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Results for “in-transit”

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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12 records

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NASA NTRS1991

Induced gravity Mars transportation systems configuration and hardware penalties

The need for an induced gravity environment in-transit to Mars is assessed based on current knowledge. Two possible alternatives to constant in-transit spinning, periodic spinning and Mars surface reconditioning are discussed and compared. Four propulsion options: cryogenic/aerobraking, solid core nuclear thermal, solar electric and nuclear electric are evaluated for concept adaptability to induced gravity, and salient differences from their microgravity counterparts are assessed. Configurations to the systems level are presented and accompanied by mass estimates. Hardware subsystems required for induced gravity vehicles, such as tether crawlers, tether reels, high-power roll-ring assemblies, etc., have been defined to a sufficient level of detail to confidently determine mass penalties. Results of this study show the mass penalties and complexity involved in producing an induced gravity environment.

Capps, Stephen↗

NASA NTRS1963

SURVEY OF RENDEZVOUS PROGRESS

Apollo/lem mission - requirements of orbital rendezvous, in-transit rendezvous, & planetary rendezvous

APOLLO SPACECRAFT↗

NASA NTRS1968

Facsimile video enhancement device

Video remodulation unit enhances facsimile transmission using an amplitude-modulated 2400 Hz carrier. The unit demodulates the signal and then remodulates it, using the same carrier. By using the unit controls, modulation can be set to levels that compensate for picture in-transit degradation.

Vermillion, C. H.↗

NASA NTRS1993

Space Reclamation for Uncoordinated Checkpointing in Message-Passing Systems

Checkpointing and rollback recovery are techniques that can provide efficient recovery from transient process failures. In a message-passing system, the rollback of a message sender may cause the rollback of the corresponding receiver, and the system needs to roll back to a consistent set of checkpoints called recovery line. If the processes are allowed to take uncoordinated checkpoints, the above rollback propagation may result in the domino effect which prevents recovery line progression. Traditionally, only obsolete checkpoints before the global recovery line can be discarded, and the necessary and sufficient condition for identifying all garbage checkpoints has remained an open problem. A necessary and sufficient condition for achieving optimal garbage collection is derived and it is proved that the number of useful checkpoints is bounded by N(N+1)/2, where N is the number of processes. The approach is based on the maximum-sized antichain model of consistent global checkpoints and the technique of recovery line transformation and decomposition. It is also shown that, for systems requiring message logging to record in-transit messages, the same approach can be used to achieve optimal message log reclamation. As a final topic, a unifying framework is described by considering checkpoint coordination and exploiting piecewise determinism as mechanisms for bounding rollback propagation, and the applicability of the optimal garbage collection algorithm to domino-free recovery protocols is demonstrated.

Wang, Yi-Min↗

NASA NTRS1994

Optimal message log reclamation for uncoordinated checkpointing

Uncoordinated checkpointing for message-passing systems allows maximum process autonomy and general nondeterministic execution, but suffers from potential domino effect and the large space overhead for maintaining checkpoints and message logs. Traditionally, it has been assumed that only obsolete checkpoints and message logs before the global recovery line can be garbage-collected. Recently, an approach to identifying all garbage checkpoints based on recovery line transformation and decomposition has been developed. We show in this paper that the same approach can be applied to the problem of identifying all garbage message logs for systems requiring message logging to record in-transit messages. Communication trace-driven simulation for several parallel programs is used to evaluate the proposed algorithm.

Wang, Yi-Min↗

NASA NTRS1995

Ensuring correct rollback recovery in distributed shared memory systems

Distributed shared memory (DSM) implemented on a cluster of workstations is an increasingly attractive platform for executing parallel scientific applications. Checkpointing and rollback techniques can be used in such a system to allow the computation to progress in spite of the temporary failure of one or more processing nodes. This paper presents the design of an independent checkpointing method for DSM that takes advantage of DSM's specific properties to reduce error-free and rollback overhead. The scheme reduces the dependencies that need to be considered for correct rollback to those resulting from transfers of pages. Furthermore, in-transit messages can be recovered without the use of logging. We extend the scheme to a DSM implementation using lazy release consistency, where the frequency of dependencies is further reduced.

Janssens, Bob↗

NASA NTRS2008

Training Concept for Long Duration Space Mission

There has been papers about maintenance and psychological training for Long Duration Space Mission (LDSM). There are papers on the technology needed for LDSMs. Few are looking at how groundbased pre-mission training and on-board in-transit training must be melded into one training concept that leverages this technology. Even more importantly, fewer are looking at how we can certify crews pre-mission. This certification must ensure, before the crew launches, that they can handle any problem using on-board assets without a large ground support team.

O'Keefe, William↗

NASA NTRS2011

Validating the AIRS Version 5 CO Retrieval with DACOM In Situ Measurements During INTEX-A and -B

Herein we provide a description of the atmospheric infrared sounder (AIRS) version 5 (v5) carbon monoxide (CO) retrieval algorithm and its validation with the DACOM in situ measurements during the INTEX-A and -B campaigns. All standard and support products in the AIRS v5 CO retrieval algorithm are documented. Building on prior publications, we describe the convolution of in situ measurements with the AIRS v5 CO averaging kernel and first-guess CO profile as required for proper validation. Validation is accomplished through comparison of AIRS CO retrievals with convolved in situ CO profiles acquired during the NASA Intercontinental Chemical Transport Experiments (INTEX) in 2004 and 2006. From 143 profiles in the northern mid-latitudes during these two experiments, we find AIRS v5 CO retrievals are biased high by 6% 10% between 900 and 300 hPa with a root-mean-square error of 8% 12%. No significant differences were found between validation using spiral profiles coincident with AIRS overpasses and in-transit profiles under the satellite track but up to 13 h off in time. Similarly, no significant differences in validation results were found for ocean versus land, day versus night, or with respect to retrieved cloud top pressure or cloud fraction.

McMillan, Wallace W.↗

NASA NTRS2012

Traverse Planning Experiments for Future Planetary Surface Exploration

The purpose of the investigation is to evaluate methodology and data requirements for remotely-assisted robotic traverse of extraterrestrial planetary surface to support human exploration program, assess opportunities for in-transit science operations, and validate landing site survey and selection techniques during planetary surface exploration mission analog demonstration at Haughton Crater on Devon Island, Nunavut, Canada. Additionally, 1) identify quality of remote observation data sets (i.e., surface imagery from orbit) required for effective pre-traverse route planning and determine if surface level data (i.e., onboard robotic imagery or other sensor data) is required for a successful traverse, and if additional surface level data can improve traverse efficiency or probability of success (TRPF Experiment). 2) Evaluate feasibility and techniques for conducting opportunistic science investigations during this type of traverse. (OSP Experiment). 3) Assess utility of remotely-assisted robotic vehicle for landing site validation survey. (LSV Experiment).

Hoffman, Stephen J.↗

NASA NTRS2009

Use of IPsec by Manned Space Missions

NASA's Constellation Program is developing its next generation manned space systems for missions to the International Space Station (ISS) and the Moon. The Program is embarking on a path towards standards based Internet Protocol (IP) networking for space systems communication. The IP based communications will be paired with industry standard security mechanisms such as Internet Protocol Security (IPsec) to ensure the integrity of information exchanges and prevent unauthorized release of sensitive information in-transit. IPsec has been tested in simulations on the ground and on at least one Earth orbiting satellite, but the technology is still unproven in manned space mission situations and significant obstacles remain.

Pajevski, Michael J.↗

NASA NTRS2015

In-Space Manufacturing: Pioneering a Sustainable Path to Mars

ISM is responsible for developing the on-demand manufacturing capabilities that will be required for affordable, sustainable operations during Exploration Missions (in-transit and on-surface) to destinations such as Mars. This includes advancing the needed technologies, as well as establishing the skills & processes (such as certification and characterization) that will enable the technologies to go from novel to institutionalized. These technologies are evolving rapidly due to terrestrial markets. ISM is leveraging this commercial development to develop these capabilities within a realistic timeframe and budget. ISM utilizes the International Space Station (ISS) as a test-bed to adapt these technologies for microgravity operations and evolve the current operations mindset from earth-reliant to earth-independent.

Werkheiser, Niki↗

NASA NTRS2019

ISM In-Space Manufacturing Project Brochure

The In-Space Manufacturing (ISM) Project is a NASA asset managed out of Marshall Space Flight Center that is responsible for developing the capabilities to provide on-demand, sustainable manufacturing, repair, and recycling operations during NASA Exploration Missions (in-transit and on-surface). One of ISM’s primary objectives with the key capabilities being developed is a “Make it, Don’t take it” approach. This includes testing and advancing the desired technologies, as well as establishing the required skills and processes for the processes (such as certification and characterization) that will enable the technologies to become institutionalized.

Brochure↗