Category Archives: Code

FreeFlyer Demonstration: 2:00pm Sep. 28, 2017 for UA faculty and students

I will be giving a demonstration of FreeFlyer on Thursday, September 28 at 2:00 pm in SERC 3070. Faculty and Students feel free to drop on by! I have attached the flyer, here: FreeFlyerWithAttitude

Christopher Simpson will present a FreeFlyer demonstration, “FreeFlyer with Attitude,” on Thursday, September 28, 2017 at 2:00 pm in SERC 3070. FreeFlyer with Attitude will showcase the high-fidelity flight dynamics software with a Earth imaging satellite mission plan with specific pointing requirements. FreeFlyer is currently used on several NASA missions, including the Magnetosphere Multiscale (MMS) mission which set the record for closest flying formation at 7.2 km in September of 2016. Mr. Simpson recently interned with a.i. solutions, Inc. over the summer and worked with the FreeFlyer Tech Support team. He recently graduated with his B.S. in Aerospace Engineering and Mechanics from The University of Alabama in May 2016. He was recently awarded a SMART scholarship from the Naval Air Warfare Center – Weapons Division, China Lake. He is pursuing his Ph.D. at The University of Alabama under Dr. Charles O’Neill.


Showcase of FreeFlyer Students & Faculty SERC 3070 2:00 PM

September 28, 2017

 A high fidelity flight dynamics software comparable to STK used on multiple NASA missions, including the ISS, MMS, OSIRIS-Rex, and for the SLS All with an interest in spacecraft and astrodynamics are welcome


STK Certified


I’m now STK Certified Level 1. This means that I can use the GUI and some snippets of code to develop and analyze a scenario. The testing scenario involved the ability to analyze the access of sensors on a small UAV to ground sites and compare that access with satellites and other vehicles given certain restrictions.

The video of the scenario I developed is available here: Video of Test Scenario

Cesium Demo Using STK Scenario/TLE Data

Coming Soon: Orbital Mechanics/Astrodynamic Problem Solutions

While in the midst of preparing for a journal paper I decided that I wanted to showcase my abilities. I will solve all the problems from Vladimir Chobotov’s Orbital Mechanics, Third Edition, and Richard Battin’s An Introduction to the Mathematics and Methods of Astrodynamics, Revised Edition and post the solutions online. I hope to have this done by January 2.

Not only will this be a good review for myself but it will showcase my abilities to solve problems relating to the field I want to enter. Hopefully, it will prove to be a valuable tool in the future.

As for the featured picture: I am in the process of getting myself certified Level 1 with STK. I dropped this scenario into Cesium while I was practicing and exploring STK before the exam. My exam is due December 22. I will let you know the results soon!

Grade Distribution Plot Creation

Currently, I’m a graduate teaching assistant for Aerodynamics 1 and Aerospace Structures at the University of Alabama. After grading homework, quizzes, and exams I usually input the data into an Excel file. After a bout of procrastination I created a grade distribution plot for my classes.

I used MATLAB to pull the grades out of an Excel file, count the number of occurrences for each grade, and then plot the distribution. I created an Excel sheet that creates random grades so as to avoid using any of my students’ information. I already know the possible range of grades so these are hard-coded. I’ll post updates to the code throughout the semester.

Areas of future work:

  • Updating the way Excel files are called. Using the currentgradesheet variable will cause the error the second time it is called because it will use the first file name it contains.
  • Changing possible grades into a user input or created from the range of grades uploaded from Excel.
  • Tracking student data: being able to call a student’s name and seeing their grade history. This might take another function and a lot more time than I want to spend using MATLAB.

I have no problems with you using my code: just be sure to reference me.

Grade Distribution Plot Routine:

Code and Output in .pdf Format