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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 NTRSDate not supplied

Lidar-Based Safe Site Relative Navigation

There has been a renewed focus in exploration of the lunar surface and maximizing scientific potential of such missions is made possible in part by minimizing the time required to set up operations; that is, reducing transit time on the surface by increasing the landing precision with respect to the intended target. Established SPLICE project precision landing requirements necessitate a navigation filter architecture and underlying models developed specifically with these needs in mind. To date, test flights to characterize SPLICE GNC system performance have not provided a means to divert from the a priori selected landing site due to hazardous conditions. With the inclusion of a new sensor, the HDL, coupled with safe landing site selection algorithms, GNC can divert from the originally planned trajectory and navigate relative to the new targeted landing site. This work presents a novel hazard relative measurement model and covariance transformation methodology that enable the navigation system to inform a safe-site relative guidance profile to meet project precision landing goals.

Navigation↗
NASA NTRS2018

Nguyen Xuan Vinh - A Life In Hypersonic Flight

Nguyễn Xuân Vinh (born January 1930 in Yên Bái, Vietnam) is a noted Vietnamese-American aerospace scientist and educator whose seminal work on the guidance, dynamics and optimal control of space vehicles and their interaction with the atmosphere has played a fundamental role in space exploration. Vinh is Professor Emeritus of Aerospace Engineering at the University of Michigan, where he taught for nearly thirty years. Among his many publications was "Hypersonic and Planetary Entry Flight Mechanics” (1980. Vinh, N. X.; Busemann, A.; Culp, R. D. University of Michigan Press) which contains equations for hypersonic flight that came to be known as “the Vinh equations”.

Lu, Ping↗
NASA NTRS2018

Entry Systems Modeling Project

ESM (Entry Systems Modeling Project) is the only dedicated research effort for EDL (Entry, Descent and Landing) modeling at NASA. ESM provides consistent support for experts to develop high-priority model improvements and validation testing, driven by mission needs, that can be delivered in 3-5 years to reduce mission risk and improve performance. Focused research in four elements: Predictive Materials Modeling; Guidance, Navigation and Control; Computational and Experimental Aerosciences; Shock Layer Kinetics and Radiation.

CFD↗
NASA NTRSDate not supplied

Safe and Precise Landing Integrated Capabilities Evolution (SPLICE)

NASA needs for entry, descent, and landing call for improved Precision Landing and Hazard Avoidance (PL&HA) technologies. SPLICE continues to develop, mature, demonstrate, and infuse these technologies as a portfolio. SPLICE will achieve TRL 5 on a hazard detection lidar mapping sensor and TRL 6 on two key flight software libraries for advanced guidance and hazard detection. A High-Performance Space Computing surrogate multiprocessor (ARM A53) integrates sensors and FSW. This portfolio of technologies may be infused separately or fully integrated.

Guidance Navigation and Control↗
NASA NTRS1994

Comment on 'Guidance for an Aerocapture Maneuver

It is stated that the aerodynamic forces on the vehicle being aerocaptured are controlled by "altering the angle of attack" and thereby controlling the lift coefficient. Furthermore, the resulting variation of drag coefficient with angle of attack was ignored. The purpose of this Comment is to point out that an aerodynamic control method that is much more effective than the pitch modulation has been studied and utilized during entries for many years. During aerocapture, it is desirable to have a large range of lift coefficients available, while keeping the vehicle's ballistic coefficients constant. This is accomplished by modulating the vehicle's bank angle, i.e., by rolling the vehicle about its velocity vector. By this method, the angle of attack can be held constant (at the trim angle, if desired), and the C(sub D) and the ballistic coefficient remain constant. Furthermore, the vertical component of the normal force vector (essentially the lift) can be varied over its entire range, from maximum positive to maximum negative values. Reaction controls, rather than aerodynamic ones, are usually utilized to change the bank angle of the vehicle, thus requiring the use of fuel. However, the fuel expenditure that is required to change the bank angle is far less than the amount that would have to be used to continuously hold the vehicle at pitch angles that differ significantly from its trim angle of attack. Also, it has been shown that bank angle modulation to vary the lift can enlarge the entry corridor by increasing the entry angle for the undershoot boundary, where both the heating rate and deceleration reach a maximum. Finally, the crew's deceleration tolerance can be increased somewhat when the bank angle is varied, as opposed to the pitch angle. For bank modulation, the deceleration force vector can be kept at a constant angle with respect to the occupants whose tolerance to g loads is highest when the force is applied in a direction normal to the upper torso. The advantages of bank angle variation to modulate the lift vector were recognized long ago, and this method of control was used successfully on the Apollo command module during lunar return' and, more recently, for the Space Shuttle Orbiter.

Tauber, Michael E.↗
NASA NTRSDate not supplied

Orion Artemis I Descent and Landing Performance

The Artemis I mission successfully demonstrated the Orion Multi-Purpose Crew Module ability to trigger parachute deployment, control angular rate and touch-down heading using reaction control jets while under parachutes, and automatically detect splashdown. Guidance and control logic is implemented to initiate para-chute events in a favorable dynamic state and select a touchdown heading direction that will minimize impact loads at splashdown. Detection of splashdown inhibits control to prevent firing reaction control jets under water and begin the transition into post-landing activities that cut parachutes and deploy the Crew Module Up-righting System (CMUS). This paper presents analysis of Orion descent and landing guidance and control performance for the Artemis I mission utilizing imagery taken from the vehicle, recorded flight data, and results from high fidelity simulations.

Artemis 1↗
NASA NTRS1994

Further development and flight test of an autonomous precision landing system using a parafoil

NASA Dryden Flight Research Center and NASA Johnson Space Center are jointly conducting a phased program to determine the feasibility of the autonomous recovery of a spacecraft using a ram-air parafoil system for the final stages of entry from space to a precision landing. The feasibility is being studied using a flight model of a spacecraft in the generic shape of a flattened biconic that weighs approximately 120 lb and is flown under a commercially available ram-air parafoil. Key components of the vehicle include the global positioning system (GPS) guidance for navigation, a flight control computer, an electronic compass, a yaw rate gyro, and an onboard data recorder. A flight test program is being used to develop and refine the vehicle. The primary flight goal is to demonstrate autonomous flight from an altitude of 3,000 m (10,000 ft) with a lateral offset of 1.6 km (1.0 mi) to a precision soft landing. This paper summarizes the progress to date. Much of the navigation system has been tested, including a heading tracker that was developed using parameter estimation techniques and a complementary filter. The autoland portion of the autopilot is still in development. The feasibility of conducting the flare maneuver without servoactuators was investigated as a means of significantly reducing the servoactuator rate and load requirements.

Murray, James E.↗
NASA NTRS1993

The development and flight test of a deployable precision landing system for spacecraft recovery

A joint NASA Dryden Flight Research Facility and Johnson Space Center program was conducted to determine the feasibility of the autonomous recovery of a spacecraft using a ram-air parafoil system for the final stages of entry from space that included a precision landing. The feasibility of this system was studied using a flight model of a spacecraft in the generic shape of a flattened biconic which weighed approximately 150 lb and was flown under a commercially available, ram-air parachute. Key elements of the vehicle included the Global Positioning System guidance for navigation, flight control computer, ultrasonic sensing for terminal altitude, electronic compass, and onboard data recording. A flight test program was used to develop and refine the vehicle. This vehicle completed an autonomous flight from an altitude of 10,000 ft and a lateral offset of 1.7 miles which resulted in a precision flare and landing into the wind at a predetermined location. At times, the autonomous flight was conducted in the presence of winds approximately equal to vehicle airspeed. Several techniques for computing the winds postflight were evaluated. Future program objectives are also presented.

Sim, Alex G.↗
NASA NTRS1994

Development and flight test of a deployable precision landing system

A joint NASA Dryden Flight Research Facility and Johnson Space Center program was conducted to determine the feasibility of the autonomous recovery of a spacecraft using a ram-air parafoil system for the final stages of entry from space that included a precision landing. The feasibility of this system was studied using a flight model of a spacecraft in the generic shape of a flattened biconic that weighed approximately 150 lb and was flown under a commercially available, ram-air parachute. Key elements of the vehicle included the Global Positioning System guidance for navigation, flight control computer, ultrasonic sensing for terminal altitude, electronic compass, and onboard data recording. A flight test program was used to develop and refine the vehicle. This vehicle completed an autonomous flight from an altitude of 10,000 ft and a lateral offset of 1.7 miles that resulted in a precision flare and landing into the wind at a predetermined location. At times, the autonomous flight was conducted in the presence of winds approximately equal to vehicle airspeed. Several novel techniques for computing the winds postflight were evaluated. Future program objectives are also presented.

TRT-EXPERIMENTAL↗
NASA NTRS2018

Entry, Descent, and Landing Performance for a Mid-Lift-to-Drag Ratio Vehicle at Mars

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.

mars↗
NASA NTRS1975

Preliminary Entry Trajectory for 1st Orbital Flight Test (OFT). Space Shuttle Engineering and Operations Support, Engineering Systems Analysis

A preliminary trajectory from entry interface to terminal area energy management interface for the first orbital flight test is presented based on information in the Strawman master flight test assignments document Reference A. The enclosed point-mass trajectory may be utilized for preliminary purposes, meeting the requirements of this document. The trajectory was derived utilizing the January 1975 analytic drag control guidance, the latest thermal protection subsystem model information from NASA ES and December 1974 Aerodynamics for a mid center-of-gravity location.

Frohme, K. R.↗
NASA NTRS1980

STS-1 operational flight profile. Volume 5: Descent, cycle 3

The trajectory data presented are to be used for orbiter systems and subsystems evalation, flight and mission control center software verification, flight techniques and timeline development, crew training, and evaluation of operational mission suitability. The entry profile is very similar to cycle 2, however, elevon and body flap temperature margins have increased and the elevon schedule was changed. The terminal area energy management (TAEM) profile was completely reshaped to conform with new angle of attack constraints and left hand turn around the heading alignment cylinder. Also, the entry/TAEM interface was adjusted to minimize guidance induced angle of attack transients across the interface. The approach and landing phase was reshaped for a 20 deg glideslope and reduced velocity at touchdown. The definition of the runway threshold was standardized for all landing sites. This results in a shift at Edwards Air Force Base in aim points and touchdown relative to the threshold of 1000 feet. The rollout remains essentially unchanged with the exception of the speedbrake, which is now deployed to 50 percent at touchdown.

Moore, R.↗
NASA NTRS1990

Guidance and control strategies for aerospace vehicles

The first part of the report concerns broadly the summary of the work done in the areas of singular perturbations and time scales (SPaTS), aerobraking technology, guidance and aerocruise. The synergistic plane change problem connected with orbital transfer employing aeroassist technology, is addressed. The mission involves transfer from high Earth orbit to low Earth orbit with plane change being performed within the atmosphere. The complete mission consists of a deorbit phase, atmospheric phase, and finally reorbit phase. The atmospheric maneuver is composed of an entry mode, a cruise mode, and finally an exit mode. During the cruise mode, constant altitude and velocity are maintained by means of bank angle control with constant thrust or thrust control with constant bank angle. Comparisons between these two control strategies bring out some interesting features.

Hibey, Joseph L.↗
NASA NTRSDate not supplied

JANNAF Guidelines for the Application of Technology Readiness Levels (TRLs) to Micro-Propulsion Systems, 2022 Edition

Spacecraft developers place considerable emphasis on stated Technology Readiness Levels (TRLs) to establish system-level maturity; however, the methodology for determining TRL is often inconsistent across various technologies. In 2019, the MicroPropulsion Panel of the JANNAF Spacecraft Propulsion Subcommittee developed a set of TRL guidelines for the micro-propulsion community. That work expanded on the general guidance provided by Department of Defense (DoD) and the National Aeronautics and Space Administration (NASA) documentation and sought to provide a consistent metric by which TRLs may be assigned to spacecraft micro-propulsion systems. Since the release of the 2019 guide, community feedback is motivating an updated edition of the guidelines to provide clarifications on critical TRL entry and exit criteria as well as to facilitate continued usage of the TRL guidelines.

Thomas Liu↗
NASA NTRS1994

Guidance and Navigation for the Mars Pathfinder Mission

The Mars Pathfinder Project is being developed by the U.S. (NASA) to demonstrate new technologies for landing on Mars, and to conduct focused, but significant scientific observations.

Pathfinder cheaper faster better low cost new tech↗
NASA NTRS2005

Development of a Coherent Lidar for Aiding Precision Soft Landing on Planetary Bodies

Coherent lidar can play a critical role in future planetary exploration missions by providing key guidance, navigation, and control (GNC) data necessary for navigating planetary landers to the pre-selected site and achieving autonomous safe soft-landing. Although the landing accuracy has steadily improved over time to approximately 35 km for the recent Mars Exploration Rovers due to better approach navigation, a drastically different guidance, navigation and control concept is required to meet future mission requirements. For example, future rovers will require better than 6 km landing accuracy for Mars and better than 1 km for the Moon plus maneuvering capability to avoid hazardous terrain features. For this purpose, an all-fiber coherent lidar is being developed to address the call for advancement of entry, descent, and landing technologies. This lidar will be capable of providing precision range to the ground and approach velocity data, and in the case of landing on Mars, it will also measure the atmospheric wind and density. The lidar obtains high resolution range information from a frequency modulated-continuous wave (FM-CW) laser beam whose instantaneous frequency varies linearly with time, and the ground vector velocity is directly extracted from the Doppler frequency shift. Utilizing the high concentration of aerosols in the Mars atmosphere (approx. two order of magnitude higher than the Earth), the lidar can measure wind velocity with a few watts of optical power. Operating in 1.57 micron wavelength regime, the lidar can use the differential absorption (DIAL) technique to measure the average CO2 concentration along the laser beam using, that is directly proportional to the Martian atmospheric density. Employing fiber optics components allows for the lidar multi-functional operation while facilitating a highly efficient, compact and reliable design suitable for integration into a spacecraft with limited mass, size, and power resources.

Amzajerdian, Farzin↗