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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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76 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Space Transportation Infrastructure Supported By Propellant Depots

A space transportation infrastructure is described that utilizes propellant depot servicing platforms to support all foreseeable missions in the Earth-Moon vicinity and deep space out to Mars. The infrastructure utilizes current expendable launch vehicle (ELV) systems such as the Delta IV Heavy, Atlas V, and Falcon 9, for all crew, cargo, and propellant launches to orbit. Propellant launches are made to Low-Earth-Orbit (LEO) Depot and an Earth-Moon Lagrange Point 1 (L1) Depot to support a new reusable in-space transportation vehicles. The LEO Depot supports missions to Geosynchronous Earth Orbit (GEO) for satellite servicing and to L1 for L1 Depot missions. The L1 Depot supports Lunar, Earth-Sun L2 (ESL2), Asteroid and Mars Missions. New vehicle design concepts are presented that can be launched on current 5 meter diameter ELV systems. These new reusable vehicle concepts include a Crew Transfer Vehicle (CTV) for crew transportation between the LEO Depot, L1 Depot and missions beyond L1; a new reusable lunar lander for crew transportation between the L1 Depot and the lunar surface; and Mars orbital Depot are based on International Space Station (ISS) heritage hardware. Data provided includes the number of launches required for each mission utilizing current ELV systems (Delta IV Heavy or equivalent) and the approximate vehicle masses and propellant requirements. Also included is a discussion on affordability with ideas on technologies that could reduce the number of launches required and thoughts on how this infrastructure include competitive bidding for ELV flights and propellant services, developments of new reusable in-space vehicles and development of a multiuse infrastructure that can support many government and commercial missions simultaneously.

Smitherman, David↗
NASA NTRS2014

Remote Software Application and Display Development

The era of the shuttle program has come to an end, but only to give rise to newer and more exciting projects. Now is the time of the Orion spacecraft, a work of art designed to exceed all previous endeavors of man. NASA is exiting the time of exploration and is entering a new period, a period of pioneering. With this new mission, many of NASAs organizations must undergo a great deal of change and development to support the Orion missions. The Spaceport Command and Control System (SCCS) is the new system that will provide NASA the ability to launch rockets into orbit and thus control Orion and other spacecraft as the goal of populating Mars becomes ever increasingly tangible. Since the previous control system, Launch Processing System (LPS), was primarily designed to launch the shuttles, SCCS was needed as Kennedy Space Center (KSC) reorganized to a multiuser spaceport for commercial flights, providing a more versatile control over rockets. Within SCCS, is the Launch Control System (LCS), which is the remote software behind the command and monitoring of flight and ground system hardware. This internship at KSC has involved two main components in LCS, including Remote Software Application and Display development. The display environment provides a graphical user interface for an operator to view and see if any cautions are raised, while the remote applications are the backbone that communicate with hardware, and then relay the data back to the displays. These elements go hand in hand as they provide monitoring and control over hardware and software alike from the safety of the Launch Control Center. The remote software applications are written in Application Control Language (ACL), which must undergo unit testing to ensure data integrity. This paper describes both the implementation and writing of unit tests in ACL code for remote software applications, as well as the building of remote displays to be used in the Launch Control Center (LCC).

ACL↗
NASA NTRS1996

A New Approach to Parallel Interference Cancellation for CDMA

This paper introduces an improved nonlinear parallel interference cancellation scheme that significantly reduces the degrading effect of user interference with implementation complexity linear in the number of users. The scheme operates on the fact that parallel processing simultaneously removes from each user a part of the interference produced by the remaining users accessing the channel the amount being proportional to their reliability. The parallel processing can be done in multiple stages. Simulation results are given for a multitude of different situations, in particular those cases for which the analysis is too complex.

interference cancellation multiuser communication ↗
NASA NTRS1994

Improved CDMA Performance Using Parallel Interference Cancellation

This paper considers a general parallel interference cancellation scheme that significantly reduces the degradation effect of user interference but with a lesser implementation complexity than the maximum-likelihood technique. The scheme operates on the fact that parallel processing simultaneously removes from each user the total interference produced by the remaining most reliably received users accessing the channel. The parallel processing can be done in multiple stages. The proposed scheme uses tentative decision devices with different optimum thresholds at the multiple stages to produce the most reliably received data for generation and cancellation of user interference.

CDMA↗