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NASA NTRS2021

Contact with Bennu! Flight Performance Versus Prediction of OSIRIS-REx TAG Sample Collection

The Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) mission collected a sample from the surface of the near-Earth asteroid (101955) Bennu in late 2020. Bennu challenged the team with a surface that was much rockier than expected, resulting in modifications to the prelaunch design of the Touch And Go (TAG) sequence. Following enhancements in onboard trajectory correction, ground-based navigation, and maneuver execution error modeling, the spacecraft was delivered to the chosen TAG site within 1 m of the target, and a sample was successfully collected on the first attempt. This paper provides a comprehensive description of all flight dynamics aspects of TAG trajectory planning and execution. It also describes hazard map generation and how that combined with error analysis results to predict the probability of safe contact before TAG and the onboard wave-off determination during TAG.

Kevin E Berry↗
NASA NTRS2021

OSIRIS-REx Proximity Operations and Navigation Performanceat (101955) Bennu

The NASA Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) spacecraft began close proximity operations at the small (500-m diameter) B-type asteroid (101955) Bennu in December 2018 and concluded in May 2021. Hundreds of grams of pristine surface regolith were collected on October 20, 2020, when the OSIRIS-REx spacecraft successfully executed the Touch and Go (TAG) sample collection sequence. The spacecraft touched down within 1 meter of the targeted site on the surface of Bennu. TAG was the culmination of over 2 years of navigation performance refinement as a result of extraordinary interagency teamwork between the Flight Dynamics System (FDS), science and spacecraft teams while in close proximity to Bennu. This paper will discuss the navigation processes, planning and performance during the proximity operations at Bennu.

Peter G. Antreasian↗
NASA NTRSDate not supplied

OSIRIS-REx Proximity Operations and Navigation Performance at (101955) Bennu

The NASA Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) spacecraft began close proximity operations at the small (500-mdiameter) B-type asteroid (101955) Bennu in December 2018 and concluded in May 2021.Hundreds of grams of pristine surface regolith were collected on October 20, 2020, when the OSIRIS-REx spacecraft successfully executed the Touch and Go (TAG) sample collection sequence. The spacecraft touched down within 1 meter of the targeted site on the surface of Bennu. TAG was the culmination of over 2 years of navigation performance refinement as a result of extraordinary interagency teamwork between the Flight Dynamics System (FDS),science and spacecraft teams while in close proximity to Bennu. This paper will discuss the navigation processes, planning and performance during the proximity operations at Bennu.

Peter G Antresian↗
NASA NTRS2020

Establishing Launch Readiness of NASA ISS Payload OCO-3

The Orbiting Carbon Observatory – 3 (OCO-3) is a NASA Earth-monitoring payload, designed and built by the Jet Propulsion Laboratory (JPL) to perform space-based observation of variations of global carbon dioxide (CO2) by sampling its emission sources and gradients from the unique vantage point of the International Space Station (ISS). This paper describes the development and results of the end-to-end verification, validation and calibration activities that were performed to meet OCO-3's science measurement, functional and performance requirements prior to launch. The pre-launch activities encompassed a suite of tests and analyses that were performed after payload integration and during launch vehicle integration that helped the OCO-3 project demonstrate its launch and mission readiness in terms of ISS compatibility, ground-based instrument calibrations, flight dynamics and environmental integrity and pointing knowledge and accuracy.

Srivastava, Priyanka↗
NASA NTRSDate not supplied

Global Reference Atmospheric Model (GRAM) Suite Overview and Current Status

• Engineering-oriented atmospheric models that estimate mean values and statistical variations of atmospheric properties for numerous planetary destinations • Currently available for Earth, Mars, Venus, Titan, Neptune, Uranus, and Jupiter • Outputs include atmospheric density, temperature, pressure, chemical composition, radiative fluxes (for Mars-GRAM), and wind components along a user-defined path – Includes seasonal, diurnal, geographic, and altitude variations • Widely used by the engineering community because of their ability to create realistic atmospheric dispersions • Can be integrated into high fidelity flight dynamic simulations of launch, entry, descent and landing (EDL), aerobraking and aerocapture • Optional trajectory input file consisting of time, height, latitude, and longitude can be used to provide the GRAM trajectory path • Optional auxiliary profile consisting of height, latitude, longitude, temperature, pressure, density, eastward wind, and northward wind may be used to replace model data in the GRAMs • Not a forecast model

atmospheric models↗
NASA NTRSDate not supplied

Efficient Variable-Pitch Propeller Aerodynamic Model Development for Vectored-Thrust eVTOL Aircraft

This paper describes a variable-pitch propeller testing and aerodynamic modeling methodology for electric vertical takeoff and landing (eVTOL) aircraft using wind tunnel testing. Propellers used for eVTOL aircraft propulsion systems experience a wide range of operating conditions resulting in significant variation of axial thrust and torque, as well as off-axis forces and moments, across a typical flight envelope. An experimental design is developed to collect informative wind tunnel data in an efficient manner using response surface methods. System identification methods are then applied to isolated propeller wind tunnel data to develop a mathematical model of the propeller valid throughout the transition envelope of a vectored-thrust eVTOL aircraft. Multiple explanatory variable definitions are postulated and compared using modeling and prediction performance metrics. Modeling results validated against data withheld from the modeling process indicate good predictive capability and agree with theoretical expectations. All identified propeller models are provided, which allows the models to be used in future eVTOL aircraft flight dynamics simulations.

aerodynamic modeling↗
NASA NTRSDate not supplied

New Releases and Upgrades of Giant Planet Global Reference Atmospheric Models (GRAMs)

• GRAMs are engineering-oriented atmospheric models that estimate mean values and statistical variations of atmospheric properties for numerous planetary destinations – Outputs atmospheric density, temperature, pressure, winds, and chemical composition along a user-defined path – Provide mean values and variability for any point in an atmosphere – Includes seasonal, geographic, and altitude variations – Used by engineering community because of their ability to create realistic atmospheric dispersions; can be integrated into high fidelity flight dynamic simulations of launch, entry, descent, and landing (EDL), aerobraking, and aerocapture • GRAMs are not forecast models • GRAMs are available for: Earth, Mars, Venus, Neptune, Titan, Jupiter, and Uranus • Available through the NASA Software Catalog https://software.nasa.gov/software/MFS-33888-1

atmospheric models↗
NASA NTRSDate not supplied

Orbit Determination for the James Webb Space Telescope During Launch and Early Orbit

The NASA James Webb Space Telescope (JWST) mission successfully launched on December 25, 2021, at 12:20 UTC. This paper details several novel challenges encountered in the orbit determination (OD) of JWST during the launch and early orbit. The first OD solution used only 6.5 hours of tracking data, much less than the 24 hours of data usually required for libration orbiters on an outbound trajectory. In addition, the observatory area exposed to solar radiation pressure changed through a series of sunshield deployments while concurrent momentum unloads and attitude telemetry outages occurred. This paper covers how the Flight Dynamics Team (FDT) prepared for these challenges, how these challenges were handled on-orbit, and the performance of the resulting OD solutions.

Orbit Determination↗
NASA NTRSDate not supplied

Feasibility and Performance Analysis of Magnetohydrodynamics Control for Aerocapture at Neptune

NASA’s most recent Decadal Survey posed a mission to one of the Ice Giants as the top priorityfor flagship missionsin the organization’s future. However, current technologieslimit the amount of scientific payload available for future Uranian and Neptunian missions due to the need for fuel for orbit insertion maneuvers. Thus, to maximize the scientific potential of futuremissions, atmospheric aerocapture has been heavily researched. While atmospheric aerocapture simulations have proven enabling for capturing around Neptune, its deep atmospheric pass requiresan aeroshell with thermal protection systems(TPS).Magnetohydrodynamically-controlled aerocapture serves as a potential solution to both fully-propulsive orbit insertion and atmospheric aerocapture. Through NASA Langley’s high-fidelity flight dynamics simulation, the Program to Optimize Simulated Trajectories II, both the atmospheric and magnetohydrodynamic aerocapture methods were simulated and compared for identical missions to Neptune. After applying a guidance algorithm for both methods, the results showed that magnetohydrodynamics has not only the control authority to successfully capture around Neptune, but also the unique advantage of a shallower atmospheric pass which decreases the maximum heat load and the required TPS mass.

Danny N Nguyen↗
NASA NTRSDate not supplied

Orbit Determination For The James Webb Space Telescope During Launch And Early Orbit

The NASA James Webb Space Telescope (JWST) mission successfully launched on December 25, 2021, at 12:20 UTC. This paper details several novel challenges encountered in the orbit determination (OD) of JWST during the launch and early orbit. The first OD solution used only 6.5 hours of tracking data, much less than the 24 hours of data usually required for libration orbiters on an outbound trajectory. In addition, the observatory area exposed to solar radiation pressure changed through a series of sunshield deployments while concurrent momentum unloads and attitude telemetry outages occurred. This paper covers how the Flight Dynamics Team (FDT) prepared for these challenges, how these challenges were handled on-orbit, and the performance of the resulting OD solutions.

Orbit Determination↗
NASA NTRSDate not supplied

Feasibility and Performance Analysis of Magnetohydrodynamics Control for Aerocapture at Neptune

NASA’s most recent Decadal Survey posed a mission to one of the Ice Giants as the top priority for flagship missions in the organization’s future. However, current technologies limit the amount of scientific payload available for future Uranian and Neptunian missions due to the need for fuel for orbit insertion maneuvers. Thus, to maximize the scientific potential of future missions, atmospheric aerocapture has been heavily researched. While atmospheric aerocapture simulations have proven enabling for capturing around Neptune, its deep atmospheric pass requires an aeroshell with thermal protection systems(TPS). Magnetohydrodynamically-controlled aerocapture serves as a potential solution to both fully-propulsive orbit insertion and atmospheric aerocapture. Through NASA Langley’s high-fidelity flight dynamics simulation, the Program to Optimize Simulated Trajectories II, both the atmospheric and magnetohydrodynamic aerocapture methods were simulated and compared for identical missions to Neptune. After applying a guidance algorithm for both methods, the results showed that magnetohydrodynamics has not only the control authority to successfully capture around Neptune, but also the unique advantage of a shallower atmospheric pass which decreases the maximum heat load and the required TPS mass.

Danny Nguyen↗
NASA NTRSDate not supplied

Status of Venus Global Reference Atmospheric Model (Venus-GRAM) Upgrades

Venus-GRAM Overview - Engineering-oriented atmospheric model that estimates mean values and statistical variations of Venus atmospheric properties - Outputs include atmospheric density, temperature, pressure, chemical composition, and wind components along a user-defined path - Widely used by the engineering community because of its ability to create realistic atmospheric dispersions - Can be integrated into high fidelity flight dynamic simulations of launch, entry, descent and landing (EDL), aerobraking and aerocapture - Has been used in multiple studies and proposals including NASA Engineering and Safety Center (NESC) Autonomous Aerobraking Study and various Discovery proposals - Optional trajectory input file consisting of time, height, latitude, and longitude can be used to provide the Venus-GRAM trajectory path - Optional auxiliary profile consisting of height, latitude, longitude, temperature, pressure, density, eastward wind, and northward wind may be used to replace model data in Venus-GRAM - Not a forecast model - GRAMs are also available for Earth, Mars, Titan, Neptune, Uranus, and Jupiter - Available through the NASA Software Catalog https://software.nasa.gov/software/MFS-33888-1

atmospheric models↗
NASA NTRS2022

The Atmosphere-Space Transition Region Explorer (ASTRE) – A Low Perigee Satellite to Investigate the Coupling of the Earth’s Upper Atmosphere and Magnetosphere

The Atmosphere-Space Transition Region Explorer (ASTRE) is a mission concept designed to carry out an unprecedented study of the interaction between the Earth’s atmosphere and the ionized gases of space within the atmosphere-space transition region. By gathering direct measurements of the coupling of ion and neutral gases in this region, ASTRE provides the critical missing link in our knowledge of the transfer, dissipation, and regulation of energy and momentum between the sun and the upper atmosphere. ASTRE provides the first detailed, systematic investigation of this important unexplored region, vastly improves and constrains models of the upper atmosphere, and fills a critical gap in our understanding of how the coupled lower ionosphere/upper atmosphere “works” as a system. To achieve its science objectives, ASTRE gathers accurate measurements of plasma and neutral gases, electric and magnetic fields, and energetic particles using well-proven, in situ instruments with excellent flight heritage. Furthermore, as described herein, all the instruments have been designed to perform well in the low perigee environment, including altitudes of 150 km and lower. ASTRE utilizes a three-axis stabilized satellite that uses on-board propulsion to carry out systematic, low perigee measurements at high latitudes. The satellite design incorporates a “form follows function” approach with a cylindrical shape and conductive body-mounted solar arrays to minimize drag and perturbations to the space environment. Atomic-oxygen resistant materials are utilized and a passive thermal design with heat pipes and radiator panels minimizes the impact of aero-heating. ASTRE launches into a 250 km × 1500 km elliptical insertion orbit with an inclination of 83°. Perigee precesses from its highest northern latitude to its highest southern latitude every ~60 days. Hydrazine propulsion provides over 2000 orbits with perigee below 200 km, with a significant fraction as low as 150 km, during high latitude, two-week campaigns when perigee precesses to either the northern or southern high latitude region. At mid and low latitudes, the perigee is near 225 km. Because very conservative assumptions were made with respect to the orbital analysis and drag, including continuous 3-sigma “worst-case” solar flux and atmospheric density, when additional propellant is included (accommodated in the current design) and some of the stringent assumptions are relaxed, the ASTRE mission described herein may be expected to include repeated excursions to altitudes of ~130 km or even lower. This paper presents an overview of the ASTRE mission, its science motivation, and objectives. It includes a discussion of the science-driven requirements and traceability, followed by a “proof-of concept” implementation that includes notional instruments and a straightforward spacecraft design. Three key points are demonstrated: 1) There is a critical knowledge gap in the high latitude, atmosphere-space transition region below 250 km; 2) The instrument and measurement techniques needed to obtain the ASTRE measurements are well-proven and function well in the low-altitude environment; and 3) A mature spacecraft design, flight dynamics analysis, and concept of operations have been developed that demonstrate that the ASTRE mission can be achieved in a straightforward manner using current technologies.

Ionosphere↗
NASA NTRS2023

Risk Trade-Space Analysis for Safe Human Expeditions to Mars

We assessed the integrated safety, health, and performance risk to crews on long-duration missions, specifically to Mars. Using a systems approach rather than one focused on individual countermeasures, we examined the trade space around several such risks to identify high-potential risk mitigation strategies and characterize aspects of Mars mission architectures that could lower aggregated risk. Current Mars Design Reference missions would require durations well over two years and would increase crew exposure to radiation and microgravity well beyond ISS levels, likely resulting in significantly reduced performance beyond our current capability to mitigate that could jeopardize mission success. A “fast Mars transit” round-trip mission concept was studied using an innovative flight dynamics approach to quantify the minimum total mission energy required for a Mars transit with total mission duration less than 400 days. This approach holds promise for sending humans to Mars and returning them safely with acceptable, potentially mitigatable, exposure to microgravity and radiation using current or near-term technologies. The fast transit concept would also result in fewer time-driven vehicle failures and enable sustainable deployment of humans and infrastructure to Mars on a regular cadence, allowing steady exploration and colonization of Mars. Finally, we conclude that reliance on the Low Earth Orbit (LEO) mission operations paradigm – i.e., one of near-complete real-time dependence on experts at Mission Control to manage the combined state of the mission, vehicle, and crew – is high risk given the communication delays and limited resupply of any Mars mission, and this risk is not eliminated by the shorter missions durations of fast transit scenarios. Based on historical trends, it is highly likely that the crew will face a high-consequence problem of uncertain origin during Mars transit when ground support will be greatly reduced. While it may be possible to reduce anomaly rates through improved reliability analysis and testing, and to reduce anomaly impacts through added robustness, such mitigations address only known failure modes and known uncertainties. Therefore, a radical shift in the Human-Systems Integration Architecture (HSIA) that defines the operational paradigm, systems design, and human-systems interactions is required to improve the risk posture to an acceptable level regardless of mission duration.

Mars↗
NASA NTRSDate not supplied

Mars Sample Recovery Helicopter: Rotorcraft to Retrieve the First Samples from the Martian Surface

The Mars Sample Return Mission (MSR) will carry the next set of Mars helicopters, Sample Recovery Helicopters (SRHs), to the Martian surface. After successfully demonstrating extraterrestrial flight in 2021, Ingenuity has acted as a “scout” for the Perseverance rover while the rover gathers samples of Martian soil. In 2028, the MSR mission will launch a lander and two Ingenuity-sized SRHs to retrieve these samples. These will be the first samples of the Martian surface delivered to Earth. The SRH project will maintain heritage from Ingenuity’s design when possible. However, several key changes must be made, including a ground mobility system, a robotic arm for tube manipulation, and the ability to carry the weight of a science payload (the sample tubes). In addition, the onboard software and cameras will be upgraded, and the rotor radius will be increased. Furthermore, new rotor performance and flight dynamics models and thorough characterization of vehicle limits will be required. The new vehicle design will be described, as well as validation and verification efforts to date.

Rotorcraft↗
NASA NTRS2021

Mars 2020 Perseverance Entry Descent and Landing Simulation Statistical Analysis and Operations

On February 18, 2021, the Perseverance rover and Ingenuity helicopter demonstra- tion landed at Jezero Crater. The Entry, Descent, and Landing (EDL) architecture, largely the same used to land Curiosity at Gale Crater on August 6, 2012, required high-fidelity flight dynamics simulation with two independent tools to verify per- formance. The process for creating the EDL simulation using the Dynamics Sim- ulator for Entry, Descent and Surface landing (DSENDS) tool will be discussed, along with its use for for independent verification of the EDL statistical analy- sis results and reference trajectory simulation. Analysis and usage details both in development and cruise, along with post-landing assessment of the prediction performance of the simulation, will also be discussed.

"O'Farrell, Clara"↗
NASA NTRS2021

Mars 2020 Navigation Performance

On February 18, 2021, the Perseverance rover and Ingenuity helicopter demonstration landed at Jezero Crater. The Entry, Descent, and Landing (EDL) architecture, largely the same used to land Curiosity at Gale Crater on August 6, 2012, required high-fidelity flight dynamics simulation with two independent tools to verify performance. The process for creating the EDL simulation using the Dynamics Simulator for Entry, Descent and Surface landing (DSENDS) tool will be discussed, along with its use for for independent verification of the EDL statistical analysis results and reference trajectory simulation. Analysis and usage details both in development and cruise, along with post-landing assessment of the prediction performance of the simulation, will also be discussed.

Wagner, Sean↗
NASA NTRSDate not supplied

Laser Communications Relay Demonstration Optimetrics Experiment

Within this paper, we report on an Optimetrics experiment conducted on the National Aeronautics and Space Administration (NASA) Laser Communication Relay Demonstration (LCRD). The high precision two-way ranging is conducted on the optical communications link between the LCRD space terminal in a geosynchronous orbit and the Optical Ground Station 1 (OGS1) at Table Mountain, California, and is referred to as optimetrics ranging. The receiver to transmitter clock loopback is implemented in the LCRD space modem. A digital dual mixer time difference phase meter (DDMTD) is implemented in the OGS1 ground modem. The round-trip time is measured with the DDMTD by counting the frame and data clock ticks between transmitter and receiver frame synchronization markers for coarse range, and the relative phase of the transmit and receive clock for high precision range. This approach provides coverage for all potential ranges with no ranging ambiguity. The flight modem FPGA code was modified for frame and data clock loopback and the OGS1 FPGA code was modified for the DDMTD phase meter implementation. The experiment team conducted a 36-hour continuous ranging measurement. Preliminary two-way optimetrics ranging data show a noise floor of 3cm (rms). Based on our theoretical noise analysis and ground tests with spare flight modems, we expected one order of magnitude improvement on ranging precision. We are conducting detailed post data processing to identify the differences to further reduce the noise level and formulating an improved implementation approach for future missions. For reference and comparison, traditional Radio Frequency (RF) ranging between LCRD and OGS1 was conducted at the same time and indicates a ranging noise floor of 30cm(rms). Other telemetry and relevant environmental parameters such as weather and atmosphere temperature were also collected for offline data processing. The high precision ranging and range rate measurements from the laser communications data link clock and clock phase are performed simultaneously with continuous optical communication. No extra hardware added to existing system. This high precision optimetrics measurement implementation provides alternative ranging and range rate measurements for orbit determination (OD) and flight dynamics calculations with higher precision. We see significant improvement on OD for navigation upon implementation in future optical communication systems.

Rafael Garcia↗