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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS1990

The 4-D descent trajectory generation techniques under realistic operating conditions

NASA-Langley has been conducting and sponsoring research in airborne energy management for a number of years. During the course of this research, two fundamental techniques for the generation of 4D (fixed time) descent trajectories have emerged as viable candidates for advanced flight management systems. The first technique utilizes speed schedules of constant Mach number transitioning to constant calibrated airspeed chosen empirically to produce minimum fuel usage. The second technique computes cost optimized speed schedules of variable airspeed developed through application of optimal control theory. Both techniques have been found to produce reasonable and flyable descent trajectories. The formulation of the algorithms for each technique is evaluated and their suitability for operations in realistic conditions is discussed. Operational factors considered include: airplace speed, thrust, and altitude rate constaints; wind, temperature, and pressure variations; Air Traffic Control altitude, speed, and time constaints; and pilot interface and guidance considerations. Time flexibility, fuel usage, and airborne computational requirements were the primary performance measures.

Williams, David H.↗

NASA NTRS1992

Air-Traffic Controllers Evaluate The Descent Advisor

Report describes study of Descent Advisor algorithm: software automation aid intended to assist air-traffic controllers in spacing traffic and meeting specified times or arrival. Based partly on mathematical models of weather conditions and performances of aircraft, it generates suggested clearances, including top-of-descent points and speed-profile data to attain objectives. Study focused on operational characteristics with specific attention to how it can be used for prediction, spacing, and metering.

Tobias, Leonard↗

NASA NTRS1996

Capture Conditions for Merging Trajectory Segments to Model Realistic Aircraft Descents

A typical commercial aircraft trajectory consists of a series of flight segments. An aircraft switches from one segment to another when certain specified variables reach their desired values. Trajectory synthesis for air traffic control automation must be consistent with practical pilot procedures. We examine capture conditions for merging trajectory segments to model commercial aircraft descent in trajectory synthesis. These conditions translate into bounds on measurements of atmospheric wind, pressure, and temperature. They also define ranges of thrust and drag feasible for a descent trajectory. Capture conditions are derived for the Center-TRACON Automation System developed at NASA Ames Research Center for automated air traffic control. Various uses of capture conditions are discussed. A Boeing 727-200 aircraft is used to provide numerical examples of capture conditions.

Zhao, Yiyuan↗

NASA NTRS2002

Mars Smart Lander Simulations for Entry, Descent, and Landing

Two primary simulations have been developed and are being updated for the Mars Smart Lander Entry, Descent, and Landing (EDL). The high fidelity engineering end-to-end EDL simulation that is based on NASA Langley's Program to Optimize Simulated Trajectories (POST) and the end-to-end real-time, hardware-in-the-loop simulation testbed, which is based on NASA JPL's (Jet Propulsion Laboratory) Dynamics Simulator for Entry, Descent and Surface landing (DSENDS). This paper presents the status of these Mars Smart Lander EDL end-to-end simulations at this time. Various models, capabilities, as well as validation and verification for these simulations are discussed.

Striepe, S. A.↗

NASA NTRS2004

Mars Exploration Rover Terminal Descent Mission Modeling and Simulation

Because of NASA's added reliance on simulation for successful interplanetary missions, the MER mission has developed a detailed EDL trajectory modeling and simulation. This paper summarizes how the MER EDL sequence of events are modeled, verification of the methods used, and the inputs. This simulation is built upon a multibody parachute trajectory simulation tool that has been developed in POST I1 that accurately simulates the trajectory of multiple vehicles in flight with interacting forces. In this model the parachute and the suspended bodies are treated as 6 Degree-of-Freedom (6 DOF) bodies. The terminal descent phase of the mission consists of several Entry, Descent, Landing (EDL) events, such as parachute deployment, heatshield separation, deployment of the lander from the backshell, deployment of the airbags, RAD firings, TIRS firings, etc. For an accurate, reliable simulation these events need to be modeled seamlessly and robustly so that the simulations will remain numerically stable during Monte-Carlo simulations. This paper also summarizes how the events have been modeled, the numerical issues, and modeling challenges.

Raiszadeh, Behzad↗

NASA NTRS2005

Entry, Descent, and Landing Technology Concept Trade Study for Increasing Payload Mass to the Surface of Mars

A trade study was conducted that compared various entry, descent, and landing technologies and concepts for placing an 1,800 kg payload on the surface of Mars. The purpose of this trade study was to provide data, and make recommendations, that could be used in making decisions regarding which new technologies and concepts should be pursued. Five concepts were investigated, each using a different combination of new technologies: 1) a Baseline concept using the least new technologies, 2) Aerocapture and Entry from Orbit, 3) Inflatable Aeroshell, 4) Mid L/D Aeroshell-A (high ballistic coefficient), and 5) Mid L/D Aeroshell-B (low ballistic coefficient). All concepts were optimized to minimize entry mass subject to a common set of key requirements. These key requirements were: A) landing a payload mass of 1,800 kg, B) landing at an altitude 2.5 km above the MOLA areoid, C) landing with a descent rate of 2.5 m/s, and D) using a single launch vehicle available within the NASA Expendable Launch Vehicle Contract without resorting to in-space assembly. Additional constraints were implemented, some common to all concepts and others specific to the new technologies used. Among the findings of this study are the following observations. Concepts using blunt-body aeroshells (1, 2, and 3 above) had entry masses between 4,028 kg and 4,123 kg. Concepts using mid L/D aeroshells (4 and 5 above) were significantly heavier with entry masses of 5,292 kg (concept 4) and 4,812 kg (concept 5). This increased weight was mainly due to the aeroshell. Based on a comparison of the concepts it was recommended that: 1) re-qualified and/or improved TPS materials be developed, 2) large subsonic parachutes be qualified. Aerocapture was identified as a promising concept, but system issues beyond the scope of this study need to be investigated. Inflatable aeroshells were identified as a promising new technology, but they require additional technology maturation work. For the class of missions investigated in this trade study, mid L/D aeroshells were not competitive on an entry mass basis as compared to blunt-body aeroshells.

Cruz, Juan R.↗

NASA NTRS2005

First Results from the Descent Imager/Spectral Radiometer (DISR) Experiment on the Huygens Entry Probe of Titan

The Cassini-Huygens mission was launched on October 15, 1997, and arrived in Orbit around Saturn in July, 2004. The Huygens Probe was released from the Cassini Orbiter on December 24, 2004 and entered Titan s atmosphere on January 14, 2005. Here we give the first results from the Descent Imager/Spectral Radiometer (DISR) instrument aboard the Huygens Probe during its descent into the atmosphere of Titan. Measurements were made by several different optical systems and sensors.

Tomasko, M. G.↗

NASA NTRS2002

System engineering challenges of real-time simulation for Mars SmartLander entry, descent, and landing

The Jet Propulsion Laboratory (JPL) is developing a high-fidelity, real-time spacecraft simulator for Entry, Descent and Landing (EDL) on planetary and small bodies. This simulator, DSENDS (Dynamics Simulator for Entry, Descent and Surface landing), is an EDL-specific extension of the JPL Darts/Dshell multi-mission spacecraft dynamics and devices simulation toolkit which is in use by missions such as Cassini, Galileo, SIM, and Starlight.

Dshell EDL simulator↗

NASA NTRS2005

Overview of the Phoenix Entry, Descent and Landing System

A viewgraph presentation on the entry, descent and landing system of Phoenix is shown. The topics include: 1) Phoenix Mission Goals; 2) Payload; 3) Aeroshell/Entry Comparison; 4) Entry Trajectory Comparison; 5) Phoenix EDL Timeline; 6) Hypersonic Phase; 7) Parachute Phase; 8) Terminal Descent Phase; and 9) EDL Communications.

Grover, Rob↗

NASA NTRS2005

Attitude Issues on the Huygens Probe: Balloon Dropped Mock up Role in Determining Reconstruction Strategies During Descent in Lower Atmosphere

As part of the collaboration with Italian Space Agency on HASI instrument for Huygens mission, University of Padova has been conducting since 2001 scientific activity on Stratospheric Balloon Launches from the Trapani base in Sicily. The most recent boomerang flight in July 2003 has successfully flown a mock up of the Huygens probe hosting spares of flight scientific units and extra housekeeping and scientific sensors on a parachuted descent from 33 kilometre altitude. This work presents the studies conducted on attitude reconstruction of the probe, as well as the utilisation of iterative extended Kalman filtering in investigating vanes induced spin rate and in providing a baseline for the performance evaluation of Huygens accelerometers operations. Finally some possible contributions on the reconstruction of the lower part of Titan descent for Huygens probe are suggested based on the confrontation of sensor data for 2003 flight.

Bettanini, C.↗

NASA NTRS2007

Flight Mechanics of the Entry, Descent and Landing of the ExoMars Mission

ExoMars is ESA's current mission to planet Mars. A high mobility rover and a fixed station will be deployed on the surface of Mars. This paper regards the flight mechanics of the Entry, Descent and Landing (EDL) phases used for the mission analysis and design of the Baseline and back-up scenarios of the mission. The EDL concept is based on a ballistic entry, followed by a descent under parachutes and inflatable devices (airbags) for landing. The mission analysis and design is driven by the flexibility in terms of landing site, arrival dates and the very stringent requirement in terms of landing accuracy. The challenging requirements currently imposed to the mission need innovative analysis and design techniques to support system design trade-offs to cope with the variability in entry conditions. The concept of the Global Entry Corridor has been conceived, designed, implemented and successfully validated as a key tool to provide a global picture of the mission capabilities in terms of landing site reachability.

HayaRamos, Rodrigo↗

NASA NTRS2008

Mars Phoenix Entry, Descent, and Landing Simulation Design and Modelling Analysis

The 2007 Mars Phoenix Lander was launched in August of 2007 on a ten month cruise to reach the northern plains of Mars in May 2008. Its mission continues NASA s pursuit to find evidence of water on Mars. Phoenix carries upon it a slew of science instruments to study soil and ice samples from the northern region of the planet, an area previously undiscovered by robotic landers. In order for these science instruments to be useful, it was necessary for Phoenix to perform a safe entry, descent, and landing (EDL) onto the surface of Mars. The EDL design was defined through simulation and analysis of the various phases of the descent. An overview of the simulation and various models developed to characterize the EDL performance is provided. Monte Carlo statistical analysis was performed to assess the performance and robustness of the Phoenix EDL system and are presented in this paper. Using these simulation and modelling tools throughout the design and into the operations phase, the Mars Phoenix EDL was a success on May 25, 2008.

Prince, Jill L.↗

NASA NTRS2008

Multibody Modeling and Simulation for the Mars Phoenix Lander Entry, Descent and Landing

A multi-body flight simulation for the Phoenix Mars Lander has been developed that includes high fidelity six degree-of-freedom rigid-body models for the parachute and lander system. The simulation provides attitude and rate history predictions of all bodies throughout the flight, as well as loads on each of the connecting lines. In so doing, a realistic behavior of the descending parachute/lander system dynamics can be simulated that allows assessment of the Phoenix descent performance and identification of potential sensitivities for landing. This simulation provides a complete end-to-end capability of modeling the entire entry, descent, and landing sequence for the mission. Time histories of the parachute and lander aerodynamic angles are presented. The response of the lander system to various wind models and wind shears is shown to be acceptable. Monte Carlo simulation results are also presented.

Queen, Eric M.↗

NASA NTRS2010

Post2 End-to-End Descent and Landing Simulation for ALHAT Design Analysis Cycle 2

The ALHAT project is an agency-level program involving NASA centers, academia, and industry, with a primary goal to develop a safe, autonomous, precision-landing system for robotic and crew-piloted lunar and planetary descent vehicles. POST2 is used as the 6DOF descent and landing trajectory simulation for determining integrated system performance of ALHAT landing-system models and lunar environment models. This paper presents updates in the development of the ALHAT POST2 simulation, as well as preliminary system performance analysis for ALDAC-2 used for the testing and assessment of ALHAT system models. The ALDAC-2 POST2 Monte Carlo simulation results have been generated and focus on HRN model performance with the fully integrated system, as well performance improvements of AGNC and TSAR model since the previous design analysis cycle

Davis, Jody L.↗

NASA NTRS2010

Entry, Descent and Landing Systems Analysis Study: Phase 1 Report

DwyerCianciolo, Alicia M.↗

NASA NTRS2010

Entry, Descent and Landing Systems Analysis: Exploration Class Simulation Overview and Results

DwyerCianciolo, Alicia M.↗

NASA NTRS2010

Overview of the NASA Entry, Descent and Landing Systems Analysis Study

Zang, Thomas A.↗

NASA NTRS2011

Entry, Descent and Landing Systems Analysis: Exploration Feed Forward Internal Peer Review Slide Package

NASA senior management commissioned the Entry, Descent and Landing Systems Analysis (EDL-SA) Study in 2008 to identify and roadmap the Entry, Descent and Landing (EDL) technology investments that the agency needed to successfully land large payloads at Mars for both robotic and human-scale missions. Year 1 of the study focused on technologies required for Exploration-class missions to land payloads of 10 to 50 mt. Inflatable decelerators, rigid aeroshell and supersonic retro-propulsion emerged as the top candidate technologies. In Year 2 of the study, low TRL technologies identified in Year 1, inflatables aeroshells and supersonic retropropulsion, were combined to create a demonstration precursor robotic mission. This part of the EDL-SA Year 2 effort, called Exploration Feed Forward (EFF), took much of the systems analysis simulation and component model development from Year 1 to the next level of detail.

Dwyer Cianciolo, Alicia M.↗