Oste s team

https://www.figma.com/proto/ZJQgjVyg1kDzSwlpVqCgbp/oste-s-team-presentation?page-id=0%3A1&node-id=1%3A110&viewport=241%2C48%2C0.5&scaling=contain

https://github.com/OsteSTeam/palca

PALCA (Potato Asteroid Light Curve Application) is an asteroid light curve tool that builds light curves using an OBJ model built on p5, a Processing implementation. Input a model, light and distance conditions, and get a visualisation together with both light curve end effective reflection surface.

Made with Pycharm using Numpy, P5, and matplotlib.

The general idea is to build a light curve based on the parameters defined by the user, including 

• relative positions of the asteroid, source of light and the observer
• .obj model of the asteroid
• albedo of the asteroid
• luminosity of the light source

After accepting the input the application generates the environment. Next, the necessary calculations are performed and based on their results the light reflection is simulated and renders the model of an object as it would really look under defined lighting. Finally, that visualization is used to create light curves.

The asteroid is loaded from an OBJ file. Each face is represented by an array of 3D vectors, each representing a vertex. The rotation matrix is applied to find coordinates after rotation. At first, faces are sorted from farthest to closest. Then, normals are calculated and faces with normals pointing away from the camera are excluded from rendering. Vertexes are projected on the camera plane.

Using the normals calculated before, we can find the brightness values of faces. Faces are treated as ideal Lambertian diffuse surfaces that reflect light in all directions. The color is based on the percent of light a face reflects: black reflects none, white reflects all.

The total brightness of asteroid pixels is added up. Bluish background pixels are ignored. Divided by a scale factor, this number yields total effective surface (i.e. how large a perfectly reflective surface must be to reflect the same amount as the asteroid). 

For each frame, after calculating the total effective surface, the program calculates the stellar magnitude and puts these values in arrays. After a full rotation, these values are fed into matplotlib functions to build plots.

The advantages of our solution are:

• Efficiency in simulation of light and reflection.
• Effective and straightforward graphic approach in calculating brightness.
• Unsophisticated and open-source code, which makes it accessible and easily modifiable.
• Using mtl material lib files, the software may be configured to use material information to take differences in surface texture and composition in different parts of the asteroid into account.

Those advantages allow us to determine the most appropriate applications and target audiences for this tool. At this stage, we estimate that this project (provided a user-friendly interface is developed) may find its use in the sphere of education. It allows students to study the relationship between the shape of an asteroid and its light curve hands on. Furthermore, we believe that if necessary additions are implemented, this application may be used as a real scientific tool. We will talk about that in a minute.

Further development

• First of all, there is potential for using Machine Learning tools with this project. By applying our algorithms on datasets of known light curves and asteroid shapes the instrument can be trained to predict one of those features, when given the other. That would pave the way for scientific usage.
• Next, it is possible to develop various interfaces to make the application more comfortable for both students and professionals, including our web interface currently under development.
• The algorithm behind the simulation of light and its reflection can be easily substituted by a more complex mathematical model. Another lighting model (such as the Phong model) can be easily implemented by modifying just one function. This is achieved by the fact that the code is open-sourced and readable (since it was written with end-user modification in mind).

The 12-years long NASA Lucy mission was the reason that challenged us to address this problem. It is going to complete a flyby of the Trojan asteroids and study them in close proximity. However, until that happens, it is important to get as much useful information about the asteroids as possible from the available observational data. We used the idea of generating the light curve for different asteroid shapes and created our own solution presented in this project.

We used the following NASA resources:

1. Lucy: The First Mission to Jupiter’s Trojans | NASA
2. Models | 3D Resources (nasa.gov)
3. Small-Body Database Query (nasa.gov)

Space Apps Challenge is a unique chance to address cutting-edge science and technology problems and design our own solutions for them. Short time frames motivated us to leave our comfort zones and quickly mobilize all our knowledge and creativity. We learned to divide tasks, tried ourselves in new roles and found new applications for our skills.

We have chosen this particular challenge because of our shared interest in space exploration and astronomy. Additionally, this problem allowed us to utilize the skills we already had, and dive deeper into new areas of programming and scientific data analysis. While working on this project, we researched a lot of open source code documentation and scientific papers to generate new ideas for our solution.

We have not faced any particular setbacks or problems. We have started our work with building a solid team structure, delegating responsibilities and defining clear tasks. However, for whichever troubles we have had, we were saved by a strong team-player attitude and friendly atmosphere :)

1. Mottola S., Hellmich S., Buie M. W. , 2020, The Planetary Science Journal, 1:73
2. Durech J., Sidorin V., Kaasalainen M., 2010, A&A 513, A46
3. Kaasalainen M., Torppa J., 2001, Icarus 153, 24–36
4. NASA Jet Propulsion Laboratory Small-Body Database Query (https://ssd.jpl.nasa.gov/tools/sbdb_query.html)
5. The Database of Asteroid Models from Inversion Techniques (DAMIT) (https://astro.troja.mff.cuni.cz/projects/damit/)
6. Karttunen H., Kröger P., Oja H., Poutanen M., Donner K. J., "Fundamental Astronomy", Springer-Verlag Berlin Heidelberg, p. 160

#software #Lucy #asteroids #Trojan #lightcurves #python #astronomy

This project has been submitted for consideration during the Judging process.