The surfaces of Asteroid Itokawa, the Moon, Venus, Mars, Titan, and Earth. All images show a view of nearby rocks to the distant horizon. The amount of surface modification evident of each of the bodies increases roughly from left to right.

From the the rubble pile asteroid of Itokawa, the cratered plains of the moon, the volcanic basalts of Venus, the basalt filled craters of Mars, the eroded icy cobbles of Titan to the great oceans of Earth, a variety of surfaces in our solar system is represented.

(Source: annesastronomynews.com)

Morning Star

Dawn on Saturn is greeted across the vastness of interplanetary space by the morning star, Venus, in this image from NASA’s Cassini spacecraft.

Venus appears just off the edge of the planet, in the upper part of the image, directly above the white streak of Saturn’s G ring. Lower down, Saturn’s E ring makes an appearance, looking blue thanks to the scattering properties of the dust that comprises the ring. A bright spot near the E ring is a distant star.

(Source: ikenbot, via scinerds)

crookedindifference:

Mariner 2

NASA brought the Mariner R-2 spacecraft out of storage and launched it just 36 days after the failure of Mariner 1. Mariner 2, as it was known after launch, was equipped with an identical complement of instrumentation to that of its predecessor (see Mariner 1).

The mission proved to be the first fully successful interplanetary mission performed by any nation. After a midcourse correction on 4 September, the spacecraft flew by Venus at a range of 34,762 km on 14 December 1962. During a 42-minute scan of the planet, Mariner 2 gathered significant data on the Venusian atmosphere and surface before continuing on to heliocentric orbit.

NASA maintained contact until 07:00 UT on 3 January 1963, when the spacecraft was 87.4 million kilometers from Earth, a new record for a deep space probe. The data returned showed that the surface temperature on Venus was at least 797 degrees Fahrenheit (425 degrees Celsius) with minimal differentiation between the day and night sides of the planet. Mariner 2 also found that there was a dense cloud layer that extended from 56 to 80 km above the surface. The spacecraft detected no discernible planetary magnetic field; this lack is partly explained by the great distance of the flyby.

After this successful mission, NASA elected to stand down the third spacecraft in the series (Mariner R-3), scheduled for the 1964 launch window.

Soviet Balloon Probes May Have Seen Rain on Venus

image: A concept for the European Venus Explorer balloon seen floating in Venus’ atmosphere. The Soviet Vega missions would have looked similar to this proposed balloon probe. credit: T.Balint / EVE

A pair of balloon probes that floated in the atmosphere of Venus nearly 30 years ago may have run into a drizzle.

This being Earth’s hellish sister planet – where surface pressure is akin to being 900 m underwater and average temperatures are hot enough to melt lead – the shower wasn’t made of friendly water but rather corrosive sulfuric acid. The finding comes from a re-analysis of data taken by the Vega 1 and 2 missions and may represent the first onsite detection of rain ever made outside of Earth.

In 1984, the Soviet Union joined with several European countries to launch the Vega probes, a complex mission that dropped a pair of landers and balloons on Venus and then sent two spacecraft to make close encounters with Halley’s comet in 1986. No other mission has ever deployed balloons on another planet.

The two 3.5-m-diameter balloons floated for nearly two days in the Venusian atmosphere around 55 km above the surface. Unlike the hostile terrain below, the cloud layers at this height are a veritable wonderland. Temperature and pressure are comparable to Earth’s average and there is ample sunlight streaming in from above. If not for the sulfuric acid clouds and hurricane-force winds, the atmosphere of Venus would be a comfortable living space.

Most previous analyses of the mission noted that the balloons slowly leaked helium and descended as they traveled, and that has been considered the end of the story.

But the balloons were well built, made of a Teflon-impregnated material and “it would have been rare for them to start leaking,” said aeronautical engineer Graham Dorrington of the Royal Melbourne Institute of Technology in Australia, author of a paper on this work that appeared Apr. 6 in Advances in Space Research.

Looking again at the old data Dorrington noticed that one of the balloons, from Vega 2, seemed to have reduced its leakage rate at some point, as if it had somehow repaired itself. “I thought that was funny,” he said.

An alternative explanation for why the balloons descended would have been that they got heavier, most likely from a buildup of liquid on their outer surface. Sulfuric acid could have precipitated out of Venus’ clouds in a fine mist, coating the balloons and then slowly dripping off. In the case of the Vega 2 balloon, sensors indicated that at one point the probe’s buoyancy changed quickly, on the order of a minute, which could have happened when the balloon ran into a light drizzling shower.

“This work is credible and interesting, but speculative,” wrote planetary scientist Kevin McGouldrick of the University of Colorado, Boulder, who was not involved in the work, in an email to Wired.

Clouds are made of extremely tiny liquid drops that are suspended in the atmosphere. Rain happens when enough of these drops stick together to form a larger drop and fall from the sky.

While tiny particles of fine mist could conceivably form in the sulfuric acid clouds on Venus, it is an open question whether or not larger rain-like drops could exist, McGouldrick wrote. NASA’s Pioneer Venus spacecraft, which dropped a probe through the Venusian cloud layers and measured their properties in 1978, did not see large sulfuric acid drops during its fall.

But even on Earth, rainstorms are sporadic events, said Dorrington. The odds of a probe dropping through our atmosphere and hitting a downpour aren’t very big, so Pioneer Venus might have missed this evidence. And other spacecraft, like Mariner 10, have seen evidence of rainstorms, though nothing definitive. It will likely take a future mission to the cloud layers of Venus to conclusively confirm or deny the possibility of rain.

If the findings were proven, they would be the first onsite detection of rain on another planet. The European Space Agency’s Huygens probe, which landed on Saturn’s moon Titan in 2005, may have photographed a liquid drop from rain, though whether this came from the moon or the probe isn’t known.

Watch: View from a proposed NASA Venus balloon mission. credit: Tibor Balint/NASA

Carl Sagan

abcstarstuff:

VENUS VORTICES GO FOR CHAOTIC MULTI-STORY STROLLS AROUND THE POLES

A detailed study of Venus’ South Polar Vortex shows a much more chaotic and unpredictable cyclone than previously thought. The analysis reveals that the center of rotation of the vortex wanders around the pole differently at different altitude levels in the clouds of Venus. In its stroll around the pole, in layers separated by 20 km, the vortex experiences unpredictable changes in its morphology. The results of this study are published online in Nature Geoscience today [http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1764.html].

The study, entitled “A chaotic long-lived vortex at the southern pole of Venus,” used infrared images from the VIRTIS instrument onboard the European Space Agency’s Venus Express spacecraft. VIRTIS provides spectral images at different levels of the atmosphere and allows the observation of the lower and upper clouds of Venus.

Atmospheric vortices are common in the atmospheres of different planets of the solar system, although they have different behaviors. Venus is a planet similar to Earth in size, but very different in other aspects. It rotates slowly around its axis, with a day on Venus lasting 243 Earth-days, and it spins in the opposite direction to Earth. Its dense carbon dioxide atmosphere, with surface pressures of 90 times that of Earth, causes a runaway greenhouse effect that raises the surface temperatures up to 450°C. Between 45 and 70 km above the surface there is a dense layer of sulfuric acid clouds that completely covers the planet and moves at speeds of 360 km/h in a phenomenon named superrotation, where the atmosphere rotates much faster than the surface of the planet. The origin of this effect is still unknown.

At the poles of Venus, the atmospheric circulation forms intense and permanent vortices that change shape and size on a daily basis. In the new analysis published today, researchers report that the winds in the vortex, which were tracked by studying images obtained by the Venus Express orbiter, change chaotically from day-to-day. This unpredictable nature of the Venus polar vortices make them different from polar vortices found on other planets, like Earth or Saturn, which are much more stable and predictable.

The large-scale cyclone extends vertically in Venus’ atmosphere over more than 20 kilometers, through a region of highly turbulent, permanent clouds. However, the centers of rotation at two different altitude levels (42 and 62 km above the surface) are not aligned and both wander around the south pole of the planet with no established pattern at velocities of up to 55k m/h. The study also finds that even when averaged cross-winds are roughly the same at both altitudes, there is still a strong vertical gradient, with winds increasing by as much as 3 km/h for every kilometer of height and leading to possible atmospheric instabilities

The vortices are fed by the atmospheric superrotation and are trapped in polar regions by a wide, shallow collar of cold air in subpolar latitudes. The eye at the center of the vortex covers an average area of 2200 kilometers by 1400 kilometers. Despite several years of observations, it is not possible to explain why the vortex is variable enough to alter its shape in just one day, or remain stable for weeks. Thus, along with the origin of the superrotation of the atmosphere, identification of a mysterious source of ultraviolet absorption in the clouds, Venus polar vortices are one of the great mysteries of our twin planet. This study will help for a more precise explanation of the vortex and its relationship with the atmospheric superrotation.

IMAGE….The South Polar Vortex of Venus changes its shape day-to-day. The upper panels of the figure show the upper clouds at 63km above the surface and the lower panels present the vortex as observed in the lower clouds at 42km altitude level. (Credit: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA/Universidad del País Vasco (I. Garate-Lopez))

Venus’s South Pole Vortex —Strange Behavior of a Whirlwind the Size of Europe

The astronomers in the UPV/EHU’s Planetary Science Group have completed a study of the atmospheric vortex of the south pole of Venus, a huge whirlwind the size of Europe similar to Jupiter’s 300-year-0ld Great Red Spot and the South Pole Vortex on Saturn. In the atmosphere there are two main cloud layers separated by a distance of 20km. The astronomers have been closely monitoring the movement of the vortex on both levels, and have been able to confirm the erratic nature of this movement.

“We knew it was a long-term vortex; we also knew that it changes shape every day. But we thought that the centres of the vortex at different altitudes formed only a single tube, but that is not so. Each centre goes its own way, yet the global structure of the atmospheric vortex does not disintegrate,” explains Itziar Garate-Lopez, head researcher and member of the UPV/EHU’s Planetary Science Group.
The centers of rotation of the upper and lower vortex rarely coincide in their position with respect to the vertical, yet they form a constantly evolving permanent structure on the surface of Venus. Long-term vortices are a frequent phenomenon in the atmospheres of fast rotating planets, like Jupiter and Saturn, for example. Venus rotates slowly, yet it has permanent vortices in its atmosphere at both poles. What is more, the rotation speed of the atmosphere is much greater than that of the planet.

“We’ve known for a long time that the atmosphere of Venus rotates 60 times faster than the planet itself, but we didn’t know why,” says Garate-Lopez. “The difference is huge; that is why it’s called super-rotation. And we‘ve no idea how it started or how it keeps going.” The images above show a thin cloud layer near the South Pole.

The permanence of the Venus vortices contrasts with the case of the Earth. “On the Earth there are seasonal effects and temperature differences between the continental zones and the oceans that create suitable conditions for the formation and dispersal of polar vortices. On Venus there are no oceans or seasons, and so the polar atmosphere behaves very differently,” added Garate-Lopez.

The UPV/EHU team has been able to monitor the evolution of the south pole vortex thanks to one of the instruments on board the European Space Agency’s Venus Express spacecraft, which has been orbiting our neighboring planet since April 2006. The orbit of this craft is very elliptical: it gets very close to the North pole and South pole, yet the planet is observed from a greater distance, which allows a more global vision to be obtained. Also needed was a more extended view offering a detailed view of the planet’s south pole, whereas the north pole is observed from much shorter distances, which prevents it from being observed globally,” explains Garate-Lopez.

The UPV/EHU astronomers have been using the VIRTIS-M infrared camera on the Venus Express probe and have been analysing data obtained in the course of 169 earth days, and in particular, they have been studying in great detail the data on the 25 most representative orbits.

“This camera doesn’t take individual photos like an ordinary camera, it divides the light into different wave lengths that enable various vertical layers of the planet’s atmosphere to be observed simultaneously, says Garate-Lopez. Besides, we have compared images separated by one-hour intervals and this has enabled us to monitor the speed at which the clouds move.”

Recent images from Venus Express shown above do not confirm previous sightings of a double storm system there (shown above), but rather found a single unusual swirling cloud vortex. In the above recently released image sequence taken in infrared light and digitally compressed, darker areas correspond to higher temperatures and hence lower regions of Venus’ atmosphere. Also illuminating are recently released movies, which show similarities between Venus’ southern vortex and the vortex that swirls over the South Pole of Saturn. Understanding the peculiar dynamics of why, at times, two eddies appear, while at other times a single peculiar eddy appears, may give insight into how hurricanes evolve on Earth, and remain a topic of research for some time.

Carl Sagan - Global Warming

(Source: ikenbot, via inspirement)

distant-traveller:

Cassini spies Venus from Saturn’s orbit

A distant world gleaming in sunlight, Venus shines like a bright beacon through Saturn’s rings in this image taken by the international Cassini spacecraft.

The image was taken last November when Cassini was placed in the shadow of Saturn. This allowed Cassini to look in the direction of the Sun and take a backlit image of the planet and its rings.

Peeking through the rings in this image is Earth’s ‘twin’ planet, Venus, just to the right of centre in the upper part of the image.

Venus is, along with Mercury, Earth and Mars, one of the rocky terrestrial planets of the inner Solar System. Although it has a similar size, mass and rocky composition to Earth, Venus is far from a true twin.

Under a thick, choking atmosphere of carbon dioxide and sulphuric dioxide clouds the surface pressure is nearly 100 times greater than on Earth, not to mention the scorching 500ºC surface temperature – the hottest planetary surface in the Solar System.

But it is Venus’ permanent sulphur clouds that reflect plentiful sunlight, making it shine brightly in the night sky, even from a distant viewpoint in the outer Solar System.

Image credit: NASA/JPL-Caltech/Space Science Institute

Beyond Apollo Posts on Piloted Mars (And Other Places) Flybys
by David S. F. Portree

The piloted Mars flyby concept was first articulated in any detail in 1956 by Italian aviation and rocketry pioneer Gaetano Crocco. NASA work on the concept began in 1962, and the space agency devoted as much study effort to piloted Mars flybys in the 1960s as it did to piloted Mars landings. NASA officials went so far as to announce that they would seek new-start funding for a 1975 manned Mars flyby in the FY 1969 NASA budget. The image at the top of this post shows NASA’s piloted flyby spacecraft design concept at the time Congress rejected the proposal in late 1967, in the wake of the January 1967 Apollo 1 fire.

You can read the entire fascinating story in my book Humans to Mars, which is available online for free on the NASA History Office website as a set of PDF files (one per chapter).

Chapters 3 and 4 concentrate on piloted flyby plans, although Chapter 7 contains a description of a 1985 piloted Mars flyby concept proposed for the 1990s. Of course, your best course would be to read the entire book so that you can put these plans into their proper context. I think that I can safely claim that my book is the definitive source on piloted flyby planning history.

Here’s my list of Beyond Apollo posts related to piloted flyby mission plans that were in some way similar to the one InspirationMars proposed yesterday. I plan many more piloted flyby posts; if you share my fascination with the concept, then please watch this space.

EMPIRE Building: Ford Aeronutronic’s Mars/Venus Piloted Flyby Study (1962)

After EMPIRE: Using Apollo Hardware to Explore Venus & Mars (1965)

Manned Asteroid Flyby Mission (1966)

Piloted Single-Launch Venus Flyby (1967)

Planetary Billiards: Triple-Planet Mars/Venus Flybys

Robot Probes for Piloted Venus Flybys (1967)

S-IIB Interplanetary Injection Stage for Piloted Mars/Venus Flybys

Blueprint for 1970s Planetary Exploration (1968)

The Common Space Fleet (1968)

Shuttle-Era Manned Mars Flyby (1985)

Castles in Space: A 50-Year Survey of Gravity-Assist Space Travel

Beyond Apollo chronicles spaceflight history through missions and programs that didn’t happen. Comments are welcome. Off-topic comments might be deleted.

David S. F. Portree
One of the most original spaceflight historians working today, David S. F. Portree researches and writes about the history of space exploration with an emphasis on missions planned but not flown. Apollo 8 and the film 2001: A Space Odyssey turned him on to spaceflight in 1968 at the tender age of six. His book-length publications include Humans to Mars: 50 Years of Mission Planning, Walking to Olympus: an EVA Chronology, NASA’s Origins and the Dawn of the Space Age, and Mir Hardware Heritage, all published by NASA and available online. He currently works as an historian, archivist, map librarian, and outreach educator at the U.S. Geological Survey’s Astrogeology Science Center in Flagstaff, Arizona.

Venus Can Have’Comet-Like’ Atmosphere

The planet Venus sometimes looks less like a planet and more like a comet, scientists say.

Scientists with the European Space Agency have discovered that a part of the upper atmosphere of Venus — its ionosphere — acts surprisingly different depending on daily changes in the sun’s weather. The side of Venus’ ionosphere that faces away from the sun can billow outward like the tail of a comet, while the side facing the star remains tightly compacted, researchers said.

The discovery was made using ESA’s Venus Express spacecraft, which observed Venus’s ionosphere during a period of low solar wind in 2010 to see exactly how the sun affects the way the planet’s atmosphere functions. In 2013, the sun is expected to reach the peak of its 11-year solar activity cycle.

“As this significantly reduced solar wind hit Venus, Venus Express saw the planet’s ionosphere balloon outwards on the planet’s ‘downwind’ nightside, much like the shape of the ion tail seen streaming from a comet under similar conditions,” ESA officials said in a statement today (Jan. 29).

It only takes 30 to 60 minutes for the planet’s comet-like tail to form after the solar wind dies down. Researchers observed the ionosphere stretch to at least 7,521 miles (12,104 kilometers) from the planet, said Yong Wei, a scientist at the Max Planck Institute in Katlenburg, Germany who worked on this research.

Earth’s ionosphere never becomes comet-like largely because the planet has its own magnetic field that balances out the sun’s influence on the way the atmospheric layer is shaped. Venus, however, doesn’t have its own magnetic field and is therefore subject to the whims of the sun’s solar wind.

Researchers think that Mars behaves in much the same way. The Red Planet doesn’t have a magnetic field to mitigate the influence of the sun’s wind either.

The Venus Express spacecraft launched in 2005 and has been orbiting the second planet from the sun since 2006. The spacecraft is equipped with seven instruments to study the atmosphere and surface of Venus in extreme detail. The spacecraft is currently in an extended mission slated to last until 2014 .

image: When the solar wind dies down, an outer layer of Venus’s atmosphere billows outward (illustrated on right), making the second planet from the sun look like a comet.
CREDIT: ESA/Wei et al.

(Source: benigoat, via ohmysagan)

thenewenlightenmentage:

You Could Be From Venus

scienceisbeauty:

Radar Image of the surface of Venus, centered at 180 degrees east longitude.

By NASA (source) [Public domain], via Wikimedia Commons