Could there be life in the clouds of Venus?

[note: this post is an excerpt from a literature review paper on Venusian Astrobiology that I wrote last year.]

3. Extant Life in the Clouds

Data returned by Mariner II in 1962 drastically changed the picture of conditions on Venus, causing most to lose interest in it as a harbor for life.  Nevertheless, within just a few years scientists were speculating that life might still survive on Venus in the clouds.  Harold Morowitz and Carl Sagan (1967) published a brief article in Nature containing a great deal of speculation about the nature of a life form they imagined could survive in such an environment: an organism constructed as a float bladder filled with molecular hydrogen for buoyancy.  This macroorganism would collect water from rain or by contact with droplets in the clouds, acquire nutrients from minerals picked up from the surface by the powerful winds, and produce its own lifting gas as a by-product of photosynthesis.  Given what they knew at the time, they claimed such life in the Venus clouds “can be envisaged which operates entirely on known terrestrial principles.”

    More realistic hypotheses involving cloud-borne microorganisms have followed that are compatible with our current knowledge of the Venusian atmosphere.  These hypotheses should be taken seriously in light of bacteria found actively growing and reproducing—at temperatures below 0° C—in cloud droplets collected at high altitude on Earth (Sattler et al. 2001).

3.1  Conditions in the Clouds

Venus may be a terribly inhospitable place on or near its surface, but the conditions at altitudes between 50 and 60 km are remarkably Earth-like.  The pressure is close to 1 bar, the temperature is in a range where water is liquid (0-100° C), there is abundant solar energy, and the atmosphere contains the primary materials required for life: carbon, oxygen, nitrogen, and hydrogen (Landis 2003).  Also present: sulfur, phosphorus, chlorine, fluorine, and iron (Grinspoon and Bullock 2007).

3.1.1  Attributes that Favor Life

In addition to the general conditions above, the following attributes are favorable for supporting life in the clouds:

• Aqueous environment:  It is certainly not abundant, but water vapor concentrations approach a few hundred parts per million in the cloud layers (Ingersoll 2007)
• Continuous clouds: the clouds on Venus are much larger, more continuous, and more stable than those of Earth, which provides an ongoing habitat for microorganisms (Schulze-Makuch et al. 2004).
• Superrotation: The clouds of Venus make a complete rotation about the planet once every 4-6 days (van den Berg et al. 2006), providing a day-night cycle for life in the clouds that is much shorter than the 117-day cycle experienced at the planet’s surface (Ingersoll 2007).  This enhances the potential for photosynthetic reactions by reducing the duration of “night” (Grinspoon and Bullock 2007).
• Atmosphere in disequilibrium: O₂, H₂, H₂S, and SO₂ coexist, providing the basis for energy-yielding redox reactions that could be harvested by microbial life  (Schulze-Makuch and Irwin 2002)

3.1.2  Challenges for cloud-hosted life

Ultraviolet (UV) radiation from the Sun presents a challenge for life in the clouds of Venus.  UV is damaging to biological macromolecules, and any surviving organisms must adapt to it in some fashion.  Using Earth-based organisms for reference, several examples are available: there are organisms that use pigments such carotenoids and scytonemin for protection, others grow beneath the safety of soil or water, and some make a shield from organic compounds derived from dead cells.  A more elaborate example are microbes such as cyanobacteria that possess internal mechanisms for repairing DNA and resynthesize UV-sensitive proteins (Schulze-Makuch et al. 2004).  Charles Cockell (1999) points out that the UV flux in the upper clouds of Venus is comparable to the surface flux on the Archean Earth, the time when life is believed to have appeared.

The acidity of the clouds of Venus (pH=0) has been raised as a possible obstacle to life (Cockell 1999).  Nevertheless, acidophile organisms have been found on Earth, such as Ferroplasma acidarmanus which thrives at pH 0 (Schulze-Makuch et al. 2004),  Picrophilus oshimae, which showed optimal growth at pH 0.7, but still grew at pH 0 (Schleper et al. 1995), and the green alga Dunaliella acidophila which can survive at Ph 0, but prefers pH 1 for maximum growth (Grinspoon and Bullock 2007).

3.2        Speculations on potential life forms

Venus researchers have proposed feasible forms that life might take to survive in the clouds.  Wickramasinghe and Wickramasinghe (2008) suggest that hydrogenogens, a group of terrestrial bacteria and archaea that can grow anaerobically using CO as their sole carbon source, are good analogs for cloud-borne organisms on Venus.  They note that the lightning present on Venus (mentioned in section 2.3) could generate large amounts of CO from the predominantly CO₂ atmosphere.  They imagine a scenario occurring within the three cloud layers of Venus where “(a) bacteria nucleate droplets containing water and nutrients, (b) colonies grow within the droplets, (c) droplets fall into regions of higher temperature where they evaporate releasing spores to convect upwards to yield further nucleation.”

Dirk Schulze-Makuch, David Grinspoon, and colleagues (2004) propose that microbial life forms, in response to the high doses of ultraviolet radiation received in the upper atmosphere, could shroud themselves in elemental sulfur, possibly a layer of cycloocta-sulfer (S₈).  It is a strong UV absorber, and Venusian organisms could produce elemental sulfur via a simple photochemical reaction combining H₂S and CO, just as some organisms on Earth do.

In another paper co-authored by Schulze-Makuch and Louis Irwin (2006), they proposed phototrophic organisms in the Venusian atmosphere that could employ a photosystem based on the oxidation of sulfur, as many terrestrial organisms thriving in warm seas and hot springs do.

3.3        Possible evidence for life in the clouds

Is there any current evidence that could suggest the existence of cloud-borne organisms on Venus?  There is more than one might think.  Of particular interest are the larger droplets or particles (referred to as “mode 3” particles) found only in the lowest of Venus’ three cloud layers (Grinspoon and Bullock 2007).  They are non-spherical (indicative of a solid core), and comparable in size to Earth bacteria.  Their composition is currently unknown, but they could represent even small bacteria colonies.

The dark regions plainly visible on UV images of Venus are caused by an unknown UV absorber.  The Venus Monitoring Camera aboard the Venus Express spacecraft took wide-angle images at the characteristic wavelength of the UV absorber, and determined that the brightness variation is the result of compositional differences, not elevation differences (Titov et al. 2008).  Elemental sulfur in the form S8 is a strong UV absorber, and could be the cause of the dark regions.  It has been proposed that the potential S8 in the Venusian clouds could be a byproduct of microbiological processes (Schulze-Makuch and Irwin 2006).

Compounds positively identified in the Venusian atmosphere could also indicate the presence of organisms.  The presence of oxygenated gases such as O2 and SO2, observed at the same time with reduced gases such as H2S and H2, indicates the atmosphere is in a state of disequilibrium.  Some active process is working to maintain this situation, and it may be biological (Landis 2003).  The second-most common sulfur gas in the Venusian atmosphere,  Carbonyl sulfide (COS), is considered a possible indicator for life since its sources on Earth are almost entirely biological (Landis 2003; Schulze-Makuch and Irwin 2002).

References:

Cockell, C. S. (1999). Life on venus. Planetary and Space Science, 47(12), 1487-1501. 

Grinspoon, D. H., & Bullock, M. A. (2007). Astrobiology and venus exploration. Exploring Venus as a Terrestrial Planet, (176), 191. 

Ingersoll, A. P. (2007). Venus: Express dispatches. Nature, 450(7170), 617-618. 

Landis, G. A. (2003). Astrobiology-the case for venus. Journal of the British Interplanetary Society, 56, 250-254. 

Morowitz, H. (1967). Life in the clouds of venus? Nature, 215, 1259-1260. 

Sattler, B., Puxbaum, H., & Psenner, R. (2001). Bacterial growth in supercooled cloud droplets. Geophysical Research Letters, 28(2), 239-242. 

Schleper, C., Puehler, G., Holz, I., Gambacorta, A., Janekovic, D., Santarius, U., . . . Zillig, W. (1995). Picrophilus gen. nov., fam. nov.: A novel aerobic, heterotrophic, thermoacidophilic genus and family comprising archaea capable of growth around pH 0. Journal of Bacteriology, 177(24), 7050-7059. 

Schulze-Makuch D, Grinspoon DH, Abbas O, Irwin LN, & Bullock MA (2004). A sulfur-based survival strategy for putative phototrophic life in the venusian atmosphere. Astrobiology, 4 (1), 11-8 PMID: 15104900

Schulze-Makuch, D., & Irwin, L. N. (2002). Reassessing the possibility of life on venus: Proposal for an astrobiology mission. Astrobiology, 2(2), 197-202. 

Schulze-Makuch, D., & Irwin, L. N. (2006). The prospect of alien life in exotic forms on other worlds. Naturwissenschaften, 93(4), 155-172. 

Titov, D. V., Taylor, F. W., Svedhem, H., Ignatiev, N. I., Markiewicz, W. J., Piccioni, G., & Drossart, P. (2008). Atmospheric structure and dynamics as the cause of ultraviolet markings in the clouds of venus. Nature, 456(7222), 620-623. 

van den Berg, M., Falkner, P., Atzei, A., Phipps, A., Underwood, J., Lingard, J., . . . Peacock, A. (2006). Venus entry probe technology reference study. Advances in Space Research, 38(11), 2626-2632. 

Wickramasinghe, N., & Wickramasinghe, J. (2008). On the possibility of microbiota transfer from venus to earth. Astrophysics and Space Science, 317(1), 133-137. 

Venus has an Ozone Layer, too

An atmospheric study using the SPICAV-UV instrument recently came to my attention where researchers (Montmessin, et al. 2011) used the data archive to identify (for the first time) a layer of ozone in the upper atmosphere of Venus (previously, ozone had only been identified in the atmospheres of Mars and Earth).

The team analyzed the complete SPICAV dataset, and determined that UV absorption by O₃ was observed during a stellar occultation run on the night side of Venus during orbit #348.  They confirmed ozone detection in 28 additional orbits, and isolated the ozone to a discrete layer no more than 10 km thick near a mean altitude of 100km.

The observed concentrations of 10⁷ – 10⁸ molecules per cubic centimeter are consistent with expected values if the upper atmosphere were dominated by the same chlorine-catalyzed destruction cycles present in Earth’s stratosphere.

Even if the same mechanisms are at work in he Venusian atmosphere, the authors state that the observed ozone layer seems too tenuous to filter out UV radiation and provide protection to organisms that could have existed on Venus.

Referenced:

Montmessin, F., Bertaux, J., Lefèvre, F., Marcq, E., Belyaev, D., Gérard, J., Korablev, O., Fedorova, A., Sarago, V., & Vandaele, A. (2011). A layer of ozone detected in the nightside upper atmosphere of Venus Icarus, 216 (1), 82-85 DOI: 10.1016/j.icarus.2011.08.010

The SPICAV-UV Instrument Aboard Venus Express

Introduction

The European Space Agency’s Venus Express (VEX) is the only active spacecraft mission at the planet Venus.  It carries a number of instruments: A magnetometer, a wide-angle CCD camera, a space plasma detector, a Fourier spectrometer, a thermal spectrometer, a radio science package, and a cluster of spectrometers specifically designed to study the Venusian atmosphere: SPICAV (Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus).  This package contains three spectrometers, one of which operates in the ultraviolet and is the subject of this article.

The Instrument

The UV instrument in SPICAV (described in great detail in Bertaux et al. 2007) is a refurbished flight spare from the Mars Express spacecraft.  Sensitive to wavelengths from 118 to 320 nm, it was designed to measure different aspects of the atmosphere in different modes.  In nadir orientation, SPICAV-UV measures SO2 and the distribution of the mysterious UV absorber in the clouds.  On the night side, it observes the γ and δ bands of NO, and it can measure vertical profiles of CO2, SO2, clouds, and aerosols in stellar occultation mode.

The UV spectrometer collects light with a 40 mm off-axis parabolic mirror that reflects light toward the spectrometer entrance.  There is a configurable slit mechanism in the focal plane that, when left in place, is used for extended source viewing.  The slit can be removed from the focal plane entirely for stellar occultation observations.  A concave UV grating causes the spectrum to fall onto an image intensifier that is blind to wavelengths greater than 320 nm.  The image created on the phosphor output screen of the intensifier is transferred to a 288x384 pixel CCD which can optionally be cooled to 270K using a Peltier cooling unit to reduce dark current.  The focal length of the telescope (120mm) results in each CCD pixel having a FOV of 0.01 x 0.01°.

The slit of the spectrometer is divided into two parts with different widths to allow differing spectral resolutions during observing of an extended source.  The narrow part of the slit is 50 μm wide, giving resolving power between 120 and 300 with lower flux, while the wider part (500 μm) provides more sensitivity at the expense of a lower resolving power of  ≈20.

Public Datasets

SPICAV-UV data (in fact, all ESA data more than six months old) are available to the public as part of the ESA Planetary Science Archive (PSA), and are found at http://www.rssd.esa.int/index.php?project=PSA&page=vex.  NASA’s Planetary Data System (PDS) standard was adopted by the PSA as a baseline for defining the structure and format of datasets. The PSA allows members of the public to browse the entire available archive via an FTP (File Transfer Protocol) interface, and also provides a Java-based Advanced Search Interface tool that lets a user specify dozens of search parameters, select datasets from search results, and it then “delivers” the requested datasets to a special folder on their server and sends the user an email containing a hypertext link to the data.

Figure 1: Quick look analysis of SPICAV-UV data from VEX orbit 520.

Datasets for the SPICAV instrument cluster are stored by spacecraft orbit number.  Each individual dataset comes with human-readable descriptor files that define the format, encoding, and semantic meaning of all data provided.  In addition to the spectral data themselves, the dataset also include all of the contextual data about the conditions under which the observations were made, such as spacecraft altitude and orientation, instrument temperature, the time and date, exposure times, instrument configuration settings, and many more.

A SPICAV-UV dataset file includes one or more Collection objects, each containing a header descriptor and data table.  A data table consists of five rows of 408 columns, which represents five rows of the CCD with each row containing 408 pixels.  Each 16-bit pixel value is a digital representation of the charge collected by that pixel during integration.

The PSA also provides a data browsing area on the FTP server where summary images of each dataset are available for a “quick look” at the data (see Figure 1).

Science with SPICAV

One example of an investigation which used data from SPICAV-UV is a recent study hoping to find evidence of extant volcanic activity.  Six years of ultraviolet spectrometer data were used to examine the density of sulphur dioxide above the clouds of Venus (Marcq et al. 2012).  They found that SO2 column densities increased prior to 2007, and then decreased by a factor of 5 over the next five years.  Read the rest of my summary of this research here.

Another study a year earlier (Montmessin, et al. 2011) used SPICAV-UV data to identify, for the first time, a layer of ozone in the upper atmosphere of Venus (previously, ozone had only been identified in the atmospheres of Mars and Earth).  Read more details here.

References

Bertaux, J., Nevejans, D., Korablev, O., Villard, E., Quémerais, E., Neefs, E., Montmessin, F., Leblanc, F., Dubois, J., Dimarellis, E., Hauchecorne, A., Lefèvre, F., Rannou, P., Chaufray, J., Cabane, M., Cernogora, G., Souchon, G., Semelin, F., Reberac, A., Van Ransbeek, E., Berkenbosch, S., Clairquin, R., Muller, C., Forget, F., Hourdin, F., Talagrand, O., Rodin, A., Fedorova, A., Stepanov, A., Vinogradov, I., Kiselev, A., Kalinnikov, Y., Durry, G., Sandel, B., Stern, A., & Gérard, J. (2007). SPICAV on Venus Express: Three spectrometers to study the global structure and composition of the Venus atmosphere Planetary and Space Science, 55 (12), 1673-1700 DOI: 10.1016/j.pss.2007.01.016

Esposito, L. W. (1984). Sulfur dioxide: Episodic injection shows evidence for active venus volcanism. Science (New York, N.Y.), 223(4640), 1072-1074.

Marcq, E., Bertaux, J. L., Montmessin, F., & Belyaev, D. (2012). Variations of sulphur dioxide at the cloud top of Venus's dynamic atmosphere. Nature geoscience, 6(1), 25-28.

Montmessin, F., Bertaux, J. L., Lefèvre, F., Marcq, E., Belyaev, D., Gérard, J. C., ... & Vandaele, A. C. (2011). A layer of ozone detected in the nightside upper atmosphere of Venus. Icarus, 216(1), 82-85.

VEXAG Update at NASA's Planetary Science Subcommittee meeting

Yesterday and today, NASA's Planetary Science Subcommittee met at NASA Headquarters in Washington D.C. Here is the agenda for the meeting, which was available for remote participants via teleconference.

During today's session, Dr. Lori Glaze (current VEXAG chair) presented the VEXAG report.  She outlined

• Recent activities,
• Results of the annual VEXAG meeting last November,
• VEXAG Endorsements (including my favorite, the use of stratospheric balloon observatories), and
• Plans for updating the Goals, Objectives, and Investigations document by the end of the year.

Here is a link to her presentation.

Scorpion-like Life Discovered on Surface of Venus?

In a recent paper published in Solar System Research (Ksanfomality, 2012), revered senior statesman of Russian planetary science Leonid Ksanfomality reported the detection of possible life forms on Venus.

Using modern image enhancement techniques to re-analyze the panoramic images captured by Veneras 9 and 13 (in 1975 and 1982, respectively), Ksanfomality discovered objects that he observed moving,

"Scorpion" appeared in image V-13-1-6 BW at the
90th minute after landing of Venera 13.  It is absent in
subsequent images.

changing shape, and disappearing from view of the cameras (the most interesting one he labeled as the "Scorpion").  He speculated that these indigenous fauna were disturbed from their hiding places in the soil when the spacecraft touched down, and made their way back to safety.

A number of scientists responded to this report in the same issue, heaping equal doses of skepticism and respect on the senior scientist and his work.  They conclude that the objects identified are abiotic, and that any apparent movement was the result of image processing artifacts and/or changing shadows cast by clouds.

Even though this is a false alarm for current life on Venus, the jury is still out on whether life may still exist below the surface, or in the thick cloud cover.  More to come.  Happy April 1st!


REFERENCES:

Ksanfomality, L. (2012). Venus as a natural laboratory for search of life in high temperature conditions: Events on the planet on March 1, 1982 Solar System Research, 46 (1), 41-53 DOI: 10.1134/S0038094612010042

Attending LPSC 2013

Just a quick note to announce that I am now planning to attend the first three days of the LPSC.  There are several people from my university (UND) attending, and I hope to take in as many oral presentations and posters on Venus as I can.

I've heard that WiFi will not be available and that cell service is spotty, but I'll do my best to blog a bit, and tweet at @VenusDispatches.

If you are not attending but want to be a part of things, some of the big events are being broadcast on Livestream:

• Curiosity Rover Science Team Press Briefing (Monday, 3/18 12:00 noon CDT
• Plenary Session Featuring Masursky Lecture by Dr. Elkins-Tanton (Monday, 1:30pm CDT)
• NASA Headquarters Briefing (Monday, 5:30pm CDT
• GRAIL/LRO Press Briefing (Tuesday, 12:00 noon CDT)

New VEXAG Newsletter Available

The February 2013 Venus Newsletter from the Venus Exploration Analysis Groups is now available at the VEXAG website.  It's only six pages, so don't be intimidated!  Read the VEXAG Newsletter #6.

Venus Game-changing Tech Forum at LPSC

From the PLANETARY EXPLORATION NEWSLETTER Volume 7, Number 6 (February 10, 2013):



VENUS GAME-CHANGING TECHNOLOGY FORUM AT LPSC - MONDAY, MARCH 18TH, 2013

Space technology is a vital tool for both scientists and engineers to reach some of the most extreme environments in our solar system. Exploring Venus with these technologies can answer key questions ranging from the history to the habitability of our universe.

To help us understand these challenges and to identify technologies that may assist you in this quest, we need your help! We would like to tell you about Space Technology and listen to your technology needs through a dialog in a Town Hall meeting format.

First, we plan to provide an overview of Space Technology and the Game-Changing Development Program, including specific examples of Venus exploration technology projects currently under development.

Next, we would like to hear from you! Your identified technology needs play a significant role in our portfolio planning and could enable innovative and exciting future Venus exploration missions.

We are looking forward to seeing y'all at LPSC on Monday March 18, from 12:00 to 13:15 in the Panther Creek Room. 

The forum is hosted by the VEXAG and will be run by Steve Gaddis, Director of the
Game-Changing Development Program, NASA LaRC.

Searching for volcanic eruptions on Venus: Nothing yet

Eugene Shalygin and colleagues report on their ongoing attempts to detect volcanic activity on Venus. The Venus Monitoring Camera (VMC) carried by the Venus Express orbiter is capable of making observations in the near-infrared centered around 1.01 microns, a wavelength at which thermal emissions from the planet's surface can be detected on the night side.  They are making observations in likely locations, specifically the area around the Maat Mons, Sapas Mons, and Ozza Mons volcanoes (Messenger spacecraft SAR data showed recent volcanism here, geologically speaking), with the hope of detecting localized bright spots in the images.

To get an idea of how often Maat Mons might erupt, the team reviewed the eruption history of Mauna Loa on Earth since 1900.  They found that even though it is an active volcano, there are only eruption events on 1.6% of the days during the 100 years they evaluated.  Accounting for the length of observation on Venus, the authors calculated a probability of seeing an eruption during any particular observation at 8.6%.

Ultimately, the series of observations made with the VMC, 12 passes in all, did not reveal any suspicious hot spots that could be interpreted as volcanic events.  This does not preclude the possibility that eruptions occurred during this time, but did so while Venus Express was not looking.

They recommend that they keep looking, of course (I concur).

REFERENCES:

Shalygin, E., Basilevsky, A., Markiewicz, W., Titov, D., Kreslavsky, M., & Roatsch, T. (2012). Search for ongoing volcanic activity on Venus: Case study of Maat Mons, Sapas Mons and Ozza Mons volcanoes Planetary and Space Science, 73 (1), 294-301 DOI: 10.1016/j.pss.2012.08.018


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Water vapor in the Venus troposphere

In a recent paper, Sarah Chamberlain from the University of Lisbon and her colleagues report on their interpretation of ground-based Venus observations from 2004 using new modeling techniques to determine the amount of water vapor present in the lower atmosphere.

Anglo-Australian Telescope

In spite of the dense clouds and haze, near-infrared windows occur on the Venus nightside where the scattered daylight radiation is minimal, allowing thermal radiation emission from the deep lower atmosphere to be detected. Immediately after the inferior conjunction of Venus in June of 2004, ground-based infrared spectroscopy of the nightside troposphere were obtained at Siding Spring Observatory using the IRIS2 spectrograph on the4-meter Anglo-Australian Telescope.

The authors took the data from the 2004 observations and fitted them with spectra simulated using VSTAR (Versatile Software for Transfer of Atmospheric Radiation).  They find a best fit water vapor abundance of 31 parts per million by volume (-6 + 9 ppmv), which is in agreement with recent results by Bézard et al. 2011 using the SPICAV instrument aboard the Venus Express spacecraft.  This is also consistent with the current consensus that water vapor abundance is approximately 30 ppmv below 30km altitude.

So why all the attention to water vapor in the troposphere of Venus? Well,

1. Water vapor is an important chemical reactant in the lower atmosphere as it is the major reservoir of hydrogen, which is hypothesized to buffer or regulate the atmospheric abundances of HCL and HF,

2. Water vapor is important to the formation of the H2SO4  clouds that enshroud the planet, and

3. combining these with the loss of water vapor over long timescales through oxidation reactions with iron minerals at the surface and through photo-disassociation in the upper atmosphere, studies of the abundance distributions and profiles of water vapor in the lower troposphere help to constrain the chemistry and evolution of the near-surface environment.


REFERENCES:

Bézard, B., Fedorova, A., Bertaux, J., Rodin, A., & Korablev, O. (2011). The 1.10- and 1.18-μm nightside windows of Venus observed by SPICAV-IR aboard Venus Express Icarus, 216 (1), 173-183 DOI: 10.1016/j.icarus.2011.08.025

Chamberlain, S., Bailey, J., Crisp, D., & Meadows, V. (2013). Ground-based near-infrared observations of water vapour in the Venus troposphere Icarus, 222 (1), 364-378 DOI: 10.1016/j.icarus.2012.11.014

Venus Upper Atmosphere Workshop on January 24th

UPDATED AGAIN: The agenda has been fleshed out with individual talks and presenters.  Geoffrey Landis is scheduled to discuss the use of UAVs!

UPDATED: Details now available for remote attendees.

Are you a planetary scientist studying the Venusian atmosphere, or an engineer looking to build spacecraft or instrumentation that will further the study of our twin planet?  Then clear your calendar on January 24th, 2013.

NASA's Glenn Research Center, along with the Ohio Aerospace Institute, is sponsoring a Science and Technical Interchange Meeting (STIM) on the topic of Venus Upper Atmosphere Investigations.

The aim of this day-long set of meetings is to encourage the discussion of shared goals and priorities with regard to the study of the atmosphere of Venus by spacecraft.

According to the agenda, they hope to

1. Foster a science discussion on goals, objectives, priorities, and significance of the Venus upper atmosphere and how Venus upper atmosphere science would contribute to overall exploration of Venus,
2. discuss the desired measurements and measurement requirements to achieve potential Venus upper atmosphere science, and 
3. discuss spacecraft concepts and technologies that could reach the Venus UA and collect and return the desired data.

If you cannot attend in person, they may be making arrangements for attending remotely-- I have a question out to one of the organizers and I'll update this post accordingly.

If you are lucky enough to be able to travel to the workshop and can arrive a day early, they are planning a tour of the nearly-completed NASA Glenn Extreme Environments Rig (GEER) on the afternoon of the 23rd. Once completed, the GEER will be able to accurately simulate any planetary environment in the solar system, including both the surface and the atmosphere of Venus. Read more about the GRC's Strategic Science work here.

If you are interested in attending, registration is required.

Venus Express flew over an electrical storm

Christopher Russell has been looking for proof of lightning in the atmosphere of Venus for quite a while (his earliest publication I could find on the subject was in 1979).  Now, Russell and his colleagues report on the strongest evidence yet for Venusian lightning (2012).

In order to remove interference from magnetometer data collected previously by Venus Express, Russell and his team devised a new algorithm that uses the inboard sensor to detect interfering signals and then removes the same signals from the outboard sensor data, resulting in a "cleaned" signal covering the frequency rane from 0 to 64 Hz.

Using the improved data collected during periapsis of the Venus Express spacecraft on April 15th of 2007, the researchers detected magnetic signals that led them to believe the craft had flown over an electrical storm.

Of note are two very different signals the authors believe are associated with electrical activity in the atmosphere of Venus:

1. a waveform that follows the prevailing magnetic field in the ionosphere and occurs at 20 Hz or above in the Extremely Low Frequency (ELF) range, and

2. a second signal that occurs at Ultra-low (ULF) frequencies (and are thus not restricted to moving along the magnetic field) and which propagates upward through the atmosphere.  The likely source is electrical activity beneath the spacecraft.

In addition, the data revealed the presence of whistler waves (which would be expected if lightning were present), and are consistent with previous studies (Russell et al. 2007).

Why is lightning on Venus important?  Knowing it is there can help in comparative studies between Earth and Venus, but more importantly it can help assist in the understanding of the chemical processes at work in the Venusian atmosphere.  The temperatures and pressures present in a lightning discharge provide a significant amount of energy that can drive chemical reactions, such as those that produce nitrous oxide.  Lightning is a proposed energy source for the creation of amino acids on the primordial Earth, the building blocks of life.


REFERENCES

Taylor, W. W. L., Scarf, F. L., Russell, C. T., & Brace, L. H. (1979). Evidence for lightning on venus. Nature, 279, 614-616.

Russell, C., Zhang, T., Delva, M., Magnes, W., Strangeway, R., & Wei, H. (2007). Lightning on venus inferred from whistler-mode waves in the ionosphere. Nature, 450(7170), 661-662.

Russell, C., Leinweber, H., Zhang, T., Daniels, J., Strangeway, R., & Wei, H. (2012). Electromagnetic waves observed on a flight over a Venus electrical storm Geophysical Research Letters DOI: 10.1029/2012GL054308

Variations in sulphur dioxide at the cloud tops of Venus: due to volcanoes? maybe not

A recent article in Nature Geoscience, Variations of sulphur dioxide at the cloud top of Venus's dynamic atmosphere, has caused the science press to get excited about the possibility of active volcanoes on Venus.

Every news headline I saw over the last few weeks that referred to this article wondered aloud if there are active volcanoes.  Even the ESA website poses the news as a question.  So, does Venus have active volcanism?  First, let's talk about the paper and what it reports.

Emmanuel Marcq and colleagues used ultraviolet spectrometer data  collected from 2007 to 2012 using the SPICAV instrument aboard the Venus Express spacecraft to examine the density of sulphur dioxide above the clouds of Venus.  They found that SO2 column densities increased prior to 2007, and then decreased by a factor of 5 over the next five years.

This finding is quite similar to observations made by the Pioneer Venus Orbiter in the 1970s and 1980s, which revealed a ten-fold decrease in  SO2 column density.  At the time, Larry Esposito (1984) of the Laboratory for Atmospheric and Space Physics in Boulder interpreted this decline to have occurred following an episode of volcanogenic upwelling from the lower atmosphere (it is important to note that SO2 is abundant and ubiquitous in the lower atmosphere of Venus).

Marcq, et al. conclude that the SO2 variability observed from the 1970s to the present is the result of long-timescale fluctuations in upward transport from the troposphere to the mesosphere.

What they do not know is whether this is the result of 1) episodic increased buoyancy from volcanic plumes, or 2) intrinsic dynamic variability in the upward component of the global circulation.

Back to our original question: Does Venus possess active volcanoes?  This study cannot answer that question.  The authors seem to want it to be so, but say in their conclusion: "By Occam's razor, we are inclined to think that this variability originates from intrinsic dynamical variability in the ascending sub-solar branch of the global circulation at cloud-top level on a decennial timescale rather than from an external forcing such as extra buoyancy caused by volcanic eruptions, but we cannot dismiss a volcanic forcing through our study alone."

It's pretty clear that most people want active volcanoes on Venus, but the jury is still out, I'm afraid.



REFERENCES:

Esposito, L. W. (1984). Sulfur dioxide: Episodic injection shows evidence for active venus volcanism. Science (New York, N.Y.), 223(4640), 1072-1074. doi: 10.1126/science.223.4640.1072

Marcq, E., Bertaux, J., Montmessin, F., & Belyaev, D. (2012). Variations of sulphur dioxide at the cloud top of Venus’s dynamic atmosphere Nature Geoscience DOI: 10.1038/NGEO1650

VEXAG Young Scholars Focus Group

The Venus Exploration Analysis Group (VEXAG) set up a forum for young Venus scholars where they can meet, interact, and coordinate their efforts.

The VEXAG Young Scholars Focus Group resides on FaceBook, where about twenty college students interested in studying Venus have joined so far.

From the "About" page:

Are you interested in Venus? Then you are in the right place. This is a VEXAG focus group aimed to allow young scientists the opportunity to discuss research related to Venus and increase interest in furthering our understanding of our sister planet.

It's an open group (they even let this old student join!), so don't be shy.  It's a great way to communicate with other people researching Venus.

4th International Venus Workshop - June 10-14, 2013

This summer, Catania, Italy is the location for the 4th International Venus Workshop, being hosted at the Museo Diocesano.  The detailed schedule is still being worked, but it is anticipated that the conference will start at 14:00 on June 10th (Monday) and conclude at 13:00 on Friday of the same week.

The conference invites talks on all aspects of Venus science, and includes a poster gallery.

Planned session topics:

Surface & Interior (Marinangeli, Ghail) Atmospheric Dynamics & Structure (Limaye, Wilson) Atmospheric Chemistry (Marcq, Widemann) Clouds and Hazes (Satoh) Plasma and Magnetosphere (Lundin TBC) Planetary evolution and comparative planetology, incl. exoplanets (Grinspoon) Supporting laboratory activities (Snels) Venus International Reference Atmosphere, VIRA II (Zasova) Future technology and new concepts (Svedhem)

Important dates:

  15-Mar-2013: Registration, abstract submission, and support request deadline

  15-Apr-2013: Accommodation pre-booking deadline


In honor of Venus' volcanic heritage, the organizers have arranged for a half-day excursion to the most active volcano in Europe: Etna.