Sunday, February 18, 2018

Will it run? (or: Important things to ask yourself when programming)

Last fall, PVL MSc Giang spent a productive term with Raymond Pierrehumbert's group at Oxford. In this post, he reflects on his experience from the perspective of a little distance as he looks forward to summing up his MSc work and assesses PhD opportunities. Above (planetary photojournal image PIA01111), a view of one of Io's forced atmospheric components - sodium - which contrasts with the volcanic emission and condensation of sulfur compounds that Giang modelled.

By Tue Giang Nguyen


While I was interning at the University of Oxford, I was involved in atmospheric modelling projects for exoplanets and grateful for working with prominent scientists in my field. As I returned home from the UK, I had briefly forgotten what Canadian winter was like and was promptly reminded as I stepped outside of the airport. Now that I have returned to York University, it is time to reminisce about the things I learned during my short 3-months stay at Oxford.
The atmospheric model I worked with started by recreating Andrew Ingersoll’s 1985 work on modelling the wind flow on Io. Useful assumptions, some more justified than the others, such as making sure the Ionian atmosphere is hydrostatically bound and neglecting Io’s rotation allowed for a simple one-dimensional model of the shallow wave equation. The gist of the dynamics in the model is that sulfur dioxide, abundant on Io’s surface, would sublimate or evaporate when illuminated by the Sun. The sublimated sulfur dioxide would then flow onto the nightside where it is much colder and the atmosphere would condense back onto the surface. This insight on thin and condensable atmospheres is useful for exoplanet research where tidally locked rocky planets would evaporate or sublimate volatiles on the dayside where they would condense on the colder nightside.

Friday, February 9, 2018

Ice on Mercury and the Moon: Why So Different?

 
 A comparison of the poles of Mercury and the Moon illustrates similarities and differences that PVL PhD Candidate Jake Kloos explores in this blog post. Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/National Astronomy and Ionosphere Center, Arecibo Observatory.

By Jake Kloos

The research I am conducting for my PhD pertains to the polar regions of the Moon, which have been active regions of study within the planetary science community for over half a century. For a variety of reasons, interest in the lunar polar regions is centered around the presence of volatile compounds, principally water ice. Ice deposits have been detected within permanently shadowed regions (PSRs), which are regions within impact craters near the poles that are permanently shielded from the Sun. Due to the lack of direct sunlight, temperatures within PSRs are extremely low, enabling them to trap, and potentially preserve, molecules such as water that are wandering about the surface. While ice has been detected within lunar PSRs, the concentrations that have been inferred from remote sensing observations appear to be unexpectedly low, at only a few percent by weight.

The low concentrations of ice found on the Moon is surprising given what we know about ice concentrations on the planet Mercury. Mercury and the Moon share certain key similarities that led many to predict that the two bodies would posses similar amounts of ice: both are considered “airless” bodies and host PSRs near the poles that exist within similar temperature regimes (although Mercury’s PSRs are slightly warmer). Despite this, ice appears to be abundant at the polar regions of Mercury, with inferred concentrations in the range of 50 to 100 % by weight. Moreover, radar data unambiguously show enhancements in nearly all of Mercury’s PSRs, whereas many PSR craters on the Moon lack similar radar enhancements. In fact, some of the lunar PSRs that do show radar enhancements are subject to debate, as some researchers feel that ice may not be the best explanation as to the cause of the enhanced signal. The large discrepancy in ice concentrations on the Moon and Mercury does raise the question: why?

Proposal Writing 101

A few weeks ago, PVL PDF Christina Smith helmed her first major proposal on a $600,000 project. In this post she describes her experience and how it compares to other writing and proposing activities she has led in the past. (Image: "Coffee and a big stack of data", missyleone, flickr)

By Dr. Christina Smith

An very important aspect of academia is proposal writing. These are documents which do pretty much exactly what they say on the tin: they propose research into something. There are many different kinds: proposals to use instruments, proposals for job positions, funding proposals, proposals to become parts of collaborations, proposals to get on missions, and many more. In the past I've written short proposals to try (sometimes successfully, sometimes unsuccessfully- that's just how it goes) to get time on telescopes and I've written ones to go with fellowship and job applications, but this last week I had my first experience of grant (funding) proposal writing which is an entirely different experience!

When you write a proposal that goes along with a job application or a fellowship application (full or partial funding for your job specifically), the proposal generally focuses on the project, the skills and experiences you have to complete it, and any relevant past work. This includes a general level of background information to set the scene, as not everyone who reviews this proposal will be a specialist in your area. You have to make sure that any person in your general discipline will, by reading your proposal alone, understand what it is you want to do, and almost more importantly, why. In addition to what you want to do and why, you have to prove to the reader that you are definitely capable of carrying out this project that you are proposing. This requires a fair bit of “blowing one's own trumpet” so-to-speak, but in a way that is backed up by evidence. So you have to describe what you've done in the past and also explain why that is relevant to what you're doing now.