Venus sees the light

A measurement system has been developed that will help scientists track the Venus Explorer spacecraft with extraordinary accuracy. Venus is 41 million kilometres from Earth yet ESA's first mission to the planet will be pinpointed with an accuracy of better than one billionth of a second. And this will be achieved by monitoring the energy from a quasar hundreds of millions of light years away.

The craft is due to enter orbit this week, five months after being launched from the Baikonur Cosmodrome, Kazakhstan. Its mission is to gather information about the atmosphere, plasma and surface of the planet and it will orbit Venus for 500 days. But getting it into precisely the right orbit is vital.

The measurement technique, called Delta-DOR, will be used to make sure the spacecraft is slowed down just the right amount so that it enters its orbit correctly. It has been developed by BAE Systems, ESA and the University of Rome for the UK company's Intermediate Frequency Modem System equipment (IFMS).