When the International Space Station goes into orbit, it will have an atomic clock on board. However, it won't help the astronauts tell the time. The US National Institute of Standards and Technology is developing a laser-cooled, caesium atomic clock that will use microgravity conditions to achieve accuracy "at least 10 times better than any clock on Earth', it is claimed. It will enable scientists to improve the performance of the Global Positioning Satellites and also synchronise all clocks down here (New Scientist , Vol 157, No 2119).