Importance of Model Simulations in Cassini In-Flight Mission Events

Brown, Jay; Wang, Eric; Hernández, Johann; Lee, Allan Y.

doi:10.2514/6.2009-5762

Cited by 3 publications

(2 citation statements)

References 18 publications

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“…The Cassini team has an all-software simulation environment called Flight Software Dynamic Simulation (FSDS), with full environmental dynamics built in 7 . Originally designed for flight software (FSW) testing before launch, it has been maintained as a high-fidelity analysis tool 8 . Currently, the Cassini team uses FSDS for FSW revision testing, sequence simulation, a Delta-V estimate generation which is used by the Navigation team.…”

Section: B Flight Software Dynamic Simulation (Fsds)mentioning

confidence: 99%

Titan Density Reconstruction Using Radiometric and Cassini Attitude Control Flight Data

Rosas¹,

Burk²

2015

AIAA Guidance, Navigation, and Control Conference

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This paper compares three different methods of Titan atmospheric density reconstruction for the Titan 87 Cassini flyby. T87 was a unique flyby that provided independent Doppler radiometric measurements on the ground throughout the flyby including at Titan closest approach. At the same time, the onboard accelerometer provided an independent estimate of atmospheric drag force and density during the flyby. These results are compared with the normal method of reconstructing atmospheric density using thruster on-time and angular momentum accumulation. Differences between the estimates are analyzed and a possible explanation for the differences is evaluated. Nomenclature F/D Slope = On-board estimate of peak external torque FSDS = Flight Software Dynamic Simulation HGA = High Gain Antenna INMS = Ion and Neutral Mass Spectrometer RCS = Reaction Control System RWA = Reaction Wheel Assembly TCA = Titan Closest Approach I. Introduction-Cassini Mission to Saturn and Titan A. Overview of Cassini Mission The Cassini-Huygens mission is a collaborative effort between the National Aeronautics and Space Administration (NASA), the European Space Agency (ESA), and the Italian Space Agency (ASI) to explore the Saturnian system. Launched in October 1997 onboard the powerful Titan IVB/Centaur, the Cassini-Huygens spacecraft still required multiple gravity assist flybys of Venus, Earth, and Jupiter to achieve the necessary velocity to reach Saturn. On June 30, 2004, Cassini achieved orbital capture at Saturn by firing its main engine for 85 minutes to slow its velocity by about 626 m/s. About 5 months later, the 320 kg ESA-built Huygens probe was successfully deployed from Cassini, and descended into Titan's atmosphere. Following playback of the probe's collected atmospheric data to Earth, Cassini then continued its primary mission of studying the Saturnian system via its suite of 12 remote and direct sensing science instruments. B. Saturn's Moon Titan Titan is an intriguing world larger than our own moon with a dense atmosphere and liquid hydrocarbon lakes on its surface. Because Titan is less massive than Earth, its gravity does not hold on to its gaseous atmosphere as tightly as Earth does, so its atmosphere extends roughly ten times farther into space than Earth's atmosphere. At the surface of Titan the atmospheric pressure is approximately 1.5 times greater than that of Earth at sea level with atmospheric density a factor of 4 larger. However, the chemical composition of Titan's atmosphere differs from Earth's; it is

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Section: B Flight Software Dynamic Simulation (Fsds)mentioning

confidence: 99%

Titan Density Reconstruction Using Radiometric and Cassini Attitude Control Flight Data

Rosas¹,

Burk²

2015

AIAA Guidance, Navigation, and Control Conference

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“…FSDS also contains updated models of Titan atmosphere and Enceladus plume models. A key aspect of operational success on Cassini is the careful design of test cases using FSDS or ITL 7 . Testing that emphasizes actual operational scenarios is especially valuable in tracking down human errors that could occur in flight.…”

Section: Cassini Integrated Test Laboratory (Itl)mentioning

confidence: 99%

Avoiding Human Error in Mission Operations - Cassini Flight Experience

Burk

2012

AIAA Guidance, Navigation, and Control Conference

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Operating spacecraft is a never-ending challenge and the risk of human error is everpresent. Many missions have been significantly affected by human error on the part of ground controllers. The Cassini mission at Saturn has not been immune to human error, but Cassini operations engineers use tools and follow processes that find and correct most human errors before they reach the spacecraft. What is needed are skilled engineers with good technical knowledge, good interpersonal communications, quality ground software, regular peer reviews, up-to-date procedures, as well as careful attention to detail and the discipline to test and verify all commands that will be sent to the spacecraft. Two areas of special concern are changes to flight software and response to in-flight anomalies. The Cassini team has a lot of practical experience in all these areas and they have found that well-trained engineers with good tools who follow clear procedures can catch most errors before they get into command sequences to be sent to the spacecraft. Finally, having a robust and fault-tolerant spacecraft that allows ground controllers excellent visibility of its condition is the most important way to ensure human error does not compromise the mission.

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Cassini Spacecraft Attitude Control System Performance and Lessons Learned, 1997–2017

Lee

Burk

2019

Journal of Spacecraft and Rockets

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Importance of Model Simulations in Cassini In-Flight Mission Events

Cited by 3 publications

References 18 publications

Titan Density Reconstruction Using Radiometric and Cassini Attitude Control Flight Data

Titan Density Reconstruction Using Radiometric and Cassini Attitude Control Flight Data

Avoiding Human Error in Mission Operations - Cassini Flight Experience

Cassini Spacecraft Attitude Control System Performance and Lessons Learned, 1997–2017

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