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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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This paper describes the architecture studies, technology studies, and testbeds that demonstrate the viability of an infrared interferometer mission architecture for the Terrestrial Planet Finder project.
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The New Millennium Program's Earth Orbiter-1 (EO-1) spacecraft was launched on 21 November 2000. EO-1 flys in a one minute trailing formation with the Landsat 7 spacecraft to validate an advanced land-imaging instrument.
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In this paper we investigate the interaction between an orbiting tethered system and a single spacecraft acting as leader of the tethered formation.
Formation estimation requires inter-spacecraft communication links to exchange sensor measurements and internal data.
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In this paper, an investigation is made of the reconfiguration dynamics of spacecraft formations.
On Nov. 17, 1996 an extraordinary Leonid meteor storm (144,000 per hour) was witnessed by observers in central and western United States. With an orbital period of 33 years, the next return to perihelion will be Feb. 28, 1998. Because the distribution of the particles flying in formation with the parent comet is poorly known, no secure predictions can be made for Leonid meteor storms in the coming years.
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We describe a high-precision inter-spacecraft metrology system designed for NASA 's StarLight mission, a space-based separated-spacecraft stellar interferometer. It consists of dual-target linear metrology, based on a heterodyne interferometer with carrier phase modulation, and angular metrology designed to sense the pointing of the laser beam and provides bearing information. The dual-target operation enables one metrology beam to sense displacement of two targets independently. We present the current design, breadboard implementation of the Metrology Subsystem in a stellar interferometer testbed and the present state of development of flight qualifiable subsystem components.
Separated spacecraft interferometry is a candidate architecture for several future NASA missions. The Formation Interferometer Testbed (FIT) is a ground based testbed dedicated to the validation of this key technology for a formation of two spacecraft. In separated spacecraft interferometry, the residual relative motion of the component spacecraft must be compensated for by articulation of the optical components. In this paper, the design of the FIT interferometer pointing control system is described. This control system is composed of a metrology pointing loop that maintains an optical link between the two spacecraft and two stellar pointing loops for stabilizing the stellar wavefront at both the right and left apertures of the instrument. A novel feedforward algorithm is used to decouple the metrology loop from the left side stellar loop. Experimental results from the testbed are presented that verify this approach and that fully demonstrate the performance of the algorithm.
An integrated control and electromagnetic/antenna formulation is presented for evaluating the performance of a distributed antenna system as a function of formation geometry.