What is Journal club
As a new grad student, I need to read a lot of papers. A rule of thumb for new grad students is to read 5-7 papers every week. As I read through them, I highlight statements, leave comments in the margins, and write up a small note about what I thought of it. My thinking was, if I’m writing up 5 paragraphs a week anyway, why not combine them together and turn it into an extra weekly post. Hopefully, this will show a part of grad school that is often glossed over and also introduce you to some state of the art research.
About these posts
These posts will come out on Thursdays, starting next Thursday. Aside from the first post, there will be no extra newsletters sent out for each post. For the time being, they will only be advertised on the gereshes subreddit (link) and twitter (link)
Why do I read so many papers
While the papers may span many different topics, there’s generally one of three reasons that I currently read a paper
- Topics that are relevant for my research
- Learning about the state of the art
- Developing good research taste (Make more gneral)
MISC Q&A
What citation manager do I use? – Mendeley
Why not End Note/Zotero? – Mainly just personal preference. I don’t like End Note’s interface. I’ve been using mendeley for a while so it would be a pain to switch over to Zotero. I like how Zotero groups notes, but I don’t like that I cant mark up PDF’s in zotero. If I was just starting again I might give zotero a real change, but switching now doesn’t fix any needs.
Will I make a public group so that people can also see my highlights? – Maybe
Journal Club 2018.10.29
Theme of this weeks readings: Planetary Science Orbits
A large number of planetary science missions have their spacecraft in a polar orbit (See Juno, LRO, etc). There’s an interesting open question I’ve been looking into for research about polar orbits, so I’ve been reading up on them, and the missions that use them for writing a motivation section.
Mission design for the lunar reconnaissance orbiter
I went over this paper because polar orbits will possibly feed into a problem I want to solve. This paper gave some rational of why they want a polar orbit for LRO, so they can map the poles. There wasn’t much useful to me in this paper except for learning about frozen orbits. Theses are orbits that have had a single orbital element fixed even with perturbations. There are two types of frozen orbits high frozen orbits, where the perturbations are from 3-body effects, and low frozen orbits, where the perturbations are from non-spherical gravity effects. I’m more interested in high frozen orbits.
Beckman, M., “Mission design for the lunar reconnaissance orbiter,” Advances in the Astronautical Sciences, vol. 128, 2007, pp. 421–436.
Control of science orbits about planetary satellites
This paper looks at ways to design long term low altitude orbits around the moons of Jupiter. In it they use averaging to lower the system from a 3-DOF system to a 1-DOF system to get an initial trajectory. Whats interesting from this paper is that even low altitude near-polar frozen orbits have short lifespans because of instability from perturbations on the spacecraft from Jupiter. One can generally assume the dynamics close around major bodies to be stable, but It appears that assumption brakes down for certain deeps space regions.
Possner, M. P., and Scheerest, D. J., “Control of science orbits about planetary satellites,” Advances in the Astronautical Sciences, vol. 127 PART 1, 2007, pp. 511–531.
Stability Analysis of Planetary Satellite Orbiters : Application to the Europa Orbiter Introduction
I briefly skimmed through this paper. It’s about the decay of low altitude, high inclination orbits due to perturbation from the planet. This paper is a preliminary work to the previous paper in this review and lays out a lot of the theory and math used in it. While an interesting paper, at the moment I’m not particularly interested in small body perturbations. One thing that I did like from this paper was how it covered most of the math behind the instabilities, but at the end it provided a list of different moons as well as their characteristic instability time. If I was recreating the work in this paper, this list would allow me to check my code and understanding of the problem extremely quickly.
Scheeres, D. J., Guman, M. D., and Villac, B. F., “Stability Analysis of Planetary Satellite Orbiters : Application to the Europa Orbiter Introduction,” Journal of Guidance Control and Dynamics, vol. 24, 2001, pp. 778–787.
Numerical Integration Methods in Dynamical Astronomy
This journal article, published in 1989, is a bit older than the rest and is a survey of different integrators used by people in the IAU commission for Celestial Mechanics. I was reading it because I’ve been doing some work on the 3 body problem and using adaptive time step algorithms (like ODE45) have been causing the Jacobi Constant (analogous to the energy in the system) to become well, not constant. I’ve switched over to a constant step size integrator (a RK4 method) and it’s keeping the Jacobi constant much more constant. This paper was me being interested in seeing how people in the past have dealt with problems like this before. After reading this paper I think I want to delve deeper into Symplectic integrators as well as Lie Group integrators.
Hiroshi, K., and Hiroshi, N., “Numerical Integration Methods in Dynamical Astronomy,” Celestial Mechanics, vol. 45, 1989.
An Open Source Radio for Low Cost Small Satellite Ranging
This paper covered a low cost way to use radios for small satellite ranging. It isn’t really relevant to any work i’m doing currently, but you might have recognized it from the Spaceport America Cup post as the payload was a test of this system. It was worked on by some friends of mine in an undergrad lab that I was a part of, the University at Buffalo Nanosatellite lab.
Iraci, G., Gnam, C., and Hall, B., “An Open Source Radio for Low Cost Small Satellite Ranging,” Small satellite conference proceedings, 2018.
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