Keith Vanderlinde/NSF
The BICEP2 telescope at the South Pole may have spied gravitational waves — or dust.
This year may be best remembered for how quickly scientific triumph morphed into disappointment, and even tragedy: breakthroughs in stem-cell research and cosmology were quickly
discredited; commercial spaceflight faced major setbacks. Yet landing a probe on a comet, tracing humanity’s origins and a concerted push to understand the brain provided reasons to celebrate.
Nature special: The year in review
Space race expands
Asian nations soared into space this year. The Indian Space Research Organisation put a mission into orbit around Mars — the first agency to do so on its first try. Japan launched the Hayabusa-2 probe, its second robotic voyage to bring back samples from an asteroid. And even as China’s lunar rover Yutu (or Jade Rabbit) stopped gathering data on the Moon’s surface, mission controllers took the next step in the country’s lunar exploration programme by sending a test probe around the Moon and back to Earth.
But for commercial spaceflight, it was a bad year. Virgin Galactic’s proposed tourism vehicleSpaceShipTwo disintegrated during a test flight in California and killed one of its pilots. That came just three days after a launch-pad explosion in Virginia destroyed an uncrewed private rocket intended to take supplies to the International Space Station. The accident wiped out a number of research experiments destined for the station, whose managers are trying to step up its scientific output. Problems on the station also delayed the deployment of a flock of tiny Earth-watching satellites, nicknamed Doves, which are part of the general trend of using miniature ‘CubeSats’ to collect space data.
On a bigger scale, the European Space Agency successfully launched the first in its long-awaited series of Sentinel Earth-observing satellites.
Comets call
After a decade-long trip, the European Space Agency’s Rosetta spacecraft arrived at comet 67P/Churyumov–Gerasimenko in August and settled into orbit. Three months later, Rosetta dropped the Philae probe to 67P’s surface, in the first-ever landing on a comet. Philae relayedscience data for 64 hours before losing power in its shadowy, rocky landing site.
Meanwhile, a flotilla of Mars spacecraft — probes from India, the United States and Europe — had an unplanned close brush with comet Siding Spring, which zipped past the red planet in October at a distance of 139,500 kilometres — about one-third of the distance from Earth to the Moon. NASA rovers continued to trundle along on the Martian surface: Curiosity finally reached the mountain that it has been heading towards since landing in 2012, and Opportunity passed 40 kilometres on its odometer, breaking a Soviet lunar rover’s distance record for off-Earth driving.
The search for planets beyond the Solar System also got a huge boost. In February, the team behind the now mostly defunct Kepler spacecraft announced that it had confirmed the existence of 715 extrasolar planets, the largest-ever single haul. Kepler data also revealed the first known Earth-sized exoplanet in the habitable zone of its star, a step closer to the long-sought ‘Earth twin’.
Human origins decoded
Considering that they have been dead for around 30,000 years, Neanderthals had a hell of a year. Their DNA survives in non-African human genomes, thanks to ancient interbreeding, and two teams this year catalogued humans’ Neanderthal heritage. Scientists learnt more about the sexual encounters between Homo neanderthalensis and early humans after analysing the two oldest Homo sapiens genomes on record — from men who lived in southwest Siberia 45,000 years ago and in western Russia more than 36,000 years ago, respectively. The DNA revealed hitherto-unknown human groups and more precise dates for when H. sapiens coupled with Neanderthals, which probably occurred in the Middle East between 50,000 and 60,000 years ago. Radiocarbon dating of dozens of archaeological sites in Europe, meanwhile, showed that humans and Neanderthals coexisted there for much longer than was once thought — up to several thousand years in some places.
Genomes old and new charted the emergence of agriculture. Contemporary Europeans carry DNA inherited from light-skinned, brown-eyed farmers who migrated from the Middle East beginning 7,000–8,000 years ago, in addition to more-ancient ancestry. The achievements of these early farmers — domestication of crops such as wheat and barley — are also being understood through genome sequencing. In July, a consortium reported a draft copy of the gargantuan wheat genome, which contains 124,000 genes and 17 billion nucleotides. Another group released the genomes of 3,000 rice varieties.
Genomes of the future may soon carry added information. Scientists in California engineeredEscherichia coli bacteria to include two chemical nucleotides in their genome in addition to the four that all other life forms use. The next step is to harness the expanded genetic alphabet to produce new kinds of protein. An effort to synthesize an entire yeast genome produced its first chromosomethis year.
Kieran Kesner
At the one-year mark, there is no telling when the Ebola epidemic in West Africa will end.
Ebola toll rises
The Ebola epidemic that ravaged West Africa this year is the largest since the virus was discovered in 1976 — and it exposed major gaps in the world’s ability to respond to emerging infectious diseases. By mid-December, around 6,800 people had died in Guinea, Liberia and Sierra Leone.
The first case in the epidemic is thought to be that of a two-year-old in Guinea, who died in early December 2013. A genetic analysis of viral samples suggests that the epidemic began with a single animal-to-human transmission.
Early on, much media attention was focused on experimental drugs, including the antibody cocktail ZMapp, but infectious-disease experts have emphasized the need to expand access to treatment and to implement basic epidemiological measures such as tracing contacts of infected people.
Fears that the epidemic would expand to other countries have proved unfounded; small numbers of cases in Mali, Nigeria, Senegal, Spain and the United States were isolated quickly, and onward spread was limited.
November brought encouraging results from the first safety trials of an experimental Ebola vaccine in healthy human volunteers, with efficacy trials of this and other vaccines set to begin in West Africa early in 2015. Experimental drugs as well as treatments that involve dosing Ebola patients with ‘convalescent’ blood and serum from survivors are also in tests. But major questions about the virus’s biology remain to be answered.
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