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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Dust Mitigation for Mars Solar Arrays

Settling of atmospheric dust onto the surface of the solar array is potentially a lifetime-limiting factor for a power system on any Mars mission. For long-term operation of arrays on Mars, it will be necessary to develop techniques to remove deposited dust. Dust is expected to adhere to the array by Van der Waals adhesive forces. These forces are quite strong at the dust particle sizes expected. Dust removal methods must overcome this force. Removal methods can be categorized briefly into four categories: natural, mechanical, electromechanical, and electrostatic. The environment of Mars is expected to be an ideal one for use of electrostatic dust-removal techniques.

Landis, Geoffrey A.↗
NASA NTRS2012

Sonic Boom Mitigation Through Aircraft Design and Adjoint Methodology

This paper presents a novel approach to design of the supersonic aircraft outer mold line (OML) by optimizing the A-weighted loudness of sonic boom signature predicted on the ground. The optimization process uses the sensitivity information obtained by coupling the discrete adjoint formulations for the augmented Burgers Equation and Computational Fluid Dynamics (CFD) equations. This coupled formulation links the loudness of the ground boom signature to the aircraft geometry thus allowing efficient shape optimization for the purpose of minimizing the impact of loudness. The accuracy of the adjoint-based sensitivities is verified against sensitivities obtained using an independent complex-variable approach. The adjoint based optimization methodology is applied to a configuration previously optimized using alternative state of the art optimization methods and produces additional loudness reduction. The results of the optimizations are reported and discussed.

Rallabhandi, Siriam K.↗
NASA NTRS2008

Field Testing of High Current Electrokinetic Nanoparticle Treatment for Corrosion Mitigation in Reinforced Concrete

This work examines field performance of nanoscale pozzolan treatments delivered el ctrokinetically to suppress chloride induced corrosion of concrete reinforcement. The particles are 20 nm silica spheres coated with 2 nm alumina particles that carry a net positive charge. Earlier work demonstrated that the alumina particles were stripped from the silica carriers and formed a dense phase with an interparticle spacing that is small enough to inhibit the transport of solvated chlorides. A D.C. field was used to inject the particles into the pores of concrete specimens, directly toward the mild steel bars that were embedded within each 3 inch diameter by 6 inch length concrete specimen. The voltage was held constant at 25 v per inch of concrete cover for a period of 7 days. These voltages permitted current densities as high as 3 A/sq m. During the final 3 days, a 1 molar solution of calcium nitrate tetrahydrate was used to provide a source of calcium to facilitate stronger and more densified phase formation within the pores. In a departure from prior work the particle treatments were started concurrent with chloride extraction in order to determine if particle delivery would inhibit chloride transport. Following treatment the specimens were immersed in seawater for 4 weeks. After this posttreatment exposure, the specimens were tested for tensile strength and the steel reinforcement was examined for evidence of corrosion. Scanning electron microscopy was conducted to assess impact on microstructure.

Calle, Luz Marina↗
NASA NTRS2013

Space Launch System (SLS) Safety, Mission Assurance, and Risk Mitigation

SLS Driving Objectives: I. Safe: a) Human-rated to provide safe and reliable systems for human missions. b) Protecting the public, NASA workforce, high-value equipment and property, and the environment from potential harm. II. Affordable: a) Maximum use of common elements and existing assets, infrastructure, and workforce. b) Constrained budget environment. c) Competitive opportunities for affordability on-ramps. III. Sustainable: a) Initial capability: 70 metric tons (t), 2017-2021. 1) Serves as primary transportation for Orion and exploration missions. 2) Provides back-up capability for crew/cargo to ISS. b) Evolved capability: 105 t and 130 t, post-2021. 1) Offers large volume for science missions and payloads. 2) Modular and flexible, right-sized for mission requirements.

May, Todd↗
NASA NTRS2013

Progress in Payload Separation Risk Mitigation for a Deployable Venus Heat Shield

A deployable decelerator known as the Adaptive Deployable Entry and Placement Technology (ADEPT) offers substantial science and mass savings for the Venus In Situ Explorer (VISE) mission. The lander and science payload must be separated from ADEPT during atmospheric entry. This paper presents a trade study of the separation system concept of operations and provides a conceptual design of the baseline: aft-separation with a subsonic parachute. Viability of the separation system depends on the vehicle's dynamic stability characteristics during deceleration from supersonic to subsonic speeds. A trajectory sensitivity study presented shows that pitch damping and Venusian winds drive stability prior to parachute deployment, while entry spin rate is not a driver of stability below Mach 5. Additionally, progress in free-flight CFD techniques capable of computing aerodynamic damping parameters is presented. Exploratory simulations of ADEPT at a constant speed of Mach number of 0.8 suggest the vehicle may have an oscillation limit cycle near 5 angle-of-attack. The proposed separation system conceptual design is thought to be viable.

Smith, Brandon P.↗
NASA NTRS2013

Orion GN and C Mitigation Efforts for Van Allen Radiation

The Orion Crew Module (CM) is NASA's next generation manned space vehicle, scheduled to return humans to lunar orbit in the coming decade. The Orion avionics and GN&C architectures have progressed through a number of project phases and are nearing completion of a major milestone. The first unmanned test mission, dubbed "Exploration Flight Test One" (EFT-1) is scheduled to launch from NASA Kennedy Space Center late next year and provides the first integrated test of all the vehicle systems, avionics and software.

King, Ellis T.↗
NASA NTRS2013

Mitigation of Autoignition Due to Premixing in a Hypervelocity Flow Using Active Wall Cooling

Preinjection of fuel on the forebody of an airbreathing vehicle is a proposed method to gain access to hypervelocity flight Mach numbers. However, this creates the possibility of autoignition either near the wall or in the core of the flow, thereby consuming fuel prematurely as well as increasing the amount of pressure drag on the vehicle. The computational fluid dynamics code VULCAN was used to conduct three dimensional simulations of the reacting flow in the vicinity of hydrogen injectors on a flat plate at conditions relevant to a Mach 12 notional flight vehicle forebody to determine the location where autoignition occurs. Active wall cooling strategies were formulated and simulated in response to regions of autoignition. It was found that tangential film cooling using hydrogen or helium were both able to nearly or completely eliminate wall autoignition in the flow domain of interest.

Axdahl, Erik↗
NASA NTRS2014

Electric Vehicle Charging Stations as a Climate Change Mitigation Strategy

In order to facilitate the use of electric vehicles at NASA Langley Research Center (LaRC), charging stations should be made available to LaRC employees. The implementation of charging stations would decrease the need for gasoline thus decreasing CO2 emissions improving local air quality and providing a cost savings for LaRC employees. A charging station pilot program is described that would install stations as the need increased and also presents a business model that pays for the electricity used and installation at no cost to the government.

Cave, Bridget↗
NASA NTRS2014

Plume Mitigation for Mars Terminal Landing: Soil Stabilization Project

Kennedy Space Center (KSC) has led the efforts for lunar and Martian landing site preparation, including excavation, soil stabilization, and plume damage prediction. There has been much discussion of sintering but until our team recently demonstrated it for the lunar case there was little understanding of the serious challenges. Simplistic sintering creates a crumbly, brittle, weak surface unsuitable for a rocket exhaust plume. The goal of this project is to solve those problems and make it possible to land a human class lander on Mars, making terminal landing of humans on Mars possible for the first time.

Technology Portfolio System↗
NASA NTRS2014

Middle Man Concept for In-Orbit Collision Risks Mitigation, CAESAR and CARA Examples

This paper describes the conjunction analysis which has to be performed using data provided by JSpOC. This description not only demonstrates that Collision Avoidance is a 2- step process (close approach detection followed by risk evaluation for collision avoidance decision) but also leads to the conclusion that there is a need for a Middle Man role. After describing the Middle Man concept, this paper introduces two examples with their similarities and particularities: the American civil space effort delivered by the NASA CARA team (Conjunction Assessment Risk Analysis) and the French response CAESAR (Conjunction Assessment and Evaluation Service: Alerts and Recommendations). For both, statistics are presented and feedbacks discussed. All together, around 80 satellites are served by CARA and/or CAESAR. Both processes regularly evolve in order either to follow JSpOC upgrades or to improve analysis according to experience acquired during the past years.

conjunction↗
NASA NTRS2014

Plume Mitigation: Soil Erosion and Lunar Prospecting Sensor Project

Demonstrate feasibility of the simplest, lowest-mass method of measuring density of a cloud of lunar soil ejected by rocket exhaust, using new math techniques with a small baseline laser/camera system. Focus is on exploring the erosion process that occurs when the exhaust plume of a lunar rocket impacts the regolith. Also, predicting the behavior of the lunar soil that would be blasted from a lunar landing/launch site shall assist in better design and protection of any future lunar settlement from scouring of structures and equipment. NASA is gathering experimental data to improve soil erosion models and understand how lunar particles enter the plume flow.

TechPort↗