EPSC-DPS 2019: Day 4


Editor’s note: We’re wrapping up a busy summer with one last conference: the EPSC-DPS joint meeting in Geneva, Switzerland. To celebrate the announcement of AAS Publishing’s new Planetary Science Journal, we’ll be bringing you some highlights from this planetary science conference all week!

Press Conference: Akatsuki Mission Results, 2020 Coordinated Venus Observations, and Science at Venus

Today’s press conference was a celebration of Venus, covering both current and future missions and theory.


Artist’s impression of the Akatsuki spacecraft at Venus. [JAXA/Akihiro Ikeshita]

Masato Nakamura (ISAS/JAXA) opened the session by providing us with an update on Akatsuki, the only operational spacecraft currently in orbit around Venus. Akatsuki was launched in 2010 and arrived in orbit at Venus in 2015. Since then, it’s been using its five different cameras to image Venus in wavelengths from infrared to ultraviolet.

Akatsuki’s primary objective is to help us understand the differences between Venus’s atmosphere and Earth’s. Besides a difference in composition and thickness, Venus’s atmosphere also has the peculiar property of rotating an astonishing 60 times faster than the planet itself (something we call “superrotation”). What causes this? How is it sustained? Akatsuki’s pictures are slowly helping us to better understand the dynamics and 3D structure of the atmosphere to answer these questions.

Akatsuki UV Venus

A false-color, global view of Venus in ultraviolet by Akatsuki. [AXA / ISAS / DARTS / Damia Bouic]

One way Akatsuki is studying Venus’s atmosphere is by making infrared observations of the planet’s cloud tops. It’s a challenging process, says Takeshi Imamura (University of Tokyo), because the thermal images taken at 10 µm appear to be fairly featureless. By averaging images together within the coordinate system that moves with the superrotating wind frame, however, the team is able to extract detail from the images, identifying small-scale, turbulent features, spirals, and streaks. These complicated structures reflect dynamics in the clouds.

In addition to the thermal imaging, ultraviolet imaging is used to track Venus’s clouds and identify wind motions. Takeshi Horinouchi (Hokkaido University) presented on the surprising variety of motions these observations have revealed, from turbulent motions to planetary-scale waves. The ultraviolet observations also revealed an apparent asymmetry in wind speeds between Venus’s northern and southern hemispheres; Horinouchi suggests that this may be due to an asymmetric distribution of as-yet unidentified particles that absorb ultraviolet light. We clearly still have a lot to learn!

Joint Observations of Venus in 2020

Akatsuki won’t be alone next year! BepiColombo, a joint ESA/JAXA mission, will pass close to Venus in 2020 during a flyby. During this time, BepiColombo, Akatsuki, and ground-based telescopes will join their powers for a combined observational campaign of Venus.


An artist’s impression of the ESA-JAXA BepiColombo spacecraft. [ESA/ATG medialab]

Valeria Mangano (INAF-IAPS) was at today’s press conference to tell us more about BepiColombo’s role in this. BepiColombo is a Mercury magnetospheric orbiter — but on its way to Mercury, it will conduct two Venus flybys: one in October 2020 and one in August 2021. During the flybys, it will coordinate with Akatsuki to produce joint observations of Venus from multiple different viewing angles.

BepiColombo has two different components: ESA’s Mercury Planetary Orbiter (MPO) and JAXA’s Mercury Magnetospheric Orbiter (MMO). During the Venus flyby, 8 of 11 instruments will operate on MPO and 3 of 5 instruments will operate on MMO, measuring Venus’s atmosphere, tenuous exosphere, and its magnetosphere and plasma environment. The first flyby will be at 10,000 km altitude, and the second one will be just 1,000 km above Venus’s surface!

In addition to Akatsuki and BepiColombo, Earth-based telescopes like the Canada France Hawaii Telescope (CHFT) and the NASA Infrared Telescope Facility (IRTF) will be able to provide an additional angle during the coordinated campaign, explains Yeon Joo Lee (Technical University of Berlin). The multiple perspectives will enable global mapping of Venus’s atmospheric features.

Exoplanet atmosphere

How did the atmosphere of Venus evolve, and what can we take away from this to better understand the atmospheres of Venus-like exoplanets, like that illustrated here? [Dana Berry / Skyworks Digital / CfA]

Science at Venus

Last up, we heard from the theory side: Michael Way (NASA Goddard Institute for Space Studies) presented on modeling work exploring the possible habitability of ancient Venus. We think that early Venus conditions likely mirrored early conditions on Earth. By conducting a series of simulations with different topographies, land seed masses, etc., Way and collaborators explored the Venus’s atmospheric evolution over time to determine whether Venus very rapidly became the hostile environment it is today, or whether it may have been more welcoming for a long period of its history.

They find that conditions on Venus were likely very similar to those on Earth up until about 1 billion years ago. At that point, Way says, it appears that a catastrophic “intrusive volcanism” event of some kind occurred, in which magma traveled through the crust and led to resurfacing. This process released into the atmosphere carbon dioxide that was locked up in Venus’s surface, leading to the runaway greenhouse effect that turned the planet into the hellish world it is today. In this scenario, Venus could indeed have had a habitable surface for most of its history.

EPEC Science Flash

Present your work in a fun and original way! You have exactly 180 seconds of time supported by one slide and/or small additional equipment.

I was intrigued by the above description of this Europlanet Early Career Network event, because it sounded very similar to 60-second Pop Talks — one of my favorite components of ComSciCon, a science communication workshop for grad students. How would the early-career planetary scientists who signed up for this do, trying to explain their research in a succinct (and hopefully accessible) way?

I dropped in for a while to find out; here are some very rapid takeaways! These researchers are working on:

  • studying occultations. I learned something new: did you know that if you’re in the exact center of an occultation path, you might see what’s known as a “central flash”, caused by focusing of the background starlight by the foreground object’s atmosphere?
  • exploring the properties of Mercury-analog matter in a laboratory
  • the WISDOM GPR instrument on the Rosalind Franklin (previously called ExoMars) rover, which will be used to explore the underground structure of Mars using radar observations
  • the conundrum of life on Mars … will we find evidence for (simple) life when we finally arrive at Mars?
  • exploring Pluto’s atmosphere and aerosols via laboratory experiments.
science without scientists

Images of science rarely include the actual people doing the science, says Eleanor Armstrong. Click to enlarge. [AAS Nova]

One presentation was especially unique: Eleanor Armstrong (University College London, UK) gave a blind presentation, taking only 15 seconds to look at someone else’s slide and then give a presentation related to it. She absolutely killed the talk, pointing out that in most of the images on the slide, “science” is represented as a sterile process with no human involvement (“Here we have experiments apparently running themselves, and a completely uninhabited planetary base…”). Her doctoral research focuses on how scientists are represented in museums — something that can certainly stand improvement!

I really enjoyed attending this session and seeing scientists challenge themselves to explain their research succinctly and clearly — and I hope to see more programs encouraging this sort of development in the future! Shameless plug: if you’re a STEM grad student and want to push yourself to do the same, do consider checking out the AAS-sponsored ComSciCon workshop series; there are ComSciCon workshop events all across the U.S. (and one now in Canada), they’re all free or very low-cost to attend, and they’re a great way of learning more about effective science communication.

Session: Ocean Worlds and Icy Moons

We’ve heard a lot about rocky bodies this week, but what’s going on with ocean and icy worlds? We stopped by the end of this session to catch a few updates.


Saturn’s icy moon Enceladus is thought to have a subsurface ocean at its southern pole. [NASA/JPL/Space Science Institute]

Marc Rovira-Navarro (Utrecht University and TU Delft, the Netherlands) presented a new tool that can be used to model tides in subsurface oceans on icy moons. In particular, this tool allows researchers to explore the dissipation of tides in oceans that don’t have a uniform depth — because it’s likely, of course, that real oceans in our solar system and beyond are going to have varying seafloor topography. As an example, he demonstrated the use of this tool for modeling the suspected subsurface ocean below the southern pole of Saturn’s icy moon Enceladus.

Observations of Enceladus have captured plumes of ice grains and vapor coming from fractures near its southern pole — and analysis of these plumes have revealed evidence of volatile organic material. Nozair Khawaja (Free University Berlin and Heidelberg University, Germany) presented new work suggesting that Enceladus’s core may be an enormous factory for organic compounds, and this material can be efficiently transported from deep within the proposed subsurface ocean to the planet’s surface and expelled into space via the plume.

subsurface ocean

Artist’s illustration of a subsurface ocean on Europa. [NASA/JPL-Caltech]

What are we seeing in observations of Jupiter’s icy Galilean moons from the Voyager flyby? Our best guess is that these moons are covered in a combination of water ice and salty ices. In order to better interpret these observations and future observations from missions like JUICE and Europa Clipper, Romain Cerubini (University of Bern, Switzerland) and collaborators are conducting laboratory experiments on salty ices — ices prepared from brines of NaCl and MgSOthat were flash-frozen — to characterize the particles that form.

Subsurface oceans on ice satellites may not be well-mixed. Teresa Wong (Westfälische Wilhelms-Universität Münster, Germany) asks whether layers can exist in these oceans — and if so, how long can they persist, and what implications might this have? Her work indicates that such layers aren’t stable, but when they exist, they can inhibit heat and material transport through the ocean. This would alter the dynamics of the ocean and how the properties at the seafloor relate to those at the icy shell at the top of the ocean.

Unfortunately, we’re unable to attend the last day of the meeting — so with that, we’re officially signing off! Thanks, EPSC/DPS attendees, for sharing with us what’s going on in planetary science at the moment and what upcoming missions we can expect soon. We’re looking forward to seeing all the exciting results that come out of this field in the near future — and of course, we’re hoping we’ll get to publish it in AAS journals!