Alok Jha and James Randerson-

Guardian Newspapers Limited 2004

Highlights of an eventful year for scientists who probed deeper into space and unravelled the secrets of DNA For the first time humans managed to hit asteroids. It happens with ease in Hollywood films but doing it is tricky in real life but scientists did it twice.

London: Genetics continues to be the biggest story in science and, with the creation of the world's first mouse with a full human chromosome, Elizabeth Fisher at the Institute of Neurology and Victor Tybulewicz at the National Institute for Medical Research in London heralded a new era in the field.

The new mouse model will allow scientists to study which genes on chromosome 21 govern the different symptoms of Down's syndrome.

Simulation of universe

The first time humans have managed to hit asteroids. It happens with ease in Hollywood films but doing it is tricky in real life. A round of applause, then, for astronomers who did it twice this year. In July, the Americans guided the Deep Impact probe on to a collision course with Tempel 1.

The resulting crater gave scientists their first look inside a speeding comet. Last month, Japan's Hayabusa probe became the first spacecraft to land on an asteroid.

Requiring 25 million megabytes of memory, the Millennium Simulation (a collaboration between British, German, U.S. and Canadian astrophysicists) is the biggest exercise of its kind - to simulate the birth and evolution of the universe. By programming in the known starting conditions, so far the simulation has managed to track the 14-billion-year history of creation in just a few months and offers a way to study why the universe is arranged in the way it is now.

It has been another difficult year for NASA, but there is light at the end of the tunnel. The success of the shuttle's return to space has been tempered by problems with the International Space Station, which saw most of its science budget slashed to help NASA pay for President George Bush's desire to send astronauts to the moon and Mars. But NASA also unveiled its replacement for the space shuttle: a crew exploration vehicle at the centrepiece of a plan to get NASA back to the moon by 2020.

In October, we learned that one of the most successful killers ever had been resurrected. U.S. scientists recreated the Spanish flu strain responsible for the global pandemic of 1918, which killed around 50 million people. Researchers showed the strain was a pure bird flu strain that had adapted to humans. This suggests, worryingly, that a few choice mutations could turn the current bird flu epidemic into a global human pandemic.

Creme brulee is not a phrase scientists often use when describing their results. But this year it became the simile of choice for conjuring an impression of Saturn's moon Titan. The successful ''splatdown'' of the Huygens probe after its seven-year and nearly 2-billion-mile journey gave us breathtaking views of Titan's eerily Earth-like landscape. The culinary analogy was meant to describe Titan's mud - soft, but with a crusty topping.

Embryo cloned

Scientists in Newcastle, England, became the first British team to clone a human embryo. Recent doubts about the work of the South Korean stem cell researcher Woo-suk Hwang suggest the British achievement may in fact have been a world first. Using 36 surplus eggs from women undergoing fertility treatment, the Newcastle team created 10 very early stage embryos.

The hope is that cloned embryos could be used to extract stem cell lines tailored to individual patients. In the U.S., intelligent design (ID), the creationist alternative to natural selection, became a significant political force but suffered a setback in a courtroom in small town Dover, Pennsylvania, in November. The school board's decision to read students a statement promoting ID was challenged by parents. Judge John Jones backed them, dismissing ID as a ''relabelling of creationism, and not a scientific theory''.

Scientists in Southampton, England, uncovered first evidence that the offshoot of the Gulf stream which gives the north western fringe of Europe its balmy climate is slowing down. Tim Holy and Zhongsheng Guo at Washington University School of Medicine in Missouri discovered that mice construct complex songs and sing them when they come across sex pheromones. British scientists found that, all else being equal, putting on a red shirt means you are more likely to win a football game.