Thursday, October 13, 2011

2011 DPS Notebook

The large mechanical elephant of Nantes as photographed by wikimedia user dyhorus. Last week, planetary scientists from around the world gathered in the home city of Jules Verne. There we discussed our work and looked forward to the year ahead. In particular for us on this side of the pond, we got a look at a European community that is seeing more and more coordination of their activities and is resembling less an less a hodgepodge of individual moving parts.

This year I spent most of my DPS-chronicling energies over on Twitter. When this was combined with my poor adaptation to Central European Summer Time, the length of the sessions (which ran to 7PM every night) and a preference to use my late night hours in productive discussion with colleagues I did not get the opportunity to write much during the conference. I've finally arrived back home now and, as such, I present a minor information dump of my thoughts regarding the conference.


Part 1: The Martians are coming!  

One satisfying aspect of this year's conference was the presence of many first time DPSers. In particular, I'd like to highlight the presence of the martians who normally shun the conference in favor of LPSC! I can say this because, until last year, I was one of them. That we usually stay away is understandable - there are often only a couple of sessions at DPS dedicated to Mars. But Mars was not left out this year. Alfred McEwen put the highlight on HiRise, presentations were given describing what we can learn if only ESA's troubled TGO gets the green-light and modelling results from our European colleagues were also featured. Thus, a confluence of additional support from the US and a strong European contingent made this a year to remember.

There were so many fascinating discoveries shared and any attempt to try and list them all would leave many out. However, I would still like to highlight a few. Candi Hansen presented interesting work that suggests that much of the active erosion of dunes and scarps in the north could be caused by the same CO2-Sublimation processes that produce the geysers that lead to spiders. Nathaniel Putzig gave us an update on SHARAD results, including the presence of a mysterious "Reflection Free Zone" within the southern polar cap which might be CO2 ice. If it is, 40% of all the CO2 on Mars is locked up in that one deposit! As well, Shane Byrne presented an update on his elegantly simple sounding of the martian permafrost by looking at small impacts that occur as HiRISE watches. The uptake is that the ground-ice margin isn't where we thought it was, suggesting that we still have much to learn about martian permafrost. Speaking of ice, Bourgeois also presented evidence of km-scale glaciation in Valles Marineras based on orbital imagery and geomorphology.

One talk in particular bears specific highlighting, however. Geronimo Villanueva updated us on what he and Mike Mumma have been up to in the search for Methane on Mars since 2009. They now have a half million spectra from three of the best telescope facilities to pour over. However, what is most impressive about this work to me isn't the methane abundances. Instead it's all the other molecules that fall out of the calculations - dozens and dozens of them. In a sense, we're already doing trace gas chemistry on Mars from afar. For instance, Villanueva flashed the first HDO map of Mars up on the screen for the briefest instant. Even so, it should be noted that the error bars are significant, and even Villanueva contended that a completely unambiguous and unassailable detection of many species, including methane, would need either orbital or in-situ verification. TGO anyone?


Part 2: EPSC-DPS or DPS-EPSC?


The second notable aspect of this year's conference was the size. Organizers presented a chart on Monday that indicated there were at least 1500 participants and once same day registration was counted, that number could have risen above 2000! That's almost LPSC-big! This speaks well of the idea of holding this conference jointly (or at least the advantages of holding an October conference on the French Atlantic Coast) and I think there was a great deal of support for repeating the exercise - perhaps with a US venue.

At the same time, we were also victims of our own success and so many researchers in one place created some problems. Some of the rooms were laughably small and it was not uncommon to see every seat occupied, people up against the walls, sitting in the asiles and lined up out the door. This is the first DPS where I've heard of people quitting the breaks 10 minutes early to try to get a seat in sessions they really cared about. Or bypassing sessions they were marginally interested in due to overcrowding. The poster sessions also became difficult to attend. Refreshment stations were poorly positioned and tended to create bottlenecks while it became a task and a half just to get swim through the crowd to get to a poster.

Part of the reason for the issue was the incredible and somewhat unexpected turn-out from the Americans. DPS in the US typically gets 800-900 participants and EPSC sees 700-800. It was perhaps assumed that by holding the joint conference in Europe, the EPSC crowd would dominate. Instead the opposite seemed to be true. This extended to twitter. The official conference title was EPSC-DPS, but many of the Americans were using the hashtag #dpsepsc. A reconciliation was required and finally even event organizer and sponsor Europlanet gave over to the reverse handle.

To me this large turnout was a plus and a minus. I have pretensions of being an equal opportunity scientist when it comes to the planets. One of the advantages of DPS was that I could take in a much larger swath of planetary science. However, with 9 sessions typically running concurrently this proved impossible.




Part 3: SwRI, the Nice Model and the triumph of the Dynamicists



All fields go through hot and cold phases. Right now in Planetary Science nothing is hotter than Dynamics. This field has really come of age in the last ten years as increasing computational power lets us examine the granularity of the early solar system and how it came to look the way it does today. This conference was in some ways a celebration of all we have learned from this dynamical renaissance. In that spirit, EPSC-DPS exhibited two particularly well known centers of Dynamical work - L'Observatoire de la Cote D'Azur in Nice and the Southwest Research Institute in Boulder. Kudos in particular go to the latter. I have to wonder if it is a first to have both senior Prize Lectures given by members of the same institution.

Both of those lectures were of excellent quality and were required viewing for all members of the community. I generally view these prize lectures as being akin to my PhD coursework; they update my fundamentals. William Ward spoke to us about work to understand planetary obliquity. William Bottke schooled us about the particulars of the so-called Late Heavy Bombardment. Present in both talks was the explicative power of the Nice Model of the solar system and the contributions made by high-power computing.

As a smattering of what was discussed:

(A) the stabilizing influence of the Moon on Earth's obliquity will wane over the next 1.5 Ga. Thus, the Earth's climate will enter a chaotic state reminiscent of Mars at that time.
(B) there are ways of tipping Uranus on its side and making Venus rotate retrograde that do not involve giant impacts.
(C) the LHB likely began earlier and lasted later than 3.9 Ga. On the Moon, basin forming impacts likely lasted until 3.7 Ga and on the Earth to 2.5 Ga. 
(D) Serious bombardment of KT-sized objects likely continued on Earth until 1.5 Ga, suggesting that Sudbury and Vredefort might be the last gasps of the LHB. This has profound implications for Astrobiology and the development of Life on the early Earth.



Part 4: Comets and Beyond: A Good Omen

I have a special place in my Scientific heart for Comets. I've done laboratory work on this in the past (and I hope to write up a blog post on this in the next few months!) and am currently involved in projects to understand how we can better study these objects. As such, I had been hoping to attend a few sessions discussing results from recent missions to these objects. But the shear volume of material absolutely blew me away! What was also surprising was the breadth of the reporting. Spacecraft results, modelling results and even ground-based telescopic observations were all presented. This last group, in particular, is unusual and it was good to see them here. In the end I got a lot of useful information that I think will be helpful for my activities in the coming months.

In terms of research, there are, of course, some highlights. I greatly enjoyed efforts to understand the dyamics of cometary coma through tracking cometary "grains" some of which are as large as basketballs! As well, it seems clear that we don't yet have a good handle on why comets produce jets where they do, though we have some very tantalizing clues.  But, particularly poignant for me is the discovery and announcement at this conference by Hartogh et al that the D/H ratio of the water ice in the coma of comet Hartley-2 is equivalent to the water content of the Earth's oceans. This ratio, known as VSMOW (Vienna-Standard Mean Ocean Water) was one of the main reasons why it had been previously thought that comets could not have provided much of the Earth's water reservoirs - comets that had been visited by spacecraft before had all exhibited high values of this ratio. But it could be that these other comets had undergone more cycling - more transits around the sun. And if there's one thing that cycling can do, it's causing isotopic fractionation, particularly as the comet gets dusty. The uptake of this new measurement is that it now becomes possible for cometary impacts to explain more of the water on our present wet world.

The other two areas in which I was interested to learn were sessions on Astrobiology and Super-Earths in other solar systems. Despite the differing titles, the subject matter was similar. In the astrobiology session, what really caught my eye was the discovery of warm dust around a nearby star called Eta Corvi. According to Lisse, this is evidence for kuiper belt material scattered into the inner solar system. I'm astounded that we can even see this stuff. Sounds like we might have a second example solar system where the Nice Model can really sink its teeth into the small bodies and Giant Planet Migrations! As for the Super Earths session, there was a lot of interesting modelling and a consensus emerged as to what we can expect to detect with JWST. While there are compounds we can expect and look for, the Signal-to-Noise story means that JWST will not be able to detect any biomarkers in the atmospheres of habitable-zone Earth-like planets. It's just not the right tool for this job.

Part 5: ESA-NASA Night

My conference concluded with ESA-NASA Night and talks by Jim Green (NASA-PSD) and Luigi Colangeli (ESA). While Jim was a bit downbeat, we did learn a great deal from his talk as to the continuing activities in the PSD. He implored us to not go negative and to declare our support for the Planetary Decadal Survey verbally - which we did. It is key, he said, that we argue for our program and say why planetary science is worthwhile of the funding we get instead of arguing against another program. The DPS issued a statement reinforcing this perspective. Jim expressed his dismay with how little he has heard from us in the way of support, so let me right here and now declare my own support for the decadal (as I have done in the past). As well, I'd encourage Jim not to loose heart! Ours is a vibrant community and I know that we are all immeasurably thankful for his excellent and tireless work at PSD.

The ESA report was more upbeat. Instead of being an update, this was almost a first-look for many of us. If that was the case, Colangeli's report succeeded in showing off what Europe has to offer. Currently 19 missions are in flight, in development or approved for flight and the program appears to be somewhat robust. Of course, we all know that ESA has its own funding issues, though Colangeli's report was light on challenges. But there are good building signs, not least of which is the coordinating outreach of the Europlanet Research Institute. Certainly, a take-home from this conference is that ESA is becoming more of a full partner with the US in planetary science, a trend which seems likely to continue for the foreseeable future!

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