Artist's impression of the surface of Venus. Credit: ESA/AOES
Venus is definitely not a friendly planet for humanity. Soviet landers that arrived on the surface a few decades back were crushed pretty quickly. Its surface temperature is more than 842 degrees Fahrenheit (450 degrees Celsius) and the atmosphere is full of noxious gases.
But descending into this pressure-filled cooker is exactly what Venus Express is going to do shortly. The European Space Agency spacecraft will conclude eight years of orbital operations with an attempt to fall into the planet. The maneuvers are complicated, and there’s no guarantee they will go as planned, but ESA plans to make the plunge by the end of this year.
For the better part of a decade, Venus Express has been orbiting the planet every 24 hours, swinging in an elliptical orbit that ranges from 155 miles (250 kilometers ) to 41,010 miles (66,000 kilometers). But now the spacecraft is almost out of fuel, and will now be redirected for “experimental aerobreaking” to slow down through skimming the atmosphere.
The maneuvers will take place between June 18 and July 17, where controllers hope to gain some information about the planet’s magnetic field, solar wind, temperature and pressure.
“The campaign also provides the opportunity to develop and practice the critical operations techniques required for aerobraking, an experience that will be precious for the preparation of future planetary missions that may require it operationally,” stated Paolo Ferri, head of mission operations.
No one is sure if the spacecraft will run out of fuel, or even if it survives, but if it does its orbit could be raised to do a few more scientific observations of the planet before going into the atmosphere forever.
Venus’ Express scientific treasure trove includes measuring hydrogen atom escape in the atmosphere, checking out the planet’s clouds and tracking the slowing rotation of the planet (which is happening for reasons that are not quite clear.) It also discovered an ozone layer on the planet.
False colour composite of a rainbow-like feature known as a ‘glory’, seen on Venus on 24 July 2011. The image is composed of three images at ultraviolet, visible, and near-infrared wavelengths from the Venus Monitoring Camera. The images were taken 10 seconds apart and, due to the motion of the spacecraft, do not overlap perfectly. The glory is 1200 km across, as seen from the spacecraft, 6000 km away. It's the only glory ever seen on another planet. Credit: ESA/MPS/DLR/IDA.
Oh glory! A rainbow-like optical phenomenon known as a ‘glory’ has been imaged for the first time on another planet. It was seen in the atmosphere of our nearest neighbor, Venus by ESA’s Venus Express orbiter.
Rainbows and glories occur when sunlight shines on cloud droplets. While rainbows arch across the sky, glories appear as circular rings of colored concentric rings centered on a bright core.
Glory with aircraft shadow in the center. Via Wikimedia Commons.
Glories are only seen when the observer is situated directly between the Sun and the cloud particles that are reflecting sunlight. On Earth, they can often be seen with the naked eye from airplanes, or when looking down upon fog or water vapor, such as when climbing a mountain.
On Earth, the simple ingredients needed for a rainbow are sunlight and raindrops. On Venus, the droplets are likely made of sulfuric acid.
Three images showing the glory at ultraviolet (left,) visible (centre) and near-infrared (right) wavelengths as taken by the Venus Monitoring Camera. The feature was observed on 24 July 2011 and measures 1,200 km across, as seen from the spacecraft, 6,000 km away. Credit: ESA/MPS/DLR/IDA.
Seeing this glory was no accident: they made a calculated effort to image the clouds with the Sun directly behind the Venus Express spacecraft. The scientists were hoping to spot a glory in order to determine important characteristics of the cloud droplets.
Today, the team reported that they were successful. The glory in the images here was seen at the Venus cloud tops, 70 km above the planet’s surface, back on July 24, 2011. Their paper was just recently accepted for publication.
The glory was 1,200 km wide as seen from the spacecraft, 6,000 km away.
The Venus Express team deduced that from these observations, the cloud particles are estimated to be 1.2 micrometres across, roughly a fiftieth of the width of a human hair.
The fact that the glory is 1,200 km wide means that the particles at the cloud tops are uniform on this scale at least.
The variations of brightness of the rings of the observed glory is different than that expected from clouds of only sulphuric acid mixed with water, suggesting that other chemistry may be at play.
One idea is that the cause is the “UV-absorber,” an unknown atmospheric component responsible for mysterious dark markings seen in the cloud tops of Venus at ultraviolet wavelengths. More investigation is needed to draw a firm conclusion.
Scientists also think that it would be possible to see a rainbow — and perhaps even a glory — on Titan since the atmosphere on this moon of Saturn is likely filled with methane droplets.
Planets conjunction over Mont-Saint-Michel, Normandy, France on May 26. Credit: Thierry Legault -
www.astrophoto.fr
Triple planets (Venus/Jupiter/Mercury) conjunction over Mont-Saint-Michel, Normandy, France on May 26. Credit: Thierry Legault – www.astrophoto.fr Update: See expanded Conjunction astrophoto gallery below[/caption]
The rare astronomical coincidence of a spectacular triangular triple conjunction of 3 bright planets happening right now is certainly wowing the entire World of Earthlings! That is if our gallery of astrophotos assembled here is any indication.
Right at sunset, our Solar System’s two brightest planets – Venus and Jupiter – as well as the sun’s closest planet Mercury are very closely aligned for about a week in late May 2013 – starting several days ago and continuing throughout this week.
And, for an extra special bonus – did you know that a pair of spacecraft from Earth are orbiting two of those planets?
Have you seen it yet ?
Well you’re are in for a celestial treat. The conjunction is visible to the naked eye – look West to Northwest shortly after sunset. No telescopes or binoculars needed.
Triple conjunction shot on May 26 from a mile high in Payson,Az. 4 second exposure, ISO200, Canon 10D, 80mm f/5 lens. Credit: Chris Schur- http://www.schursastrophotography.com
Just check out our Universe Today collection of newly snapped astrophoto’s and videos sent to Nancy and Ken by stargazing enthusiasts from across the globe. See an earlier gallery – here.
Throughout May, the trio of wandering planets have been gradually gathering closer and closer.
On May 26 and 27, Venus, Jupiter and Mercury appear just 3 degrees apart as a spectacular triangularly shaped object in the sunset skies – which
adds a palatial pallet of splendid hues not possible at higher elevations.
And don’t dawdle if you want to see this celestial feast. The best times are 30 to 60 minutes after sunset – because thereafter they’ll disappear below the horizon.
The sky show will continue into late May as the planets alignment changes every day.
On May 28, Venus and Jupiter close in to within just 1 degree.
And on May 30 & 31, Venus, Jupiter and Mercury will form an imaginary line in the sky.
Triple planetary conjunctions are a rather rare occurrence. The last one took place in May 2011. And we won’t see another one until October 2015.
Indeed the wandering trio are also currently the three brightest planets visible. Venus is about magnitude minus 4, Jupiter is about minus 2.
While you’re enjoying the fantastic view, ponder this: The three planets are also joined by two orbiting spacecraft from humanity. NASA’s MESSENGER is orbiting Mercury. ESA’s Venus Express is orbiting Venus. And NASA’s Juno spacecraft is on a long looping trajectory to Jupiter.
Send Ken you conjunction photos to post here.
And don’t forget to “Send Your Name to Mars” aboard NASA’s MAVEN orbiter- details here. Deadline: July 1, 2013
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Learn more about Conjunctions, Mars, Curiosity, Opportunity, MAVEN, LADEE and NASA missions at Ken’s upcoming lecture presentations:
June 4: “Send your Name to Mars” and “CIBER Astro Sat, LADEE Lunar & Antares Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8:30 PM
June 11: “Send your Name to Mars” and “LADEE Lunar & Antares Rocket Launches from Virginia”; NJ State Museum Planetarium and Amateur Astronomers Association of Princeton (AAAP), Trenton, NJ, 730 PM.
May 25 conjunction over Malta. Canon 450D with a 55mm. lens and an exposure of 1/2 second at ISO 200 on a tripod. Credit: Leonard Ellul-MercerMay 26 triple conjunction from Warwick, NY snapped from Canon Rebel, 100mm – 300mm lens. Credit: Pietro CarboniTriple conjunction from Hondo, Texas taken with a Nikon D800 @ ISO 400 and a 2 second exposure with a Nikon 300mm Lens at F/4. Credit: Adrian New Sunset conjunction with fast moving clouds on May 26 through 10 x 50 binoculars from a seashore town -Marina di Pisa, Tuscany, Italy. Credit: Giuseppe Petricca
Caption: Taken on 2013-05-23 from Salem, Missouri. Canon T1i, Nikkor 105mm lens. 297 1/4s at 1s interval. Images assembled by QuickTime Pro. Credit: Joseph Shuster
May 26 sunset conjunction from Princeton, NJ. Credit: Ken Kremer -kenkremer.comTriple Planetary conjunction over Onset MA. Shot with a Nikon d7000 1/200 f 4 iso 100 at 110mm. Credit: Phillip DamianoPanoramic view over Almada City and Lisbon at the Nautical Twilight, with the Full moon rising above the Eastern horizon (right side of the image), while at the same time but in the opposite direction, the planets Venus, Mercury and Jupiter, are aligned in a triangle formation, setting in the Western horizon (left side of the image).In this panoramic picture is also visible the smooth light transition in the sky, with the end of Nautical Twilight and the beginning of Astronomical Twilight (almost night), at right. Facing to North, is visible the great lighted Monument Christ the King and at the left side of it, part of the 25 April Bridge that connects Almada to Lisbon. Canon 50D – ISO200; f/4; Exp. 1,6 Sec; 35mm. Panoramic of 10 images with about 200º, taken at 21h42 in 25/05/2013. Credit: Miguel Claro – www.miguelclaro.comThe triple conjunction of Venus, Mercury and Jupiter as seen over an Arizona desert landscape. Credit and copyright: Robert Sparks.Jupiter, Venus and Mercury triple conjunction seen here reflecting off Chatsworth Lake in Chatsworth, NJ. Jupiter (on the left) was 2.4° from Mercury (upper-right in the sky) and 2.0° from Venus (bottom right in the sky), while Venus and Mercury were 1.9° apart. Venus was at 2.6° altitude. Canon EOS 6D, 105 mm focal length, 1.3 seconds, f/6.3, ISO 800. Credit: Joe Stieber – sjastro.org/Triple conjunction on May 27 with WBZ radio towers south east of Boston. Hampton Hill, Hull, MA. Nikon D3x -iso200- 1.3 sec.at f2.8. Credit: Richard W. Green
If you’ve ever wanted to see what it’s like to buzz Venus like only a spacecraft can, here’s your chance: this is a video animation of images taken by ESA’s Venus Express as it makes a pole-to-pole orbit of our neighboring world.
Captured in ultraviolet wavelengths, the images were acquired by the spacecraft’s Venus Monitoring Camera last January over a period of 18 hours. It’s truly a “day in the life” of Venus Express!
From ESA’s description of the video:
We join the spacecraft from a staggering 66,000 km above the south pole, staring down into the swirling south polar vortex. From this bird’s-eye view, half of the planet is in darkness, the ‘terminator’ marking the dividing line between the day and night sides of the planet.
Intricate features on smaller and smaller scales are revealed as Venus Express dives to just 250 km above the north pole and clouds flood the field of view, before regaining a global perspective as it climbs away from the north pole.
The observed pattern of bright and dark markings is caused by variations in an unknown absorbing chemical at the Venus cloud tops.
False-color image of cloud features on Venus. Captured by Venus Express from a distance of 30,000 km (18,640 miles) on December 8, 2011. (ESA/MPS/DLR/IDA)
Artist’s impression of an active volcano on Venus (ESA/AOES)
Incredibly dense, visually opaque and loaded with caustic sulfuric acid, Venus’ atmosphere oppresses a scorched, rocky surface baking in planet-wide 425 ºC (800 ºF) temperatures. Although volcanoes have been mapped on our neighboring planet’s surface, some scientists believe the majority of them have remained inactive — at least since the last few hundreds of thousands of years. Now, thanks to NASA’s Pioneer Venus and ESA’s Venus Express orbiters, scientists have nearly 40 years of data on Venus’ atmosphere — and therein lies evidence of much more recent large-scale volcanic activity.
The last six years of observations by Venus Express have shown a marked rise and fall of the levels of sulfur dioxide (SO2) in Venus’ atmosphere, similar to what was seen by NASA’s Pioneer Venus mission from 1978 to 1992.
These spikes in SO2 concentrations could be the result of volcanoes on the planet’s surface, proving that the planet is indeed volcanically active — but then again, they could also be due to variations in Venus’ complex circulation patterns which are governed by its rapid “super-rotating” atmosphere.
“If you see a sulphur dioxide increase in the upper atmosphere, you know that something has brought it up recently, because individual molecules are destroyed there by sunlight after just a couple of days,” said Dr. Emmanuel Marcq of Laboratoire Atmosphères in France, lead author of the paper, “Evidence for Secular Variations of SO2 above Venus’ Clouds Top,” published in the Dec. 2 edition of Nature Geoscience.
“A volcanic eruption could act like a piston to blast sulphur dioxide up to these levels, but peculiarities in the circulation of the planet that we don’t yet fully understand could also mix the gas to reproduce the same result,” added co-author Dr Jean-Loup Bertaux, Principal Investigator for the instrument on Venus Express.
The rise and fall of sulphur dioxide in the upper atmosphere of Venus over the last 40 years, expressed in units of parts per billion by volume. Credits: Data: E. Marcq et al. (Venus Express); L. Esposito et al. (earlier data); background image: ESA/AOES
Because Venus’ dense atmosphere whips around the planet at speeds of 355 km/hour (220 mph), pinpointing an exact source for the SO2 emissions is extremely difficult. Volcanoes could be the culprit, but the SO2 could also be getting churned up from lower layers by variations in long-term circulation patterns.
Venus has over a million times the concentration of sulfur dioxide than Earth, where nearly all SO2 is the result of volcanic activity. But on Venus it’s been able to build up, kept stable at lower altitudes where it’s well shielded from solar radiation.
Regardless of its source any SO2 detected in Venus’ upper atmosphere must be freshly delivered, as sunlight quickly breaks it apart. The puzzle now is to discover if it’s coming from currently-active volcanoes… or something else entirely.
“By following clues left by trace gases in the atmosphere, we are uncovering the way Venus works, which could point us to the smoking gun of active volcanism,” said Håkan Svedhem, ESA’s Project Scientist for Venus Express.
The featureless face of Venus, as seen by MESSENGER (NASA/Gordan Ugarkovic)
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With Venus about to get its day in the Sun — very much literally — the European Space Agency has assembled an excellent video about our planetary neighbor.
Watch the video below:
Once thought to be similar to Earth, possibly even having liquid water and plant life on its surface, Venus has since been discovered to be anything but hospitable to life. Beneath its cream-colored clouds lies a hellish hothouse of searing temperatures and crushing pressure, making attempts at exploration difficult at best. But ESA’s Venus Express, currently in orbit around the planet, has helped scientists learn more about Venus than ever before, opening our eyes to what really lies beneath — and within — its opaque atmosphere.
Venus is still a planet shrouded in mystery (and sulfuric acid clouds!) but we are gradually pulling away the veil.
Venus Express in orbit since 2006 around our nearest planetary neighbor. Credits: ESA
New measurements from ESA’s Venus Express spacecraft shows that Venus’ rotation rate is about 6.5 minutes slower than previous measurements taken 16 years ago by the Magellan spacecraft. Using infrared instruments to peer through the planet’s dense atmosphere, Venus Express found surface features weren’t where the scientists expected them to be.
“When the two maps did not align, I first thought there was a mistake in my calculations as Magellan measured the value very accurately, but we have checked every possible error we could think of,” said Nils Müller, a planetary scientist at the DLR German Aerospace Centre, lead author of a research paper investigating the rotation.
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Using the VIRTIS infrared instrument, scientists discovered that some surface features were displaced by up to 20 km from where they should be given the accepted rotation rate as measured by the Magellan orbiter in the early 1990s.
Over its four-year mission, Magellan determined the length of the day on Venus as being equal to 243.0185 Earth days. But the data from Venus Express indicate the length of the Venus day is on average 6.5 minutes longer.
What could cause the planet to slow down? One possibility may be the raging weather on Venus. Recent atmospheric models have shown that the planet could have weather cycles stretching over decades, which could lead to equally long-term changes in the rotation period. The most important of those forces is due to the dense atmosphere – more than 90 times the pressure of Earth’s and high-speed weather systems, which are believed to change the planet’s rotation rate through friction with the surface.
Earth experiences a similar effect, where it is largely caused by wind and tides. The length of an Earth day can change by roughly a millisecond and depends seasonally with wind patterns and temperatures over the course of a year.
But a change of 6.5 minutes over a little more than a decade is a huge variation.
Other effects could also be at work, including exchanges of angular momentum between Venus and the Earth when the two planets are relatively close to each other. But the scientists are still working to figure out the reason for the slow down.
These detailed measurements from orbit are also helping scientists determine whether Venus has a solid or liquid core, which will help our understanding how the planet formed and evolved. If Venus has a solid core, its mass must be more concentrated towards the center. In this case, the planet’s rotation would react less to external forces.
“An accurate value for Venus’ rotation rate will help in planning future missions, because precise information will be needed to select potential landing sites,” said Håkan Svedhem, ESA’s Venus Express project scientist.
Venus Express will keep monitoring the planet to determine if the rate of rotation continues to change.
Animation of Venus' southern polar vortex made from VIRTIS thermal infrared images; white is cooler clouds at higher altitudes.
Our neighboring planet Venus really is a world of extremes; searing surface temperatures, crushing air pressure, sulfuric acid clouds…Venus pretty much pushes the envelope on every aspect of rocky-planet existence. And now here’s one more thing that made scientists do a double-take: a shape-shifting vortex swirling around Venus’ south pole!
The presence of a cyclonic storm around Venus’ poles – both north and south – has been known since Mariner 10’s pass in 1974 and then afterwards during the Pioneer Venus mission when a downwardly-spiraling formation of clouds over the planet’s north pole was imaged in infrared. It wasn’t until ESA’s Venus Express orbiter arrived in 2006 that the cyclone at the south pole was directly observed via the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument…and it proved to be much stranger than anything previously expected. Continue reading “A Varying Venusian Vortex”
Venus Monitoring Camera image taken in the ultraviolet (0.365 micrometres), from a distance of about 30,000 km. Credits: ESA/MPS/DLR/IDA
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Ever read Isaac Asimov’s 1950’s novel “Lucky Starr and the Oceans of Venus”? Maybe Asimov wasn’t so wrong about Venus after all. Analyzing data from ESA’s Venus Express, planetary scientists are looking at the possibility that the planet may have once harbored oceans, and potentially could have been habitable when during its early history.
While Earth and Venus are comparable in size, they otherwise seem completely different. Earth is a lush, clement world teeming with life, while Venus is hellish, its surface roasting at temperatures higher than those of a kitchen oven.
The biggest difference between the two planets is that Venus has very little water, while Earth is bathed in it. Were the contents of Earth’s oceans to be spread evenly across the world, they would create a layer 3 km deep. If you were to condense the amount of water vapor in Venus’ atmosphere onto its surface, it would create a global puddle just 3 cm deep.
But scientists are beginning to think that billions of years ago, Venus probably had much more water. Venus Express has confirmed that the planet has lost a large quantity of water into space, by measuring the rate of how much hydrogen and oxygen is escaping into space, as the Sun’s ultraviolet radiation beats down on the planet and breaks up water molecules.
Venus Express has measured the rate of this escape and confirmed that roughly twice as much hydrogen is escaping as oxygen. It is therefore believed that water is the source of these escaping ions. It has also shown that a heavy form of hydrogen, called deuterium, is progressively enriched in the upper echelons of Venus’s atmosphere, because the heavier hydrogen will find it less easy to escape the planet’s grip.
“Everything points to there being large amounts of water on Venus in the past,” says Colin Wilson, Oxford University, UK. But that does not necessarily mean there were oceans on the planet’s surface.
Eric Chassefière, Université Paris-Sud, France, has developed a computer model that suggests the water was largely atmospheric and existed only during the very earliest times, when the surface of the planet was completely molten. As the water molecules were broken into atoms by sunlight and escaped into space, the subsequent drop in temperature probably triggered the solidification of the surface. In other words: no oceans.
Although it is difficult to test this hypothesis it is a key question. If Venus ever did possess surface water, the planet may possibly have had an early habitable phase.
Even if true, Chassefière’s model does not preclude the chance that colliding comets brought additional water to Venus after the surface crystallized, and these created bodies of standing water in which life may have been able to form.
There are many open questions. “Much more extensive modelling of the magma ocean–atmosphere system and of its evolution is required to better understand the evolution of the young Venus,” said Chassefière.
When creating those computer models, the data provided by Venus Express will prove crucial.
The Venus Express team are meeting this week to discuss their latest findings at the International Venus Conference in Aussois, France.
The colored overlay shows the emissivity derived from VIRTIS surface brightness data, acquired by ESA¹s Venus Express mission. The high emissivity area (shown in red and yellow) is centered on the summit and the bright flows that originate there. Image courtesy NASA/JPL-Caltech/ESA; image created by Ryan Ollerenshaw and Eric DeJong of the Solar System Visualization Group, JPL.
Recent infrared data from an instrument on the Venus Express spacecraft indicate there could be active volcanism on Venus. “We are pretty sure that Venus still has volcanic activity,” said Joern Helbert and Nils Mueller from the DLR Institute of Planetary Research, members of the Visible and Infrared Thermal Imaging Spectrometer(VIRTIS) team. Nine ‘hotspots’ on Venus’ southern hemisphere have been identified as possibly active, according to a paper published in Science by an international team.
Focusing on areas that showed a lack of surface weathering – which indicates a young surface — the scientists looked at variations in surface thermal emissions to identify compositional differences in lava flows at three specific hotspots. They found that lava flows at the those areas emit abnormally high amounts of heat when compared with their surroundings. That the temperatures are higher does not indicate “heat” as such from volcanism, but means that not much rock degradation by exposure to the harsh Venusian weather took place.
For planetary scientists, that indicates recent active volcanos. How recent?
“Based on a wide range of estimates for rates of volcanism on the surface, we find an upper bound of 250 years to 2.5 million years,” lead author Suzanne Smrekar from JPL told Universe Today in an email. “From predictions about how fast rocks weather on the surface of Venus, we think they are likely on the young side of these estimates. However, there is nothing to preclude them from happening today – but we don’t have any data that demonstrates that.”
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The areas are analogous to Hawaii with volcanism, broad topographic rises, and large positive gravity anomalies suggesting mantle plumes – which are rising masses of hot molten rock.
Smrekar said the temperature variations aren’t huge. “Only a degree or two above the background temperature,” she said. “‘Hot spot’ refers to the geologic environment. On Earth, places like Hawaii where there is hot material coming up from deep inside the Earth to produce volcanism, are referred to as ‘hot spots’.”
Like on Earth, Venus’s valleys are warmer than its mountains. But the venusian atmosphere is so dense that it completely determines the temperature of the planet’s surface. This enabled the scientists to predict surface temperatures with computer models. Data obtained from VIRTIS last year shows that certain areas deviate from the predictions by as much as two or three degrees, and that was the focus of the team’s study.
Smrekar said the team was surprised at the findings. “Although we suspected that these areas could be volcanically active on geologic time scales from past data sets, this is the first data to confirm very recent volcanism, geologically speaking.”
Sources: Science, email exchange with Suzanne Smrekar, DLR
