The gravity reference system
Mercury-oil pool as gravity reference system, and evaluation of vibrations in various parts of building used for housing pool
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Mercury-oil pool as gravity reference system, and evaluation of vibrations in various parts of building used for housing pool
Reference list for stability and control theory in ordinary differential equations
Objectives and design of inertial reference unit for lunar orbiter
Strapped-down inertial reference assembly and digital computer for Saturn booster guidance
Lunar orbiter objectives, mission and spacecraft configuration, detailing inertial reference unit
Stress tensor analysis of elastic plates in reference state, noting nonlinear plate theory and variational principle
Analytical methods defining location of reference horizons in earth horizon radiance profile
Strapdown inertial reference and navigation system initial alignment utilizing coordinate- transformation matrix computer
Differential correction vectors for non-Keplerian reference orbits, reexamining rotating ellipses in Hansen type intermediaries
Architectures for terrestrial data systems that are built and managed by a single organization are inherently complex. In order to understand any large-scale system architecture, and to judge its applicability for its nominal task, a description of the system must be produced that exposes a number of distinct viewpoints. Within the CCSDS Architecture Working Group we have adapted the Reference Model for Open Distributed Processing to describe large, multi-national, space data systems.
This paper introduces the Reference Architecture for Space Data Systems (RASDS) that is being developed by CCSDS and shows how it can be used to reduce the cost of development of space data systems.
Results of the VLBI astrometric program of 12 radio-emitting stars are presented and used to provide a preliminary link of the Hipparcos 37-month FAST solution to a VLBI extragalactic reference frame. The formal precisions of this link are 0.5 milliarcsecond in global rotation and 0.5 milliarcsecond per year in residual rate of rotation.
Total dose test of commercially available radiation hardened bipolar voltage regulators and references show reduced sensitivity to dose rate and varying sensitivity to bias under pressure. Behavior of critical parameters in different dose rate and bias conditions is compared and the impact to hardness assurance methodology is discussed.
A high voltage bandgap reference circuit has been designed and implemented in an SOI CMOS technology.
This paper reports on the development of a silicon bulk micromachined vibratory gyroscope designed for a micro inertial reference system for microspacecraft applications.
This paper has briefly presented the Reference Architecture for Space Data Systems (RASDS) that is being developed by the CCSDS Systems Architecture Working Group (SAWG). The SAWG generated some sample architectures (spacecraft onboard architectures, space link architectures, cross-support architectures) using this RASDS approach, and RASDS was proven to be a powerful tool for describing and relating different space data system architectures.
NASA's 2006 Solar System Exploration (SSE) Strategic Roadmap identified a set of proposed large Flagship, medium New Frontiers and small Discovery class missions, addressing key exploration objectives. These objectives respond to the recommendations by the National Research Council (NRC), reported in the SSE Decadal Survey. The SSE Roadmap is down-selected from an over-subscribed set of missions, called the SSE Design Reference Mission (DRM) set. Missions in the Flagship and New Frontiers classes can consider Radioisotope Power Systems (RPSs), while small Discovery class missions are not permitted to use them, due to cost constraints. In line with the SSE DRM set and the SSE Roadmap missions, the RPS DRM set represents a set of missions, which can be enabled or enhanced by RPS technologies. At present, NASA has proposed the development of two new types of RPSs. These are the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG), with static power conversion; and the Stirling Radioisotope Generator (SRG), with dynamic conversion. Advanced RPSs, under consideration for possible development, aim to increase specific power levels. In effect, this would either increase electric power generation for the same amount of fuel, or reduce fuel requirements for the same power output, compared to the proposed MMRTG or SRG. Operating environments could also influence the design, such that an RPS on the proposed Titan Explorer would use smaller fins to minimize heat rejection in the extreme cold environment; while the Venus Mobile Explorer long-lived in-situ mission would require the development of a new RPS, in order to tolerate the extreme hot environment, and to simultaneously provide active cooling to the payload and other electric components. This paper discusses NASA's SSE RPS DRM set, in line with the SSE DRM set. It gives a qualitative assessment regarding the impact of various RPS technology and configuration options on potential mission architectures, which could support NASA's RPS technology development planning, and provide an understanding of fuel need trades over the next three decades.
IGN and DGFI both generated realizations of the terrestrial reference frame under the auspices of the IERS from combination of the same space geodetic data. We compared the IGN and DGFI TRFs with a GSFC CALC/SOLVE TRF. WRMS position and velocity differences for the 40 most frequently observed sites were 2-3 mm and 0.3-0.4 mm/year. There was a scale difference of 0.39/0.09 ppb between the IGN/DGFI realizations and the GSFC solution. When we fixed positions and velocities to either the IGN or DGFI values in CALC/SOLVE solutions, the resulting EOP estimates were not significantly different from the estimates from a standard TRF solution.