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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Low-Latency Telerobotics from Mars Orbit: The Case for Synergy Between Science and Human Exploration

Initial, science-directed human exploration of Mars will benefit from capabilities in which human explorers remain in orbit to control telerobotic systems on the surface (Figure 1). Low-latency, high-bandwidth telerobotics (LLT) from Mars orbit offers opportunities for what the terrestrial robotics community considers to be high-quality telepresence. Such telepresence would provide high quality sensory perception and situation awareness, and even capabilities for dexterous manipulation as required for adaptive, informed selection of scientific samples [1]. Astronauts on orbit in close communication proximity to a surface exploration site (in order to minimize communication latency) represent a capability that would extend human cognition to Mars (and potentially for other bodies such as asteroids, Venus, the Moon, etc.) without the challenges, expense, and risk of putting those humans on hazardous surfaces or within deep gravity wells. Such a strategy may be consistent with goals for a human space flight program that, are currently being developed within NASA.

Valinia, A.↗
NASA NTRS2025

Orion Hardware In The Loop OIMU Stimulation Latency Effect on Navigation State Estimation

Because Hardware In The Loop (HITL) testing involves the integration of flight software and flight hardware on the ground, non-flight-like effects may arise. One of these non-flight-like effects includes Inertial Measurement Unit (IMU) stimulation latency that affects the time in which the measurement is received by the Extended Kalman Filter (EKF). This paper seeks to present the extent to which this stimulation latency affects the navigational state estimate from the Orion navigation system for all phases of flight for Artemis II.

Christopher A Ertl↗
NASA NTRSDate not supplied

Orion Hardware In The Loop OIMU Stimulation Latency Effect on Navigation State Estimation

Because Hardware In The Loop (HITL) testing involves the integration of flight software and flight hardware on the ground, non-flight-like effects may arise. One of these non-flight-like effects includes Inertial Measurement Unit (IMU) stimulation latency that affects the time in which the measurement is received by the Extended Kalman Filter (EKF). This paper seeks to present the extent to which this stimulation latency affects the navigational state estimate from the Orion navigation system for all phases of flight for Artemis II.

Christopher A Ertl↗
NASA NTRS2010

Flash Memory Reliability: Read, Program, and Erase Latency Versus Endurance Cycling

This report documents the efforts and results of the fiscal year (FY) 2010 NASA Electronic Parts and Packaging Program (NEPP) task for nonvolatile memory (NVM) reliability. This year's focus was to measure latency (read, program, and erase) of NAND Flash memories and determine how these parameters drift with erase/program/read endurance cycling.

latency↗
NASA NTRS2018

Use of Open Networks and Delay-Tolerant Protocol to Decrease WAN Latency of EOS near Real-Time Data

Since 1999, NASA's Earth Observing System Data Operations System (EDOS) project at Goddard Space Flight Center (GSFC) has provided high-rate data capture, level zero processing, and product distribution services for a majority of NASA's EOS (Earth Observing System) high-rate missions, including Terra, Aqua, Aura, ICESat, EO-1, SMAP, and OCO-2. EDOS high-rate science and engineering (150-300 Mbps) data-driven capture systems are deployed at 7 worldwide ground stations which are connected via both private (closed) and public (open) wide area networks (WANs) to the centralized EDOS Level Zero Processing Facility (LZPF) located at GSFC, where the data is processed and Level 0 products are distributed to users worldwide. All data transferred over the open networks to GSFC traverse an IPSec tunnel, providing the same level of security as a VPN connection. EDOS produces both time-based and near real-time products (session-based). Near real-time data products are produced from a single ground station contact; time-based products are produced from multiple ground station contacts. EDOS is the primary supplier of EOS Level 0 data to the NASA near real-time user community known as the Land, Atmosphere Near real-time Capability for EOS (LANCE). For the past few years, EDOS has streamlined its systems to reduce WAN latency for near real-time data delivery, including implementing Quality of Service (QoS), expanding closed network bandwidth, adding open network connections with more bandwidth, and implementing a delay-tolerant protocol to mitigate long round-trip times to remote ground stations.

Delay-Tolerant Protocol↗
NASA NTRS2018

Low-Latency Teleoperations: Operational Implications for Human Space Exploration

Low-latency teleoperations (LLT) is envisioned to be an element of human exploration missions in a number of different applications. LLT can be broadly considered to encompass any remote operation of an asset with a communication delay that is less than the human response time to allow for what is effectively "real-time" or "near real-time" operations. This paper will explore motivations and operational implications for why and how LLT might be used for human exploration space missions. LLT analyses have been performed under the auspices of the NASA Human Spaceflight Architecture Team (HAT) and Evolvable Mars Campaign (EMC). The EMC created a flexible, evolvable, capability-driven architectural strategy to enable a sustainable long-term human presence at Mars. LLT is envisioned to be part of that strategy for both in-space and on-surface applications, and this paper will expand on operational considerations within that broader strategic context, as well additional contexts. Some operational implications explored in this paper, derived largely from previous work, are: (1) crew mission support, for which we will address roles for Mission Control on earth, balanced with the capability for crew and robotic assets to operate independently, (2) science operations, with a focus on "backroom" support, highly dynamic science, and enhanced science return and efficiency, and (3) operational efficiency at a deep-space destination such as Mars, including implications for communications infrastructures and how to leverage and balance system autonomy with crew operations, both of which can inform the overall operational "choreography" between crew members, multiple shifts, and exploration assets.

human spaceflight↗
NASA NTRS1981

Measurement of fault latency in a digital avionic miniprocessor

The results of fault injection experiments utilizing a gate-level emulation of the central processor unit of the Bendix BDX-930 digital computer are presented. The failure detection coverage of comparison-monitoring and a typical avionics CPU self-test program was determined. The specific tasks and experiments included: (1) inject randomly selected gate-level and pin-level faults and emulate six software programs using comparison-monitoring to detect the faults; (2) based upon the derived empirical data develop and validate a model of fault latency that will forecast a software program's detecting ability; (3) given a typical avionics self-test program, inject randomly selected faults at both the gate-level and pin-level and determine the proportion of faults detected; (4) determine why faults were undetected; (5) recommend how the emulation can be extended to multiprocessor systems such as SIFT; and (6) determine the proportion of faults detected by a uniprocessor BIT (built-in-test) irrespective of self-test.

Mcgough, J. G.↗
NASA NTRS1983

Error latency estimation using functional fault modeling

A complete modeling of faults at gate level for a fault tolerant computer is both infeasible and uneconomical. Functional fault modeling is an approach where units are characterized at an intermediate level and then combined to determine fault behavior. The applicability of functional fault modeling to the FTMP is studied. Using this model a forecast of error latency is made for some functional blocks. This approach is useful in representing larger sections of the hardware and aids in uncovering system level deficiencies.

Manthani, S. R.↗
NASA NTRS1983

New results in fault latency modelling

The test design and results from assessment of the performance of the self-test program and the extent of fault latency in a redundant flight control system (FCS) are reported. Assembly language programming generated gate-level faults directed to every avionics component. Details of the fault-simulation software are described, noting the input needed to match the five control-surface parameters managed by the FCS. Most faults were immediately detected, and component-level faults, occurring at pins, were more easily noted than gate-level faults. The results indicated that a 200-word self-test program is sufficient to obtain a fault coverage of 85 percent. Minor hardware changes are required to reach levels over 90 percent.

Mcgough, J. G.↗
NASA NTRS1988

Statistical analysis of censored motion sickness latency data using the two-parameter Weibull distribution

The suitability of the two-parameter Weibull distribution for describing highly censored cat motion sickness latency data was evaluated by estimating the parameters with the maximum likelihood method and testing for goodness of fit with the Kolmogorov-Smirnov statistic. A procedure for determining confidence levels and testing for significance of the difference between Weibull parameters is described. Computer programs for these procedures may be obtained from an archival source.

Park, Won J.↗
NASA NTRS1993

Low-latency digital frequency synthesizer using the residue number system

A low-latency frequency synthesizer using the Direct Digital Synthesis (DDS) technique has been designed. Called the Residue Assisted Frequency Synthesizer (RAFS), it exhibits frequency switching times which are reduced by more than 50 percent below previously published designs. The switching speed advantage is made possible by the use of the Residue Number System, which allows the pipeline lengths in the Phase Accumulator and other circuitry to be reduced significantly.

Chren, William A., Jr.↗
NASA NTRS1999

Study and Simulation of Enhancements for TCP Performance Over Noisy High Latency Links

The goal of this study is to better understand how TCP behaves over noisy, high-latency links such as satellite links and propose improvements to TCP implementations such that TCP might better handle such links. This report is comprised of a series of smaller reports, presentations and recommendations. Included in these documents are a summary of the TCP enhancement techniques for large windows, protect against wrap around (PAWS), use of selective acknowledgements (SACK), increasing TCP's initial window and recommendations to implement TCP pacing.

Partridge, Craig↗
NASA NTRS2001

Hiding the Disk and Network Latency of Out-of-Core Visualization

This paper describes an algorithm that improves the performance of application-controlled demand paging for out-of-core visualization by hiding the latency of reading data from both local disks or disks on remote servers. The performance improvements come from better overlapping the computation with the page reading process, and by performing multiple page reads in parallel. The paper includes measurements that show that the new multithreaded paging algorithm decreases the time needed to compute visualizations by one third when using one processor and reading data from local disk. The time needed when using one processor and reading data from remote disk decreased by two thirds. Visualization runs using data from remote disk actually ran faster than ones using data from local disk because the remote runs were able to make use of the remote server's high performance disk array.

Ellsworth, David↗
NASA NTRS2001

Latency Hiding in Dynamic Partitioning and Load Balancing of Grid Computing Applications

The Information Power Grid (IPG) concept developed by NASA is aimed to provide a metacomputing platform for large-scale distributed computations, by hiding the intricacies of highly heterogeneous environment and yet maintaining adequate security. In this paper, we propose a latency-tolerant partitioning scheme that dynamically balances processor workloads on the.IPG, and minimizes data movement and runtime communication. By simulating an unsteady adaptive mesh application on a wide area network, we study the performance of our load balancer under the Globus environment. The number of IPG nodes, the number of processors per node, and the interconnected speeds are parameterized to derive conditions under which the IPG would be suitable for parallel distributed processing of such applications. Experimental results demonstrate that effective solution are achieved when the IPG nodes are connected by a high-speed asynchronous interconnection network.

Das, Sajal K.↗
NASA NTRS1997

Analysis of the Role of Update Rate and System Latency in Interactive Virtual Acoustic Environments

The ultimate goal of virtual acoustics is to simulate the complex acoustic field experienced by a listener freely moving around within an environment. This paper discusses some of the engineering constraints that may be faced during implementation and the perceptual consequences of these constraints. In particular, the perceptual impact of parameters like the update rate and overall system latency of interactive spatial audio systems is addressed.

Wenzel, Elizabeth M.↗