.

Despite early vaccine shortages, however, the influenza A 2009 H1N1 strain (as it is formally known) has so far proved to be about as virulent as the seasonal flu, having infected about one in six and killed some 10,000 in the U.S. as of November.

See also the In-Depth Report: "A Guide to Swine Flu" CDC
Restart of the Large Hadron Collider Last year was supposed to be the year of the Large Hadron Collider (LHC), but a faulty connection between two magnets quashed the machine's operations just days after it was powered up in September 2008. After more than a year of repairs, retrofits and testing, the LHC's operators switched the massive collider back on in November of this year. In short order the machine began eclipsing world records, first accelerating beams of protons to unprecedented energies and then colliding those beams head-on, producing the most energetic collisions ever seen in a particle collider. © CERN MAXIMILLIEN BRICE