Japan to Launch Venus Orbiter and Solar Sail Missions

IKAROS - solar sail from Japan. Image: JAXA
IKAROS - solar sail from Japan. Image: JAXA

Bad weather postponed a scheduled multi-mission launch of an H-IIA rocket from Japan early Tuesday, which includes the first Japanese probe to Venus and an experimental solar sail. The next launch attempt for the “Akatsuki” Venus Climate Orbiter and the solar sail called IKAROS will be Thursday, May 20, at 21:58 UTC (May 20 at 5:58 EDT) – which is May 21 at 6:58 in Japan. Akatsuki is Japan’s first mission to Venus, and it will work closely with the ESA’s Venus Express, already at Venus. Also called Planet C, the box-shaped orbiter should arrive at Venus in December and observe the planet from an elliptical orbit, from a distance of between 300 and 80,000 kilometers (186 to 49,600 miles), looking for — among other things — signs of lightning and active volcanoes.

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Another payload is the solar sail, or “space yacht” IKAROS (Interplanetary Kite-craft Accelerated by Radiation of the Sun). This 320kg, 1.8m-wide, disc-shaped spacecraft will deploy an ultra-thin, ultra-light, 14 meter sail that will propel the structure from the radiation pressure from sunlight hitting it.

“The purpose of IKAROS is to demonstrate the technology of the Solar Power Sail,” said Osamu Mori, project leader of IKAROS. “Simply put, the solar sail is a ‘space yacht.’ A yacht moves forward on water, pushed by wind captured in its sails. A solar sail is propelled by sunlight instead of wind, so it’s a dream spaceship – it doesn’t require an engine or fuel. Part of IKAROS’s sail is covered by a solar cell made of an ultra-thin film, which generates electricity from sunlight.”

So far, solar sails have only been tested, but never flown successfully. It is hoped IKAROS will be the world’s first solar-powered sail, and that the structure will sail towards Venus, following Akatsuki.

The experimental sail is thinner than a human hair, is also equipped with thin-film solar cells to generate electricity, creating what JAXA calls “a hybrid technology of electricity and pressure.”

To control the path of IKAROS, engineers will change the angle at which sunlight particles bounce off the sail.

Akatsuki and IKAROS on the launch pad Taken on May 17, 2010, about 24 hours before the planned launch of Akatsuki and IKAROS toward Venus. They are stacked aboard an H-IIA rocket. Credit: Mitsubishi Heavy Industries, Ltd.

If you are a member of The Planetary Society, your name will be heading to Venus on both Akatsuki and IKAROS. The Planetary Society, a long-time proponent of solar sail technology, and Japan’s space exploration center, JSPEC/JAXA, have an agreement to collaborate and cooperate on public outreach and on technical information and results from IKAROS, which will help TPS plan for its upcoming launch of its own solar sail vehicle, LightSail-1, which they hope to launch in early 2011.

Emily Lakdawalla at the Planetary Blog has more details about the two missions and TPS’s involvement.

The H-IIA will also carry four other small satellites, developed by Japanese universities and other institutions. They include:

The 2-pound Negai CubeSat, developed by Soka University of Japan. Negai will test an information processing system during a three-week mission.

The WASEDA-SAT2, developed by Waseda University. The 2.6-pound spacecraft will conduct technology experiments in orbit.

The 3.3-pound KSAT spacecraft developed by Kagoshima University will conduct Earth observation experiments.

The 46-pound UNITEC-1 satellite from the Japanese University Space Engineering Consortium will test computer technologies and broadcast radio waves from deep space for decoding by amateur radio operators.

The rocket will launch from Japan’s Tanegashima Space Center in southern Japan.

For more information on IKAROS, read this interview with the project leader, Osamu Mori

Volcanoes on Venus May Still Be Active

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

Where To Next for NASA’s Solar System Exploration?

From top to bottom, pictured are the moon, Venus, and an asteroid.From top to bottom, pictured (not to scale) are the moon, Venus, and an asteroid. These three celestial bodies from our solar system are possible candidates for NASA's next space venture.

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Where is NASA going next to probe our solar system? The space agency announced today they have selected three proposals as candidates for the agency’s next space venture to another celestial body in our solar system. The proposed missions would probe the atmosphere composition and crust of Venus; return a piece of a near-Earth asteroid for analysis; or drop a robotic lander into a basin at the moon’s south pole to return lunar rocks back to Earth for study. All three sound exciting!

Here are the finalists:

Surface and Atmosphere Geochemical Explorer, or SAGE, mission to Venus would release a probe to descend through the planet’s atmosphere. During descent, instruments would conduct extensive measurements of the atmosphere’s composition and obtain meteorological data. The probe then would land on the surface of Venus, where its abrading tool would expose both a weathered and a pristine surface area to measure its composition and mineralogy. Scientists hope to understand the origin of Venus and why it is so different from Earth. Larry Esposito of the University of Colorado in Boulder, is the principal investigator.

Origins Spectral Interpretation Resource Identification Security Regolith Explorer spacecraft, called Osiris-Rex, would rendezvous and orbit a primitive asteroid. After extensive measurements, instruments would collect more than two ounces of material from the asteriod’s surface for return to Earth. The returned samples would help scientists better undertand and answer long-held questions about the formation of our solar system and the origin of complex molecules necessary for life. Michael Drake, of the University of Arizona in Tucson, is the principal investigator.

MoonRise: Lunar South Pole-Aitken Basin Sample Return Mission would place a lander in a broad basin near the moon’s south pole and return approximately two pounds of lunar materials for study. This region of the lunar surface is believed to harbor rocks excavated from the moon’s mantle. The samples would provide new insight into the early history of the Earth-moon system. Bradley Jolliff, of Washington University in St. Louis, is the principal investigator.

The final project will be selected in mid-2011, and for now, the three finalists will receive approximately $3.3 million in 2010 to conduct a 12-month mission concept study that focuses on implementation feasibility, cost, management and technical plans. Studies also will include plans for educational outreach and small business opportunities.

The selected mission must be ready for launch no later than Dec. 30, 2018. Mission cost, excluding the launch vehicle, is limited to $650 million.

“These are projects that inspire and excite young scientists, engineers and the public,” said Ed Weiler, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. “These three proposals provide the best science value among eight submitted to NASA this year.”

The final selection will become the third mission in the program. New Horizons, launched in 2006, will fly by the Pluto-Charon system in 2015 then target another Kuiper Belt object for study. The second mission, called Juno, is designed to orbit Jupiter from pole to pole for the first time, conducting an in-depth study of the giant planet’s atmosphere and interior. It is slated for launch in August 2011.

Visit the New Frontiers program site for more information.

UFOs, a Green Venus and Sun Gobbling? Isn’t That Going a Little Far, Mrs Hatoyama?

Venus? Green? Are you sure?

[/caption]“While my body was asleep, I think my soul rode on a triangular-shaped UFO and went to Venus.”

This might sound like a quote taken from the ramblings of a conspiracy theorist or the chant from someone who spent an hour too many at an Amsterdam coffee shop, but it wasn’t.

Actually, these are the words of the wife of the Japanese premier-in-waiting Yukio Hatoyama.

Mrs Miyuki Hatoyama might be married to a man Japan nicknames “The Alien,” but it looks like it’s not him who has dreams of an extraterrestrial nature…

If there’s one thing politicians must dread when they are voted into a position of power, it’s the past. Previous indiscretions, past conversations, old business that involved major campaign donors; all of these must keep many government ministers awake at night, worried that the media will dig up some dirt.

However, in the case of the soon-to-be prime minister of Japan (who won the recent elections with a landslide victory), it’s his 66-year old wife who wrote something last year in a book called Very Strange Things I’ve Encountered, that’s causing a stir. But through his wife’s own admission, Yukio Hatoyama is an open minded fellow and probably won’t be concerned about what the public may think of Miyuki’s book.

Very Strange Things documents Mrs Hatoyama’s experiences 20 years ago when a UFO picked her up and took her to Venus. “It was a very beautiful place and it was really green,” she observed.

If by “green” she actually means “dark brown,” and by “beautiful” she means “a tropical, bone crushing atmosphere, stuffed with poisonous gas and a landscape resembling hell,” then I think Miyuki really did fly there.

Naturally, after she had her joyride to Venus, Miyuki arrived back in bed, next to her now ex-husband who told her it was just a dream.

In addition to her night-time jaunts around the Solar System, Miyuki also partakes in a little solar feast every now and again. On a Japanese TV show earlier this year, Miyuki went into some detail about her spiritualistic beliefs.

I also eat the sun,” she said on the program, closing her eyes, pulling pieces off an imaginary Sun. “Like this, hum, hum, hum. It gives me enormous energy […] My husband has recently started doing that too.”

This all seems like a lot of fun, but what does this mean for Japan? As noted by Keith Cowing over at NASA Watch, perhaps we’ll see a boost in JAXA (the Japanese space agency) funding. It might also go some way to explaining why there’s been a surge of interest in Japanese space solar power!

Things might go a little too far if we start seeing JAXA UFO patrols in low-Earth orbit, but for now, I suspect it’s going to be a rather flamboyant term in office for the Hatoyama’s…

Sources: Reuters, NASA Watch, Time

Characteristics of Venus

Venus. Credit: NASA

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Venus is the second planet from the Sun, and considered in many ways to be a twin planet of Earth. It has a similar size, mass, density and gravity, as well as a very similar chemical composition. In other ways, Venus is very different than Earth, with its high surface temperature, crushing pressure, and poisonous atmosphere. Let’s take a look at some of the characteristics of Venus.

As I said at the beginning, Venus is the second planet from the Sun. It orbits at an average distance of 108 million km from the Sun, taking almost 225 days to complete one revolution around the Sun. One of the strange characteristics of Venus is that it’s actually rotating backwards from the rest of the planets. Seen from above, all of the planets rotate counter-clockwise, but Venus turns clockwise on its axis. Even stranger, a day on Venus lasts 243 days, which is longer its year.

In terms of size, Venus is quite similar to Earth. Its radius is 6,052 km (95% the size of the Earth). Its volume is about 86% the volume of Earth, and its mass is 4.87 x 1024 kg, which is about 82% the mass of the Earth. The gravity on Venus is 90% the gravity on Earth, so if you could actually walk around on the surface of Venus, the gravity would feel very similar to Earth.

It’s when you get to the atmosphere of Venus that you see that the planet is very different from Earth. The temperature on the surface of Venus is a blistering 462 °C. That’s hot enough to melt lead! Furthermore, the atmospheric pressure on the surface of Venus is 92 times Earth pressure. You would have to travel a kilometer down beneath the surface of the ocean on Earth to feel that kind of pressure here. Venus’ atmosphere is composed almost entirely of carbon dioxide (97%), and it’s this thick atmosphere that acts like a blanket, keeping Venus so hot.

Venus has no water on its surface, and very little water vapor in its atmosphere. Scientists think that the runaway greenhouse effect that makes Venus so hot today boiled away its oceans long ago. Since Venus lacks a planetary magnetic field, the Sun’s solar wind was able to blast the hydrogen atoms out of Venus’ atmosphere and into space. Venus can never be cool again.

Most of the surface of Venus is covered by smooth volcanic plains, and its dotted with extinct volcanic peaks and impact craters. Venus has much fewer impact craters than other planets in the Solar System, and scientists have estimated that some event resurfaced Venus between 300-500 million years ago, wiping out all of the old impact craters and volcanoes.

Venus has no moons or rings.

We have written many articles about Venus for Universe Today. Here’s an article about Venus’ wet, volcanic past, and here’s an article about how Venus might have had continents and oceans in the ancient past.

Want more information on Venus? Here’s a link to Hubblesite’s News Releases about Venus, and here’s a link to NASA’s Solar System Exploration Guide on Venus.

We have recorded a whole episode of Astronomy Cast that’s only about planet Venus. Listen to it here, Episode 50: Venus.

Reference:
NASA Solar System Exploration: Venus

New Map Hints at Venus’ Wet, Volcanic Past

Artistic interpretation of a possible volcano on Venus. Credits: ESA - AOES Medialab

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Venus is often referred to as Earth’s twin, as the two planets share a similar size. But perhaps the similarities don’t end there. A new infrared map from Venus Express hints that our neighboring world may once have been more Earth-like, with a plate tectonics system and an ocean of water. While previous radar images have given us a glimpse of Venus’ cloud-shrouded surface, this is the first map that hints at the chemical composition of the rocks. The new data are consistent with suspicions that the highland plateaus of Venus are ancient continents, once surrounded by ocean and produced by past volcanic activity.

“This is not proof, but it is consistent. All we can really say at the moment is that the plateau rocks look different from elsewhere,” says Nils Müller at the Joint Planetary Interior Physics Research Group of the University Münster and DLR Berlin, who headed the mapping efforts.

The first temperature map of the planet's southern hemisphere at infrared wavelengths, charted with Venus Express's Visible and Infrared Thermal Imaging Spectrometer, VIRTIS. Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA
The first temperature map of the planet's southern hemisphere at infrared wavelengths, charted with Venus Express's Visible and Infrared Thermal Imaging Spectrometer, VIRTIS. Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA

The map shows Venus’ southern hemisphere comprised over a thousand individual images, recorded between May 2006 and December 2007. The Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument captured infrared radiation given off by the various surfaces on Venus during the spacecraft’s night-time orbits around the planet’s southern hemisphere.

Different types of rocks radiate different amounts of heat at infrared wavelengths owing to a material characteristic known as emissivity. The new map shows that the rocks on the Phoebe and Alpha Regio plateaus are lighter in color and look old compared to the majority of the planet. On Earth, such light-colored rocks are usually granite and form continents.

“If there is granite on Venus, there must have been an ocean and plate tectonics in the past,” says Müller.
Granite is formed when ancient rocks, made of basalt, are driven down into the planet by shifting continents, a process known as plate tectonics. The water combines with the basalt to form granite and the mixture is reborn through volcanic eruptions.

Müller points out that the only way to know for sure whether the highland plateaus are continents is to send a lander there. Over time, Venus’ water has been lost to space, but there might still be volcanic activity. The infrared observations are very sensitive to temperature. But in all images they saw variations of only 3–20°C, instead of the kind of temperature difference they would expect from active lava flows.

“Venus is a big planet, being heated by radioactive elements in its interior. It should have as much volcanic activity as Earth,” he says. Indeed, some areas do appear to be composed of darker rock, which hints at relatively recent volcanic flows.

Lead image caption: Artistic interpretation of a possible volcano on Venus. Credits: ESA – AOES Medialab

Source: ESA

Earth Cyclones, Venus Vortices Have Much in Common

Scientists have spotted an S-shaped feature in the center of the vortices on Venus that looks familiar — because they’ve seen it in tropical cyclones on Earth.

Researchers from the United States and Europe spotted the feature using NASA’s Pioneer Venus Orbiter and The European Space Agency’s Venus Express. Their new discovery confirms that massive, swirling wind patterns have much in common where they have been found — on Venus, Saturn and Earth.

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At cloud top level, Venus’ entire atmosphere circles the planet in just about four Earth days, much faster than the solid planet does. Despite this “superrotation,” some dynamical and morphological similarities exist between the vortex organization in the atmospheres of Venus’s northern and southern hemispheres and tropical cyclones and hurricanes on Earth.

Organization of the Venus atmospheric circulation into two circumpolar vortices, one centered on each pole, was first deduced more than 30 years ago from Mariner 10 ultraviolet images. The S-shaped feature in the center of the vortices on Venus was first detected by the Pioneer Venus Orbiter near the northern pole and recently by Venus Express orbiter around the southern pole. It is also known to occur in Earth’s tropical cyclones.

Using an idealized nonlinear and nondivergent barotropic model, lead author Sanjay S. Limaye, of the University of Wisconsin-Madison, and his colleagues are proposing that these S-shaped features are the manifestations of barotropic instability. The feature can be simulated with a barotropic model and, like in the vortices on Venus and in tropical cyclones, it is found to be transient.

Another similarity between the observed features in the vortex circulations of Venus and in terrestrial hurricanes is the presence of transverse waves extending radially outward from the vortex centres. The lack of observations of such features in Earth’s polar vortices is suggestive that the dynamics of the Venus polar vortices may have more in common with hurricanes than their more direct terrestrial counterparts. 

Given the challenges in measuring the deep circulation of Venus’s atmosphere, the authors expect that the morphological similarities between vortices on Earth and Venus might help scientists better understand atmospheric superrotation on Venus and guide future observations.

IMAGE CAPTIONS: 1. The ‘eye of the hurricane’ on Venus, taken by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board Venus Express. The yellow dot represents the south pole. Credit: ESA 2. An infrared satellite image of Hurricane Howard [1998], showing an S-shaped pattern in the low (warm) clouds in the tropical cyclone’s eye. Credit: Sanjay S. Limaye. 

Source: Geophysical Research Letters

Venus is Glowing in the Dark!

A false-colour composite image of Venus’s atmosphere was obtained by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board ESA’s Venus Express, from a limb (or profile) perspective.

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Venus is glowing in infrared! At least at night, anyway. The Venus Express spacecraft has observed an eerie glow in the night-time atmosphere of Venus. This infrared glow comes from nitric oxide and is showing scientists that the atmosphere of Earth’s nearest neighbor is a temperamental place of high winds and turbulence. Since this glow is infrared, we can’t see it with our eyes but lucky for us, the ESA’s spacecraft is equipped with the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument, which can see these wavelengths. A glow like this has never been detected in the atmospheres of Earth or Mars, even though nitric oxide molecules are present. So just why is Venus glowing, and what is this glow telling us?

“The nightglow can give us a lot of information,” says Antonio García Muñoz, who was at the Australian National University when the research was carried out; he is now located at the Instituto de Astrofísica de Canarias, Tenerife, Spain. “It can provide details about the temperature, wind direction, composition and chemistry of an atmosphere.”

VIRTIS has made two clear-cut detections of the so-called nightglow for nitric oxide at Venus. This is the first time such infrared detections have been made for any planet and provide a new insight into Venus’s atmosphere

The nightglow is ultimately caused by the Sun’s ultraviolet light, which streams into a planet’s atmosphere and breaks the molecules up into atoms and other simpler molecules. The free atoms may recombine again and, in specific cases, the resulting molecule is endowed with some extra energy that is subsequently lost in the form of light. On the day-side of the planet, any atoms that do find their way back together are outshone by the sunlight falling into the atmosphere.

But on the night-side, where atoms are transported by a vigorous diurnal circulation, the glow can be seen with appropriate instruments, such as VIRTIS.

It also highlights a new mystery. “These results show that there could be at least twice as much hydrogen in the upper atmosphere of Venus than we thought,” says Delva. The detected hydrogen ions could exist in atmospheric regions high above the surface of the planet; but the source of these regions is unknown.

Artist's impression shows Venus Express focussing on studying the peculiar atmosphere of Venus,
Artist's impression shows Venus Express focussing on studying the peculiar atmosphere of Venus,

The nightglow on Venus has been seen at infrared wavelengths before, betraying oxygen molecules and the hydroxyl radical, but this is the first detection of nitric oxide at those wavelengths. It offers data about the atmosphere of Venus that lies above the cloud tops at around 70 km. The oxygen and hydroxyl emissions come from 90-100 km, whereas the nitric oxide comes from 110-120 km altitude.

Yet, even VIRTIS cannot see the nitric oxide nightglow all the time because it is often just too faint. “Luckily for us, Venus has a temperamental atmosphere,” says García Muñoz, “Packets of oxygen and nitrogen atoms are blown around.” Sometimes these become dense enough to boost the brightness of the nightglow, making it visible to VIRTIS.

Venus Express can observe the three nightglow emissions simultaneously, and this gives rise to a mystery. The nightglows from the different molecules do not necessarily happen together. “Perhaps when we have more observations, we will understand the correlation between them,” says García Muñoz.

In order to do that, the VIRTIS team plans to continue monitoring the planet, building up a database of this fascinating phenomenon.

Source: ESA

Venus Possibly Had Continents, Oceans

Venus. Credit: NASA

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A new look at data gathered from the Galileo spacecraft in 1990 reveals that Venus at one time may have been habitable, with evidence of past continents and oceans. In a flyby of Venus on the spacecraft’s journey to Jupiter, a near-infrared mapping instrument detected signatures which the researchers have interpreted as granite. An international team led by planetary scientist George Hashimoto, at Okayama University, Japan, found that Venus’s highland regions emitted less infrared radiation than its lowlands. One interpretation of this dichotomy, says the team’s new paper, is that the highlands are composed largely of ‘felsic’ rocks, particularly granite. Granite, which on Earth is found in continental crust, requires water for its formation.

The Galileo spacecraft was the first use of infrared to look at Venus. Scientists had believed that only radar could see through the dense clouds of sulfuric acid in Venus’s atmosphere to the surface. “Detecting the surface in the infrared is a breakthrough,” co-author Kevin Baines from JPL was quoted in an article in Nature.

The article also quoted another JPL scientist, David Crisp, who was not involved in this study as saying these new conclusions aren’t supported either by the available data or the team’s own models.

“We understand our paper doesn’t resolve everything,” responds co-author Seiji Sugita, a planetary scientist at the University of Tokyo. Sugita says the next step is to apply their models to data from the European Space Agency’s Venus Express spacecraft, which is already orbiting Venus, and the Japanese Space Agency’s Venus Climate Orbiter, scheduled for launch in 2010.

The possible presence of granite suggests that tectonic plate movement and continent formation may have occurred on Venus, as well as recycling of water and carbon between the planet’s mantle and atmosphere.
Venus is now hellishly hot and dry, with an atmosphere of 96% carbon dioxide and a surface temperature of around 460 degrees C, but some scientists think our neighboring planet may have once have been more like Earth.

Another scientist quoted in the Nature article, geophysicist Norm Sleep of Stanford University in California said Venus might have once been almost entirely underwater. “Although without further geochemical data, he adds, we don’t know whether this early ocean’s temperature was 30 degrees C or 150 degrees C,” he said.

But any ocean on Venus would have lasted only a few hundred million years. As the Sun became hotter and brighter, the planet experienced a runaway greenhouse effect. “Any life on Venus that hadn’t figured out how to colonize the cloud tops a billion years after the planet’s formation would have been in big trouble,” says Sleep.

Sources: Nature, Abstract

How Hot is Venus?

The first color pictures taken of the surface of Venus by the Venera-13 space probe. Credit: NASA
The first color pictures taken of the surface of Venus by the Venera-13 space probe. The Venera 13 probe lasted only 127 minutes before succumbing to Venus's extreme surface environment. Part of building a longer-lasting Venus lander is figuring out how to power it. Credit: NASA

You might be surprised to know that Venus is the hottest planet in the Solar System. The temperature across the entire planet is 735 Kelvin, or 462 degrees Celsius.

That makes it hotter than Mercury, which can dip down to -220 degrees Celsius and get up to 420 degrees C. Venus is nearly twice as far away from the Sun as Mercury, and receives 25% of it’s sunlight.

The temperature on the surface of Venus is the same across the entire planet. It doesn’t matter if it’s day or night, at the poles or at the equator – the temperature is always the same 462 degrees.

[/caption]So why is Venus so hot? Billions of years ago, the atmosphere of Venus was probably very similar to the Earth’s, with liquid water lasting on the surface. But a runaway greenhouse effect evaporated all the water, leaving a thick atmosphere of carbon dioxide. The light from the Sun is trapped by the carbon dioxide atmosphere and keeps the planet so warm.

It’s also believed that Venus once had plate tectonics like we have on Earth. Here on Earth, the plate tectonics help regulate the amount of carbon dioxide in the atmosphere by trapping excess carbon dioxide underneath the surface of the Earth. When the plate tectonics stopped, the carbon cycle stopped as well, and carbon dioxide was able to accumulate in the atmosphere of Venus.

Want to learn about other planets in the Solar System? Here’s how hot Mercury can get, and here’s an article about the hottest place on Earth.

Want more information on Venus? Here’s a link to Hubblesite’s News Releases about Venus, and here’s NASA’s Solar System Exploration Guide to Venus.

We have also recorded a whole episode of Astronomy Cast that’s just about planet Venus. Listen to it here, Episode 50: Venus.