I NTHISNote,wewill examine nonlinear estimation techniques to solve nonlinear problems that have been traditionally solved by linear methods. In the area of nonlinear estimation, a class of sampling algorithms known asMarkov chainMonte Carlo (MCMC) was extensively used to obtain a solution that is often a general, nonGaussian, nonunimodal probability distribution. Therefore, there is a natural ...

Long-term, incoming total solar irradiance (TSI) measurement trends were validated using proxy TSI values, derived from indices of solar magnetic activity. Spacecraft active cavity radiometers (ACR) are being used to measure longterm TSI variability, which may trigger global climate changes. The TSI, typically referred to as the “solar constant,” was normalized to the mean earth-sun distance. S...

All powered spacecraft experience residual systematic acceleration due to anisotropy of the thermal radiation pressure and fuel leakage. The residual acceleration limits the accuracy of any test of gravity that relies on the precise determination of the spacecraft trajectory. We describe a novel two-step laser ranging technique, which largely eliminates the effects of non-gravity acceleration s...

On September 1991, NASA launched the Upper Atmosphere Research Satellite. In addition to its atmospheric science mission, spacecraft dynamic effects on science measurements were analyzed. The investigation included two in-flight experiments to determine how each on-board instrument, subsystem and environmental disturbance contributed to the spacecraft dynamic response and how these disturbances...

The CCSDS Telecommand (TC) and Telemetry (TM) standards are today being employed for a large number of scientific and commercial spacecraft. Using this standard allows reduced costs for on-board, ground and test equipment, as well as for spacecraft testing and in-orbit operation. This paper introduces the CCSDS/ESA standards, and presents the supporting standard components developed by ESA and ...

Differential drag is a technique for altering the semimajor axis, velocity, and alongtrack position of a spacecraft in low Earth orbit. It involves varying the spacecraft’s cross-sectional area relative to its velocity direction by temporarily changing attitude and solar array angles, thus varying the amount of atmospheric drag on the spacecraft. The technique has recently been proposed and use...

We are investigating the design of user interaction with autonomous spacecraft in particular, with spacecraft where contact is made only intermittently. Our initial efforts focus on designs supporting existing spacecraft capabilities, where autonomy is reflexive and based on complicated rules. We report here an initial design concept for human interaction based on an abstraction hierarchy, prod...

This work introduces a novel control algorithm for close proximity multiple spacecraft autonomous maneuvers, based on hybrid linear quadratic regulator/artificial potential function (LQR/APF), for applications including autonomous docking, on-orbit assembly and spacecraft servicing. Both theoretical developments and experimental validation of the proposed approach are presented. Fuel consumptio...

Simultaneous observations of the solar wind velocity as measured at the Pioneer 9 and Ogo 5 spacecraft during five solar rotations in 1968 and 1969 are presented. During this time, Pioneer 9 was traveling in toward the sun to approximately 0.7 AU while the earth orbiter Ogo 5 was spending long periods in the interplanetary medium. A comparison of the 3-hour averages of solar wind velocity obtai...

In this paper, we consider a distributed attitude alignment problem for a team of deep space formation flying spacecraft through local information exchange. We propose control laws for three different cases. In the first case, multiple spacecraft converge to their (possibly time-varying) desired attitudes while maintaining the same attitude or given relative attitudes during formation maneuvers...