Category: Venus

ESA’s Venus Express has been constantly watching the huge swirling vortex of clouds around Venus’ southern pole. It’s a strange weather feature, morphing and changing shape within just a few days. And scientists, as you can probably imagine, are puzzled about what’s going on.

Venus’ south pole vortex is similar to a hurricane here on Earth. It measures 2,000 km (1,240 miles) across, and was discovered by the Mariner 10 flyby in 1974. A second, similar vortex was found at the planet’s north pole by the Pioneer Venus mission in 1979.

“Simply put, the enormous vortex is similar to what you might see in your bathtub once you have pulled out the plug” says Giuseppe Piccioni, co-Principal Investigator for the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on Venus Express, at IASF-INAF, Rome, Italy.

When Venus express observed the vortex in June 2006, it had a roughly hourglass-shape, similar to what Pioneer Venus saw in the north polar region. But with continued observations from Venus Express, scientists are seeing that the storm is much more fickle than they previously thought.

Over the course of just a single day, scientists watched the shape of the storm’s vortex change from a circle to a oval. It’s believed that atmospheric gases are flowing into the region from different directions at different altitudes. The shape of the vortex is a result of changes in temperature across different parts of the planet.

The actual vortex is created because atmospheric gases are heated by the Sun at the equator. They cool near the polar regions and sink down. The rotation of Venus deflects them sideways so they swirl together, like water going down the drain of a bathtub.

Original Source: ESA News Release

As if the cloudy planet couldn’t get any more mysterious, Venus and its global weather patterns are baffling European Space Agency (ESA) scientists. The ESA Venus Express mission is continuing to unearth the details of what lies in and under its thick atmosphere, but Venus’s dynamic global weather patterns are very quick to consume the whole planet, like nothing we experience on Earth…

The ESA Venus Express missions Venus Monitoring Camera (VMC) is a long-term data gathering experiment to monitor the long-term progression of weather systems on the planet. On numerous occasions, the VMC has observed massive clouds of bright, hazy sulphuric acid particles form from equator to pole in a matter of days, only for it to disappear just as quickly. This suggests that fast dynamical, chemical and microphysical processes are at work on the planet in scales never before realized.

“This bright haze layer is made of sulphuric acid […] the process is a bit similar to what happens with urban smog over cities.” – Dmitri Titov, VMC Co-Investigator and Venus Express Science Coordinator, Max Planck Institute for Solar System Research, Germany.

With over 600 orbits completed, the VMC is observing the effects that solar radiation has on the dynamics of Venus’s atmosphere. It is well known that Venus’s atmosphere is carbon dioxide-rich and also contains water molecules and gaseous sulphur dioxide. Should this mix be exposed to UV radiation, the molecules will break up, forming a mix of highly reactive chemicals. As these chemicals bond, droplets of sulphuric acid form, creating planetary-scale clouds of bright haze. However, the planets atmosphere is too thick for much of the solar radiation to penetrate. For the gases to be exposed to UV radiation, some powerful atmospheric process must force them aloft, above much of the dense atmosphere, allowing them to react.

Although the bright haze of Venus’s atmosphere has been identified, many dark patches have also been observed. So far, there is no explanation for these patches of atmospheric chemicals absorbing solar UV, but the presence of the orbiting Venus Express is hoped to shine light on the dark and bright atmospheric features and how the atmosphere is mysteriously driving them.

Source: ESA

There’s a real advantage to having a spacecraft orbit a planet for days, months and even years. You have lots and lots of time to really pull in the science. And now, almost 2 years into its visit at our evil twin planet, ESA’s Venus Express has been able to map the planet’s atmosphere at lower altitudes, searching for chemicals that will help scientists understand the planet’s global climate and weather systems.

The planet’s clouds block the visible light from escaping the surface, but other wavelengths, such as infrared, do escape. Since temperatures can reach 200 degrees C at an altitude of 35 km, and more than 450 C at the surface, infrared – or heat – pours out, going right through the clouds. This radiation can then be analyzed to see the chemicals present.

ESA’s Venus Express spacecraft is equipped with a special instrument called the VIRTIS spectrometer, which can measure the atmosphere at various altitudes. It’s already mapped the high altitude clouds, and now VIRTIS has spent the last few orbits mapping the lower atmosphere.

Of course, like the rest of Venus’ atmosphere, the lower altitude clouds are dominated by carbon dioxide – the greenhouse gas that traps the heat in, raising temperatures. VIRTIS also detected carbon monoxide, a chemical that scientists weren’t expecting to see at such low altitudes.

Since carbon monoxide is so rare, scientists can use this as a way to trace global winds that cycle across the planet – sort of like dropping ink into water to study turbulence. VIRTIS was able to determine the large-scale circulation of winds as they rise at the equator and then move north and south towards the poles. Once at the poles, the winds lose altitude again, and circulate back to the beginning.

Venus Express has also detected and mapped the amount of water vapour in the lower atmosphere with high resolution. Since this molecule is so difficult to detect, this has ended a scientific debate about how much there is on Venus.

Original Source: ESA News Release

Venus is a hostile world, with high temperatures, intense pressures, and an atmosphere with sulphuric acid. The Russian spacecraft sent to explore it succumbed in mere hours. Well, now it appears that Venus is even more dangerous than previously imagined, with lightning flashing in the atmosphere.

This latest discovery was made using ESA’s Venus Express spacecraft, currently orbiting our evil twin planet. In a recent article published in the November 29th issue of the journal Nature, planetary geologists describe the lightning storms that flare across the planet.

And these storms aren’t rare. In fact, the scientists think that Venus has more lightning activity than we have here on Earth.

The source of the lightning is different, though. Here on Earth (and Jupiter and Saturn), the electrical energy comes from clouds made up of water vapour. On Venus, however, it’s those clouds of sulphuric acid that generate the electrical charge.

The discovery was made with the Venus Express magnetometer instrument on board the spacecraft. It took measurements once a day for two minutes, when the spacecraft was closest to the planet.

With Venus Express’ primary mission now complete, scientists are expanding its mission to other scientific questions, such as trying to spot infrared radiation from lava flows on the planet’s surface. In 2010, another spacecraft will arrive at Venus: the Japanese Venus Climate Orbiter. Scientists will then be able to compare observations between the two spacecraft.

And any future landers will need to be hardened against these lightning strikes, just in case they happened to descend through a lightning storm.

Original Source: NASA News Release

NASA’s MESSENGER and ESA’s Venus Express spacecraft are going to be at Venus together on June 6, giving scientists an opportunity to see our “evil” twin planet from two vantage points.

Of course, Venus Express has been orbiting its namesake planet since April 11, 2006, but Messenger is passing through, enroute to Mercury. And that’s not all. Several ground-based observatories will be joining in on the party as well, taking images and gathering data during the MESSENGER flyby.

During its closest approach, MESSENGER will pass just 337 kilometres (210 miles) above the surface of Venus. And during this time, Venus Express will be behind Venus, but will be able to view many of the same regions imaged by MESSENGER. Scientists will then be able to compare the data gathered by the two spacecraft.

After 30 hours of observations, MESSENGER will be finished with Venus, and focused again on its final target. It’ll finally reach Mercury in March, 2011.

Original Source: ESA News Release