IEEE - Aerospace and Electronic Systems - July 2022 - 22

Feature Article:
DOI. No. 10.1109/MAES.2022.3159237
Development and Validation of a Canfield Joint
as a Precision-Pointing System for Deep Space
Instrumentation
Kristina V. Collins , Case Western Reserve University, Cleveland, OH 44106,
USA
Daniel Raible and Laura Burke, NASA Glenn Research Center at Lewis Field,
Cleveland, OH 44135, USA
INTRODUCTION
Deep space imaging and remote sensing technologies are
continually advancing, and this places an increasing demand
on the ability to accurately point optical instrumentation.
Recent flight instruments, such as the JunoCam [1], LongRange
Reconnaissance Imager [2]-[4], Mercury Dual Imaging
System [5], [6], Framing Camera [7], and the upcoming
Multispectral Imager [8] all impart demanding pointing
requirements in terms of accuracy and stability on their
respective spacecraft. This trend will continue as ever-higher
resolution optical instrumentation are developed.
The emergence of laser communications systems to
meet the increasing data bandwidth needs from spacecraft
instrumentation will also necessitate similar superior
pointing requirements in order to maintain a communications
link with Earth by ensuring beam alignment with a
ground terminal. A first demonstration of deep space laser
communication will be made by the Deep Space Optical
Communications payload [9] launching in 2022, and will
be conducted from the metal asteroid 16-Psyche [10]
within the asteroid belt approximately 3-4 AU from Earth.
Such distances establish a subarcsecond order of magnitude
performance on the pointing capability of the laser
Author's current address: Kristina V. Collins is with the
Department of Electrical Engineering and Computer Science
Case Western Reserve University, Cleveland, OH
44106, USA (e-mail: kvc2@case.edu). Daniel Raible and
Laura Burke are with NASA Glenn Research Center at
Lewis Field, Cleveland, OH44135, USA (e-mails: daniel.e.
raible@nasa.gov; laura.m.burke@nasa.gov). Manuscript
received April 16, 2021, revised February 12, 2022;
accepted March 1, 2022, and ready for publication March
11, 2022.
Review handled by Daniel O'Hagan.
0885-8985/22/$26.00 ß 2022 IEEE
22
CONCEPT OF OPERATIONS
MISSION PARAMETERS
The pointing requirements used for validation are based
on a use case of a Mars orbiter communicating optically
with a Deep Space Network receiver on Earth, as shown
in Figure 1. The orbiter circles Mars with a downward-facing
camera, and its coordinate frame is defined as shown
in Figure 2. The pointing requirements used in this
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JULY 2022
beam to maintain a communications link with the Earth.
While laser communications and optical sensing represent
different functionalities and requirements-a communications
link might need to remain established for many
minutes of duration while the mechanism tracks Earth,
while in the instrumentation case the imager needs to be
pointed for the duration of frame acquisition-both applications
require a high degree of pointing accuracy.
In addition, the capability for a spacecraft to direct an
instrument independent of the orientation of the satellite bus
is a requirement derived from the need for more multifunctional
missions. Consider a planetary orbiter spacecraft,
whose primary role may be to maintain a host of nadirmounted
instruments pointed at the surface of the planet for
the duration of an orbit. A secondary objective of the spacecraft
would be to serve as an intermediate communications
relay for other local orbiters and landers, requiring that the
communications payload be continually articulated in order
to maintain links with Earth and the other space assets, while
simultaneously operating the nadir instruments to maintain
science data collection. This objective implies a pointing system
with a large field of regard (FOR) given the geometries
oforbital dynamics, which from an optomechanical perspective
appears at odds with the superior pointing accuracy
requirement, and so establishes the technology challenge.
https://orcid.org/0000-0002-3816-1948
IEEE - Aerospace and Electronic Systems - July 2022

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