Venus Express Probe Reveals the Planet’s Mysterious Night Side

Venus’ atmosphere is as mysterious as it is dense and scorching. For generations, scientists have sought to study it using ground-based telescopes, orbital missions, and the occasional atmospheric probe. And in 2006, the ESA’s Venus Express mission became the first probe to conduct long-term observations of the planet’s atmosphere, which revealed much about its dynamics.

Using this data, a team of international scientists – led by researchers from the Japan Aerospace and Exploration Agency (JAXA) – recently conducted a study that characterized the wind and upper cloud patterns on the night side of Venus. In addition to being the first of its kind, this study also revealed that the atmosphere behaves differently on the night side, which was unexpected.

The study, titled “Stationary Waves and Slowly Moving Features in the Night Upper Clouds of Venus“, recently appeared in the scientific journal Nature Astronomy. Led by Javier Peralta, the International Top Young Fellow of JAXA, the team consulted data obtained by Venus Express’ suite of scientific instruments in order to study the planet’s previously-unseen cloud types, morphologies, and dynamics.

The atmospheric super-rotation at the upper clouds of Venus. While the super-rotation is present in both day and night sides of Venus, it seems more uniform in the day. Credits: JAXA, ESA, J. Peralta and R. Hueso.

Whereas plenty of studies have been conducted of Venus’ atmosphere from soace, this was the first time that a study was not focused on the dayside of the planet. As Dr. Peralta explained in an ESA press statement:

This is the first time we’ve been able to characterize how the atmosphere circulates on the night side of Venus on a global scale. While the atmospheric circulation on the planet’s dayside has been extensively explored, there was still much to discover about the night side. We found that the cloud patterns there are different to those on the dayside, and influenced by Venus’ topography.

Since the 1960s, astronomers have been aware that Venus’ atmosphere behaves much differently that those of other terrestrial planets. Whereas Earth and Mars have atmospheres that co-rotate at approximately the same speed as the planet, Venus’ atmosphere can reach speeds of more than 360 km/h (224 mph). So while the planet takes 243 days to rotate once on its axis, the atmosphere takes only 4 days.

This phenomena, known as “super-rotation”, essentially means that the atmosphere moves over 60 times faster than the planet itself. In addition, measurements in the past have shown that the fastest clouds are located at the upper cloud level, 65 to 72 km (40 to 45 mi) above the surface. Despite decades of study, atmospheric models have been unable to reproduce super-rotation, which indicated that some of the mechanics were unknown.

Artist’s impression of the atmosphere of Venus, showing its lightning storms and a volcano in the distance. Credit and ©: European Space Agency/J. Whatmore

As such, Peralta and his international team – which included researchers from the Universidad del País Vasco in Spain, the University of Tokyo, the Kyoto Sangyo University, the Center for Astronomy and Astrophysics (ZAA) at Berlin Technical University, and the Institute of Astrophysics and Space Planetology in Rome – chose to look at the unexplored side to see what they could find. As he described it:

“We focused on the night side because it had been poorly explored; we can see the upper clouds on the planet’s night side via their thermal emission, but it’s been difficult to observe them properly because the contrast in our infrared images was too low to pick up enough detail.”

This consisted of observing Venus’ night side clouds with the probe’s Visible and Infrared Thermal Imaging Spectrometer (VIRTIS). The instrument gathered hundreds of images simultaneously and different wavelengths, which the team then combined to improve the visibility of the clouds. This allowed the team to see them properly for the first time, and also revealed some unexpected things about Venus’ night side atmosphere.

What they saw was that atmospheric rotation appeared to be more chaotic on the night side than what has been observed in the past on the dayside. The upper clouds also formed different shapes and morphologies – i.e. large, wavy, patchy, irregular and filament-like patterns  – and were dominated by stationary waves, where two waves moving in opposite directions cancel each other out and create a static weather pattern.

Examples of new types of cloud morphology discovered on the night side of Venus thanks to Venus Express (ESA) and the infrared telescope IRTF (NASA). Credits: ESA/NASA/J. Peralta and R. Hueso.

The 3D properties of these stationary waves were also obtained by combining VIRTIS data with radio-science data from the Venus Radio Science experiment (VeRa). Naturally, the team was surprised to find these kinds of atmospheric behaviors since they were inconsistent with what has been routinely observed on the dayside. Moreover, they contradict the best models for explaining the dynamics of Venus’ atmosphere.

Known as Global Circulation Models (GCMs), these models predict that on Venus, super-rotation would occur in much the same way on both the dayside and the night side. What’s more, they noticed that stationary waves on the night side appeared to coincide with high-elevation features. As Agustin Sánchez-Lavega, a researcher from the University del País Vasco and a co-author on the paper, explained:

Stationary waves are probably what we’d call gravity waves–in other words, rising waves generated lower in Venus’ atmosphere that appear not to move with the planet’s rotation. These waves are concentrated over steep, mountainous areas of Venus; this suggests that the planet’s topography is affecting what happens way up above in the clouds.

This is not the first time that scientists have spotted a possible link between Venus’ topography and its atmospheric motion. Last year, a team of European astronomers produced a study that showed how weather patterns and rising waves on the dayside appeared to be directly connected to topographical features. These findings were based on UV images taken by the Venus Monitoring Camera (VMC) on board the Venus Express.

Schematic illustration of the proposed behaviour of gravity waves in the vicinity of mountainous terrain on Venus. Credit: ESA

Finding something similar happening on the night side was something of a surprise, until they realized they weren’t the only ones to spot them. As Peralta indicated:

It was an exciting moment when we realized that some of the cloud features in the VIRTIS images didn’t move along with the atmosphere. We had a long debate about whether the results were real–until we realised that another team, led by co-author Dr. Kouyama, had also independently discovered stationary clouds on the night side using NASA’s Infrared Telescope Facility (IRTF) in Hawaii! Our findings were confirmed when JAXA’s Akatsuki spacecraft was inserted into orbit around Venus and immediately spotted the biggest stationary wave ever observed in the Solar System on Venus’ dayside.

These findings also challenge existing models of stationary waves, which are expected to form from the interaction of surface wind and high-elevation surface features. However, previous measurements conducted by the Soviet-era Venera landers have indicated that surface winds might too weak for this to happen on Venus. In addition, the southern hemisphere, which the team observed for their study, is quite low in elevation.

And as Ricardo Hueso of the University of the Basque Country (and a co-author on the paper) indicated, they did not detect corresponding stationary waves in the lower cloud levels. “We expected to find these waves in the lower levels because we see them in the upper levels, and we thought that they rose up through the cloud from the surface,” he said. “It’s an unexpected result for sure, and we’ll all need to revisit our models of Venus to explore its meaning.”

Artist’s impression of Venus Express performing aerobreaking maneuvers in the planet’s atmosphere in June and July 2014. Credit: ESA–C. Carreau

From this information, it seems that topography and elevation are linked when it comes to Venus’ atmospheric behavior, but not consistently. So the standing waves observed on Venus’ night side may be the result of some other undetected mechanism at work. Alas, it seems that Venus’ atmosphere – in particular, the key aspect of super-rotation – still has some mysteries for us.

The study also demonstrated the effectiveness of combining data from multiple sources to get a more detailed picture of a planet’s dynamics. With further improvements in instrumentation and data-sharing (and perhaps another mission or two to the surface) we can expect to get a clearer picture of what is powering Venus’ atmospheric dynamics before long.

With a little luck, there may yet come a day when we can model the atmosphere of Venus and predict its weather patterns as accurately as we do those of Earth.

Further Reading: ESA, Nature Astronomy

How Do We Colonize Venus?

The planet Venus, as imaged by the Magellan 10 mission. Credit: NASA/JPL

Welcome back to our series on Colonizing the Solar System! Today, we take a look at Earth’s “sister planet”, the hellish, yet strangely similar planet Venus. Enjoy!

Since humans first began looking up at the skies, they have been aware of Venus. In ancient times, it was known as both the “Morning Star” and the “Evening Star”, due to its bright appearance in the sky at sunrise and sunset. Eventually, astronomers realized that it was in fact a planet, and that like Earth, it too orbited the Sun. And thanks to the Space Age and numerous missions to the planet, we have learned exactly what kind of environment Venus has.

With an atmosphere so dense that it makes regular surface imaging impossible, heat so intense it can melt lead, and sulfuric acid rain, there seems little reason to go there. But as we’ve learned in recent years, Venus was once a very different place, complete with oceans and continents. And with the right technology, colonies could be built above the clouds, where they would be safe.

So what would it take to colonize Venus? As with other proposals for colonizing the Solar System, it all comes down to having the right kinds of methods and technologies, and how much are we willing to spend.

At a closest average distance of 41 million km (25,476,219 mi), Venus is the closest planet to Earth. Credit: NASA/JPL/Magellan
At a closest average distance of 41 million km (25,476,219 mi), Venus is the closest planet to Earth. Credit: NASA/JPL/Magellan

Examples in Fiction:

Since the early 20th century, the idea of colonizing Venus has been explored in science fiction, mainly in the form of terraforming it. The earliest known example is Olaf Stapleton’s Last And First Men (1930), two chapters of which are dedicated to describing how humanity’s descendants terraform Venus after Earth becomes uninhabitable; and in the process, commit genocide against the native aquatic life.

By the 1950s and 60s, terraforming began to appear in many works of science fiction. Poul Anderson also wrote extensively about terraforming in the 1950s. In his 1954 novel, The Big Rain, Venus is altered through planetary engineering techniques over a very long period of time. The book was so influential that the term term “Big Rain” has since come to be synonymous with the terraforming of Venus.

In 1991, author G. David Nordley suggested in his short story (“The Snows of Venus”) that Venus might be spun-up to a day-length of 30 Earth days by exporting its atmosphere of Venus via mass drivers. Author Kim Stanley Robinson became famous for his realistic depiction of terraforming in the Mars Trilogy – which included Red Mars, Green Mars and Blue Mars.

In 2012, he followed this series up with the release of 2312, a science fiction novel that dealt with the colonization of the entire Solar System – which includes Venus. The novel also explored the many ways in which Venus could be terraformed, ranging from global cooling to carbon sequestration, all of which were based on scholarly studies and proposals.

Artist's conception of a terraformed Venus, showing a surface largely covered in oceans. Credit: Wikipedia Commons/Ittiz
Artist’s conception of a terraformed Venus, showing a surface largely covered in oceans. Credit: Wikipedia Commons/Ittiz

Proposed Methods:

All told, most proposed methods for colonizing Venus emphasize ecological engineering (aka. terraforming) to make the planet habitable. However, there have also been suggestions as to how human beings could live on Venus without altering the environment substantially.

For instance, according to Inner Solar System: Prospective Energy and Material Resources, by Viorel Badescu, and Kris Zacny (eds), Soviet scientists have suggested that humans could colonize Venus’ atmosphere rather than attempting to live on its hostile surface since the 1970s.

More recently, NASA scientist Geoffrey A. Landis wrote a paper titled “Colonization of Venus“, in which he proposed that cities could be built above Venus’ clouds. At an altitude of 50 km above the surface, he claimed, such cities would be safe from the harsh Venusian environment:

“[T]he atmosphere of Venus is the most earthlike environment (other than Earth itself) in the solar system. It is proposed here that in the near term, human exploration of Venus could take place from aerostat vehicles in the atmosphere, and that in the long term, permanent settlements could be made in the form of cities designed to float at about fifty kilometer altitude in the atmosphere of Venus.”

Artist's concept of a Venus cloud city — a possible future outcome of the High Altitude Venus Operational Concept (HAVOC) plan. Credit: Advanced Concepts Lab/NASA Langley Research Center
Artist’s concept of a Venus cloud city — a possible future outcome of the High Altitude Venus Operational Concept (HAVOC) plan. Credit: Advanced Concepts Lab/NASA Langley Research Center

At an altitude of 50 km above the surface, the environment has a pressure of approximately 100,000 Pa, which is slightly less than Earth’s at sea level (101,325 Pa). Temperatures in this regions also range from 0 to 50 °C (273 to 323 K; 32 to 122 °F), and protection against cosmic radiation would be provided by the atmosphere above, with a shielding mass equivalent to Earth’s.

The Venusian habitats, according to Landis’ proposal, would initially consists of aerostats filled with breathable air (a 21:79 oxygen-nitrogen mix). This is based on the concept that air would be a lifting gas in the dense carbon dioxide atmosphere, possessing over 60% of the lifting power that helium has on Earth.

These would provide initial living spaces for colonists, and could act as terraformers, gradually converting Venus’ atmosphere into something livable so the colonists could migrate to the surface. One way to do this would be to use these very cities as solar shades, since their presence in the clouds would prevent solar radiation from reaching the surface.

This would work particularly well if the floating cities were made of low-albedo materials. Alternately, reflective balloons and/or reflecting sheets of carbon nanotubes or graphene could be deployed from these. This offers the advance of in-situ resource allocation, since atmospheric reflectors could be built using locally-sourced carbon.

In addition, these colonies could serve as platforms where chemical elements were introduced into the atmosphere in large amounts. This could take the form of calcium and magnesium dust (which would sequester carbon in the form of calcium and magnesium carbonates), or a hydrogen aerosol (producing graphite and water, the latter of which would fall to the surface and cover roughly 80% of the surface in oceans).

NASA has begun exploring the possibility of mounting crewed missions to Venus as part of their High Altitude Venus Operational Concept (HAVOC), which was proposed in 2015. As outlined by Dale Arney and Chris Jones from NASA’s Langley Research Center, this mission concept calls for all crewed portions of the missions to be conducted from lighter than air craft or from orbit.

Potential Benefits:

The benefits of colonizing Venus are many. For starters, Venus it the closest planet to Earth, which means it would take less time and money and send missions there, compared to other planets in the Solar System. For example, the Venus Express probe took just over five months to travel from Earth to Venus, whereas the Mars Express probe took nearly six months to get from Earth to Mars.

In addition, launch windows to Venus occur more often, every 584 days when Earth and Venus experience an inferior conjunction. This is compared to the 780 days it takes for Earth and Mars to achieve opposition (i.e. the point in their orbits when they make their closest approach).

Compared to a mission to Mars, a mission to Venus’ atmosphere would also subject astronauts to less in the way of harmful radiation. This is due in part to Venus’ greater proximity, but also from Venus’ induced magnetosphere – which comes from the interaction of its thick atmosphere with solar wind.

Also, for floating settlements established in Venus’ atmosphere, there would be less risk of explosive decompression, since there would not be a significant pressure difference between the inside and outside of the habitats. As such, punctures would pose a lesser risk, and repairs would be easier to mount.

In addition, humans would not require pressurized suits to venture outside, as they would on Mars or other planets. Though they would still need oxygen tanks and protection against the acid rain when working outside their habitats, work crews would find the environment far more hospitable.

Venus is also close in size and mass to the Earth, resulting in a surface gravity that would be much easier to adapt to (0.904 g). Compared to gravity on the Moon, Mercury or Mars (0.165 and 0.38 g), this would likely mean that the health effects associated with weightlessness or microgravity would be negligible.

In addition, a settlement there would have access to abundant materials with which to grow food and manufacture materials. Since Venus’ atmosphere is made mostly out of carbon dioxide, nitrogen and sulfur dioxide, these could be sequestered to create fertilizers and other chemical compounds.

CO² could also be chemically separated to create oxygen gas, and the resulting carbon could be used to manufacture graphene, carbon nanotubes and other super-materials. In addition to being used for possible solar shields, they could also be exported off-world as part of the local economy.

Challenges:

Naturally, colonizing a planet like Venus also comes with its share of difficulties. For instance, while floating colonies would be removed from the extreme heat and pressure of the surface, there would still be the hazard posed by sulfuric acid rain. So addition to the need for protective shielding in the colony, work crews and airships would also need protection.

Second, water is virtually non-existent on Venus, and the composition of the atmosphere would not allow for synthetic production. As a result, water would have to be transported to Venus until it be produced onsite (i.e. bringing in hydrogen gas to create water form the atmosphere), and extremely strict recycling protocols would need to be instituted.

Solar shades placed in orbit of Venus are  a possible means of terraforming the planet. Credit: IEEE Spectrum/John MacNeill
Solar shades placed in orbit of Venus are a possible means of terraforming the planet. Credit: IEEE Spectrum/John MacNeill

And of course, there is the matter of the cost involved. Even with launch windows occurring more often, and a shorter transit time of about five months, it would still require a very heavy investment to transport all the necessary materials – not to mention the robot workers needed to assemble them – to build even a single floating colony in Venus’ atmosphere.

Still, if we find ourselves in a position to do so, Venus could very become the home of “Cloud Cities”, where carbon dioxide gas is processed and turned into super-materials for export. And these cities could serve as a base for slowly introducing “The Big Rain” to Venus, eventually turning into the kind of world that could truly live up to the name “Earth’s sister planet”.

We have written many interesting articles about terraforming here at Universe Today. Here’s The Definitive Guide To Terraforming, Could We Terraform the Moon?, Should We Terraform Mars?, How Do We Terraform Mars? and Student Team Wants to Terraform Mars Using Cyanobacteria.

We’ve also got articles that explore the more radical side of terraforming, like Could We Terraform Jupiter?, Could We Terraform The Sun?, and Could We Terraform A Black Hole?

For more information, check out Terraforming Mars  at NASA Quest! and NASA’s Journey to Mars.

And if you liked the video posted above, come check out our Patreon page and find out how you can get these videos early while helping us bring you more great content!

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What is the Closest Planet to Earth?

A common question when looking at the Solar System and Earth’s place in the grand scheme of it is “which planet is closest to Earth?” Aside from satisfying a person’s general curiosity, this question is also of great importance when it comes to space exploration. And as humanity contemplates mounting manned missions to neighboring planets, it also becomes one of immense practicality.

If, someday, we hope to explore, settle, and colonize other worlds, which would make for the shortest trip? Invariable, the answer is Venus. Often referred to as “Earth’s Twin“, Venus has many similarities to Earth. It is a terrestrial planet, it orbits within the Sun’s habitable zone, and it has an atmosphere that is believed to have once been like Earth’s. Combined with its proximity to us, its little wonder we consider it our twin.

Venus’ Orbit:

Venus orbits the Sun at an average distance (semi-major axis) of 108,208,000 km (0.723 AUs), ranging between 107,477,000 km (0.718 AU) at perihelion and 108,939,000 km (0.728 AU) at aphelion. This makes Venus’ orbit the least eccentric of all the planets in the Solar System. In fact, with an eccentricity of less than 0.01, its orbit is almost circular.

Earth and Venus' orbit compared. Credit: Sky and Telescope
Earth and Venus’ orbit compared. Credit: Sky and Telescope

When Venus lies between Earth and the Sun, it experiences what is known as an inferior conjunction. It is at this point that it makes its closest approach to Earth (and that of any planet) with an average distance of 41 million km (25,476,219 mi). On average, Venus achieves an inferior conjunction with Earth every 584 days.

And because of the decreasing eccentricity of Earth’s orbit, the minimum distances will become greater over the next tens of thousands of years. So not only is it Earth’s closest neighbor (when it makes its closest approach), but it will continue to get cozier with us as time goes on!

Venus vs. Mars:

As Earth’s other neighbor, Mars also has a “close” relationship with Earth. Orbiting our Sun at an average distance of 227,939,200 km (1.52 AU), Mars’ highly eccentric orbit (0.0934) takes it from a distance of 206,700,000 km (1.38 AU) at perihelion to 249,200,000 km (1.666 AU) at aphelion. This makes its orbit one of the more eccentric in our Solar System, second only to Mercury

For Earth and Mars to be at their closest, both planets needs to be on the same side of the Sun, Mars needs to be at its closest distance from the Sun (perihelion), and Earth needs to be at its farthest (aphelion). This is known as opposition, a time when Mars appears as one of the brightest objects in the sky (as a red star), rivaling that of Venus or Jupiter.

The eccentricity in Mars' orbit means that it is . Credit: NASA
The eccentricity in Mars’ orbit means that it is . Credit: NASA

But even at this point, the distance between Mars and Earth ranges considerably. The closest approach to take place occurred back in 2003, when Earth and Mars were only 56 million km (3,4796,787 mi) apart. And this was the closest they’d been in 50,000 years. The next closest approach will take place on July 27th, 2018, when Earth and Mars will be at a distance of 57.6 million km (35.8 mi) from each other.

It has also been estimated that the closest theoretical approach would take place at a distance of 54.6 million km (33.9 million mi). However, no such approach has been documented in all of recorded history. One would be forced to wonder then why so much of humanity’s exploration efforts (past, present and future) are aimed at Mars. But when one considers just how horrible Venus’ environment is in comparison, the answer becomes clear.

Exploration Efforts:

The study and exploration of Venus has been difficult over the years, owing to the combination of its dense atmosphere and harsh surface environment. Its surface has been imaged only in recent history, thanks to the development of radar imaging. However, many robotic spacecraft and even a few landers have made the journey and discovered much about Earth’s closest neighbor.

The first attempts were made by the Soviets in the 1960s through the Venera Program. Whereas the first mission (Venera-1) failed due to loss of contact, the second (Venera-3) became the first man-made object to enter the atmosphere and strike the surface of another planet (on March 1st, 1966). This was followed by the Venera-4 spacecraft, which launched on June 12th, 1967, and reached the planet roughly four months later (on October 18th).

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. Credit: NASA

NASA conducted similar missions under the Mariner program. The Mariner 2 mission, which launched on December 14th, 1962, became the first successful interplanetary mission and passed within 34,833 km (21,644 mi) of Venus’ surface. Between the late 60s and mid 70s, NASA conducted  several more flybys using Mariner probes – such as the Mariner 5 mission on Oct. 19th, 1967 and the Mariner 10 mission on Feb. 5th, 1974.

The Soviets launched six more Venera probes between the late 60s and 1975, and four additional missions between the late 70s and early  80s. Venera-5, Venera-6, and Venera-7 all entered Venus’ atmosphere and returned critical data to Earth. Venera 11 and Venera 12 detected Venusian electrical storms; and Venera 13 and Venera 14 landed on the planet and took the first color photographs of the surface. The program came to a close in October 1983, when Venera 15 and Venera 16 were placed in orbit to conduct mapping of the Venusian terrain with synthetic aperture radar.

By the late seventies, NASA commenced the Pioneer Venus Project, which consisted of two separate missions. The first was the Pioneer Venus Orbiter, which inserted into an elliptical orbit around Venus (Dec. 4th, 1978) to study its atmosphere and map the surface. The second, the Pioneer Venus Multiprobe, released four probes which entered the atmosphere on Dec. 9th, 1978, returning data on its composition, winds and heat fluxes.

Pioneer Venus
Artist’s impression of NASA’s Pioneer Venus Orbiter in orbit around Venus. Credit: NASA

In 1985, the Soviets participated in a collaborative venture with several European states to launch the Vega Program. This two-spacecraft initiative was intended to take advantage of the appearance of Halley’s Comet in the inner Solar System, and combine a mission to it with a flyby of Venus. While en route to Halley on June 11th and 15th, the two Vega spacecraft dropped Venera-style probes into Venus’ atmosphere to map its weather.

NASA’s Magellan spacecraft was launched on May 4th, 1989, with a mission to map the surface of Venus with radar. In the course of its four and a half year mission, Magellan provided the most high-resolution images to date of the planet, was able to map 98% of the surface and 95% of its gravity field. In 1994, at the end of its mission, Magellan was sent to its destruction into the atmosphere of Venus to quantify its density.

Venus was observed by the Galileo and Cassini spacecraft during flybys on their respective missions to the outer planets, but Magellan was the last dedicated mission to Venus for over a decade. It was not until October of 2006 and June of 2007 that the MESSENGER probe would conduct a flyby of Venus (and collect data) in order to slow its trajectory for an eventual orbital insertion of Mercury.

The Venus Express, a probe designed and built by the European Space Agency, successfully assumed polar orbit around Venus on April 11th, 2006. This probe conducted a detailed study of the Venusian atmosphere and clouds, and discovered an ozone layer and a swirling double-vortex at the south pole before concluding its mission in December of 2014. Since December 7th, 2015, Japan’s Akatsuki has been in a highly elliptical Venusian orbit.

Because of its hostile surface and atmospheric conditions, Venus has proven to be a tough nut to crack, despite its proximity to Earth. In spite of that, NASA, Roscosmos, and India’s ISRO all have plans for sending additional missions to Venus in the coming years to learn more about our twin planet. And as the century progresses, and if certain people get their way, we may even attempt to send human colonists there!

We have written many articles about Earth and its closest neighbor here at Universe Today. Here’s The Planet Venus, Venus: 50 Years Since Our First Trip, And We’re Going Back, Interesting Facts About Venus, Exploring Venus By Airship, Colonizing Venus With Floating Cities, and How Do We Terraform Venus?

If you’d like more info on Earth, check out NASA’s Solar System Exploration Guide on Earth. And here’s a link to NASA’s Earth Observatory.

Astronomy Cast also has an interesting episode on the subject. Listen here, Episode 50: Venus.

The Next Generation of Exploration: The DAVINCI Spacecraft

It’s no secret that there has been a resurgence in interest in space exploration in recent years. Much of the credit for this goes to NASA’s ongoing exploration efforts on Mars, which in the past few years have revealed things like organic molecules on the surface, evidence of flowing water, and that the planet once had a denser atmosphere –  all of which indicate that the planet may have once been hospitable to life.

But when it comes to the future, NASA is looking beyond Mars to consider missions that will send missions to Venus, near-Earth objects, and a variety of asteroids. With an eye to Venus, they are busy investigating the possibility of sending the Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (DAVINCI) spacecraft to the planet by the 2020s.

Led by Lori Glaze of the Goddard Spaceflight Center, the DAVINCI descent craft would essentially pick up where the American and Soviet space programs left off with the Pioneer and Venera Programs in the 1970s and 80s. The last time either country sent a probe into Venus’ atmosphere was in 1985, when the Soviet probes Vega 1 and 2 both orbited the planet and released a balloon-supported aerobot into the upper atmosphere.

Model of the Vega 1 solar system probe bus and landing apparatus (model) - Udvar-Hazy Center, Dulles International Airport, Chantilly, Virginia, USA. Credit: historicspacecraft.com
Model of the Vega 1 probe and landing apparatus at the Udvar-Hazy Center, Dulles International Airport, Chantilly, Virginia. Credit: historicspacecraft.com

These probes both remained operational for 46 hours and discovered just how turbulent and powerful Venus’ atmosphere was. In contrast, the DAVINCI probe’s mission will be to study both the atmosphere and surface of Venus, and hopefully shed some light on some of the planet’s newfound mysteries. According to the NASA release:

“DAVINCI would study the chemical composition of Venus’ atmosphere during a 63-minute descent. It would answer scientific questions that have been considered high priorities for many years, such as whether there are volcanoes active today on the surface of Venus and how the surface interacts with the atmosphere of the planet.”

These studies will attempt to build upon the data obtained by the Venus Express spacecraft, which in 2008/2009 noted the presence of several infrared hot spots in the Ganis Chasma region near the the shield volcano of Maat Mons (shown below). Believed to be due to volcanic eruptions, this activity was thought to be responsible for significant changes that were noted in the sulfur dioxide (SO²) content in the atmosphere at the time.

What’s more, the Pioneer Venus spacecraft – which studied the planet’s atmosphere from 1978 until its orbit decayed in 1992 – noted a tenfold decreased in the density of SO² at the cloud tops, which was interpreted as a decline following an episode of volcanogenic upwelling from the lower atmosphere.

3-D perspective of the Venusian volcano, Maat Mons generated from radar data from NASA’s Magellan mission.
3-D perspective of the Venusian volcano, Maat Mons, generated from radar data from NASA’s Magellan mission. Credit: NASA/JPL

Commonly associated with volcanic activity here on Earth, SO² is a million times more abundant in Venus’ atmosphere, where it helps to power the runaway greenhouse effect that makes the planet so inhospitable. However, any SO² released into Venus’ atmosphere is also short-lived, being broken down by sunlight within a matter of days.

Hence, any significant changes in SO² levels in the upper atmosphere must have been a recent addition, and some scientists believe that the spike observed in 2008/2009 was due to a large volcano (or several) erupting. Determining whether or not this is the case, and whether or not volcanic activity plays an active role in the composition of Venus’s thick atmosphere, will be central to DAVINCI’s mission.

Along with four other mission concepts, DAVINCI was selected as a semifinalist for the NASA Discovery Program‘s latest calls for proposed missions. Every few years, the Discovery Program – a low-cost planetary missions program that is managed by the JPL’s Planetary Science Division – puts out a call for missions with an established budget of around $500 million (not counting the cost of launch or operation).

The latest call for submissions took place in February 2014, as part of the Discovery Mission 13. At the time, a total of 27 teams threw their hats into the ring to become part of the next round of space exploration missions. Last Wednesday, September 30th, 2015, five semifinalists were announced, one (or possibly two) of which will be chosen as the winner(s) by September 2016.

Artist rendition of NASA’s Mars InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) Lander. InSight is based on the proven Phoenix Mars spacecraft and lander design with state-of-the-art avionics from the Mars Reconnaissance Orbiter (MRO) and Gravity Recovery and Interior Laboratory (GRAIL) missions. Credit: JPL/NASA
Artist rendition of NASA’s Mars InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) Lander, which was selected as part of the Discovery Programs 2010 call for submissions and will be launched by 2016. Credit: JPL/NASA

These finalists will receive $3 million in federal grants for detailed concept studies, and the mission (or missions) that are ultimately chosen will be launched by December 31st, 2021. The Discovery Program began back in 1992, and launched its first mission- the Mars Pathfinder – in 1996. Other Discovery missions include the NEAR Shoemaker probe that first orbited an asteroid, and the Stardust-NExT project, which returned samples of comet and interstellar dust to Earth.

NASA’s MESSENGER spacecraft, the planet-hunting Kepler telescope, and the Dawn spacecraft were also developed and launched under the Discovery program. The winning proposal of the Discovery Program’s 12th mission, which was issued back in 2010, was the InSight Mars lander. Set to launch in March of 2016, the lander will touch down on the red planet, deploy instruments to the planet’s interior, and measure its seismic activity.

NASA hopes to infuse the next mission with new technologies, offering up government-furnished equipment with incentives to sweeten the deal for  each proposal. These include a supply of deep space optical communications system that are intended to test new high-speed data links with Earth. Science teams that choose to incorporate the laser telecom unit will be entitled to an extra $30 million above their $450 million cost cap.

If science teams wish to send entry probes into the atmospheres of Venus or Saturn, they will need a new type of heat shield. Hence, NASA’s solicitation includes a provision to furnish a newly-developed 3D-woven heat shield with a $10 million incentive. A deep space atomic clock is also available with a $5 million bonus, and NASA has offered to provide xenon ion thrusters and radioisotope heater units without incentives.

As with previous Discovery missions, NASA has stipulated that the mission must use solar power, limiting mission possibilities beyond Jupiter and Saturn. Other technologies may include the NEXT ion thruster and/or re-entry technology.

Interesting Facts About Venus

Venus was once considered a twin to Earth, as it’s roughly the same size and is relatively close to our planet. But once astronomers looked at it seriously in the past half-century or so, a lot of contrasts emerged. The biggest one — Venus is actually a hothouse planet with a runaway greenhouse effect, making it inhospitable to life as we know it. Here are some more interesting facts about Venus.

1. Venus’ atmosphere killed spacecraft dead very quickly:
You sure don’t want to hang around on Venus’ surface. The pressure there is so great that spacecraft need shielding to survive. The atmosphere is made up of carbon dioxide with bits of sulfuric acid, NASA says, which is deadly to humans. And if that’s not bad enough, the temperature at the surface is higher than 470 degrees Celsius (880 degrees Fahrenheit). The Soviet Venera probes that ventured to the surface decades ago didn’t last more than two hours.

2. But conditions are more temperate higher in the atmosphere:
While you still couldn’t breathe the atmosphere high above Venus’ surface, at about  50 kilometers (31 miles) you’ll at least find the same pressure and atmosphere density as that of Earth. A very preliminary NASA study suggests that at some point, we could deploy airships for humans to explore Venus. And the backers suggest it may be more efficient to go to Venus than to Mars, with one large reason being that Venus is closer to Earth.

Artist's conception of the High Altitude Venus Operational Concept (HAVOC) mission, a far-out concept being developed by NASA, approaching the planet. Credit: NASA Langley Research Center/YouTube (screenshot)
Artist’s conception of the High Altitude Venus Operational Concept (HAVOC) mission, a far-out concept being developed by NASA, approaching the planet. Credit: NASA Langley Research Center/YouTube (screenshot)

3. Venus is so bright it is sometimes mistaken for a UFO:
The planet is completely socked in by cloud, which makes it extremely reflective to observers looking at the sky on Earth. Its brightness is between -3.8 and -4.8 magnitude, which makes it brighter than the stars in the sky. In fact, it’s so bright that you can see it go through phases in a telescope — and it can cast shadows! So that remarkable appearance can confuse people not familiar with Venus in the sky, leading to reports of airplanes or UFOs.

4. And those clouds mean you can’t see the surface:
If you were to look at Venus with your eyes, you wouldn’t be able to see its surface. That’s because the clouds are so thick that they obscure what is below. NASA got around that problem when it sent the Magellan probe to Venus for exploration in the 1990s. The probe orbited the planet and got a complete surface picture using radar.

Artist's impression of the surface of Venus Credit: ESA/AOES
Artist’s impression of the surface of Venus Credit: ESA/AOES

5. Venus has volcanoes and a fresh face:
Venus has fresh lava flows on its surface, which implies that volcanoes erupted anywhere from the past few hundred years to the past three million years. What this means is there are few impact craters on the surface, likely because the lava flowed over them and filled them in. While scientists believe the volcanoes are responsible, the larger question is how frequently this occurs.

6. Venus has a bizarre rotation:
Venus not only rotates backwards compared to the other planets, but it rotates very slowly. In fact, a day on Venus (243 days) lasts longer than it takes the planet to orbit around the Sun (225 days). Even more strangely, the rotation appears to be slowing down; Venus is turning 6.5 minutes more slowly in 2014 than in the early 1990s. One theory for the change could be the planet’s weather; its thick atmosphere may grind against the surface and slow down the rotation.

Artist's conception of Venus Express doing an aerobraking maneuver in the atmosphere in 2014. Credit: ESA–C. Carreau
Artist’s conception of Venus Express doing an aerobraking maneuver in the atmosphere in 2014. Credit: ESA–C. Carreau

7. Venus has no moons or rings:
The two planets closest to the Sun have no rings or moons, which puts Venus in the company of only one other world: Mercury. Every other planet in the Solar System has one or the other, or in many cases both! Why this is is a mystery to scientists, but they are doing as much comparison of different planets as possible to understand what’s going on.

8. Venus appears to be a spot where spacecraft go to extremes:
We briefly mentioned the Venera probes that landed on the surface, but that’s not the only unusual spacecraft activity at Venus. In 2014, the European Space Agency put an orbiter — that’s right, a spacecraft not designed to survive the atmosphere — into the upper parts of Venus’ dense atmosphere. Venus Express did indeed survive the encounter (before it ran out of gas), with the goal of providing more information about how the atmosphere looks at high altitudes. This could help with landings in the future.

As you can see, Venus is an interesting, mysterious, and extremely hostile world. With such a corrosive atmosphere, such incredible heat, a volcanically-scarred surface, and thick clouds of toxic gas, one would have to be crazy to want to live there. And yet, there are some who believe Venus could be terraformed for human use, or at the very least explored using airships, in the coming generations.

But that’s the thing about interesting places. Initially, they draw their fair share of research and attention. But eventually, the dreamers and adventurers come.

A Swirling Vortex at Venus’ South Pole

Here’s the latest view of the mass of swirling gas and clouds at Venus’ south pole. The Venus Express’s Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) has been keeping an eye on this polar vortex since the spacecraft arrived and discovered this huge storm in 2006. During the mission, VIRTIS has seen the vortex constantly transform, morphing from a double vortex into a squashed shape and into the eye-like structure seen here.

This image was taken in April 2007 but was just released this week.

Venus has a very choppy and fast-moving atmosphere, even though wind speeds are much slower at the planet’s surface. At the cloud tops about 70 km above the surface, winds can reach 400 km/h. At this altitude, Venus’ atmosphere spins about 60 times faster than the planet itself. Compared to Earth, this is a dizzying speed: even Earth’s fastest winds move at most about 30% of our planet’s rotation speed.

These polar vortices form when heated air from equatorial latitudes rises and spirals towards the poles, carried by the fast winds. As the air converges on the pole and then sinks.

High velocity winds spin westwards around the planet, and take just four days to complete a rotation. This ‘super-rotation’, combined with the natural recycling of hot air in the atmosphere, would induce the formation of a vortex structure over each pole.

A video of the vortex, made from 10 images taken over a period of five hours, can be seen here. The vortex rotates with a period of around 44 hours.

Source: ESA

Japan’s Akatsuki Spacecraft to Make Second Attempt to Enter Orbit of Venus in December 2015

Back in 2010, the Japanese Aerospace Exploration Agency (JAXA) launched the The Venus Climate Orbiter “Akatsuki” with the intention of learning more about the planet’s weather and surface conditions. Unfortunately, due to engine trouble, the probe failed to make it into the planet’s orbit.

Since that time, it has remained in a heliocentric orbit, some 134 million kilometers from Venus, conducting scientific studies on the solar wind. However, JAXA is going to make one more attempt to slip the probe into Venus’ orbit before its fuel runs out.

Since 2010, JAXA has been working to keep Akatsuki functioning so that they could give the spacecraft another try at entering Venus’ orbit.

After a thorough examination of all the possibilities for the failure, JAXA determined that the probe’s main engine burned out as it attempted to decelerate on approach to the planet. They claim this was likely due to a malfunctioning valve in the spacecraft’s fuel pressure system caused by salt deposits jamming the valve between the helium pressurization tank and the fuel tank. This resulted in high temperatures that damaged the engine’s combustion chamber throat and nozzle.

A radar view of Venus taken by the Magellan spacecraft, with some gaps filled in by the Pioneer Venus orbiter. Credit: NASA/JPL
A radar view of Venus taken by the Magellan spacecraft, with some gaps filled in by the Pioneer Venus orbiter. Credit: NASA/JPL

JAXA adjusted the spacecraft’s orbit so that it would establish a heliocentric orbit, with the hopes that it would be able to swing by Venus again in the future. Initially, the plan was to make another orbit insertion attempt by the end 2016 when the spacecraft’s orbit would bring it back to Venus. But because the spacecraft’s speed has slowed more than expected, JAXA determined if they slowly decelerated Akatsuki even more, Venus would “catch up with it” even sooner. A quicker return to Venus would also be advantageous in terms of the lifespan of the spacecraft and its equipment.

But this second chance will likely be the final chance, depending on how much damage there is to the engines and other systems. The reasons for making this final attempt are quite obvious. In addition to providing vital information on Venus’ meteorological phenomena and surface conditions, the successful orbital insertion of Akatsuki would also be the first time that Japan deployed a satellite around a planet other than Earth.

If all goes well, Akatsuki will enter orbit around Venus at a distance of roughly 300,000 to 400,000 km from the surface, using the probe’s 12 smaller engines since the main engine remains non-functional. The original mission called for the probe to establish an elliptical orbit that would place it 300 to 80,000 km away from Venus’ surface.

This wide variation in distance was intended to provide the chance to study the planet’s meteorological phenomena and its surface in detail, while still being able to observe atmospheric particles escaping into space.

Artist's impression of Venus Express entering orbit in 2006. Credit: ESA - AOES Medialab
Artist’s impression of Venus Express entering orbit in 2006. Image Credit: ESA – AOES Medialab

At a distance of 400,000 km, the image quality and opportunities to capture them are expected to be diminished. However, JAXA is still confident that it will be able to accomplish most of the mission’s scientific goals.

In its original form, these goals included obtaining meteorological information on Venus using four cameras that capture images in the ultraviolet and infrared wavelengths. These would be responsible for globally mapping clouds and peering beneath the veil of the planet’s thick atmosphere.

Lightning would be detected with a high-speed imager, and radio-science monitors would observe the vertical structure of the atmosphere. In so doing, JAXA hopes to confirm the existence of surface volcanoes and lighting, both of which were first detected by the ESA’s Venus Express spacecraft. One of the original aims of Akatsuki was to complement the Venus Express mission. But Venus Express has now completed its mission, running out of gas and plunging into the planet’s atmosphere.

But most of all, it is hoped that Akatsuki can provide observational data on the greatest mystery of Venus, which has to do with its surface storms.

Artists impression of lightning storms on Venus. Credit: ESA
Artists impression of lightning storms on Venus. Credit: ESA

Previous observations of the planet have shown that winds that can reach up to 100 m/s (360 km/h or ~225 mph) circle the planet every four to five Earth days. This means that Venus experiences winds that are up to 60 times faster than the speed at which the planet turns, a phenomena known as “Super-rotation”.

Here on Earth, the fastest winds are only capable of reaching between 10 and 20 percent of the planet’s rotation. As such, our current meteorological understanding does not account for these super-high speed winds, and it is hoped that more information on the atmosphere will provide some clues as to how this can happen.

Between the extremely thick clouds, sulfuric rain storms, lightning, and high-speed winds, Venus’ atmosphere is certainly very interesting! Add to the fact that the volcanic, pockmarked surface cannot be surveyed without the help of sophisticated radar or IR imaging, and you begin to understand why JAXA is eager to get their probe into orbit while they still can.

And be sure to check out this video, courtesy of JAXA, detailing the Venus Climate Orbiter mission:

Further Reading: JAXA

Universe Today’s Top 10 Space Stories of 2014

It seems a lot of the space stories of this year involve spacecraft making journeys: bouncing across a comet, or making their way to Mars. Private companies also figure prominently, both in terms of successes and prominent failures.

These are Universe Today’s picks for the top space stories of the year. Disagree? Think we forgot something? Let us know in the comments.

10. End of Venus Express

Artist's impression of Venus Express performing aerobreaking maneuvers in the planet's atmosphere in June and July 2014. Credit: ESA–C. Carreau
Artist’s impression of Venus Express performing aerobreaking maneuvers in the planet’s atmosphere in June and July 2014. Credit: ESA–C. Carreau

This month saw the end of Venus Express’ eight-year mission at the planet, which happened after the spacecraft made a daring plunge into part of the atmosphere to learn more about its properties. The spacecraft survived the aerobraking maneuvers, but ran out of fuel after a few engine burns to raise it higher. Soon it will plunge into the atmosphere for good. But it was a productive mission overall, with discoveries ranging from a slowing rotation to mysterious “glories”.

9. Continued discoveries by Curiosity and Opportunity

1 Martian Year on Mars!  Curiosity treks to Mount Sharp in this photo mosaic view captured on Sol 669, June 24, 2014.    Navcam camera raw images stitched and colorized.   Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer – kenkremer.com
1 Martian Year on Mars! Curiosity treks to Mount Sharp in this photo mosaic view captured on Sol 669, June 24, 2014. Navcam camera raw images stitched and colorized. Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer – kenkremer.com

Methane? Organics? Water? Mars appears to have had these substances in abundance over its history. Continued work from the Curiosity rover — passing its second Earth year on Mars — found methane fluctuating in Gale Crater, and the first confirmed discovery of organics on the Martian surface. Opportunity is almost 11 years into its mission and battling memory problems, but the rover is still on the move (passing 41 kilometers) to an area that could be full of clay.

8. Siding Spring at Mars and the level of study of the comet by other missions at Mars

Comet Siding Spring near Mars in a composite image by the Hubble Space Telescope, capturing their positions between Oct. 18 8:06 a.m. EDT (12:06 p.m. UTC) and Oct. 19 11:17 p.m. EDT (Oct. 20, 3:17 a.m. UTC). Credit: NASA, ESA, PSI, JHU/APL, STScI/AURA
Comet Siding Spring near Mars in a composite image by the Hubble Space Telescope, capturing their positions between Oct. 18 8:06 a.m. EDT (12:06 p.m. UTC) and Oct. 19 11:17 p.m. EDT (Oct. 20, 3:17 a.m. UTC). Credit: NASA, ESA, PSI, JHU/APL, STScI/AURA

We had a rare opportunity to watch a comet make a grazing pass by Mars, not close enough to pose significant danger to spacecraft, but definitely close enough to affect its atmosphere! Siding Spring caught everyone’s attention throughout the year, and did not disappoint. The numerous spacecraft at the Red Planet caught glimpses, including from the surface and from orbit. It likely created a meteor shower and could alter the Martian atmosphere forever.

7. Kepler K2

Illustration of the Kepler spacecraft (NASA/Kepler mission/Wendy Stenzel)
Illustration of the Kepler spacecraft (NASA/Kepler mission/Wendy Stenzel)

The Kepler space telescope lost the second of its four pointing devices last year, requiring a major rethink for the veteran planet hunter. The solution was a new mission called K2 that uses the pressure of the Sun to maintain the spacecraft’s direction, although it has to flip every 83 days or so to a new location to avoid the star’s glare. It’s not as precise as before, but with the mission approved we now know for sure K2 can locate exoplanets. The first confirmed one is a super-Earth.

6. MAVEN at Mars

An artist's conception of MAVEN orbiting Mars. Image Credit: NASA / Goddard Space Flight Center
An artist’s conception of MAVEN orbiting Mars. Image Credit: NASA / Goddard Space Flight Center

Where did the Martian atmosphere go? Why was it so thick in the past, allowing water to flow on the surface, and so thin right now? The prevailing theory is that the Sun’s pressure on the Martian atmosphere pushed lighter isotopes (such as that of hydrogen) away from the planet, leaving heavier isotopes behind. NASA is now investigating this in more detail with MAVEN (Mars Atmosphere and Volatile Evolution), which arrived at the planet this fall.

5. India’s MOM

Artist's impression of India’s Mars Orbiter Mission (MOM). Credit ISRO
Artist’s impression of India’s Mars Orbiter Mission (MOM). Credit ISRO

India made history this year as only the third entity to successfully reach the Red Planet (after the United States and Europe). While updates from the Mars Orbiter Mission have been slow in recent weeks, we know for sure that it observed Siding Spring at Mars and it has been diligently taking pictures of the Red Planet, such as this one of the Solar System’s largest volcano and a huge canyon on Mars.

4. Accidents by Virgin and Orbital

NTSB investigators are seen making their initial inspection of debris from the Virgin Galactic SpaceShipTwo. The debris field stresses over a fiver mile range in the Mojave desert. (Credit: Getty Images)
NTSB investigators are seen making their initial inspection of debris from the Virgin Galactic SpaceShipTwo. The debris field stresses over a fiver mile range in the Mojave desert. (Credit: Getty Images)

In one sobering week in October, the dangers of space travel were again made clear after incidents affected Virgin Galactic and Orbital Sciences. Virgin lost a pilot and seriously injured another when something went seriously awry during a flight test. Investigators have so far determined that the re-entry system turned on prematurely, but more details are being determined. Orbital meanwhile suffered the catastrophic loss of one of its Antares rockets, perhaps due to Soviet-era-designed engines, but the company is looking at other ways to fulfill its NASA contractual obligations to send cargo to the International Space Station.

3. SpaceX rocket landing attempts

The Falcon 9 rocket with landing legs in SpaceX’s hangar at Cape Canaveral, Fl, preparing to launch Dragon to the space station this Sunday March 30.  Credit: SpaceX
The Falcon 9 rocket with landing legs in SpaceX’s hangar at Cape Canaveral, Fl, preparing to launch Dragon to the space station this Sunday March 30. Credit: SpaceX

SpaceX is attempting a daunting technological feat, which is bringing back its rocket first stages for re-use. The company is hoping that this will cut down on the costs of launch in the long term, but this technological innovation will take some time. The Falcon 9 rocket stage that made it back to the ocean in July was deemed a success, although the force of the landing broke it apart. Next, SpaceX is trying to place its rocket on an ocean platform.

2. Orion flight

Orion Service Module fairing separation. Credit: NASA TV
Orion Service Module fairing separation. Credit: NASA TV

NASA’s spacecraft for deep space exploration (Orion) successfully finished its first major uncrewed test this month, when it rode into orbit, made a high-speed re-entry and successfully splashed down in the ocean. But it’s going to be a while before Orion flies again, likely in 2017 or even 2018. NASA hopes to put a crew on this spacecraft type in the 2020s, potentially for trips to the Moon, an asteroid or (more distantly) Mars.

1. Rosetta

New Rosetta mission findings do not exclude comets as a source of water in and on the Earth's crust but does indicate comets were a minor contribution. A four-image mosaic comprises images taken by Rosetta’s navigation camera on 7 December from a distance of 19.7 km from the centre of Comet 67P/Churyumov-Gerasimenko. (Credit: ESA/Rosetta/Navcam Imager)
New Rosetta mission findings do not exclude comets as a source of water in and on the Earth’s crust but does indicate comets were a minor contribution. A four-image mosaic comprises images taken by Rosetta’s navigation camera on 7 December from a distance of 19.7 km from the centre of Comet 67P/Churyumov-Gerasimenko. (Credit: ESA/Rosetta/Navcam Imager)

It’s been an exciting year for the Rosetta mission. First it woke up from a lengthy hibernation, then it discovered that Comet 67P/Churyumov-Gerasimenko looks a bit like a rubber duckie, and then it got up close and released the Philae lander. The soft touchdown did not go as planned, to say the least, as the spacecraft bounced for two hours and then came to rest in a spot without a lot of sunlight. While Philae hibernates and controllers hope it wakes up again in a few months, however, science results are already showing intriguing things. For example, water delivered to Earth likely came mostly from other sources than comets.

Morning Star, We Hardly Knew Ya: Venus Express’ Best Discoveries In 8 Years

Venus Express is mostly dead. The spacecraft spent more than eight years faithfully relaying information from the Morning Star/Evening Star planet, but it’s now out of fuel, out of control and within weeks of burning up in the atmosphere.

While we mourn the end of the productive mission, the European Space Agency spacecraft showed us a lot about the planet that we once considered a twin to Earth. Some of the surprises, as you can see below, including a possibly slowing-down rotation, and the realization that volcanoes may still be active on the hellish 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.
False color 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.

Quick video summary: Venus Express found that the spacecraft’s rotation may have slowed down by 6.5 minutes between 1996 (when the Magellan spacecraft was in orbit) and 2012. The surprising information emerged when scientists discovered surface features weren’t in the expected areas, and couldn’t find any calculation errors between the data.

Animation of Venus’ southern polar vortex made from VIRTIS thermal infrared images; white is cooler clouds at higher altitudes. Credit: ESA/VIRTIS-VenusX/INAF-IASF/LESIA-Obs. de Paris (G. Piccioni, INAF-IASF)

Quick video summary: Volcanic flows may still be active on Venus’ surface, according to 2010 data from the mission. Scientists looked at surface areas that had not been “weathered” very much (indicating that they are relatively young) and detected at least nine spots where the heat in those zones is much higher than the areas around it.

Venus Express picture of clouds on the planet. Despite the planet being extremely hot, the spacecraft found a cold layer in the atmosphere at temperatures of about -175 degrees Celsius (-283 Fahrenheit) that is colder than anything on Earth. It's so chilling that carbon dioxide may freeze and fall as snow or ice. Credit: ESA/MPS/DLR/IDA
A picture of Venus’ clouds. Despite the planet being extremely hot, Venus Express found a cold layer in the atmosphere at temperatures of about -175 degrees Celsius (-283 Fahrenheit) that is colder than anything on Earth. It’s so chilling that carbon dioxide may freeze and fall as snow or ice. Credit: ESA/MPS/DLR/IDA
Artist's impression of Venus with the solar wind flowing around the planet, which has little magnetic protection. Venus Express found that a lot of water has bled into space over the years from the planet, which happens when the sun's ultraviolet radiation breaks oxygen and hydrogen molecules apart and pushes them into space. Credit: ESA - C. Carreau
Artist’s impression of Venus with the solar wind flowing around the planet, which has little magnetic protection. Venus Express found that a lot of water has bled into space over the years from the planet, which happens when the sun’s ultraviolet radiation breaks oxygen and hydrogen molecules apart and pushes them into space. Credit: ESA – C. Carreau

Venus Express Out Of Gas; Mission Concludes, Spacecraft On Death Watch

After surviving an eight-year mission and a daring plunge into part of the atmosphere of Venus, a plucky spacecraft orbiting the hothouse planet is finished its mission, the European Space Agency declared. Venus Express can no longer communicate consistently with Earth. The spacecraft itself will fall into the atmosphere and likely be destroyed in the coming weeks.

“The available information provides evidence of the spacecraft losing attitude control,” stated Patrick Martin, ESA’s Venus Express mission manager, who added it was because the machine exhausted its fuel as controllers tried to raise it to a more stable altitude above Venus.

The demise of the mission, in a sense, began when controllers chose to bring Venus Express into the atmosphere this summer. The goal was not only to learn more about Venus, but also to get information on how future spacecraft could “surf” the atmosphere when, say, landing on the planet.

Artist's conception of Venus Express doing an aerobraking maneuver in the atmosphere in 2014. Credit: ESA–C. Carreau
Artist’s conception of Venus Express doing an aerobraking maneuver in the atmosphere in 2014. Credit: ESA–C. Carreau

The orbit was reduced to about 130 km to 135 km (80.7 miles to 83.9 miles) above the planet at its lowest approach, which took place in earnest between June 18 and July 11. Controllers then did 15 small thruster burns, which raised the spacecraft’s minimum altitude to 460 km (286 miles).

But it wasn’t a stable orbit, with the spacecraft continuing to spiral into the planet as gravity pulled it down. ESA decided to again try raising the spacecraft’s altitude between Nov. 23 and Nov. 30, but lost consistent contact with the spacecraft Nov. 28. It appears Venus Express is out of gas, the agency said.

It’s hard to know exactly when the spacecraft will die, but it serves as a good example of how space recycling can end up making an interesting mission. The design and some of the instruments on Venus Express were based upon those used for other missions, particularly Mars Express and Rosetta. And the lessons of the spacecraft will certainly be used in future missions.

Tomorrow, we’ll run down some of the highlights of the mission.

Source: European Space Agency