Ten most significant scientific discoveries in 2011

File photo shows bottles containing antiretroviral (ARV) drugs. The journal “Science” has lauded an eye-opening HIV study, known as HPTN 052, as the most important scientific breakthrough of 2011. This clinical trial demonstrated that people with HIV are 96 per cent less likely to transmit the virus to their partners if they take ARVs. Photo: A

THE HAYABUSA MISSION: After some near-disastrous technical difficulties and a stunningly successful recovery, Japan's Hayabusa spacecraft returned to Earth with dust from the surface of a large, S-type asteroid. This asteroid dust represented the first direct sampling of a planetary body in 35 years, and analysis of the grains confirmed that the most common meteorites found on Earth, known as ordinary chondrules, are born from these much larger, S-type asteroids. In picture, Japanese actor Ken Watanabe poses with members of the Hay

UNRAVELLING HUMAN ORIGINS: Studying the genetic code of both ancient and modern human beings, researchers discovered that many humans still carry DNA variants inherited from archaic humans, such as the mysterious Denisovans in Asia and still-unidentified ancestors in Africa. One study this year revealed how archaic humans likely shaped our modern immune systems, and an analysis of Australopithecus sediba fossils in South Africa showed that the ancient hominin possessed both primitive and Homo-like traits. Image shows one of two sets of bones from the Australopithecus Sediba. Photo: AP

CAPTURING A PHOTOSYNTHETIC PROTEIN: In vivid detail, researchers in Japan have mapped the structure of the Photosystem II, or PSII, protein that plants use to split water into hydrogen and oxygen atoms. The crystal-clear image shows off the protein's catalytic core and reveals the specific orientation of atoms within. Now, scientists have access to this catalytic structure that is essential for life on Earth — one that may also hold the key to a powerful source of clean energy. Image shows structure of Photosystem II, PDB 2AXT as featured in a Wikipedia article.

PRISTINE GAS IN SPACE: Astronomers using the Keck telescope in Hawaii discovered two clouds of hydrogen gas that seem to have maintained their original chemistry for two billion years after the big bang. Other researchers identified a star that is almost completely devoid of metals, just as the universe's earliest stars must have been, but that formed much later. The discoveries show that pockets of matter persisted unscathed amid eons of cosmic violence. This undated composite picture shows an image of the centre of our galaxy from laser-guide-star adaptive optics on the Keck telescope. Photo: AP

GETTING TO KNOW THE MICROBIOME: Research into the countless microbes that dwell in the human gut demonstrated that everyone has a dominant bacterium leading the gang in their digestive tract: Bacteroides (in picture), Prevotella or Ruminococcus. Follow-up studies revealed that one of these bacteria thrives on a high-protein diet while another prefers vegetarian fare. These findings and more helped to clarify the interplay between diet and microbes in nutrition and disease. Photo: Wikipedia

A PROMISING MALARIA VACCINE: Early results of the clinical trial of a malaria vaccine, known as RTS,S, provided a shot in the arm to malaria vaccine research. The ongoing trial, which has enrolled more than 15,000 children from seven African countries, reassured malaria researchers, who are used to bitter disappointment, that discovering a malaria vaccine remains possible. Image shows an Anopheles funestus mosquito taking a blood meal from a human host. Photo: AP

STRANGE SOLAR SYSTEMS: This year, astronomers got their first good views of several distant planetary systems and discovered that things are pretty weird out there. First, NASA's Kepler observatory helped identify a star system with planets orbiting in ways that today's models cannot explain. Then, researchers discovered a gas giant caught in a rare "retrograde" orbit, a planet circling a binary star system and 10 planets that seem to be freely floating in space — all unlike anything found in our own solar system. Image provided by NASA shows an artist's depiction showing a discovery by the Kepler mission of a world where two suns set over the horizon instead of just one. Photo: AP

DESIGNER ZEOLITES: Zeolites are porous minerals that are used as catalysts and molecular sieves to convert oil into gasoline, purify water, filter air and produce laundry detergents (to name a few uses). This year, chemists really showed off their creativity by designing a range of new zeolites that are cheaper, thinner and better equipped to process larger organic molecules. Image shows Zeolites featured on the website of the U.S House Subcommittee on Energy and Natural Resources.

CLEARING SENESCENT CELLS: Experiments have revealed that clearing senescent cells (those that have stopped dividing) from the bodies of mice can delay the onset of age-related symptoms. Mice whose bodies were cleared of these loitering cells didn't live longer than their untreated cage-mates — but they did seem to live better, which provided researchers with some hope that banishing senescent cells might also prolong our golden years. File photo: AP