Tag Archives: Consulting

Statistical Orbit Determination

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Class time/Preliminary Notes

I will be teaching a statistical orbit determination course this summer. This will be on my own time. All lectures will be posted to YouTube. I will be teaching the course out of Bob Schutz’s, Byron Tapley’s, and George H. Born’s, Statistical Orbit Determination. Feel free to use any textbook you desire but the problems and solutions will be assigned from this text. I have included some precursor notes in question and answer format on statistics and probability below.

AppendixA-ProbabilityAndStatistics

Syllabus

AEM_StatisticalOrbitDetermination_Syllabus_CRS

STATISTICAL ORBIT DETERMINATION

EXECUTIVE SUMMARY:

Orbit Determination (OD) is the problem of determining the best estimate of the state of a spacecraft whose initial state is unknown, from observations influenced by random and systematic errors, using a mathematical model that is not exact. Mordern OD is used to support all space missions from JSpOC’s observations of artificial Earth satellites to the International Space Station’s trajectory planning incorporating elements of probability, statistics, and matrix theory. A special projects class is needed to cover this vital part of the space curriculum that arguably makes the backbone of any space program.

DISCUSSION:

Modern OD approaches have been developed by the NASA Jet Propulsion Laboratory (JPL) to fulfill Earth and planetary navigation requirements and at the NASA Goddard Space Flight Center (GSFC) and the Department of Defense Naval Surface Weapons Center in applications of satellite tracking to problems in geodesy, geodynamics, and oceanography. The Joint Space Operations Center (JSpOC) at Vandenberg Air Force Base, the Conjunction Assessment Risk Analysis (CARA) at GSFC, and Trajectory Operation Officers (TOPO) at Johnson Space Center (JSC) use modern OD techniques in applications of satellite tracking, conjunction assessment, and protecting vital assets from the International Space Station to the National Reconnaissance Office (NRO) spy satellites.

Clearly, OD is an important part of any space mission. The proposed class will use the classical text, Statistical Orbit Determination, by Drs. Byron Tapley, Bob Schutz, and George Born. This basic OD course will cover:

  • Introduction to OD problem
    • Dynamic system and associated state
    • Observations are non-linear functions of state variables
    • Classical well-determined approach
    • Modern over-determined approach
  • Observations to measure satellite motion
    • Ground-based systems: laser, radiometric, etc.
    • Space-based systems: GPS, etc.
    • Error sources and media corrections
  • Non-linear OD reduced to linear state estimation
    • Application of linear system theory
    • Incorporation of algorithms to computational environment
    • Sequential processing of observations
    • Control of real-time processes

This will be supported by background and supplemental information in:

  • Probability and Statistics
  • Review of Matrix Concepts
  • Examples of State Noise and Dynamic Model Compensation
  • Solution of the Linearized Equations of Motion

Students can expect to incorporate their classroom knowledge into real-life by building optical and radiometric sensors supporting The University of Alabama’s new satellite ground station.

LECTURES:

Lecture 1 – Orbit Determination Concepts

Lecture 2 – Orbital Mechanics Review

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.

DemonstrationPhotos

WHAT WHO WHERE WHEN
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

 

2017 ESPRMC Graduate Research Symposium – The University of Alabama

I will be presenting “Benefits of Tracking Aids on a 1U CubeSat,” on Thursday, April 13 at the 2017 ESPRMC Graduate Research Symposium. Dr. O’Neill was my co-author. I hope to see you there.

Abstract:

Incoporating active/passive tracking aids into the design of a university/high school CubeSat mission promotes good space stewardship. Tracking aids are necessary for improved tracking covariance of CubeSats. Tracking aid support and design-space cost are covered. Reflectarrays, patch array(s), and deployable antennas show the potential benefit of transmitting data over S-band frequencies and tracking aids that enhance the mission capabilities. Passive and active tracking aids with low impact on the mission provide reduced covariance of CubeSats orbit tracks shown through use of modeling tools.

STK Certified

stk_certification

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!

CODER 2016: Panelist/Presentation/Experience

I presented Tuesday at the Center for Orbital Debris Education and Research on “CubeSat Network for Prediction and Tracking of Orbital Debris.” The key points:

  1. Conceptual Stage of Development
  2. LIDAR ~700W and CubeSat ~200 W
  3. Assuming UV laser, 355 nm, resolution of 1 mm would require a 2 m telescope diameter for a range of 5 km

Presentation is attached here: simpson_v2

Several topics that are of interest specifically to my presentation:

  • Research that suggests that the satellite operators that do not follow good practices will be the primary source of new collisions in the future. Roger Thompson, The Aerospace Corporation, spoke to this on my panel.
  • Space is about to get a lot more crowded. To put it in context their have been 56 launches this year. SpaceX filed for 4400 satellites with the FCC Wednesday.
  • There is a strong need for knowledge of conjunctions and good covariance analysis. I.E. there seems to be the need for secondary analysis for conjunction warnings from JSpOC. On my panel Don Greiman, Schafer Commercial Space Situational Awareness Team, spoke to this from the commercial side and Ryan Shepperd as analysis in-house for Iridium.

Talk about a huge learning experience. I hope to take what I’ve learned back to The University of Alabama and disseminate this knowledge among our academic community. I also plan to stay in touch with the contacts I’ve made to help expand my horizons.