Todd Ely
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View article: The Benefit of Space Clocks for the Deep Space Network
The Benefit of Space Clocks for the Deep Space Network Open
Ground‐based atomic clocks have been the foundation of the Deep Space Network's (DSN's) ability to provide high‐precision tracking to deep space users for navigation and radio science since its inception in the mid‐1960s. This paper descri…
View article: DSAC and next generation high stability, long life trapped mercury ion frequency standards
DSAC and next generation high stability, long life trapped mercury ion frequency standards Open
The methods of trapping and cooling of atoms and ions have been transformative for atomic clocks due to the reduction, and in some cases elimination, of major systematic frequency shifts. Continuously operating atomic clocks based on trapp…
View article: Formulation and Characterization of One-Way Radiometric Tracking with the Iris Radio Using a Chip-Scale Atomic Clock
Formulation and Characterization of One-Way Radiometric Tracking with the Iris Radio Using a Chip-Scale Atomic Clock Open
The Iris software radio has been updated to collect one-way Doppler and range data for potential use with deep space autonomous navigation. One-way radiometric data have found limited use because a typical radio oscillator is not sufficien…
View article: Testing the gravitational redshift with an inner Solar System probe: The VERITAS case
Testing the gravitational redshift with an inner Solar System probe: The VERITAS case Open
The NASA Discovery-class mission VERITAS, selected in June 2021, will be launched toward Venus after 2027. In addition to the science instrumentation that will build global foundational geophysical datasets, VERITAS proposed to conduct a t…
View article: Testing the gravitational redshift with an inner Solar System probe: the VERITAS case
Testing the gravitational redshift with an inner Solar System probe: the VERITAS case Open
The NASA Discovery-class mission VERITAS, selected in June 2021, will be launched towards Venus after 2027. In addition to the science instrumentation that will build global foundational geophysical datasets, VERITAS proposed to conduct a …
View article: Anomaly Detection in Autonomous Deep-Space Navigation via Filter Bank Gating Networks
Anomaly Detection in Autonomous Deep-Space Navigation via Filter Bank Gating Networks Open
This study investigates methods for autonomous navigation of a deep-space spacecraft where one-way radiometric and on-board optical information are fused to create a fully informed state estimate. The specific focus is on using filter bank…
View article: Results of the Deep Space Atomic Clock Deep Space Navigation Analog Experiment
Results of the Deep Space Atomic Clock Deep Space Navigation Analog Experiment Open
The timing and frequency stability provided by the Deep Space Atomic Clock (DSAC) is nearly commensurate to the Deep Space Network’s ground clocks and enables one-way radiometric measurements with accuracy equivalent to current two-way tra…
View article: Application of Shaken Lattice Interferometry Based Sensors to Space Navigation
Application of Shaken Lattice Interferometry Based Sensors to Space Navigation Open
High-sensitivity shaken lattice interferometry (SLI) based sensors have the potential to provide deep space missions with the ability to precisely measure non-gravitational perturbing forces. This work considers the simulation of the OSIRI…
View article: Solar System Interiors, Atmospheres, and Surfaces Investigations via Radio Links: Goals for the Next Decade
Solar System Interiors, Atmospheres, and Surfaces Investigations via Radio Links: Goals for the Next Decade Open
From Mercury to the outer reaches of the solar system, the past six decades have witnessed a vast set of discoveries utilizing radio science (RS) methods. For example, based on key gravitational evidence, sub-surface oceans have been infer…
View article: Radiometric Autonomous Navigation Fused with Optical for Deep Space Exploration
Radiometric Autonomous Navigation Fused with Optical for Deep Space Exploration Open
With the advent of the Deep Space Atomic Clock, operationally accurate and reliable one-way radiometric data sent from a radio beacon (i.e., a DSN antenna or other spacecraft ) and collected using a spacecraft’s radio receiver enables the …
View article: The Deep Space Atomic Clock: the first demonstration of a trapped ion atomic clock in space
The Deep Space Atomic Clock: the first demonstration of a trapped ion atomic clock in space Open
Atomic clocks, which lock the frequency of an oscillator to the extremely stable quantized energy levels of atoms, are essential for navigation applications such as deep space exploration1 and the Global Positioning System (GPS)2 and as sc…
View article: Accurate Ground-based Near-Earth-Asteroid Astrometry Using Synthetic Tracking
Accurate Ground-based Near-Earth-Asteroid Astrometry Using Synthetic Tracking Open
Accurate astrometry is crucial for determining orbits of near-Earth-asteroids (NEAs) and therefore better tracking them. This paper reports on a demonstration of 10 mas level astrometric precision on a dozen NEAs using the Pomona College 4…
View article: Solar System Ephemerides, Pulsar Timing, Gravitational Waves, & Navigation
Solar System Ephemerides, Pulsar Timing, Gravitational Waves, & Navigation Open
In-spiraling supermassive black holes should emit gravitational waves, which would produce characteristic distortions in the time of arrival residuals from millisecond pulsars. Multiple national and regional consortia have constructed puls…
View article: Transforming Mean and Osculating Elements Using Numerical Methods
Transforming Mean and Osculating Elements Using Numerical Methods Open
Mean element propagation of perturbed two body orbits has as its mathematical basis the averaging theory of nonlinear dynamical systems. Mean elements define an orbit's long-term evolution characteristics consisting of both secular and lon…