The International Space Station from a Former DSMC Practitioner's Perspective

Gerald "Jay" LeBeau, Deputy Manager-International Space Station Program Mission Integration and Operations Office, NASA Johnson Space Center

What has a wingspan as large as a American football field, weighs in at 900,000 pounds, is powered by an acre of solar panels, and travels continuously at over 17,000 miles per hour?  If you guessed the International Space Station, you would be correct.  By its name alone you may already have some appreciation of the international partnership of countries from around the world that have come together to provide a continuous human presence in low Earth orbit for over 18 years.  But have you ever wondered what it took to assemble this monumental engineering feat and what it takes to maintain its operations?  Or maybe more importantly, what are its capabilities, and what is its role going forward? 

This and other aspects of the International Space Station will be addressed by Mr. Gerald “Jay” LeBeau.  The speaker is the Deputy Manager of the Mission Integration and Operations Office in the International Space Station Program at NASA’s Johnson Space Center (JSC) in Houston, Texas.  Prior to this role he served 25 years in JSC’s Engineering Directorate as an aerosciences analysist and manager supporting various NASA programs including the Space Shuttle, International Space Station, Orion, Commercial Cargo, and Commercial Crew programs.  Much of his technical work involved the application of Direct Simulation Monte Carlo tools to these and other applications.  He is also the primary original author of NASA’s DSMC Analysis Code (DAC) software, which is used within NASA, industry, and academia to analyze Rarefied Gas Dynamic environments.

A Quick Overview of Planetary Exploration Missions

J. Rabinovitch, C. Sotin, Jet Propulsion Laboratory

Starting with the Explorer 1 satellite launch in 1958, which enabled the discovery of the Van Allen Radiation Belts, NASA has been exploring space and making new discoveries for over 60 years. NASA planetary missions range in scope and size from low-cost small-satellite science missions to multi-billion-dollar flagship-class missions. Each mission has specific scientific objectives, a different risk posture, and different stages of formulation, design, and execution. Currently, in order to focus future scientific investigations, if a planetary mission is going to receive NASA funding, it should address key scientific/technical objectives specifically outlined in the Decadal Survey reports [1]. The last decadal survey, entitled “Vision and Voyages for Planetary Science in the Decade 2013-2022,” defines three cross-cutting themes (Building New Worlds, Planetary Habitats, and Workings of the Solar System) that lead to ten priority questions that can be responded to by exploring different targets in our Solar System. It explicitly supports Mars Sample Return (MSR) and prioritizes five flagship missions. Mars 2020, which is potentially the first element of MSR, and Europa Clipper are under development and will be launched in 2020 and 2023, respectively.
DSMC simulations and analysis play a large role in space missions—ranging from entry analysis and thruster plume analysis to contamination control calculations and many things in between. However, space missions take extremely large teams, are extremely multi-disciplinary, and require many complex analyses outside of DSMC. Understanding the complex interactions between the different systems of a spacecraft can help one understand where DSMC analysis fits into the overall spacecraft design process.
For any space mission, in order to relate scientific objectives to specific mission and instrument requirements, a Science Traceability Matrix (STM) is created. The STM creates a direct link between specific science objectives and the required measurements to meet the scientific objectives and also justifies what accuracy and precision specific instruments must be able to accommodate for their measurements [2]. Spacecraft requirements flow down from science requirements, not vice versa.
This work will give examples of planetary missions of different scales and different scopes and emphasize how the science return of a mission will always drive its design. Furthermore, an overview of how JPL addresses different aspects of mission formulation will be provided, with a brief description of JPL’s Innovation Foundry, which includes JPL’s A-Team and Team-X internal design teams [3]. Interesting design anecdotes from the MSL and InSight missions will be used in order to illustrate the complexities associated with planetary exploration missions.

Mars-Cube-One.png
An artist's rendering of the twin Mars Cube One (MarCO) spacecraft. Image credit: NASA/JPL-Caltech.

 

[1] National Research Council 2011, Vision and Voyages for Planetary Science in the Decade 2013-2022, The National Academies Press, Washington, DC (2011), https://doi.org/10.17226/13117.
[2] J. R. Weiss, W. D. Smythe, and W. Lu, “Science Traceability,” 2005 IEEE Aerospace Conference, Big Sky, MT, 292-299 (2005), https://doi.org/10.1109/AERO.2005.1559323.
[3] B. Sherwood and D. McCleese, “JPL Innovation Foundry,” Acta Astronautica, 89, 236-247 (2013), ISSN 0094-5765. https://doi.org/10.1016/j.actaastro.2013.04.020.
Acknowledgements: The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.