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  • 1
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    Assured crew return vehicle (1991)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A return vehicle is disclosed for use in returning a crew to Earth from low earth orbit in a safe and relatively cost effective manner. The return vehicle comprises a cylindrically-shaped crew compartment attached to the large diameter of a conical heat shield having a spherically rounded nose. On-board inertial navigation and cold gas control systems are used together with a de-orbit propulsion system to effect a landing near a preferred site on the surface of the Earth. State vectors and attitude data are loaded from the attached orbiting craft just prior to separation of the return vehicle.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Aeroassist vehicle requirements for a Mars Rover/Sample Return Mission (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A three degree-of-freedom computer simulation has been developed to perform Martian aeroassist trajectories using the HYPAS guidance algorithm. This simulator was used to perform a parametric study at the Johnson Space Center of various low L/D vehicles and their performance with the inclusion of vehicle and atmospheric dispersions. The ultimate goal is to define an extreme (minimum L/D) aeroassist configuration for the Mars Rover/Sample Return Mission to compare with the previously defined biconic aeroshell. The study shows that a raked cone vehicle with L/D betweeen 0.3 and 0.6 will perform adequately in the Martian environment in the presence of dispersions. Average apoapsis error for the 0.6 L/D vehicle was 11.9 km (6.4 nm) above the 2000 km target which compares fairly well with an error of 3.5 km (1.9 nm) for the 1.5 L/D biconic vehicle. The study concluded that the low L/D raked configuration warrants further study which could include stability analysis as well as the inclusion of density shears and dynamic atmospheric variations.
    Keywords: LAUNCH VEHICLES AND SPACE VEHICLES
    Type: AIAA PAPER 88-0303
    Format: text
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    NASA TECHNICAL REPORTS
  • 3
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    Entry, Descent, and Landing Performance for a Mid-Lift-to-Drag Ratio Vehicle at Mars (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: In an effort to mature the design of the Mid-Lift-to-Drag ratio Rigid Vehicle (MRV) candidate of the NASA Evolvable Mars Campaign (EMC) architecture study, end-to-end six-degree-of-freedom (6DOF) simulations are needed to ensure a successful entry, descent, and landing (EDL) design. The EMC study is assessing different vehicle and mission architectures to determine which candidate would be best to deliver a 20 metric ton payload to the surface of Mars. Due to the large mass payload and the relatively low atmospheric density of Mars, all candidates of the EMC study propose to use Supersonic Retro-Propulsion (SRP) throughout the descent and landing phase, as opposed to parachutes, in order to decelerate to a subsonic touchdown. This paper presents a 6DOF entry-to-landing performance and controllability study with sensitivities to dispersions, particularly in the powered descent and landing phases.
    Keywords: Spacecraft Design, Testing and Performance; Astronautics (General)
    Type: JSC-E-DAA-TN51349 , 2018 American Astronautical Society Guidance and Control Conference; Feb 02, 2018 - Feb 07, 2018; Breckenridge, CO; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Development of a Numeric Predictor-Corrector Aerocapture Guidance for Direct Force Control (2020)
    In:  CASI
    Details
    Publication Date: 2020-01-18
    Description: Direct force control, where the angle of attack and sideslip angle are modulated, has been proposed as an alternative to bank angle control for a spacecraft performing an aeroassist maneuver. This paper reimplements the current state-of-the-art aerocapture guidance for bank angle control, Fully Numeric Predictor-corrector Aerocapture Guidance (FNPAG), for direct force control. The optimal control theory underlying the structure of FNPAG is shown to not be applicable to the direct force control approach. Several solution structures for the longitudinal channel are compared by simulating dispersed three-degree-of-freedom trajectories for a reference mission consisting of a low lift-to-drag vehicle and a highly elliptical, 1-sol target orbit. The equations of motion for the lateral channel are derived, and a controller is designed to target a specified orbital plane. Finally, a Monte Carlo is used to demonstrate the performance of the new guidance.
    Keywords: Spacecraft Design, Testing and Performance
    Type: JSC-E-DAA-TN75426 , AIAA Guidance, Navigation, and Control Conference; Jan 06, 2020 - Jan 10, 2020; Orlando, FL; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    A Rigid Mid-Lift-to-Drag Ratio Approach to Human Mars Entry, Descent, and Landing (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Current NASA Human Mars architectures require delivery of approximately 20 metric tons of cargo to the surface in a single landing. A proposed vehicle type for performing the entry, descent, and landing at Mars associated with this architecture is a rigid, enclosed, elongated lifting body shape that provides a higher lift-to-drag ratio (L/D) than a typical entry capsule, but lower than a typical winged entry vehicle (such as the Space Shuttle Orbiter). A rigid Mid-L/D shape has advantages for large mass Mars EDL, including loads management, range capability during entry, and human spaceflight heritage. Previous large mass Mars studies have focused more on symmetric and/or circular cross-section Mid-L/D shapes such as the ellipsled. More recent work has shown performance advantages for non-circular cross section shapes. This paper will describe efforts to design a rigid Mid-L/D entry vehicle for Mars which shows mass and performance improvements over previous Mid-L/D studies. The proposed concept, work to date and evolution, forward path, and suggested future strategy are described.
    Keywords: Spacecraft Design, Testing and Performance
    Type: JSC-CN-37857 , AIAA SciTech 2017 Conference; Jan 09, 2017 - Jan 13, 2017; Grapevine, TX; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Angle of Attack Modulation for Mars Entry Terminal State Optimization (2009)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: From the perspective of atmospheric entry, descent, and landing (EDL), one of the most foreboding destinations in the solar system is Mars due in part to its exceedingly thin atmosphere. To benchmark best possible scenarios for evaluation of potential Mars EDL system designs, a study is conducted to optimize the entry-to-terminal-state portion of EDL for a variety of entry velocities and vehicle masses, focusing on the identification of potential benefits of enabling angle of attack modulation. The terminal state is envisioned as one appropriate for the initiation of terminal descent via parachute or other means. A particle swarm optimizer varies entry flight path angle, ten bank profile points, and ten angle of attack profile points to find maximum-final-altitude trajectories for a 10 30 m ellipsled at 180 different combinations of values for entry mass, entry velocity, terminal Mach number, and minimum allowable altitude. Parametric plots of maximum achievable altitude are shown, as are examples of optimized trajectories. It is shown that appreciable terminal state altitude gains (2.5-4.0 km) over pure bank angle control may be possible if angle of attack modulation is enabled for Mars entry vehicles. Gains of this magnitude could prove to be enabling for missions requiring high-altitude landing sites. Conclusions are also drawn regarding trends in the bank and angle of attack profiles that produce the optimal trajectories in this study, and directions for future work are identified.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-18477 , AIAA Atmospheric Flight Mechanics Conference; Aug 10, 2009 - Aug 13, 2009; Chicago, IL; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    Mid-Lift-to-Drag Ratio Rigid Vehicle Control System Design and Simulation for Human Mars Entry (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The Mid-Lift-to-Drag Ratio Rigid Vehicle (MRV) is a proposed candidate in the NASA Evolvable Mars Campaign's (EMC) Pathfinder Entry, Descent, and Landing (EDL) architecture study. The purpose of the study is to design a mission and vehicle capable of transporting a 20mt payload to the surface of Mars. The MRV is unique in its rigid, asymmetrical lifting-body shape which enables a higher lift-to-drag ratio (L/D) than the typical robotic Mars entry capsule vehicles that carry much less mass. This paper presents the formulation and six-degree-of-freedom (6DOF) performance of the MRV's control system, which uses both aerosurfaces and a propulsive reaction control system (RCS) to affect longitudinal and lateral directional behavior.
    Keywords: Lunar and Planetary Science and Exploration; Aircraft Stability and Control
    Type: JSC-E-DAA-TN49125 , American Institute of Aeronautics and Astronautics (AIAA) SciTech Forum; Jan 08, 2018 - Jan 12, 2018; Kissimmee, FL; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Comparison of Aerocapture Performance Using Bank Control and Direct Force Control with Two Human-Scale Vehicles at Mars (2020)
    In:  CASI
    Details
    Publication Date: 2020-01-22
    Description: Recent studies of human-scale missions to Mars have included a wide trade space of vehicle configurations and control schemes. Some configurations fly at a low angle of attack with a low L/D, while others fly at a high angle of attack with a mid L/D. Some use bank angle control, while others use direct force control, where the angle of attack and sideslip angle are independently modulated. This paper compares three potential vehicle configurations: a low-L/D vehicle using direct force control, a low-L/D vehicle using bank control, and a mid-L/D vehicle using bank control. The reference mission is aerocapture at Mars into a highly elliptical, 1-sol orbit. The trajectories are integrated in three degrees of freedom. All three cases utilize numeric predictor-corrector guidance and emulate control system responses with rate and acceleration limits. The configurations are compared using a Monte Carlo analysis. The robustness of each configuration to increased dispersions is also compared.
    Keywords: Spacecraft Design, Testing and Performance
    Type: JSC-E-DAA-TN75425 , 2019 SciTech Forum ; Jan 06, 2020 - Jan 10, 2020; Orlando, FL; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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