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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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At least 109 records · Page 6

Analysis of Solar Wind Damage in Genesis Sapphire Sample 61527

The Genesis mission collected samples of the solar wind (SW) by passive implantation into a variety of semiconductor (and other) materials and re-turned them to Earth in 2004. Subsets of these col-lector materials were exposed to either bulk solar wind, high-speed (coronal hole) solar wind, low speed (inter-stream) solar wind, or coronal mass ejections (CMEs). Although of short duration relative to naturally space-weathered materials, these exposures to SW caused structural damage (and related chemical changes) in silicon. Here we explore the structural consequences of bulk SW collection into Genesis single crystal sapphire.

L P Keller↗

Genesis Solar Wind Sample Curation Facility

The controlled access facility designed and constructed for storing and examining Genesis solar wind samples consists of two adjacent laboratories, both ISO Class 4 cleanrooms (vertical laminar flow, ULPA filtered). One cleanroom is equipped with ultrapure water (UPW) for experimental cleaning of containers and tools used in handling the solar wind samples, flight hardware and witness plates. The ultrapure water is also used for cleaning the solar wind samples. The other cleanroom is for long-term nitrogen storage of samples and for examination and processing of Genesis samples.

Curation Facility↗

Genesis Solar Wind – Capture, Return, Curate and Analyze: Looking Backward Reviewing Sample Collection Hardware

Genesis, as the first U.S. spacecraft to return astromaterial samples since Apollo, not only integrated the mission planning and flight teams, but also the science and sample curation teams during the mission development period. Since Genesis is a sample return mission, the Science Team was essential in certifying the collectors (sample containers for solar atoms). Burnett and the science team defined the purity of collector materials and ability to analyze solar wind composition to the precision required for planetary science. The science team’s choices included a variety of very pure materials which are described, including rationale for selection. The JPL Project Scientist networked with specialty vendors refining specifications and fabricating several of the materials. JPL engineering team designed and fabricated the collector arrays. LANL designed and built an electrostatic concentrator. JSC procured these materials with exacting specifications.

SOLAR WIND↗

Genesis Halo Orbit Station Keeping Design

As the fifth mission of NASA's Directory Program, Genesis is designed to collect solar wind samples for approximately two years in a halo orbit near the Sun-Earth L(sub 1) Lagrange point for return to the Earth.

Genesis Mission Design↗

The NASA Discovery 5, Genesis Mission

Genesis is the NASA Discovery 5 mission to solar wind return samples to the Earth for analyses in terrestrial laboratories. This will significantly increase our knowledge of the chemical and isotopic composition of the solar system.

sample return Genesis NASA Discovery 5 solar wind↗

The Genesis Trajectory and Heteroclinic Cycles

The Genesis Mission will be NASA's first robotic sample return mission. The purpose of this mission is to collect solar wind samples for two years in L1 halo orbit and return it to the Utah Test and Training Range (UTTR) for mid-air retrieval by helicopters.

Genesis Halo Orbit Sample Return periodic orbits a↗

A Genesis breakup and burnup analysis in off-nominal Earth return and atmospheric entry

The Genesis project conducted a detailed breakup/burnup analysis before the Earth return to determine if any spacecraft component could survive and reach the ground intact in case of an off-nominal entry. In addition, an independent JPL team was chartered with the responsibility of analyzing several definitive breakup scenarios to verify the official project analysis. This paper presents the analysis and results of this independent team.

off-nominal entry↗

Prototype maneuver decomposition algorith for genesis

This paper addresses a prototype of a maneuver decomposition algorithm developed by the Genesis Navigation Team at JPL. The algorithm described herein is an early prototype designed to support navigation analyses and to provide the basis for later development of operational software by the Spacecraft Team. The basis algorithm is applicable to any spin-stabilized spacecraft with axisymmetric thrusters.

Genesis↗

Genesis Trajectory Design

The Genesis mission will launch in 2001, sending a spacecraft into an L1 halo orbit in the Sun-Earth system to collect solar wind samples.

Genesis↗

Genesis Mission Design

The Genesis spacecraft will collect solar wind samples from a halo orbit about the Sun-Earth L1 point for two years, returning those samples to Earth in 2003 for on-Earth analysis and examination.

Genesis↗

Pterodactyl: 6-DOF Integration of Guidance and Control Algorithms in Genesis

The NASA-funded Pterodactyl project seeks to advance the current state-of-the-art for entry vehicles by developing novel guidance and control technologies for Deployable Entry Vehicles. This paper builds upon the Pterodactyl architecture that employed eight individually articulating flaps with two options for guidance, bank angle modulation with the Fully Numerical Predictor Corrector Entry Guidance (FNPEG) technique and angle of attack and sideslip modulation with FNPEG uncoupled range control. These, with a linear quadratic regulator controller, have previously been presented in separate 3-DOF trajectory simulations, one for translational motion and another for rotational dynamics. This work will show results for integrated 6-DOF simulations, leveraging recent advancements in trajectory simulation tools, namely the Julia-based Genesis package. Results show similar performance for both schemes when compared to the previously presented 3-DOF results once the controllers were adequately tuned. Angle of attack and sideslip modulation necessitated a controller designed at high dynamic pressure conditions, and bank angle modulation necessitated a controller designed at lower dynamic pressure conditions. Notably, angle of attack and sideslip modulation could not achieve the parachute deploy point target Mach number of 2, when only tuning the controller gains, thus future work will be needed to tune guidance specific parameters to achieve acceptable range targeting and guidance command tracking.

DEV↗

Pterodactyl: 6-DOF Integration of Guidance and Control Algorithms in Genesis

The NASA-funded Pterodactyl project seeks to advance the current state-of-the-art for entry vehicles by developing novel guidance and control technologies for Deployable Entry Vehicles. This paper builds upon the Pterodactyl architecture that employed eight individually articulating flaps with two options for guidance, bank angle modulation with the Fully Numerical Predictor Corrector Entry Guidance (FNPEG) technique and angle of attack and sideslip modulation with FNPEG uncoupled range control. These, with a linear quadratic regulator controller, have previously been presented in separate 3-DOF trajectory simulations, one for translational motion and another for rotational dynamics. This work will show results for integrated 6-DOF simulations, leveraging recent advancements in trajectory simulation tools, namely the Julia-based Genesis flight simulation tool. Results show similar performance for both schemes when compared to the previously presented 3-DOF results once the controllers were adequately tuned. Angle of attack and sideslip angle modulation necessitated a controller designed at high dynamic pressure conditions, and bank angle modulation necessitated a controller designed at lower dynamic pressure conditions. Notably, the angle of attack and sideslip modulation approach could not achieve the parachute deploy point target Mach number of 2, when only tuning the controller gains, so future work will be needed to improve guidance and control tracking.

EDL↗

Perturbative unitarity and NEC violation in genesis cosmology

Explorations of the violation of null energy condition (NEC) in cosmology could enrich our understanding of the very early universe and the related gravity theories. Although a fully stable NEC violation can be realized in the “beyond Horndeski” theory, it remains an open question whether a violation of the NEC is allowed by some fundamental properties of UV-complete theories or the consistency requirements of effective field theory (EFT). We investigate the tree-level perturbative unitarity for stable NEC violations in the contexts of both Galileon and “beyond Horndeski” genesis cosmology, in which the universe is asymptotically Minkowskian in the past. We find that the constraints of perturbative unitarity imply that we may need some unknown new physics below the cut-off scale of the EFT other than that represented by the “beyond Horndeski” operators.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Genesis and Propagation of Fractal Structures During Photoelectrochemical Etching of n-Silicon

The genesis, propagation, and dimensions of fractal-etch patterns that form anodically on front- or back-illuminated n-Si(100) photoelectrodes in contact with 11.9 M NH 4 F (aqueous) have been investigated during either a linear potential sweep or a constant potential hold ( E = +6.0 V versus Ag/AgCl). Optical images collected in situ during electrochemical experiments reflected the location and underlying mechanism of initiation and propagation of the structures on the surface. X-ray photoelectron spectroscopic (XPS) data collected for samples emersed from the electrolyte at varied times provided detailed information about the chemistry of the surface during fractal etching. The fractal structure was strongly influenced by the orientation of the crystalline Si sample. Furthermore, the etch patterns were initially generated at points along the circumference of bubbles that formed upon immersion of n-Si(100) samples in the electrolyte, most likely due to the electrochemical and electronic isolation of areas beneath bubbles. XPS data showed the presence of a tensile-stressed silicon surface throughout the etching process as well as the presence of SiO x F y on the surface. The two-dimensional fractal dimension, D f,2D , of the patterns increased with etching time to a maximum observed value of D f,2D = 1.82. Promotion of fractal etching near etch masks that electrochemically and electronically isolated areas of the photoelectrode surface enabled the selective placement of highly branched structures at desired locations on an electrode surface.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗