Category: Venus

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The Venus Express spacecraft has been continuously monitoring the planet in orbit since 2006, and scientists now have enough data to start building a complete picture of the planet’s atmospheric phenomena. They have put together a 3-D picture of Venusian winds for the southern hemisphere. It was known that the winds on Venus are extremely fast and powerful, but what was not known was their extreme variability. The winds are highly influenced by the sun, as well as an unusual and unknown mechanism that seems to re-set itself every five days.

The Venus Express Visual and Infrared Thermal Imaging Spectrometer, VIRTIS, has been studying the thick blanket of clouds that surround Venus, gathering data on the winds. The area studied spans altitudes of 45 to 70 km above the surface and covers the entire southern hemisphere, up to the equator. It is above the southern hemisphere that Venus Express reaches its highest point in orbit (about 66 000 km), allowing the instruments to obtain a global view.

Agustin Sánchez-Lavega, from the Universidad del País Vasco in Bilbao, Spain, led the research on 3-D wind mapping with data from the first year of VIRTIS observations. “We focused on the clouds and their movement. Tracking them for long periods of time gives us a precise idea of the speed of the winds that make the clouds move and of the variation in the winds,” he said.

The spacecraft has the ability to peer through Venus’s thick atmospheric layers and obtain a truly global picture. The scientists tracked three atmospheric layers and followed the movement of hundreds of clouds in each layer.

In total, the team tracked 625 clouds at about 66 km altitude, 662 at around 61 km altitude, and 932 at about 45-47 km altitude, on the day and night sides of the planet. The individual cloud layers were imaged over several months for about 1-2 hours each time.

“We have learnt that between the equator and 50-55˚ latitude south, the speed of the winds varies a lot, from about 370 km/h at a height of 66 km down to about 210 km/h at 45-47 km”, said Sánchez-Lavega.

“At latitudes higher than 65Ëš, the situation changes dramatically – the huge hurricane-like vortex structure present over the poles takes over. All cloud levels are pushed on average by winds of the same speed, independently of the height, and their speed drops to almost zero at the centre of the vortex.”

Sánchez-Lavega and colleagues observed that the speed of the zonal winds (which blow parallel to the lines of latitude) strongly depend on the local time. The difference in the Sun’s heat reaching Venus in the mornings and in the evenings – called the solar tide effect – influences the atmospheric dynamics greatly, making winds blow more strongly in the evenings.

Most unusual was the finding that, on average, the winds regain their original speeds every five days. But the mechanism that produces this periodicity needs further investigation. VIRTIS will continue its observations in an effort to understand the mechanism, as well as getting more precise readings on the variability of the Venusian winds.

Source: ESA

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Astronomers observing Venus back in the 1960’s discovered that the top level of Venusian cloud layers moved very rapidly, orbiting the planet in only four Earth days, compared to the planet’s own rotation of 243 Earth days. This phenomenon is called the “superotation” of Venus. The winds carrying these clouds travel at 360 km/hr, while winds at the planet’s surface are just a breeze at a few km/hr, and there have been indications that at times there’s no wind on Venus’ surface. This unique characteristics have been perplexing, but new observations carried out with ESA’s Venus Express, in orbit around Venus since April 2006, are offering insights to the planet’s atmosphere. Scientists have been able to determine in detail the global structure of the winds on Venus at the different levels of clouds while, at the same time, observe unexpected changes in the wind speeds, and which will help to interpret this mysterious phenomenon.

Venus is similar to Earth in size, and sometimes is called Earth’s sister planet. Nevertheless, it is quite different in other aspects. It’s slow rotation is also retrograde, or in the opposite direction to that of our planet, i.e. from East to West. It’s dense atmosphere of carbon dioxide with surface pressures 90 times that of Earth (equivalent to what we find at 1000 meters below the surface of our oceans), causes a runaway greenhouse effect that raises the surface temperatures up to 450ºC, to such as extent that metals like lead are in a liquid state on Venus.

At a height of between 45 km and 70 km above the surface there are dense layers of sulfuric acid clouds which totally cover the planet. Our continued explorations and observations of Venus seemed to indicate that the “superotation” was a permanent phenomenon. A team led by scientists and the University of Basque Country used images recorded by both day and night on Venus with the VIRTIS spectral camera on board the Venus Express, to measure these clouds over several months and have discovered new aspects of the “superotation.”

First, between the equator and the median latitudes of the planet there dominates a superotation with constant winds blowing from East to West. The wind speeds within the clouds decrease with height, from 370 km/h to 180 km/h. At these median latitudes, the winds decrease to a standstill at the pole, where an immense vortex forms. Other aspects of the superotation are that wind movements from north to south, or meridional, are very weak, about 15 km/h.

Second, unlike what was previously believed, the superotation appears to be not so constant over time. “We have detected fluctuations in its speed that we do not yet understand,” said the team of scientists, led by Agustín Sánchez Lavega. Moreover, for the first time they observed “the solar thermal tide” effect at high latitudes on Venus. “The relative movement of the Sun on the clouds and the intense heat deposited on them makes the superotation more intense at sunset than at sunrise”, they stated in their paper, which was published in Geophysical Research Letters.

“Despite all the data brought together, we are still not able to explain why a planet than spins so slowly has hurricane global winds that are much more intense than terrestrial ones and are, moreover, concentrated at the top of its clouds,” said Lavega. “This study has enabled advances to be made in a precise explanation of the origin of superotation in Venusian winds as well as in the knowledge of the general circulation of planetary atmospheres.”

Source: University of Basque Country press release

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We’ve heard about the possibility of extraterrestrial life arriving on Earth from another planet, asteroid or comet, but the mode of transport usually includes a chunk of rock falling through the atmosphere as a meteorite. But there could be another form of interplanetary transportation. What if there are microbial forms of alien life floating in the upper atmosphere of Venus (the planet’s clouds contain compounds that could indicate presence of micro organisms)? Could they make the trip to Earth? Apparently it is possible, if Earth and Venus are correctly aligned, the solar wind may carry microbes from the upstream Venus to downstream Earth in a matter of days…

Earth and Venus are often referred to as ‘sisters’ as their size and geology are very similar. Although the Venusian surface may appear unsuitable for life to thrive (the temperature and atmospheric pressures are very extreme), it may be possible that microbial life exists in the clouds. As Nancy pointed out in her recent article about colonizing Venus, the environment 50 km above the Venusian surface is the most terrestrial-like in the whole of the Solar System (except Earth of course).

So it should come as no surprise that some scientists believe this may be a good location to search for the most basic forms of life. Two such scientists are Prof Chandra Wickramasinghe and Dr Janaki Wickramasinghe from the Cardiff Centre for Astrobiology, UK, who believe the chemical composition of Venus clouds are consistent with the presence of micro-organisms. Their research uses data from Venus Express (launched by ESA in 2005) which is currently orbiting the planet, trying to understand why Venus is so different from the Earth after 4.6 billion years of planetary evolution.

So the Wickramasinghe’s think that Venus and Earth are not only geologically similar, they may be biologically similar too. “Venus and Earth have often been referred to as sisters because of their geological similarities. Our research proposes that the two sisters may be biologically interconnected as well,” Chandra says. But they don’t stop there. If life does exist in the Venusian cloud tops, perhaps these micro organisms can survive the trip through space, seeding the terrestrial atmosphere. Naturally, this can only occur if the planets are in alignment, so the solar wind can erode the Venus atmosphere, transporting microbes as it does so.

However, the life on Venus theory has its critics. “The idea of life on Venus, particularly the clouds where the temperature and pressure are similar to the Earth, has been floated around for a while but is not really very likely,” says Prof Fred Taylor, a planetary scientist at Oxford University.

This is however an interesting field of research that may go to some way in explaining the phrase and book title: “Men Are From Mars, Women Are From Venus.” So, looking for life on Mars and Venus doesn’t seem so outrageous after all…

(A thank you goes to my friend Ross Fenion who sent me the lead to this story and made the “…Women Are From Venus” link, it wasn’t me…)

Source: BBC

ESA’s Venus Express spacecraft will be cozying up to the planet it has been studying for over two years to begin new and more detailed observations of Venus. This week, engineers began executing a series of maneuvers to gradually bring the spacecraft to a new orbit, closer to Venus. In its new, modified orbit the spacecraft will be able to observe unexplored regions and investigate phenomena that were not within its reach before. The maneuvers will be executed through the month of July, settling it into its new orbit by August 4. Venus Express will eventually get close enough to the planet to dip slightly into the atmosphere, testing out its aerobraking capabilities to further alter its orbit, as well as evaluating the density of the upper atmosphere by measuring the drag on the spacecraft with its on-board accelerometers.

Until now, Venus Express has occupied a highly eccentric polar orbit: at its closest point (pericentre), the spacecraft is between 250 km and 400 km from the planet, and at its farthest (apocentre), it is about 66,000 km away. The pericentre is located at 84° north.

This eccentric orbit was designed to facilitate observation of the southern hemisphere for extended periods, while being able to obtain close observations of northern hemisphere and northern polar regions.
The lowering of the Venus Express orbit is the first step in for more ambitious explorations of Venus, especially of its atmosphere.

Venus Express has already found a highly variable quantity of the volcanic gas sulphur dioxide in the atmosphere of the planet. Scientists are trying to determine if this is evidence for active volcanoes on Venus, or by another unknown mechanism affecting the upper atmosphere.

Now, the altitude of the pericentre will now be lowered to between 185 and 300 km. This modification will enable the following science advantages:
• Study of the magnetic field in the northern polar region
• Study of the plasma environment deeper in the ionosphere
• To indirectly deduce the density of the planet’s atmosphere by measuring the force, or drag, exerted by the planet’s atmosphere on the body of the spacecraft as it moves closer to the planet

Venus Express is European Space Agency’s first mission to Venus. Launched in November 2005, the spacecraft arrived at the planet on 11 April 2006 and began science observations within a month. Since then, it has continuously been making new discoveries and revising our knowledge of Venus.

As of April of this year the spacecraft had returned over 1277 gigabits of data to Earth.

Seemingly, people in the space community have a tendency to push the boundaries of thought about all the possibilities that await us in the universe. Case in point: Geoffrey Landis. Landis is a scientist at NASA’s Glenn Research Center who writes science fiction in his spare time. Last week Landis shared with us his ideas for using a solar powered airplane to study Venus.

This week, Landis goes a step farther (actually, several steps farther) with his ideas about colonizing Venus. Yes, Venus, our hot, greenhouse-effect-gone-mad neighboring planet with a crushing surface pressure that has doomed the few spacecraft that have attempted to reach the planet’s mysterious landscape. Landis knows Venus’ surface itself is pretty much out of the question for human habitation.

But up about 50 kilometers above the surface, Landis says the atmosphere of Venus is the most Earth-like environment, other than Earth itself, in the solar system. What Landis proposes is creating floating cities on Venus where people could live and work, as well as study the planet below.

“There’s been a lot of people who have been proposing space colonies, such as colonies that are in free space, separate from any planet,” said Landis. “And I said, well, if you’re thinking that far into the future why don’t we think of some more groundbreaking, or perhaps we should say atmosphere-breaking possibilities.”

50 km above the surface, Venus has air pressure of approximately 1 bar and temperatures in the 0°C to 50°C range, a quite comfortable environment for humans. Humans wouldn’t require pressurized suits when outside, but it wouldn’t quite be a shirtsleeves environment. We’d need air to breathe and protection from the sulfuric acid in the atmosphere.

In looking at Venus, the fact that struck Landis the most is that Earth’s atmosphere of nitrogen and oxygen would actually float in Venus’ atmosphere of carbon dioxide. “Because the atmosphere of Venus is CO2, the gases that we live in all the time, nitrogen and oxygen, would be a lifting gas,” he said. “On Earth, we know to get something to lift, you need something lighter than air. Well, on Venus, guess what? Our air is lighter than air, or at least lighter than the Venus atmosphere.”

So, create a bubble, fill it with Earth-like atmosphere, and it would float on Venus. “If you could just take the room you’re sitting in and replace the walls with something thinner, the room would float on Venus,” said Landis.

The biggest challenge would be using a substance resistant to sulfuric acid to form the outer layer of the bubble; ceramics or metal sulfates could possibly serve in this role, but of course, you’d want to be able to see outside, as well. “Just think of the great pictures you could get,” said Landis.

Asked if he has ever thought about terraforming Venus, Landis said, “Oh, yes, of course! That’s one of the reasons I started thinking about the floating cities on Venus. The more you look at Venus, the more you say, ‘oh my goodness, terraforming would be a really hard project.'”

Back in about 1962 when Carl Sagan first talked about the concept of terraforming Venus, it wasn’t known what a challenge Venus would be.

“They didn’t quite know how difficult Venus is, they didn’t know how thick the atmosphere was on Venus and how hot it was,” said Landis. “They knew it had a greenhouse effect, but they didn’t know how bad. But the more we look at the problems, the more we say, goodness, terraforming is a very difficult proposition.”

But Landis thinks Venus already has a very nice environment.

“What I like to say, the problem with Venus is if you define sea level as the place in the atmosphere where it’s the same as Earth, the place of “sea level” on Venus is just too far above the ground.”

While Landis’ plans for a solar powered airplane are a true possibility for an upcoming mission to Venus, his ideas about colonizing that planet are a little more speculative. “This is really just a thought exercise,” said Landis, “an exercise in imagination rather than something we’re likely to do in the near term. I don’t expect people will be building cities on Venus, at least probably not in this century.”

Anyone having visions of Bespin and Lando Calrissian from “The Empire Strikes Back”?

Maybe that should be “Landis” Calrissian.

More information about Geoffrey Landis.

With all the orbital missions at the various planets in our solar system, scientists have been able to glean an amazing amount of data to help us understand our neighboring worlds. But imagine a mission that could fly lower than orbital altitudes — actually flying in the atmosphere of another planet and closer to the surface — and imagine how much more detailed the data could be. This type of mission would be especially helpful on Venus, where the intense heat and crushing air pressure at the surface basically precludes the success of any type of lander mission. So, last year, when NASA formed a Science and Technology Definition Team (STDT) to study the concept of a flagship mission to Venus, waiting in the wings was Dr. Geoffrey Landis. For the past several years Landis and a group of scientists and engineers from NASA’s Glenn Research Center have been studying the concept of a solar-powered airplane at Venus. Landis says a small aircraft powered by solar energy could fly continuously in Venus’ atmosphere, and would be an ideal vehicle for gathering data on both the planet’s atmosphere and surface, with the ability to maneuver almost anywhere.

“There’s a lot of interest in Venus at the moment,” said Landis. “We’ve been looking at Mars quite a bit lately, and in some ways Mars is Earth’s twin, but in even more ways, Venus is Earth’s twin. So we learn a lot about Earth by studying Venus.”

A solar powered airplane has been a long-time interest for Landis. “I spent a lot of time in college building model airplanes, so the idea of flying an airplane on Venus sounded very interesting to me,” he said.

Since 2000, Landis and his team have been studying this concept, and Landis recently presented their findings to NASA’s STDT for Venus. “I’ve been trying to drum up enthusiasm for the things we’ve done,” he said. The main work the group has done so far has been focusing on the airplane itself, verifying that the concept is actually going to work.

“We’ve done a thorough design study to determine if there are any showstoppers,” said Landis. “We don’t think there are. We think it’s a very doable project.”

The airplane would have to fold up to fit inside a small aeroshell for a “Discovery” class scientific mission. After arriving at Venus the craft would deploy from the aeroshell, unfold and begin gliding through the atmosphere. With solar cells covering the entire surface, the airplane would fly strictly on solar power, not needing fuel. The team has come up with a foldable design that has a wingspan of 9 meters and a length of just under 7 meters.

Surprisingly, the density of Venus’ atmosphere shouldn’t be a problem for a solar airplane mission. “At the altitudes we’ll be flying, it would be like flying at moderate altitudes on Earth,” said Landis. “Venus is actually a very easy planet to fly on. Interestingly, the problem on Venus is the wind. It turns out it’s a very windy planet, and we would like to be able to keep our solar airplane flying underneath the sun, so we have to fly faster than the wind so we can stay in the sunlight. If we can do that we can basically fly forever.”

The craft would have to be capable of sustained flight at or above the wind speed, about 95 m/sec at the cloud-top level, 65 to 75 km above the surface. For exploration at lower altitudes, the aircraft could glide down for periods of several hours and then climb back to higher altitudes, allowing the cloud layers to be probed. But the airplane would have to be in sunlight for a majority of the time. The team’s analysis of a flight using battery storage shows that it wouldn’t work to keep the aircraft aloft on battery power during the passage across the night side of the planet.

As far as the science that can be gleaned from a solar-powered airplane at Venus, Landis’ team has primarily envisioned a mission to study Venus’ atmosphere. However, they’ve also looked at using it for a radar mission, and in particular if two airplanes could be used, one could be a transmitter and the other a receiver to do what’s called “bistatic radar” where you vary the angle between the transmission and the receiver to provide additional information about the planet. But mainly, an airplane flies much closer to the surface than an orbiting spacecraft, to gather greater detailed information about the planet.

The current focus of Landis’ team has been deciding what type of science could be done, and how it could best be achieved. “What we’ve been doing lately is just studying Venus and asking ourselves, what do we want to do,” said Landis. “Is an airplane the right thing? We’ve also been looking at airships. You can make a zeppelin fly at the planet Venus, which has both advantages and disadvantages over an airplane, so we’re asking ourselves, at what altitude in the clouds do we want to fly — above, below, or in the clouds — and what science we can do? The very hard part on Venus is flying low. It’s very easy to fly high, but the lower you could fly, the better the science you could accomplish. But flying low will be tricky.”

Interestingly enough, last year, students from Boston University also conducted a design study of a solar airplane at Venus, and they looked at the design that Landis’ team had come up with. The BU students also concluded such as mission was quite feasible. “They looked at the basic airplane design: Can you actually fly on Venus? We looked at things like, could you fold it up into the aeroshell, and how would it be deployed, etc.,” Landis said. “We found this second study to be a very useful sanity check for us, that an independent group of people looked at our ideas, and said that no, this isn’t out of the question.”

So, when could a solar-powered airplane mission be ready to fly over Venus? “It depends on how hard the mission you want to do is,” said Landis. “If you’re doing a simple solar airplane mission, we’ve shown that there aren’t any technology showstoppers in the airplane itself, so I think it’s something we could do in the near term, by the next decade. But the more difficult the mission you’re interested in, say if you’re interested in flying low or in the polar regions, places where it’s harder to fly, we’d have to back off and think about what the correct type of vehicle would be.”

This paper discusses more information about the Venus Solar Powered Airplane

Hydroxyl, an important but difficult-to-detect molecule, has been found in the upper atmosphere of Venus by the Venus Express spacecraft. This is the first time this molecule has been detected on another planet, and even though it is thought to be an “atmospheric cleanser,” knowing that it is part of Venus’ thick, greenhouse-like atmosphere will help scientists better understand the environment on our next-door planet. “Venus Express has already shown us that Venus is much more Earth-like than once thought. The detection of hydroxyl brings it a step closer,” said one of the Principal Investigators of the VIRTIS experiment on the Venus Express, Giuseppe Piccioni.

Hydroxyl is thought to be important for any planet’s atmosphere because it is highly reactive. On Earth it has a key role in cleaning pollutants from the atmosphere. On Mars, scientists believe it helps stabilize the carbon dioxide in Mars’ atmosphere, preventing it from converting to carbon monoxide. Also, hydroxyl is thought to play a vital role in sterilizing the Martian soil, making the top layers hostile to microbial life.

Hydroxyl is made up of a hydrogen and oxygen atom each. It has been seen around comets, but the method of production there is thought to be completely different from the way it forms in planetary atmospheres.

On Earth, the glow of hydroxyl in the atmosphere has been shown to be closely linked to the abundance of ozone. From this study, the same is thought to be true at Venus.

Venus Express has shown that the amount of hydroxyl at Venus is highly variable. It can change by 50% from one orbit to the next and this may be caused by differing amounts of ozone in the atmosphere.

“Ozone is an important molecule for any atmosphere, because it is a strong absorber of ultraviolet radiation from the Sun,” says Piccioni. The amount of the radiation absorbed is a key parameter driving the heating and dynamics of a planet’s atmosphere. On Earth, it heats the stratosphere (layer of the atmosphere) making it stable and protecting the biosphere from harmful ultraviolet rays.

Computer models will now be able to tell how this jump and drop in ozone levels over short intervals affects the Venus’ restless atmosphere.

Original News Source: ESA Press Release

The folks over at Ars Technica report that the Japanese Space Agency, JAXA, announced they are now accepting proposals for a microprobe that can hitch a ride with the Venus Climate Orbiter, Japan’s upcoming robotic mission to Venus. They will provide a free ride to either a low-Earth orbit or on a trajectory toward Venus. There are just a few requirements that JAXA has specified:

The launch booster for the Venus Climate Orbiter has room for one piggyback probe that can weigh up to 40 kilograms. It must fit into a 50x50x50 centimeter cube. After the microprobe is released, it will be on its own. JAXA will not assist with further correcting its trajectory or inserting it into an orbit around Venus.

The proposal must be submitted by a researcher based at a Japanese institution, and the mission will have to be managed in Japan. However, this does not preclude a Japanese team from collaborating with foreign researchers on a proposal. Also, all the documents for information and proposals are written in Japanese.

But if you’re in the market for a ride to Venus, the deadline for submitting your proposal is May 23, 2008. The announcement of JAXA’s micro-satellite program is posted here, and the specific announcement for piggybacking on Venus Climate Orbiter is here. The requirements for the micro-satellite and the application forms are found here.

Piggybacked micro-mission to a planet has been done before: NASA’s failed Mars Polar Lander mission had two accompanying microprobes, each weighing only 2.4 kilograms, that would have penetrated the Martian soil to take measurements if the mission had gone better. Mars Polar Lander and the two penetrator probes—named Deep Space 2—all failed independently of one another.

Original News Source: Ars Technica