Tuesday, January 29, 2013

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 H2SO 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.


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


Thursday, January 17, 2013

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.

Monday, January 14, 2013

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.


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


Sunday, January 13, 2013

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.


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


Wednesday, January 9, 2013

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.