Visiting Venus: Earth's twisted sister

24 October 2005

Tension is mounting as space scientists prepare to launch their latest mission, Venus Express. They plan to answer vexing questions about Venus's hellish environment. Could life exist on Earth's nearest neighbour?

Antenna lifts the veil on Venus.

Image: ESA/AOES Medialab

The Venus Express craft is almost identical to its famous forerunner Mars Express, which is currently orbiting the Red Planet. Copying much of the Mars mission's technology meant that Venus Express was ready in record time - the project was only begun at the end of 2002.
The voyage to Venus will be rapid too. The launch has been timed for the period when Venus is closest to the Earth, cutting the journey time to only 162 days. The craft will arrive in April 2006.

Venus Express preparing for liftoff. It can only launch between 26 October and 24 November 2005.

Image: ESA

Why is Venus worth a visit?

'Venus is Earth's "evil" twin: it started off at the same time, 4.6 billion years ago when the planets formed, with similar size and composition - but evolved quite differently.
'Now, Venus has sulphuric acid clouds and crushing pressure at the surface, where it's hotter than an oven. It spins - slowly - the wrong way around its axis and it has no magnetic field. Why is it so different to Earth? Venus Express will use new tools to find out.'
Andrew Coates, space scientist, Mullard Space Science Laboratory, UCL

Venus and Earth are non-identical twins.

Image: ESA

'I've worked on the ASPERA-4 experiment. It will make measurements of the electrons and ions in the solar wind, the escaping "planetary wind" and the ionosphere, the outer layer of Venus's atmosphere.'
Andrew Coates
Venus Express will make the first ever global study of the complex chemistry and movements of Venus's thick atmosphere.

Venus is hit by a stream of electrically charged particles including electrons and ions - known as the solar wind - that constantly flows from the Sun.

These are parts of the electron spectrometer in ASPERA.

Image: SwRI/MSSL

'It's hard to imagine how deep and thick the atmosphere on Venus really is. Although it's still gas, it's as thick as water on the Earth. It's a pea soup sort of atmosphere.'
Manuel Grande, space scientist, Rutherford Appleton Laboratory
The dense clouds of carbon dioxide keep temperatures on the surface of Venus a blistering 470 degrees Celsius. That's hot enough to melt lead.
Does Venus give us a glimpse of our own future, if climate change continues unchecked?

Earth's climate appears to be changing rapidly, as we pump ever-greater quantities of carbon dioxide into the atmosphere. Scientists are hoping that results from Venus Express will help us understand how and why Venus's atmosphere went haywire.

Image: ESA

Could there be life on Venus?

Something strange is happening above the planet's surface. Eighty kilometres up, where temperature and pressure are most Earth-like, something is absorbing ultraviolet radiation.
Alien-hunting space scientists claim that because bacteria survive in clouds above the Earth, they might also live above Venus. Could they be absorbing ultraviolet rays like plants on Earth take in carbon dioxide?

Is there something living in the clouds shrouding Venus?

Image: NASA

'Some scientists have suggested that life may be able to survive in layers of the atmosphere near the sulphuric acid clouds. I think it's unlikely that life would be found in such a hostile environment - there is only about 20 cm equivalent depth of water in the Venus atmosphere now - probably not enough to sustain life.
'But it is an intriguing possibility and perhaps worth a look with later missions.'
Andrew Coates

Andrew Coates, space scientist, Mullard Space Science Laboratory, UCL

Image: Mullard Space Science Laboratory, UCL

Look out for mission updates on the Antenna Website once Venus Express starts sending back its findings.
Find out more about the search for extraterrestrial life.

Image: ESA

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