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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Sliding GAIT Algorithm for the All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE)

The design of a surface robotic system typically involves a trade between the traverse speed of a wheeled rover and the terrain-negotiating capabilities of a multi-legged walker. The ATHLETE mobility system, with both articulated limbs and wheels, is uniquely capable of both driving and walking, and has the flexibility to employ additional hybrid mobility modes. This paper introduces the Sliding Gait, an intermediate mobility algorithm faster than walking with better terrain-handling capabilities than wheeled mobility.

terrain anomaly↗
NASA NTRS2012

Direct Imaging of Extra-Solar Planets in Star Forming Regions: Lessons Learned from a False Positive Around IM Lup

Context. Most exoplanet imagers consist of ground-based adaptive optics coronagraphic cameras which are currently limited in contrast, sensitivity and astrometric precision, but advantageously observe in the near-infrared window (1 5 m). Because of these practical limitations, our current observational aim at detecting and characterizing planets puts heavy constraints on target selection, observing strategies, data reduction, and follow-up. Most surveys so far have thus targeted young systems (1 100 Myr) to catch the putative remnant thermal radiation of giant planets, which peaks in the near-infrared. They also favor systems in the solar neighborhood (d less than 80 pc), which eases angular resolution requirements but also ensures a good knowledge of the distance and proper motion, which are critical to secure the planet status, and enable subsequent characterization. Aims. Because of their youth, it is very tempting to target the nearby star forming regions, which are typically twice as far as the bulk of objects usually combed for planets by direct imaging. Probing these interesting reservoirs sets additional constraints that we review in this paper by presenting the planet search that we initiated in 2008 around the disk-bearing T Tauri star IM Lup, which is part of the Lupus star forming region (140-190 pc). Methods. We show and discuss why age determination, the choice of evolutionary model for both the central star and the planet, precise knowledge of the host star proper motion, relative or absolute (between different instruments) astrometric accuracy (including plate scale calibration), and patience are the key ingredients for exoplanet searches around more distant young stars. Results. Unfortunately, most of the time, precision and perseverance are not paying off: we discovered a candidate companion around IM Lup in 2008, which we report here to be an unbound background object. We nevertheless review in details the lessons learned from our endeavor, and additionally present the best detection limits ever calculated for IM Lup. We also accessorily report on the successful use of innovative data reduction techniques, such as the damped-LOCI and iterative roll subtraction.

D Mawet↗
NASA NTRS2015

Advanced Extra-Vehicular Activity Pressure Garment Requirements Development

The NASA Johnson Space Center advanced pressure garment technology development team is addressing requirements development for exploration missions. Lessons learned from the Z-2 high fidelity prototype development have reiterated that clear low-level requirements and verification methods reduce risk to the government, improve efficiency in pressure garment design efforts, and enable the government to be a smart buyer. The expectation is to provide requirements at the specification level that are validated so that their impact on pressure garment design is understood. Additionally, the team will provide defined verification protocols for the requirements. However, in reviewing exploration space suit high level requirements there are several gaps in the team's ability to define and verify related lower level requirements. This paper addresses the efforts in requirement areas such as mobility/fit/comfort and environmental protection (dust, radiation, plasma, secondary impacts) to determine the method by which the requirements can be defined and use of those methods for verification. Gaps exist at various stages. In some cases component level work is underway, but no system level effort has begun; in other cases no effort has been initiated to close the gap. Status of on-going efforts and potential approaches to open gaps are discussed.

Ross, Amy↗
NASA NTRS2016

Experiences with Extra-Vehicular Activities in Response to Critical ISS Contingencies

Initial "Big 14" work was put to the test for the first time in 2010. Deficiencies were found in some of the planning and approaches to that work; Failure Response Assessment Team created in 2010 to address deficiencies -Identify and perform engineering analysis in operations products prior to failure; incorporate results into operations products -Identify actions for protecting ISS against a Next Worse Failure after the first failure occurs -Better document not only EVA products but also planning products, assumptions, and open actions; Pre-failure investments against critical failures best postures ISS for swift response and recovery -A type of insurance policy -Has proven effective in a number of contingency EVA cases since 2010. Planning for MBSU R&R in 2012, Second PM R&R in 2013, EXT MDM R&R in 2014; Current FRAT schedule projects completion of all analysis in 2018

Van Cise, Edward A.↗
NASA NTRS2017

Thermal Design for Extra-Terrestrial Regenerative Fuel Cell System

The Advanced Exploration Systems (AES) Advanced Modular Power Systems (AMPS) Project is investigating different power systems for various lunar and Martian mission concepts. The AMPS Fuel Cell (FC) team has created two system-level models to evaluate the performance of regenerative fuel cell (RFC) systems employing different fuel cell chemistries. Proton Exchange Membrane fuel cells PEMFCs contain a polymer electrolyte membrane that separates the hydrogen and oxygen cavities and conducts hydrogen cations (protons) across the cell. Solid Oxide fuel cells (SOFCs) operate at high temperatures, using a zirconia-based solid ceramic electrolyte to conduct oxygen anions across the cell. The purpose of the modeling effort is to down select one fuel cell chemistry for a more detailed design effort. Figures of merit include the system mass, volume, round trip efficiency, and electrolyzer charge power required. PEMFCs operate at around 60 C versus SOFCs which operate at temperatures greater than 700 C. Due to the drastically different operating temperatures of the two chemistries the thermal control systems (TCS) differ. The PEM TCS is less complex and is characterized by a single pump cooling loop that uses deionized water coolant and rejects heat generated by the system to the environment via a radiator. The solid oxide TCS has its own unique challenges including the requirement to reject high quality heat and to condense the steam produced in the reaction. This paper discusses the modeling of thermal control systems for an extraterrestrial RFC that utilizes either a PEM or solid oxide fuel cell.

thermal modeling↗
NASA NTRS2019

Boom Retraction Mechanism as Part of Sample Acquisition System from Remote and Hazardous Extra-Terrestrial Sites

This paper discusses the development of a mechanism as part of a comet sampling system. The mechanism, known by the acronym BRAD for Boom Retraction and Deployment, is part of a mission proposal to return a comet regolith sample to earth. The mission proposal; CORSAIR for Comet Rendezvous, Sample Acquisition, Investigation, and Return, was coordinated by Johns Hopkins Applied Physics Lab in Laurel, MD as a response to the NASA 2017 New Frontiers AO or Announcement of Opportunity. BRAD functions as a means to tend and control a deployable boom that connects a sample projectile to the spacecraft.

Comet Sample Acquisition Mechanism↗
NASA NTRSDate not supplied

Liquefaction of Cryogenic Fluids for Production and Storage of Commodities on Extra-Terrestrial Surfaces

The Cryogenic Fluid In-situ Liquefaction for Landers (CryoFILL) activity has been investigating concepts for the liquefaction of cryogenic fluids produced on the surface of the Moon and Mars. CryoFILL consists of four activities: liquid nitrogen liquefaction testing that was completed in 2019, liquid oxygen liquefaction testing planned to begin in early 2022, fiber-optic sensor temperature measurement system development, and lightweight vacuum jacketed systems designed for the atmosphere of Mars. Additional activities include the development and validation of numerical modeling systems at three stages: thermodynamic models of the liquefaction process for basic energy/mass estimates, nodal models to predict liquefaction tank system level performance, and computational fluid dynamics to assess fluid phenomena occurring within the tank, specifically condensation and stratification within the ullage. These developments form a combined liquefaction and storage solution to support Lunar and Martian exploration. Key testing results from liquid nitrogen testing as well as plans for liquid oxygen testing will be discussed including key sensitivities from analytical evaluation of completed test results. Progress on the development and improvements on fiber optic sensor testing and developments will also be provided. Finally, work on the progress of the lightweight vacuum jacketed systems being co-developed by NASA and industry will be summarized.

Liquefaction↗
NASA NTRS2022

Water Quality Contamination Sources and Controls for the Exploration Extra-vehicular Mobility Unit (xEMU)

NASA has been developing a new spacesuit, called the Exploration Extravehicular Mobility Unit (xEMU) for over a decade. This spacesuit is underdevelopment to support missions to the International Space Station (ISS) and also to the Moon. The xEMU uses controlled evaporative cooling through a membrane to reject waste heat from the crewmember, avionics, and environmental in-leak during autonomous operation. Given the unique mass and volume constraints imposed by the spacesuit application and the opportunities presented by the selection of a given membrane, the xEMU does not possess a separate feedwater loop to feed the evaporation process, rather the feedwater for the evaporation process is fed directly from the transport loop which collects heat from the sources within the suit. This has many benefits including mass/volume reductions from a lower component count within the system but does pose some additional potential constraints on water quality within the system in order to provide a working fluid that can be pumped, filtered, and used in contact with the remainder of the system while both avoiding fouling of the membrane as well as other deleterious effects such as creating conditions for corrosion of wetted surfaces within the transport loop. The discussion will seek to address the main sources of contamination and the applied controls. Sources considered will include: self-generated via materials selection and processes applied, influent working fluid, contamination of the influent working fluid via Ground Support Equipment (GSE) or processing equipment, microbial activity, and environmental influences such as elevated ambient CO2.

Colin Campbell↗