Science news highlights of 2011
The year 2011 offered up glimpses of Earth-like planets, hints of the Higgs boson and suggestions of a discovery that could turn modern physics on its head.
Headlines were dominated by the catastrophic earthquake and tsunami in Japan, which resulted in the loss of thousands of lives and plunged the country into a nuclear emergency.
The BBC News website's science editor Paul Rincon looks back at an eventful year in science and the environment.
January - Another Earth?
The scientific year kicked off with the American Astronomical Society meeting in a chilly Seattle. Among the most anticipated results were those from Nasa's Kepler space telescope, which had hit its stride after being launched in 2009. At the conference, Dr Natalie Batalha outlined details of Kepler 10b, which was at the time the smallest planet yet discovered outside our Solar System - and the first that is undoubtedly rocky.
Kepler - with its huge 95 Megapixel camera - has transformed the hunt for distant Earth-like worlds. In a demonstration of just how rapid the pace of discovery has become, Kepler would smash the record announced in Seattle before the year was out.
February - Private space
In his 2012 budget request for Nasa, Barack Obama asked Congress for more money to develop commercial rockets and capsules that will take astronauts into space. Proposed private launch systems such as the Liberty rocket and the Falcon 9-Heavy could play important roles in those plans.
The request also called for $2.8bn to spend on a government vehicle to replace the space shuttle. In 2010, Mr Obama scrapped the Constellation programme to develop an Apollo-like system that would take astronauts back to the Moon. Obama's failure - in the eyes of his critics - to define a vision for what should take its place sparked a backlash in Congress. The result was a classic compromise that resurrected key elements of Constellation, such as the Orion capsule. Several key contracts with aerospace companies were also re-negotiated as part of the outcome.
March - Devastating quake
At 1446 local time on 11 March 2011, Japan was struck by its most powerful earthquake on record. The Magnitude 9 quake - thought to have been a 1,000-year event - unleashed huge waves that inundated Japan's north-east coast. The world was still absorbing the scale of the tragedy when the cooling system at Fukushima Daiichi nuclear plant failed, setting off a chain of events that plunged Japan into a nuclear emergency.
A mammoth operation to stabilise the plant - which had been damaged by tsunami waves - was soon underway. The brave efforts met with varying degrees of success, however, and the operation was not able to prevent a major release of radioactive material. The International Atomic Energy Agency (IAEA) would subsequently assign the nuclear accident a "level seven" designation, placing it on a par with the Chernobyl disaster in 1986 - though some disputed this decision.
April - Lemur business
This month it emerged that Richard Branson was to import lemurs to one of the islands he owns in the Caribbean. The animals are native to the African island of Madagascar, where many species are threatened due to deforestation.
Sir Richard told the BBC that the plan would help preserve the animals in a protected rainforest habitat on Moskito island. But some conservationists raised the alarm. This was perhaps inevitable, given that introducing non-native animals has a long and frequently destructive history. But in the eyes of some observers, the plan gave much-needed publicity to the plight of this charismatic animal.
May - Murky waters
One year on from the BP Deepwater Horizon oil spill, the largest of its kind, the ecological impact on the Gulf of Mexico's remained still shrouded in uncertainty. Jane Lubchenco, head of the US National Oceanic and Atmospheric Administration (Noaa), said the Gulf's health was "much better than people feared". But Prof Samantha Joye from the University of Georgia told journalists the full effects may take a decade to appear.
The problems faced by fishermen are immediate: Nick Collins of the 90-year-old Collins Oyster Company told the BBC: "This is the biggest oyster kill in Louisiana history". Last year, valves on the Mississippi river were opened in an effort to push oil back to sea. This devastated oyster beds, which need salt water to survive. Ongoing scientific work remains vital not only for assessing effects on the Gulf, but also for evaluating risks as oil companies expand drilling into even deeper waters.
June - Under the ice
A survey of Antarctica's "belly" allowed scientists to map the shape of the bedrock buried deep under the ice. Ice-penetrating radar antennas were fitted to a refurbished DC-3 plane which was flown across the white continent. It revealed many new details of a landscape hidden under the ice for millions of years.
Later in the year, a different team would release the most detailed map of Antarctica's rock underbelly, less than 1% of which projects above the continent's frozen veil. The map represents more than just a pretty picture - it offers critical knowledge in the quest to understand how the last wilderness might respond to a warming world.
July - Last hurrah
On 8 July, Nasa launched its last-ever space shuttle mission from Cape Canaveral. The shuttle Atlantis flew into history on a 12-day mission to the International Space Station and will soon become a permanent visitor attraction at Florida's Kennedy Space Center.
Nasa chief Charles Bolden insisted the prospects for human spaceflight were bright. But the shuttle retirement leaves America reliant on Russia Soyuz flights to ferry astronauts to and from the space station. Bolden's predecessor Dr Mike Griffin told BBC News that "the human spaceflight programme of the US will come to an end for the indefinite future".
August - Life at the beginning
Scientists reported finding some of the oldest and best preserved evidence of life on our planet. The tiny microbes at Strelley Pool in Australia processed sulphur for energy and growth rather than oxygen, offering a fascinating window into conditions on the early Earth.
At the time these life forms flourished, Earth's atmosphere would probably have been rich in carbon dioxide and methane. So the ability to "breathe" something other than oxygen would have been a major requirement for any organism. Such bacteria are still common today, being found in smelly ditches, soil, hot springs and hydrothermal vents.
This is not the oldest claim for life on Earth; rocks at Isua in Greenland arguably show the imprint of life at least 3.75 billion years ago. But those rocks contain no fossil forms.
September - (Much) faster than a speeding bullet
If there is one science story for which 2011 will be remembered, it is this - the observation that sub-atomic neutrino particles can apparently cheat the speed of light. If confirmed, the finding would upend more than a century of physics, even making time travel look more feasible. So it was unsurprising to find reactions like that from physicist Jim Al-Khalili, who pledged to "eat my boxer shorts live on TV" if the result was proven correct.
Other scientists stepped up to challenge the finding, but no one was more baffled than the researchers in Italy who had first reported the result. They even ran the experiment again before submitting their analysis for publication. These additional tests backed up the original findings, calling Dr Al-Khalili's bluff. So physicists will now have to wait for cross-checks by other neutrino experiments.
October - Glittering awards
Saul Perlmutter, Adam Riess and Brian Schmidt shared this year's Nobel prize in physics for their discovery that the expansion of the Universe was accelerating. Oft-tipped to win, the discovery led to the bizarre concept of dark energy, which makes up some 73% of the cosmos.
The chemistry prize was awarded to Daniel Schechtman, a single researcher. His story fits the classic narrative of the lone scientist who battles academic orthodoxy to win acceptance for his radical idea. In this case, it was the existence of "quasicrystals" - a structural form previously thought to be impossible in nature.
November - ClimateGate: The Return
November saw the much anticipated launch of Nasa's next robotic explorer on Mars. About the size of a Mini Cooper, Mars Science Laboratory - is the biggest rover ever sent to the Red Planet. Less anticipated was the release of a new batch of emails from the University of East Anglia's (UEA) Climatic Research Unit. Unlike the 2009 ClimateGate publication, which prompted three separate inquiries, the reaction this time was more muted.
The email release came just ahead of the climate talks in Durban, and followed just behind the publication of the Berkeley Earth Project's analysis of global average temperatures, which showed that the world was indeed getting warmer. The Berkeley group included sceptical scientists and received funds from sources that back organisations lobbying against action on climate change.
December - Edge of glory
The decades-long search for the Higgs boson, that elusive but frustratingly vital building block of the Universe, entered its endgame. In December, scientists at the Large Hadron Collider (LHC) announced that they might have glimpsed the Higgs particle - which explains why the "stuff" around us has mass. They expect a definitive "yes or no" answer to be available by next year, when the LHC has gathered more data.
At the UN climate talks in Durban, it was a question of "deal or no deal?" The talks closed with a late agreement that the chair said had "saved tomorrow, today". And, as the year drew to a close, there were further spectacular findings from the Kepler space telescope: the announcement of an "Earth twin" in the habitable zone around its star and the discovery of the first truly Earth-sized planets.