Venus Express clears biggest hurdle

The Venus Express orbiter successfully completed its voyage to our inner neighbour this morning with a handbrake turn. Engineers fired up rockets to slow it down so that Venus' gravity could capture the European Space Agency probe.

The burn was a tense affair for the team at ESA's mission control centre in Darmstadt, Germany. Relieved Venus specialist Professor Fred Taylor, who helped instigate the mission, said: “It could hardly have gone better.”

There was a nail-biting 10 minutes when the signal was cut as the satellite went behind the planet. The success of the 50-minute manoeuvre was confirmed when the connection was reestablished. Engineers gave the nod that the 400 Newton main engine had done its job at 9.08AM BST.

The next task is for the polar orbit to be brought closer to the Venusian surface for the measurements to be made. At its closest, Venus Express will be 250km above the South Pole.

A bevy of instruments will investigate the mysteries of the super-thick spinning Venusian atmosphere, where winds in the clouds rip around the planet at 200 miles per hour and complex storm systems batter low latitudes. The data will serve as a testing ground for climate scientists to push their models to the limit.

The oppressive CO2 and sulphur dioxide produce an extreme greenhouse effect that roasts the surface at 450°C. Dr Colin Wilson, a scientist at the University of Oxford, said if Earth climate models can work in an environment as extreme as Venus, global warming predictions are strengthened.

The pressure on Venus's surface is nearly 100 times that of Earth. But lacking a magnetic field to protect the gases from the solar wind, Venus loses around 100 tons of it to space every day.

The same nakedness has depleted Mars' atmosphere to just one hundredth of Earth's pressure, so one of the key questions for Venus Express scientists is what maintains it.

The obvious suspect is active vulcanism on the surface. The scientists will use a very specific region of the infra-red spectrum, where all the waves come from the planet surface, to peer through the permanent pea-souper for hotspots. Volcano hunt image data will be backed up by atmospheric measurements.

After the Sun and Moon, Venus is the brightest object in the sky. It's close to Earth's size, and was formed from the same materials. Its atmosphere and temperature make it extremely inhospitable to life. Scientists have described Venus as Earth's “evil twin”.

Its known from hydrogen ion signatures in the atmosphere that there was water there in the past.

Venus Express is the first to mission to probe the planet since the 1980s. Back in the days of the space race, the Russians sent 19 probes to Venus. Now, many of the scientists who worked in secret then are collaborating on Venus Express, which launched in November aboard a Russian Soyuz rocket.

The mission was piggybacked on technology developed for Mars Express. Some of the £140m satellite was cobbled together from spares in double-quick time.

Dr Wilson expects the probe to start beaming back useful data in the next week. Taylor added that now the most difficult hurdle was behind them, the mission was “only just beginning”. The mission is planned for 500 Earth days, or just two for Venusians. ®