Entity

Time filter

Source Type

Outer, United States

Bhaskaran S.,Jet Propulsion Laboratory | Bhaskaran S.,Outer Planet Navigation Group
SpaceOps 2012 Conference | Year: 2012

Autonomous navigation (AutoNav) for deep space missions is a unique capability that was developed at JPL and used successfully for every camera-equipped comet encounter flown by NASA (Borrelly, Wild 2, Tempel 1, and Hartley 2), as well as an asteroid flyby (Annefrank). AutoNav is the first on-board software to perform autonomous interplanetary navigation (image processing, trajectory determination, maneuver computation), and the first and only system to date to autonomously track comet and asteroid nuclei as well as target and intercept a comet nucleus. In this paper, the functions used by AutoNav and how they were used in previous missions are described. Scenarios for future mission concepts which could benefit greatly from the AutoNav system are also provided. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. Source


Park R.S.,Outer Planet Navigation Group | Bhaskaran S.,Outer Planet Navigation Group | Cheng Y.,Computer Vision Group | Johnson A.J.,Optical Navigation Group | And 2 more authors.
Journal of Spacecraft and Rockets | Year: 2010

This paper presents trajectory reconstruction of the ST-9 (space technology) sounding rocket experiment using the onboard inertial measurement unit data and descent imagery. The raw inertial measurement unit accelerometer measurements are first converted into inertial acceleration and then used in trajectory integration. The descent images are preprocessed using a map-matching algorithm and unique landmarks for each image are created. Using the converted inertial measurement unit data and descent images, the result from dead-reckoning and the kinematicfix approaches are first compared with the global positioning system measurements. Then, both the inertial measurement unit data and landmarks are processed together using a batch least-squares filter and the position, velocity, stochastic acceleration, and camera orientation of each image are estimated. The reconstructed trajectory is compared with the global positioning system data and the corresponding formal uncertainties are presented. The result shows, that inertial measurement unit data and descent images processed with a batch filter algorithm provide the trajectory accuracy required for pinpoint landing. © 2010 by the American Institute of Aeronautics and Astronautics, Inc. Source


Park R.S.,Jet Propulsion Laboratory | Park R.S.,Outer Planet Navigation Group | Werner R.A.,Jet Propulsion Laboratory | Werner R.A.,Outer Planet Navigation Group | And 2 more authors.
Journal of Guidance, Control, and Dynamics | Year: 2010

This paper presents a method to model the external gravitational field and to estimate the internal density variation of a small body. The first problem discussed is the modeling of the external gravitational field using finite element definitions, such as cubes and spheres, assuming the polyhedral shape and internal density distribution are provided. The gravitational attractions computed using finite element approach are compared with the true uniform-density polyhedral attraction and the level of accuracies are presented. The second problem discussed is the inverse problem where the internal density variation is determined by estimating the density of each finite element assuming the body shape, radiometric measurements, and a priori density constraints are given. This is presented via covariance analysis, which gives the level of uncertainty in the estimated densities. The result shows that the accuracy of the estimated density variation can be significantly improved depending on the orbit altitude, finite element resolution, and measurement accuracy, which indicates that the finite element approach can be used as a close-proximity navigation model around small bodies. Copyright © 2008 by the American Institute of Aeronautics and Astronautics, Inc. Source

Discover hidden collaborations