The Role of the Flight Software Development System Simulator Throughout the Cassini Mission

Brown, Jay; Lam, Danny; Chang, Larry; Burk, Thomas A.; Wette, M.

doi:10.2514/6.2005-6389

Cited by 18 publications

(8 citation statements)

References 2 publications

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“…FSDS is a workstation-based simulation without any hardware in the loop 4 . The spacecraft hardware and environmental inputs are simulated in this environment via software, but it runs a compiled version of the Flight Software (FSW), and is very accurate for modeling software command interactions.…”

Section: B Main Engine Burn Fuel Depletion Testingmentioning

confidence: 99%

Cassini Attitude and Articulation Control Subsystem Fault Protection Challenges During Saturn Proximal Orbits

Bates

2015

AIAA Guidance, Navigation, and Control Conference

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is the largest and most ambitious interplanetary spacecraft in history. As the first spacecraft to achieve orbit at Saturn, Cassini has collected science data throughout its fouryear prime mission (2004-08), and has since been approved for a first and second extended mission through 2017. As part of the final extended mission, Cassini will begin an aggressive and exciting campaign of high inclination low altitude flybys within the inner most rings of Saturn, skimming Saturn's outer atmosphere, until the spacecraft is finally disposed of via planned impact with the planet. This final campaign, known as the proximal orbits, presents unique fault protection related challenges, the details of which are discussed in this paper. NomenclatureAACS = Attitude and Articulation Control Subsystem CBH = Catbed Heater FP = Fault Protection FSDS = Flight Software Development Suite FSW = Flight Software ITL = Integrated Test Laboratory ME = Main Engine MPD

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Section: B Main Engine Burn Fuel Depletion Testingmentioning

confidence: 99%

Cassini Attitude and Articulation Control Subsystem Fault Protection Challenges During Saturn Proximal Orbits

Bates

2015

AIAA Guidance, Navigation, and Control Conference

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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 .…”

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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“…It is a closed-loop environment using the latest version of the AACS FSW. 2,3,12 For any Cassini events of interest, FSDS is a faster-than-real-time simulation environment of choice for AACS team and has been used extensively to develop and validate AACS FSW loads, perform various testing of critical events for Cassini, e.g. the launch, Saturn orbit insertion, Probe release, and Probe relay tracking, check first-time events, and investigate flight anomalies.…”

Section: Rcs Controllermentioning

confidence: 99%

“…Spacecraft dynamics model within FSDS includes a rigid body plus system flexibilities such as the Magnetometer boom and Radio and Plasma Wave Science antennas, and propellant sloshing. 2,3,12 The use of the RCS often imparts undesired ∆V on the spacecraft. The Cassini navigation requires that the spacecraft system provides predictions of the ∆V in spacecraft coordinates resulting from a turn using RCS thrusters and a reaction wheel bias.…”

Section: Rcs Controllermentioning

confidence: 99%

A Flight-Calibrated Methodology for Determination of Cassini Thruster On-Times for Reaction Wheel Biases

Sarani

2010

AIAA Guidance, Navigation, and Control Conference

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This paper describes a methodology for accurate and flight-calibrated determination of the on-times of the Cassini spacecraft Reaction Control System (RCS) thrusters, without any form of dynamic simulation, for the reaction wheel biases. The hydrazine usage and the ΔV vector in body frame are also computed from the respective thruster on-times. The Cassini spacecraft, the largest and most complex interplanetary spacecraft ever built, continues to undertake ambitious and unique scientific observations of planet Saturn, Titan, Enceladus, and other moons of Saturn. In order to maintain a stable attitude during the course of its mission, this three-axis stabilized spacecraft uses two different control systems: the RCS and the reaction wheel assembly control system. The RCS is used to execute a commanded spacecraft slew, to maintain three-axis attitude control, control spacecraft's attitude while performing science observations with coarse pointing requirements, e.g. during targeted low-altitude Titan and Enceladus flybys, bias the momentum of reaction wheels, and to perform RCS-based orbit trim maneuvers. The use of RCS often imparts undesired ΔV on the spacecraft. The Cassini navigation team requires accurate predictions of the ΔV in spacecraft coordinates and inertial frame resulting from slews using RCS thrusters and more importantly from reaction wheel bias events. It is crucial for the Cassini spacecraft attitude control and navigation teams to be able to, quickly but accurately, predict the hydrazine usage and ΔV for various reaction wheel bias events without actually having to spend time and resources simulating the event in flight software-based dynamic simulation or hardware-in-the-loop simulation environments. The methodology described in this paper, and the ground software developed thereof, are designed to provide just that. This methodology assumes a priori knowledge of thrust magnitudes and thruster pulse rise and tail-off time constants for eight individual attitude control thrusters, the spacecraft's wet mass and its center of mass location, and a few other key parameters.

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The Role of the Flight Software Development System Simulator Throughout the Cassini Mission

Cited by 18 publications

References 2 publications

Cassini Attitude and Articulation Control Subsystem Fault Protection Challenges During Saturn Proximal Orbits

Cassini Attitude and Articulation Control Subsystem Fault Protection Challenges During Saturn Proximal Orbits

Titan Density Reconstruction Using Radiometric and Cassini Attitude Control Flight Data

A Flight-Calibrated Methodology for Determination of Cassini Thruster On-Times for Reaction Wheel Biases

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