SEARCH · Search NASA

Results for “low - thrust mission trade studies”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6

All sources NASA NTRS DOE OSTI

NASA NTRSDate not supplied

NASA Near Earth Network (NEN) DVB-S2 Demonstration Testing for Enhancing Higher Data Rates for CubeSat/Small Satellite Missions at X-/Ka-band

National Aeronautics and Space Administration (NASA) CubeSat/SmallSat missions are moving to higher data rates. Digital Video Broadcast, Satellite Second Generation (DVB-S2) is a communications standard that uses power and bandwidth efficient modulation and coding techniques to deliver performance approaching radio frequency (RF) channel theoretical limits. The Near Earth Network (NEN) will test DVB-S2’s ability to provide higher data rates for CubeSat/SmallSat missions at X-band and Ka-band at Wallops Flight Facility (WFF). The goal is to upgrade the NEN with DVB-S2 to increase science data return for missions and enable support for more CubeSat/SmallSat missions. This paper describes NEN DVB-S2 X-band and Ka-band demonstration objectives, scope, and performance measures as well as NEN channel test configuration. The NEN has planned 2020 tests to demonstrate all modulation and coding schemes in the Consultative Committee for Space Data Systems (CCSDS) DVB-S2 standard over X-band and Ka-band. A link analysis study for the trade-offs among achievable data rates, modulations, codes, spacecraft antenna sizes and power amplifiers (PA) is provided. This paper identifies Commercial off-the-shelf (COTS) CubeSat/SmallSat X-band and Ka-band communication systems and discusses low cost DVB-S2 X-band software defined radio (SDR) transmitter development concepts and implementation with a practical system for CubeSats/SmallSats.

Yen Wong↗

NASA NTRS2016

Transition-Edge Sensor Pixel Parameter Design of the Microcalorimeter Array for the X-Ray Integral Field Unit on Athena

The focal plane of the X-ray integral field unit (X-IFU) for ESA's Athena X-ray observatory will consist of approximately 4000 transition edge sensor (TES) x-ray microcalorimeters optimized for the energy range of 0.2 to 12 kiloelectronvolts. The instrument will provide unprecedented spectral resolution of approximately 2.5 electronvolts at energies of up to 7 kiloelectronvolts and will accommodate photon fluxes of 1 milliCrab (90 counts per second) for point source observations. The baseline configuration is a uniform large pixel array (LPA) of 4.28 arcseconds pixels that is read out using frequency domain multiplexing (FDM). However, an alternative configuration under study incorporates an 18 by × 18 small pixel array (SPA) of 2 arcseconds pixels in the central approximately 36 arcseconds region. This hybrid array configuration could be designed to accommodate higher fluxes of up to 10 milliCrabs (900 counts per second) or alternately for improved spectral performance (less than 1.5 electronvolts) at low count-rates. In this paper we report on the TES pixel designs that are being optimized to meet these proposed LPA and SPA configurations. In particular we describe details of how important TES parameters are chosen to meet the specific mission criteria such as energy resolution, count-rate and quantum efficiency, and highlight performance trade-offs between designs. The basis of the pixel parameter selection is discussed in the context of existing TES arrays that are being developed for solar and x-ray astronomy applications. We describe the latest results on DC biased diagnostic arrays as well as large format kilo-pixel arrays and discuss the technical challenges associated with integrating different array types on to a single detector die.

Smith, S. J.↗

NASA NTRS1983

Thermal-protection requirements for near-earth aero-assisted orbital-transfer vehicle missions

The thermal protection required for decelerating and maneuvering spacecraft by aerodynamic forces is determined for return missions from geosynchronous to low-earth orbits. The effect of vehicle configuration on surface heating rates and selection of heat-shield materials is analyzed. Effects of the current widespread estimates in the structure of atmospheric density are also evaluated. It is shown that nonequilibrium radiation can be a major source of surface heating during atmospheric entry and a significant factor to heat-shielding requirements. It is also demonstrated that drag-brake concepts have application to a broad range of orbital-transfer missions, because of the favorable trade-offs with aeromaneuvering vehicles in volumetric efficiency, retrothrust plane-change capability, and heat-protection requirements. In addition, the results of this study indicate that the aero-assist technique produces small penalties in vehicle payload capacity for drag-brake concepts, because of the system's heat protection requirements, and is highly attractive relative to all-propulsive orbital-change maneuvers.

Menees, G. P.↗

NASA NTRS2010

Constellation Probabilistic Risk Assessment (PRA): Design Consideration for the Crew Exploration Vehicle

Managed by NASA's Office of Safety and Mission Assurance, a pilot probabilistic risk analysis (PRA) of the NASA Crew Exploration Vehicle (CEV) was performed in early 2006. The PRA methods used follow the general guidance provided in the NASA PRA Procedures Guide for NASA Managers and Practitioners'. Phased-mission based event trees and fault trees are used to model a lunar sortie mission of the CEV - involving the following phases: launch of a cargo vessel and a crew vessel; rendezvous of these two vessels in low Earth orbit; transit to th$: moon; lunar surface activities; ascension &om the lunar surface; and return to Earth. The analysis is based upon assumptions, preliminary system diagrams, and failure data that may involve large uncertainties or may lack formal validation. Furthermore, some of the data used were based upon expert judgment or extrapolated from similar components~systemsT. his paper includes a discussion of the system-level models and provides an overview of the analysis results used to identify insights into CEV risk drivers, and trade and sensitivity studies. Lastly, the PRA model was used to determine changes in risk as the system configurations or key parameters are modified.

Prassinos, Peter G.↗

NASA NTRS1998

Evaluation of Some Candidate Propulsion Technologies for Mars Ascent Vehicle

A Mars ascent propulsion system trade study was conducted to determine 1) what propulsion technologies allow a Mars sample return mission to be launched on a Delta III class launch verhicle, and 2) whether more exotic technologies, such as in-situ propellant production, allow major cost savings by enabling the use of a smaller launch vehicle or a direct return from the Martian surface to Earth without the need of a rendezvous in the Martian orbit.

lightweight components↗

NASA NTRS2006

Reduced Pressure Atmosphere Impacts on Life Support and Internal Thermal Systems

Selecting the appropriate atmosphere for a spacecraft and mission is a complicated problem. NASA has previously used atmospheres from Earth normal composition and pressure to pure oxygen at low pressures. Future exploration missions will likely strike a compromise somewhere between the two, trying to balance operation impacts on EVA, safety concerns for flammability and health risks, life science and physiology questions, and other issues. Life support systems and internal thermal control systems are areas that will have to respond to changes in the atmospheric composition and pressure away from the Earthlike conditions currently used on the International Space Station. This paper examines life support and internal thermal control technologies currently in use or in development to find what impacts in design, efficiency and performance, or feasibility might be expected. Understanding these changes should be helpful in producing better results during future trade studies or mission analyses.

Anderson, Molly↗

NASA NTRS2010

Altair Lander Life Support: Design Analysis Cycles 4 and 5

Life support systems are a critical part of human exploration beyond low earth orbit. NASA s Altair Lunar Lander team is pursuing efficient solutions to the technical challenges of human spaceflight. Life support design efforts up through Design Analysis Cycle (DAC) 4 focused on finding lightweight and reliable solutions for the Sortie and Outpost missions within the Constellation Program. In DAC-4 and later follow on work, changes were made to add functionality for new requirements accepted by the Altair project, and to update the design as knowledge about certain issues or hardware matured. In DAC-5, the Altair project began to consider mission architectures outside the Constellation baseline. Selecting the optimal life support system design is very sensitive to mission duration. When the mission goals and architecture change several trade studies must be conducted to determine the appropriate design. Finally, several areas of work developed through the Altair project may be applicable to other vehicle concepts for microgravity missions. Maturing the Altair life support system related analysis, design, and requirements can provide important information for developers of a wide range of other human vehicles.

Anderson, Molly↗

NASA NTRS2011

Altair Lander Life Support: Design Analysis Cycles 4 and 5

Anderson, Molly↗

NASA NTRS2014

BioSentinel: Enabling CubeSat-Scale Biogical Research Beyond Low Earth Orbit

The introduction of the Space Launch System will provide NASA with a new means of access to space beyond low Earth orbit (LEO), creating opportunities for scientific research in a range of spacecraft sizes. This presentation describes the preliminary design of the BioSentinel spacecraft, a CubeSat measuring 10cm x 20cm x 30cm, which has been manifested for launch on the maiden voyage of the Space Launch System in 2017. BioSentinel will provide the first direct experimental data from a biological study conducted beyond LEO in over forty years, which in turn will help to pave the way for future human exploration missions. The combination of an advanced biology payload with standard spacecraft bus components required for operation in deep space within a CubeSat form factor poses a unique challenge, and this paper will describe the early design trades under consideration. The baseline spacecraft design calls for the biology payload to occupy four cube-units of volume (denoted 4U), with all spacecraft bus components occupying the remaining 2U.

Space Biology↗

NASA NTRS2019

Innovative Approaches to Using the International Space Station as a Mars Transit Analog

Human research on the International Space Station (ISS) crew has made significant advances in understanding of the effects of physiology on human health in space missions. However, ISS has not been as suitable for research on other hazards of human spaceflight such as isolation and communications delay. NASA recently completed a special assessment of whether modifications could be made to operations or facilities so that ISS could be used more effectively as an analog to simulate long-duration crew missions beyond low earth orbit. A cross-disciplinary team met to identify concept of operations, trade spaces, challenges, and opportunities to making ISS more operationally relevant as a Mars transit mission analog, and the results and implementation plans are summarized in this manuscript. In addition to the use case of 12-month missions (already in planning by the NASA ISS Program to bound expected Mars transit durations), three new use cases where ISS could provide valuable high-fidelity experience were identified. (1) Testing of operations procedures and medical care could be enhanced by demonstrating crew handling a simulated medical event in microgravity, autonomously, and with significant communications delay. (2) Isolation and confinement effects of deep space transit could be studied on ISS to validate current habitable volume requirements for Mars transit as well as provide context for evaluating the results of the extensive ground-based simulations in HERA and NEK. A trade study of possible operational and hardware changes that would make ISS applicable to these use cases was completed. (3) Surface operations after the physiological deconditioning of a long transit could be conducted to validate crew ability to perform critical ground tasks after 6-month Mars transit and aid in conceptual design of Mars surface element architectures. Each of the case studies includes a trade space between operational impacts on nominal ISS activities and degree of fidelity. A phased approach to implementation means that several "quick start" activities can be done in 2019-2020 at the same time as planning continues for more complex exploration analog options beginning as early as 2022. The team determined that many of these quick-start tasks could be done with available assets, entirely independent of other exploration system development timelines (such as Orion, Space Launch System). The consideration of the full suite of human spaceflight capabilities in the lunar vicinity can also be included as each step in human exploration serves as a simulation opportunity for some aspect of subsequent missions. Further discussions of options with the international community are critical for considering the benefits as well as impacts of simulation activities on ISS, as well as to better formulate future mission architectures.

Robinson, Julie A.↗

NASA NTRSDate not supplied

Pressurized Rover Lunar Surface Windows Thermal Trade Study

The pressurized rover (PR) is a habitable lunar vehicle that supports up to two crew members and EVAs. The PR is expected to operate with a crew at the lunar south pole for up to 30 consecutive days. Lunar surface missions represent a significant thermal challenge due in part to the extreme changes in temperature environment. Minimizing heat leaks is essential to be able to survive cold phases of lunar surface missions. Windows in particular can be a significant source of heat leak when designed without thermal performance in mind. In addition, correctly modeling windows, and transparent materials in general, represents a significant thermal challenge. It can also be challenging to obtain accurate radiative properties for modern window materials. This study focuses on the modeling approach, results, and possible window heat leak mitigation techniques for pressurized rover. Mitigation techniques explored in this study include low emissivity coatings and removable internal or external covers. Window layup, geometry, and size are also assessed in this study for their impact to heat leak.

Sydney June Taylor↗

NASA NTRS2013

A Next Generation Air Monitor: Combining Orion and ISS Requirements for a Common Major Constituent Analyzer

The Major Constituent Analyzer (MCA) is a mass spectrometer-based instrument designed to provide critical monitoring of six major atmospheric constituents; nitrogen, oxygen, hydrogen, carbon dioxide, methane, and water vapor on-board the International Space Station. The analyzer has been an integral part of the Environmental Control and Life Support System (ECLSS) since the station went on-line. The Orion Air Monitor (OAM) was derived from the MCA and heavily optimized for reduced mass, lower power, faster water vapor response, and maintenance-free operation. The resulting OAM is approximately the size of the analyzer portion of the MCA, orbital-replacement unit 02 (ORU 02), while incorporating the functions of three other modules: Data Processing and Communication (ORU 01), Verification Gas Assembly (ORU 08), and Low Voltage Power Supply (ORU 04). The overlap in MCA and OAM requirements makes it possible to derive a common Air Monitor design that spans both applications while minimally impacting the weight and power limits imposed by the Multipurpose Crew Vehicle (MPCV). Benefits to ISS include the retirement of ORUs 01, 04, and 08, reducing up-mass and eliminating EEE parts obsolescence issues through the extended ISS mission phases. Benefits to MPCV and future deployed habitats under the Constellation program include greater interchangeability across ECLSS subsystems. This paper discusses the results of the requirements development study, where a superset of ISS and Orion air monitoring requirements were distilled; evaluated against increases in OAM functionality, mass, and power; and traded-off where possible using simple operating mode modifications. A system architecture and preliminary design addressing the common requirements will be presented.

Burchfield, David E.↗

NASA NTRS2022

Lunar Communications Services with Emphasis on Commercialization

In mid-2020 Lockheed Marin Space (LM) and NASA’s Jet Propulsion Laboratory (JPL) formed a working group to study and address the need for a lunar communications network to service a growing lunar economy, beginning with the initial crewed and robotic mission needs in 2024. Multiple commercial relay architectures were studied and evaluated for platform requirements, communications capabilities, and commercial business viability in a growing ecosystem. The evolution of communications needs around the Moon were mapped to infrastructure build out. Trade studies were performed to evaluate reliability and lifetime requirements, and the viability of various data protocols. Mission concepts and operations plans were developed for both initial mission support and future autonomous network support. This work has led to Lockheed Martin and JPL to evaluate a single dedicated relay satellite in a frozen lunar orbit, with simultaneous coverage of the far-side and south pole landing sites for over 10 hours per day as a first step towards a comprehensive solution to lunar connectivity. This first satellite is compatible with an ESPA Grande launch volume and would be capable of launching on a rideshare into a variety of orbits and trajectories. The satellite is equipped with both high- and low-rate communications relay payloads with software-defined radios and a delay/disruption tolerant networking protocol. The system is designed to service initial and future mission needs in a commercialized manner, enabling a new class of missions to the Moon. The relay satellite leverages prior spacecraft platform work with on-orbit heritage in a lunar environment expected by 2023.

Davarian, Faramaz↗

NASA NTRS2017

Revisiting Nuclear Thermal Propulsion for Human Mars Exploration

Nuclear Thermal Propulsion (NTP) has long been considered as a viable in-space transportation alternative for delivering crew and cargo to the Martian system. While technology development work in nuclear propulsion has continued over the year, general interest in NTP propulsion applications has historically been tied directly to the ebb and flow of interest in sending humans to explore Mars. As far back as the 1960’s, plans for NTP-based human Mars exploration have been proposed and periodically revisited having most recently been considered as part of NASA Design Reference Architecture (DRA) 5.0. NASA has been investigating human Mars exploration strategies tied to its current Journey to Mars for the past few years however, NTP has only recently been added into the set of alternatives under consideration for in-space propulsion under the Mars Study Capability (MSC) team, formerly the Evolvable Mars Campaign (EMC) team. The original charter of the EMC was to find viable human Mars exploration approaches that relied heavily on technology investment work already underway, specifically related to the development of large Solar Electric Propulsion (SEP) systems. The EMC team baselined several departures from traditional Mars exploration ground rules to enable these types of architectures. These ground rule changes included lower energy conjunction class trajectories with corresponding longer flight times, aggregation of mission elements in cis-Lunar space rather than Low Earth Orbit (LEO) and, in some cases, the pre-deployment of Earth return propulsion systems to Mars. As the MSC team continues to refine the in-space transportation trades, an NTP-based architecture that takes advantage of some of these ground rule departures is being introduced.

Percy, Thomas K.↗

NASA NTRS2012

Influence of Alternative Engine Concepts on LCTR2 Sizing and Mission Profile

The Large Civil Tiltrotor (LCTR) was developed as part of the NASA Heavy Lift Rotorcraft Systems Investigation in order to establish a consistent basis for evaluating the benefits of advanced technology for large tiltrotors. The concept has since evolved into the second-generation LCTR2, designed to carry 90 passengers for 1,000 nm at 300 knots, with vertical takeoff and landing. This paper examines the impact of advanced propulsion system concepts on LCTR2 sizing. Two concepts were studied: an advanced, single-speed engine with a conventional power turbine layout (Advanced Conventional Engine, or ACE), and a variable-speed power turbine engine (VSPT). The ACE is the lighter engine, but requires a multi-speed (shifting) gearbox, whereas the VSPT uses a lighter, fixed-ratio gearbox. The NASA Design and Analysis of Rotorcraft (NDARC) design code was used to study the trades between rotor and engine efficiency and weight. Rotor performance was determined by Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics (CAMRAD II), and engine performance was estimated with the Numerical Propulsion System Simulation (NPSS). Design trades for the ACE vs. VSPT are presented in terms of vehicle weight empty for variations in mission altitude and range; the effect of different One Engine Inoperative (OEI) criteria are also examined. Because of its strong effect on gearbox weight and on both rotor and engine efficiency, rotor speed was chosen as the reference design variable for comparing design trades. The two propulsion concepts had nearly identical vehicle weights and mission fuel consumption, and their relative advantages varied little with cruise altitude, mission range, or OEI criteria; high cruise altitude and low cruise tip speed were beneficial for both concepts.

Acree, C. W., Jr.↗

NASA NTRS2004

Continuing Evolution of Mars Sample Return

This paper addresses the continued evolution of the Groundbreaking MSR concept over the last year. One of the tenets of the low-cost approach is to use substantial heritage from an earlier mission, Mars Science Laboratory (MSL). Recently, the MSL project developed and switched to a revolutionary landing approach, coined 'sky-crane' where the MSL, which is a rover, is lowered gently to the Martian surface from a hovering vehicle. MSR has adopted this approach, again continuing to capitalize on the heritage for a significant portion of the new lander. In parallel, a MSR Technology Board was formed to reexamine MSR technology needs and participate in a continuing refinement of architectural trades. While the focused technology program continues to be definitized through the remainder of this year, the current assessment of what technology development is required, is discussed in this paper. In addition, the results of new trade studies and considerations will be discussed.

Mars Sample Return (MSR)↗

NASA NTRS2008

Power System Trade Studies for the Lunar Surface Access Module

A Lunar Lander Preparatory Study (LLPS) was undertaken for NASA's Lunar Lander Pre-Project in 2006 to explore a wide breadth of conceptual lunar lander designs. Civil servant teams from nearly every NASA center responded with dozens of innovative designs that addressed one or more specific lander technical challenges. Although none of the conceptual lander designs sought to solve every technical design issue, each added significantly to the technical database available to the Lunar Lander Project Office as it began operations in 2007. As part of the LLPS, a first order analysis was performed to identify candidate power systems for the ascent and descent stages of the Lunar Surface Access Module (LSAM). A power profile by mission phase was established based on LSAM subsystem power requirements. Using this power profile, battery and fuel cell systems were modeled to determine overall mass and volume. Fuel cell systems were chosen for both the descent and ascent stages due to their low mass. While fuel cells looked promising based on these initial results, several areas have been identified for further investigation in subsequent studies, including the identification and incorporation of peak power requirements into the analysis, refinement of the fuel cell models to improve fidelity and incorporate ongoing technology developments, and broadening the study to include solar power.

Kohout, Lisa, L.↗

NASA NTRS1978

Preliminary design trade-offs for a multi-mission stored cryogen cooler

Preliminary design studies were performed for a multi-mission solid cryogen cooler having a wide range of application for both the shuttle sortie and free flyer missions. This multi-mission cooler (MMC) is designed to be utilized with various solid cryogens to meet a wide range of instrument cooling from 10 K (with solid hydrogen) to 90 K. The baseline cooler utilizes two stages of solid cryogen and incorporates an optional, higher temperature third stage which is cooled by either a passive radiator or a thermoelectric cooler. The MMC has an interface which can accommodate a wide variety of instrument configurations. A shrink fit adapter is incorporated which allows a drop-in instrument integration. The baseline design provides cooling of approximately 1 watt over a 60 to 100 K temperature range and about 0.5 watts from 15 to 60 K for a one year lifetime. For low cooling loads and with use of the optional radiator shield, cooling lifetimes as great as 8 years are predicted.

Sherman, A.↗