orrery

The watercooler chats for the Fall 2017 class of Datanauts are close to wrapping up, but they’re not finished yet!

This week we had three chats: Data Science in a Networked Era, an intro to orbital dynamics with Datnauts mentor Dan O'Neil, and an overview of web-based space mission mission visualization, also with Dan O'Neil. 

Most of us use networks every day when we log on to Facebook or Twitter. Datanaut Dr. Noemi Derzsy spent her whole Ph.D. dissertation looking at datasets she could use to build networks in order to understand the complexities of the connections within them.

“In the current state of the art, every tech system will be interconnected,” said Noemi. Networks are a graphic representation of a set of objects where each point or node is connected by links, creating a network or complex system. To understand the behavior of a system and how changes to nodes or the connections between nodes can impact other nodes, you need to be able to model the network.

Many theories have emerged over the years—centuries, really—to attempt to mathematically model networks. Enter network theory. To provide a foundation of network theory, Noemi went through the strengths and weaknesses of various attempts to represent networks over the centuries. From graph theories by Euler in 1735 and Hamilton in 1856 to random network models by Erdos and Renyi to small-world networks by Watts and Strogatz to scale-free networks by Barabasi and Albert, researchers got closer and closer to mathematically representing real complex systems.

And now we see networks everywhere—from Facebook to power grid systems to disease epidemics. Theoretical research topics include: network controlling, monitoring, and influencing (what Instagram influencers should brands support to get their name out?); network resilience against random failures or attacks (how does a power line failure affect the rest of the network?), network dynamics, and information flow on networks—like the NASA Deep Space Network (SCaN) Notional Integrated Communication Architecture.

 An orrery is typically a mechanical model of the solar system depicting the relative positions of planetary and lunar bodies. The name orrery is derived from Charles Boyle, the 4th Earl of Orrery, who produced the first modern solar system model. Dan’s idea is to create an ontology-orrery that is embedded in a webpage. But in order to be able to model the motions of the solar system, one needs to know the basics of orbital dynamics.

orreryweb

 Dan referred to Datanaut Rob Rovetto’s Space Situational Awareness Ontology,

http://rrovetto.github.io/Orbital-Space-Ontology-Project/

which defines a lot of the orbit parameters, including the type of orbit (e.g. heliocentric) needed to build a solar syst

em model, and added real-life orbital terms taken from NASA fact sheets. Using the JSON-LD file derived from the ontology, Dan developed some Javascript code to build an html table that renders the webpage.

 Building a web-based orrery is just one method to realize web-based space mission visualization concepts. Beyond just modeling planetary orbits, you can simulate other celestial bodies, spacecraft, orbital debris, or orbital trajectories.

 Dan outlined a notional workflow to make this happen through mission design with NASA’s General Mission Analysis Tool (GMAT)—available in NASA’s Open Source Code Catalog—export of trajectory data, conversion to JSON, integration with Javascript and WebGL (Web Graphics Library) code, and deployment of the rendered webpage.

 With decreased cost and increased ease of satellite launches, more objects are orbiting the Earth than ever. Dan modeled these objects in orbit using two line element (TLE) data provided by CelesTrak, a service provided by NORAD (incidentally, NORAD also tracks Santa Claus’ gift-delivering progress) and a trajectory propagator.

 Dan is already working with Datanauts to develop open source prjects that implement the web-based space mission visualization system. Next week, he and Datanaut Cindy Chin will talk about progress on one of their group projects to model the flight of the Friendship 7 spacecraft.

 

More on that next week!

veronicaPhillips

About Veronica

Ronnie has been enthusiastically showcasing NASA data as a member of NASA's Open Data team since 2013. She supports NASA's open source efforts by helping to curate and administrate datasets on NASA's Open Data Portal and Open Source Code Catalog, managing citizen and internal requests for NASA data, contributing to the Space Data Daily Open NASA blog, teaching Datanauts courses, and coordinating logistics and data support for the International Space Apps Challenge hackathons.