Yazar "Kluever, Craig A." seçeneğine göre listele

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    Analytical Guidance for Mars Aerocapture via Drag Modulation
    (Springer Heidelberg, 2022) Cihan, Ibrahim H.; Kluever, Craig A.
    Aerocapture is a maneuver where a spacecraft makes a single pass through a planetary atmosphere, thus using aerodynamic drag to deplete enough energy to establish a captured orbit. A new analytical predictor-corrector guidance algorithm has been developed for the Mars aerocapture problem. This paper presents a drag-modulation method where ballistic coefficient is continuously adjusted in order to control the vehicle during the atmospheric flight phase. An analytical function for velocity during aerocapture serves as the basis for the guidance method, and this expression results in a closed-form control law for ballistic coefficient. Guidance periodically updates the velocity profile so that the correct exit conditions are achieved. The ballistic coefficient control law utilizes the ratio of the measured and reference drag accelerations to improve the targeting accuracy of the guidance scheme. Two different apoapsis-targeting scenarios for Mars aerocapture are investigated in this paper. Monte Carlo simulations demonstrate the performance and robustness of the proposed guidance algorithm.
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    Correction to: Analytical Guidance for Mars Aerocapture via Drag Modulation
    (Springer, 2022) Cihan, İbrahim Halil; Kluever, Craig A.
    Aerocapture is a maneuver where a spacecraft makes a single pass through a planetary atmosphere, thus using aerodynamic drag to deplete enough energy to establish a captured orbit. A new analytical predictor-corrector guidance algorithm has been developed for the Mars aerocapture problem. This paper presents a drag-modulation method where ballistic coefcient is continuously adjusted in order to control the vehicle during the atmospheric fight phase. An analytical function for velocity during aerocapture serves as the basis for the guidance method, and this expression results in a closed-form control law for ballistic coefcient. Guidance periodically updates the velocity profle so that the correct exit conditions are achieved. The ballistic coefcient control law utilizes the ratio of the measured and reference drag accelerations to improve the targeting accuracy of the guidance scheme. Two diferent apoapsis-targeting scenarios for Mars aerocapture are investigated in this paper. Monte Carlo simulations demonstrate the performance and robustness of the proposed guidance algorithm.
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    Discrete-Event Drag Modulation Aerocapture for Mars and Titan Missions
    (Amer Inst Aeronautics Astronautics, 2024) Cihan, Ibrahim H.; Al-Bakri, Fawaz F.; Kluever, Craig A.
    Aerocapture is a spaceflight maneuver that uses the atmosphere of a planet or moon to slow down a spacecraft after a single atmospheric pass and capture it into an elliptical orbit around the celestial body. This paper presents a discrete-event drag modulation method for Mars and Titan aerocapture missions. A single-stage jettison is used as a control strategy to modulate the aerodynamic drag for an aerocapture scenario. Entry corridor analysis is performed under worst-case trajectory dispersions for determining the entry flight-path angle. The jettison timing of the high-drag skirt is the single free guidance parameter that adjusts the spacecraft's trajectory during an aerocapture maneuver. A computationally simple jettison-switching guidance scheme is developed to determine when to jettison the high-drag skirt, and the result is an analytical function that represents the ballistic-coefficient switching curve. The proposed discrete-event drag-modulation strategy is extensively tested using four entry vehicles and three target orbits for Mars and Titan aerocapture scenarios. Monte Carlo simulations show that the simple switching-curve guidance provides performance metrics (apoapsis targeting errors and postexit impulsive maneuvers) that are essentially equal to the performance of more computationally burdensome guidance methods such as an onboard numerical predictor-corrector scheme.