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  • 1
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    Gain Scheduling for the Orion Launch Abort Vehicle Controller (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: One of NASAs challenges for the Orion vehicle is the control system design for the Launch Abort Vehicle (LAV), which is required to abort safely at any time during the atmospheric ascent portion of ight. The focus of this paper is the gain design and scheduling process for a controller that covers the wide range of vehicle configurations and flight conditions experienced during the full envelope of potential abort trajectories from the pad to exo-atmospheric flight. Several factors are taken into account in the automation process for tuning the gains including the abort effectors, the environmental changes and the autopilot modes. Gain scheduling is accomplished using a linear quadratic regulator (LQR) approach for the decoupled, simplified linear model throughout the operational envelope in time, altitude and Mach number. The derived gains are then implemented into the full linear model for controller requirement validation. Finally, the gains are tested and evaluated in a non-linear simulation using the vehicles ight software to ensure performance requirements are met. An overview of the LAV controller design and a description of the linear plant models are presented. Examples of the most significant challenges with the automation of the gain tuning process are then discussed. In conclusion, the paper will consider the lessons learned through out the process, especially in regards to automation, and examine the usefulness of the gain scheduling tool and process developed as applicable to non-Orion vehicles.
    Keywords: Structural Mechanics
    Type: JSC-CN-24145 , AIAA GN and C (Guidance, Navigation, and Control) Conference; Aug 08, 2011 - Aug 11, 2011; Portland, OR; United States
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    NASA TECHNICAL REPORTS
  • 2
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    Attitude Control and Orbit Determination of a Crewed Spacecraft with Lunar Lander in near Rectilinear Halo Orbit (2019)
    In:  CASI
    Details
    Publication Date: 2019-07-20
    Description: NASA's Gateway program plans to place a crew-tended spacecraft in cislunar Near Rectilinear Halo Orbit (NRHO). The craft will support arrivals of crews in Orion and the undocking and return of a crewed lunar lander. The impact to at-titude control of a Gateway with the addition of a lunar lander is investigated. Perturbations from Orion and a lander's docking and undocking from the Gate-way are considered. Deep Space Network (DSN) tracking is supplemented with optical measurements to lunar north pole craters to analyze the possible benefit in solution accuracy and/or DSN scheduling relief.
    Keywords: Spacecraft Design, Testing and Performance; Lunar and Planetary Science and Exploration
    Type: JSC-E-DAA-TN64528 , AAS/AIAA Space Flight Mechanics Meeting; Jan 13, 2019 - Jan 17, 2019; Ka''anapali, HI; United States
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    NASA TECHNICAL REPORTS
  • 3
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    Low Thrust Cis-Lunar Transfers Using a 40 kW-Class Solar Electric Propulsion Spacecraft (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper captures trajectory analysis of a representative low thrust, high power Solar Electric Propulsion (SEP) vehicle to move a mass around cis-lunar space in the range of 20 to 40 kW power to the Electric Propulsion (EP) system. These cis-lunar transfers depart from a selected Near Rectilinear Halo Orbit (NRHO) and target other cis-lunar orbits. The NRHO cannot be characterized in the classical two-body dynamics more familiar in the human spaceflight community, and the use of low thrust orbit transfers provides unique analysis challenges. Among the target orbit destinations documented in this paper are transfers between a Southern and Northern NRHO, transfers between the NRHO and a Distant Retrograde Orbit (DRO) and a transfer between the NRHO and two different Earth Moon Lagrange Point 2 (EML2) Halo orbits. Because many different NRHOs and EML2 halo orbits exist, simplifying assumptions rely on previous analysis of orbits that meet current abort and communication requirements for human mission planning. Investigation is done into the sensitivities of these low thrust transfers to EP system power. Additionally, the impact of the Thrust to Weight ratio of these low thrust SEP systems and the ability to transit between these unique orbits are investigated.
    Keywords: Astrodynamics; Spacecraft Propulsion and Power
    Type: AAS 17-583 , GRC-E-DAA-TN45566 , AAS/AIAA Astrodynamics Specialist Conference 2017; Aug 20, 2017 - Aug 24, 2017; Stevenson, WA; United States
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  • 4
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    Enhanced Stationkeeping Maneuver Control Technique for Delta-V Cost Reduction in the Korea Pathfinder Lunar Orbiter (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Final document is attached. This paper proposes an enhanced control technique for stationkeeping maneuvers to reduce delta-v costs for the Korea Pathfinder Lunar Orbiter (KPLO). A scheduled circularization control technique exploits patterns in the evolution of the line of apsides and eccentricity to achieve a significant reduction in stationkeeping delta-v costs based on spacecraft requirements. The technique is compared against previous algorithms implemented for maneuver operations of the Lunar Prospector and Lunar Reconnaissance Orbiter (LRO) missions in the USA and KAGUYA in Japan. Through Monte Carlo analysis, the efficacy and robustness of the proposed method are verified, and the technique is shown to meet the operational requirements of KPLO.
    Keywords: Spacecraft Design, Testing and Performance
    Type: JSC-E-DAA-TN60023 , AAS Astrodynamics Specialists Conference; Aug 19, 2018 - Aug 23, 2018; Snowbird, Ut; United States
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  • 5
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    Stationkeeping, Orbit Determination, and Attitude Control for Spacecraft in Near Rectilinear Halo Orbits (2018)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Final document is attached. From a Near Rectilinear Halo Orbit (NRHO), NASA's Gateway at the Moon is planned to serve as a proving ground and a staging location for human missions beyond Earth. Stationkeeping, Orbit Determination (OD), and attitude control are examined for uncrewed and crewed Gateway configurations. Orbit maintenance costs are investigated using finite maneuvers, considering skipped maneuvers and perturbations. OD analysis assesses DSN tracking and identifies OD challenges associated with the NRHO and crewed operations. The Gateway attitude profile is simulated to determine an effective equilibrium attitude. Attitude control propellant use and sizing of the required passive attitude control system are assessed.
    Keywords: Astrodynamics
    Type: AAS 18-388 , JSC-E-DAA-TN59836 , AAS Astrodynamics Specialists Conference; Aug 19, 2018 - Aug 23, 2018; Snowbird, Ut; United States
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  • 6
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    Moon Next Early DRMs (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-28238 , International Space Exploration Coordination Group meeting (ISECG); Feb 25, 2013 - Mar 01, 2013; Houston, TX; United States
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    NASA TECHNICAL REPORTS
  • 7
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    An Alternative Humans to Mars Approach: Reducing Mission Mass with Multiple Mars Flyby Trajectories and Minimal Capability Investments (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Mars flyby trajectories and Earth return trajectories have the potential to enable lower- cost and sustainable human exploration of Mars. Flyby and return trajectories are true minimum energy paths with low to zero post-Earth departure maneuvers. By emplacing the large crew vehicles required for human transit on these paths, the total fuel cost can be reduced. The traditional full-up repeating Earth-Mars-Earth cycler concept requires significant infrastructure, but a Mars only flyby approach minimizes mission mass and maximizes opportunities to build-up missions in a stepwise manner. In this paper multiple strategies for sending a crew of 4 to Mars orbit and back are examined. With pre-emplaced assets in Mars orbit, a transit habitat and a minimally functional Mars taxi, a complete Mars mission can be accomplished in 3 SLS launches and 2 Mars Flyby's, including Orion. While some years are better than others, ample opportunities exist within a given 15-year Earth-Mars alignment cycle. Building up a mission cadence over time, this approach can translate to Mars surface access. Risk reduction, which is always a concern for human missions, is mitigated by the use of flybys with Earth return (some of which are true free returns) capability.
    Keywords: Lunar and Planetary Science and Exploration; Astrodynamics
    Type: JSC-CN-34093 , AIAA Space 2015; Aug 31, 2015 - Sep 02, 2015; Pasadena, CA; United States
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  • 8
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    Targeting Cislunar Near Rectilinear Halo Orbits for Human Space Exploration (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Part of the challenge of charting a human exploration space architecture is finding locations to stage missions to multiple destinations. To that end, a specific subset of Earth-Moon halo orbits, known as Near Rectilinear Halo Orbits (NRHOs) are evaluated. In this paper, a systematic process for generating full ephemeris based ballistic NRHOs is outlined, different size NRHOs are examined for their favorability to avoid eclipses, the performance requirements for missions to and from NRHOs are calculated, and disposal options are evaluated. Combined, these studies confirm the feasibility of cislunar NRHOs to enable human exploration in the cislunar proving ground.
    Keywords: Lunar and Planetary Science and Exploration; Space Transportation and Safety; Computer Programming and Software
    Type: JSC-CN-38615 , AAS/AIAA Space Flight Mechanics Meeting; Feb 05, 2017 - Feb 09, 2017; San Antonio, TX; United States
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  • 9
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    Day of Launch Profile Selection for Pad Abort Guidance (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A day of launch selection approach that involves choosing from an array of pitch profiles of varying loft was analyzed with the purpose of reducing the risk of a land landing failure during a pad abort. It was determined that selecting from three pitch profiles can reduce the number of waterline abort performance requirement failures approximately in half without compromising other performance metrics.
    Keywords: Space Transportation and Safety
    Type: JSC-CN-19750 , JSC-CN-21015 , AIAA Guidance, Navigation and Control Conference; Aug 02, 2010 - Aug 05, 2010; Toronto, Ontario; Canada
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  • 10
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    Implementation of an Autonomous Multi-Maneuver Targeting Sequence for Lunar Trans-Earth Injection (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Using a fully analytic initial guess estimate as a first iterate, a targeting procedure that constructs a flyable burn maneuver sequence to transfer a spacecraft from any closed Moon orbit to a desired Earth entry state is developed and implemented. The algorithm is built to support the need for an anytime abort capability for Orion. Based on project requirements, the Orion spacecraft must be able to autonomously calculate the translational maneuver targets for an entire Lunar mission. Translational maneuver target sequences for the Orion spacecraft include Lunar Orbit Insertion (LOI), Trans-Earth Injection (TEI), and Trajectory Correction Maneuvers (TCMs). This onboard capability is generally assumed to be supplemental to redundant ground computation in nominal mission operations and considered as a viable alternative primarily in loss of communications contingencies. Of these maneuvers, the ability to accurately and consistently establish a flyable 3-burn TEI target sequence is especially critical. The TEI is the sole means by which the crew can successfully return from the Moon to a narrowly banded Earth Entry Interface (EI) state. This is made even more critical by the desire for global access on the lunar surface. Currently, the designed propellant load is based on fully optimized TEI solutions for the worst case geometries associated with the accepted range of epochs and landing sites. This presents two challenges for an autonomous algorithm: in addition to being feasible, the targets must include burn sequences that do not exceed the anticipated propellant load.
    Keywords: Space Communications, Spacecraft Communications, Command and Tracking
    Type: JSC-CN-19825 , JSC-CN-20922 , AIAA Guidance Navigation and Control Conference; Aug 02, 2010 - Aug 05, 2010; Toronto, Ontario; Canada
    Format: application/pdf
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