31ST AAS/AIAA SPACE FLIGHT MECHANICS MEETINGCONFERENCE INFORMATIONGENERAL INFORMATION
Welcome to the 31st Space Flight Mechanics Meeting, hosted by the American Astronautical Society (AAS)
and co-hosted by the American Institute of Aeronautics and Astronautics (AIAA), February 1 – 3, 2021. This
meeting is organized by the AAS Space Flight Mechanics Committee and the AIAA Astrodynamics TechnicalCommittee, and held virtually due to the ongoing COVID-19 pandemic.

REGISTRATION
Registration Site ( https://www.xcdsystem.com/aas/attendee/index.cfm?ID=5h0LILe )In order to encourage early registration, we have implemented the following conference registration rate
structure: Register by January 22, 2021 and save $75!
Category

Early Registration(through Jan 22, 2021)

Registration (beginning
Jan 23, 2021)

Full - AAS or AIAA Member

$260

$335

Full - Non-member

$360

$435

Student* - Member

$100

$175

Student* - Non-member

$145

$220

Retired* - Member

$100

$175

Retired* - Non-member

$200

$275

*does not include proceedings CD
Cancellations must be in writing and received no later than 27 January 2021. There is a $100 cancellation fee.

SCHEDULE OF EVENTS
A Welcome and Awards Reception begins on Monday, 1 February at 9:30 AM EST. Technical sessions begin
at 10:30 AM EST. A Plenary Session will take place on Wednesday, 3 February from 9:30 AM – 10:15 AM
EST. The last technical sessions end at 3:00 PM on Wednesday, 3 February. Presentations during the technicalsessions are limited to 8-minute summary presentations followed by 4 minutes of Q&A. All live sessions aremoderated by the session chairs, much like during an in-person conference.
Social Activities: One aspect of in-person conferences that everyone misses is the chance to meet and catch up
with friends and colleagues from across the astrodynamics community. Just because the conference is virtual
doesn’t mean we can’t be social! For this virtual conference, we are introducing optional social events
organized via Gather.Town, an online platform that helps to recreate the organic feeling of in-person events
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31st AAS/AIAA Space Flight Mechanics Meetingwhile we are all unable to travel. In Gather, people can move around virtual rooms, have small groupconversations (without fear of speaking over other people’s chats), and even play various games! We will be
providing two options during the conference:
1. Lunch Bunch Rooms (12:00-1:30pm EST all conference days) that are smaller and more intimate,making conversations easier for small groups
2. Afternoon BYOB Happy Hours (3:30-4:30pm EST Monday & Tuesday) in a larger setting to allow
people the chance to see many familiar faces
Gather is entirely browser based, so no pesky downloads either. Please see the Additional Information section
later in this program for more information on how to join Gather. We hope you’ll join us!

Page 231st AAS/AIAA Space Flight Mechanics Meeting

Page 3

1 February

Monday

Day

Start

End

FunctionRoom

9:30am

10:00amWelcome and Awards Reception

Virtual Room#1

10:30am

12pm

Session 1: Interplanetary Trajectories

Virtual Room#1

10:30am

12pm

Session 2: Debris Clouds, Debris Densities, andSpace Environment

Virtual Room#2

10:30am

12pm

Session 3: Rendezvous

Virtual Room#3

10:30am

12pm

Session 4: Satellite Formations & Collision
Avoidance

Virtual Room
#4

10:30am

12pm

Session 5: Asteroids I

Virtual Room
#5

Noon

1:30pmLunch Bunch Rooms

Gather Town

Noon

1:30pmJoint AAS/AIAA Technical Committee Meeting

Meeting Link
Sent Via Email

1:30pm

3:00pmSession 6: Low Thrust Trajectories I

Virtual Room#1

1:30pm

3:00pmSession 7: Attitude Dynamics and Control

Virtual Room#2

1:30pm

3:00pmSession 8: Navigation

Virtual Room#3

1:30pm

3:00pmSession 9: Atmospheric Reentry Guidance andControl

Virtual Room#4

1:30pm

3:00pmSession 10: Artificial Intelligence inAstrodynamics

Virtual Room#5

3:30pm

4:30pmBYOB Virtual Happy Hour

Gather Town

31st AAS/AIAA Space Flight Mechanics Meeting

Page 42 February

Tuesday

Day

Start

End

FunctionRoom

10:30am

12pm

Session 11: Low Thrust Trajectories II

Virtual Room#1

10:30am

12pm

Session 12: Trajectory Design I

Virtual Room#2

10:30am

12pm

Session 13: Spacecraft Control I

Virtual Room#3

10:30am

12pm

Session 14: Cislunar Space Situational
Awareness

Virtual Room
#4

10:30am

12pm

Session 15: Dynamical System Theory I

Virtual Room
#5

Noon

1:30pmLunch Bunch Rooms

Gather Town

Noon

1:30pmAIAA Astrodynamics Technical Committee Meeting Link
Sent Via
MeetingEmail1:30pm

3:00pmSession 16: Trajectory Design II

Virtual Room#1

1:30pm

3:00pmSession 17: Spacecraft Control II

Virtual Room#2

1:30pm

3:00pmSession 18: Space Object Characterization
and Independent Attitude Determination

Virtual Room#3

1:30pm

3:00pmSession 19: Asteroids II & Mars

Virtual Room#4

1:30pm

3:00pmSession 20: Space Robotics andAutonomous Operation & Lunar

Virtual Room#5

3:30pm

4:30pmBYOB Virtual Happy Hour

Gather Town

31st AAS/AIAA Space Flight Mechanics Meeting

Page 5

3 February

Wednesday

Day

Start

End

FunctionRoom

9:00am

10:00amPlenary: “Key Considerations to Guarantee Safety of Virtual RoomOperations in Space”, Dr. Juan Carlos Dolado Pérez #1

10:30am

12pm

Session 21: Trajectory Optimization

Virtual Room#1

10:30am

12pm

Session 22: Formation Flying

Virtual Room#2

10:30am

12pm

Session 23: Guidance, Navigation, and Control

Virtual Room#3

10:30am

12pm

Session 24: Orbit Determination

Virtual Room
#4

10:30am

12pm

Session 25: Orbital Dynamics, Perturbations, andStability

Virtual Room
#5

Noon

1:30pmLunch Bunch Rooms

Gather Town

Noon

1:30pmAAS Technical Committee Meeting

Meeting Link
Sent Via Email

1:30pm

3:00pmSession 26: Trajectory Design III

Virtual Room#1

1:30pm

3:00pmSession 27: Guidance and Control

Virtual Room#2

1:30pm

3:00pmSession 28: Dynamical System Theory II

Virtual Room#3

1:30pm

3:00pmSession 29: Space Robotics and Autonomous
Operation

Virtual Room#4

1:30pm

3:00pmSession 30: Multi Object Tracking

Virtual Room
#5

3:00pm

5:00pmConference Administration Subcommittee

Meeting Link
Sent Via Email

3:00pm

5:00pmTechnical Administration Subcommittee

Meeting Link
Sent Via Email

3:00pm

5:00pmWebsite Administration Subcommittee

Meeting Link
Sent Via Email31st AAS/AIAA Space Flight Mechanics MeetingSPECIAL EVENTSWELCOME AND AWARDS RECEPTION
Monday, 1 February

9:30 – 10:00 am

Location:

Virtual Room #1

Please join us for welcoming remarks to assist you in your conference experience and a presentation of Best
Paper and Breakwell Travel Awards.

PLENARY:
Wednesday, 3 February

9:00 – 10:00 am

Location:

Virtual Room #1

Key Considerations to Guarantee Safety of Operations in Space
Dr. Juan Carlos Dolado Pérez, Head of the Space Debris Modelling and Risk Assessment Office at CNES

Juan-Carlos Dolado-Perez is the head of the space debris modelling and risk assessment office at the “Centre
National d’Etudes Spatiales” (French Space Agency). Since 2008 he has worked at the system engineering andorbital dynamics sub directorate, where his main research topics concerns the long and middle term re-entry
prediction, the long term evolution of the space debris population, the on orbit collision risk assessment, theorbit determination from radar and optical measurements and the uncertainty characterization and propagation.

He is a member of the Inter Agencies Space Debris Committee (IADC)’s French Delegation and of theInternational Academic of Astronautics (IAA). Juan-Carlos owns a B.S. in Aerospace Engineering from theMadrid’s Polytechnic University and a MSc. in Aerospace Engineering from the Institut Supérieur del’Aéronautique et de l’Espace (ISAE).

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31st AAS/AIAA Space Flight Mechanics Meeting

ADDITIONAL INFORMATIONSPEAKER INFORMATION
Authors should have submitted a brief (approximately 50 words or 3 sentences) speaker’s bio with their abstract
submission. Authors are required to be in their virtual session room 30 minutes prior to the start of their sessions
to meet their session chair and work through any technical issues to ensure a smooth session.
For
the
short
presentation,pleaseuploadyourslidesatthespeaker
portal(https://www.xcdsystem.com/aas/abstract/index.cfm?ID=gge2bwZ) by January 29 2021, 23:59:59 EasternTime.
The longer, pre-recorded, 15-minute video presentation is to be uploaded by January 29 2021, 23:59:59
Eastern Time to the speaker portal (https://www.xcdsystem.com/aas/abstract/index.cfm?ID=gge2bwZ ). This
recording will be available to the registered conference attendees during the entire time of the conference. Please
note: recordings longer than 15 minutes will be removed and counted as a no-show if no replacement video
complying with the maximum time (15 min) is re-uploaded by the deadline.
For the video presentation, you can record yourself and upload a .mp4 file or use the recording tool provided at
the speaker site. Once logged in, please find the button to record or upload your presentation.
For recording instructions and best practices please go to https://x-cd.com/virtual-presentation-guide/. It is
recommended to NOT use the safari browser, as tests have shown some hiccups there.

CONFERENCE ATTENDANCE AND PRESENTATIONS
Please see the “How-To-Attend.pdf” and “How-To-Present.pdf” files for specific instructions to access theconference and for presenting at the conference.
Each live presentation is limited to 8 minutes. An additional four minutes is allotted between presentations foraudience participation and transition. Session chairs shall maintain the posted schedule to allow attendees theoption of joining a parallel session.
"No-Paper, No-Podium" Policy Completed manuscriptsshallbe electronically uploaded to the submission site
before the conference, limited to 20 pages in length, and conform to the AAS conference paper format. If thecompleted manuscript is not contributed on time, it will not be presented at the conference. If there is noconference presentation by an author, the contributed manuscript shall be withdrawn.
Each author is also acknowledges that he or she is releasing technical information to the general public and that
respective papers and presentations have been cleared for public release. If any author of a paper is a US person(citizen or permanent resident), he or she acknowledges that the release of these data and content of the paper
and presentation conforms to ITAR and are not on the USML. The information contained in these documents
is neither classified, SBU, FOUO, nor proprietary to any sponsoring organization.

PREPRINTED MANUSCRIPTS
Physical copies of preprinted manuscripts are no longer available or required for the Space Flight Mechanics
Meetings or the Astrodynamics Specialist Conferences. Electronic preprints are available for download at least
72 hours before the conference at https://www.xcdsystem.com/aas/program/XCtzIQp for registrants who have
logged in.

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31st AAS/AIAA Space Flight Mechanics Meeting

CONFERENCE PROCEEDINGSAll full registrants will receive a CD of the proceedings mailed to them after the conference (extra copies areavailable for $60 during registration). Although the availability of proceedings enhances the longevity of yourwork and elevates the importance of your conference contribution, please note that conference proceedings are
not considered an archival publication. Authors are encouraged to submit their manuscripts after the meeting
to one of the relevant journals, such as:
Journal of the Astronautical Sciences
Editor-in-Chief: Dr. Maruthi Akella
Aerospace Engineering and Engineering Mechanics
2617 Wichita Street
ASE Building, C0600
Austin, TX 78712
makella@mail.utexas.edu
Journal of Guidance, Control and Dynamics
Editor-in-Chief: Dr. Ping Lu, San Diego State University
Manuscripts can be submitted via: https://mc.manuscriptcentral.com/aiaa-jgcd
Journal of Spacecraft and Rockets
Editor-in-Chief: Dr. Hanspeter Schaub, University of Colorado-Boulder
Manuscripts can be submitted via: https://mc.manuscriptcentral.com/aiaa-jsr

SATISFACTION SURVEY
Registrants are highly encouraged to record their level of satisfaction and conference preferences in ananonymous survey which will be online after the conference with a link provided via email.

COMMITTEE MEETINGS
Committee meetings are limited to committee members and invited guests. Committee and subcommittee
meetings will be held according to the schedule at the beginning of the program. Committee members will be
provided a virtual meeting link via email prior to the conference.

GATHER LUNCH BUNCH AND HAPPY HOUR ROOMS
Gather is a wonderful new tool for getting to both explore and chat with other people. It is also a very new
tool and has a few quirks. This guide is to help you with the basics so you can discover and play on your own.
To use the Gather sites set up for the conference, you can click on the links located on the main conference“Lobby” page. Please see the “How-To-Attend.pdf” guide for instructions on how to navigate to the main
conference “Lobby” page.

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For more information, visit the FAQ: https://gather.town/faq

Conference Etiquette Applies!
-

While we do provide spaces for “private” conversation, please be aware that Gather is much like any
real-world public space.
People may overhear your conversation as they move around the space, messages may not remain
between two people, etc.
Please, act with the professional etiquette like you would during an in-person conference
If you have any concerns or complaints about someone’s behavior, please contact one of theconference chairs (Jeff Stuart, Angela Bowes, Renato Zanetti, Carolin Freuh) either within Gather or
via an alternate means such as email.

What you need:-A desktop/laptop with a mic and camera.
A web browser (Chrome or Firefox recommended).
We strongly recommend using headphones to help preventfeedback.
That’s it! There’s nothing to install, no software to download.

Howit works:-

Page 9Gather is a video chat platform that has avatars move around a map. As you get close to other avatars,
your video’s will pop up and you will be able to chat.
Move around the space using the arrow k e ys.
By moving your avatar around you can have spontaneous conversations with those around you. Thesecan be either one-on-one or small groups depending on how many people are around your avatar.

31st AAS/AIAA Space Flight Mechanics Meeting-When your avatar moves closer to an interactable object, there will be a notification that shows up
saying ‘Press x to interact with -object-’. This can range from informational flyers, playable arcade
games, integrated Zoom meetings, and more!

Icon Explanation:
Screen sharing ability
Change your avatar character and clothing
Mini map to preview the space you’re in
Raise hand feature: good for Q&A in keynotes or classrooms
Opens the settings menu:● Change Name
● Change Audio/Video Devices● Respawn button to return to start

Not-So-Obvious Features:
Here are some things you might find useful but aren't immediately obvious.
--

There is a messaging feature that allows you to message people in three ways:
1. individually by clicking on their name in the participant panel,
2. locally to the people you are video chatting with,
3. globally to all the people in your map.
There is a locate feature to find others by clicking their name in the participant panel.
Interaction distance is also sometimes altered by designated private spaces. This allows
conversations to only include people inside that space.
Want to full screen someone else’s video? Just click on their video.
Talking to a group of people? Click the down arrows centered below the videos to shift into gridview.

Technical difficulties:-

Refreshing the page will fix most things!
- If that doesn’t work, try muting and unmuting your mic and camera in Gather.
- Check if your browser permitted camera and mic access- Additional troubleshooting at https://gather.town/video-issues

Page 1031st AAS/AIAA Space Flight Mechanics MeetingHappy Hour Map Guide:

Welcome to the SFMM Happy Hour!
Two Happy Hours have been arranged, Monday & Tuesday, 3:30-4:30pm EST
The Happy Hours are free for conference attendees, but BYOB!
The space for the Happy Hour is meant to be explored, but we want to point out two areas that might be of
special interest:
1. The tables here have been set to enable “private” conversations for those standing next to the table.
So, feel free to talk without worrying about interrupting other people’s conversations! Some of thetables have games at them. We encourage you to play!
2. We’ve provided some whiteboards with “private” spaces, if you just can’t resist the stray technicalconversation!

Lunch Bunch Rooms:
We have also provided a limited number of rooms for lunchtime social interactions (or any time, really). In
addition to “private” conversation spaces and a few games, we’ve also provided whiteboards for sidebar
technical conversations. The rooms are limited to 25 people per room and are smaller, so please be respectfulof other conference attendees!

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CONFERENCE SCHEDULE
Feb 1, 2021Virtual Room #1
01 - Interplanetary Trajectories
Chair: Kathleen C. Howell, Purdue University
10:30

AAS Transfer between planar and 3D Quasi Satellite Orbits around Mars’s moon Phobos
21-261 Stefanos Charkoutsis, University of Liverpool; Elisabet Canalias, CNES; Stefania Soldini,
University of Liverpool
This research paper is focused on the preliminary design of transfer trajectories between a planar
orbit and a spatial orbit around Phobos, as part of the MMX mission. MMX is a mission led by
JAXA, to send spacecraft to the two moons of Mars, Phobos and Deimos, in collaboration with the
French (CNES) and German (DLR) space agencies, to study their origins. Initially validation of the
CR3BP and ER3BP models was conducted, and then the theoretical and numerical minimum andmaximum costs were computed for the transfers and compared the results with that of (Canalias, etal., January 2019).

10:54

AAS Application of Halo Orbit on Extension for Launch Window Limited by Direct Earth21-300 Mars
Transfer
Zhe Xu, Kyushu University; Mai Bando, Kyushu University; Hideaki Ogawa, Kyushu
University; Shinji Hokamoto, Kyushu University
This paper aims to propose a design method on resorting to Halo orbit to overcome the problems ofhigh risk and limited launch window, which is common in traditional direct Earth-Mars transfer
mission. To overcome the big scale computation problem brought about by this multiple dimension
problem, surrogate-assisted design methodology is employed. Meanwhile, GPU parallel computation
technique is also adopted to further reduce the computational cost to an acceptable extent. Based onit, structure of solution is investigated in terms of capability and contribution of halo orbits as aphasing orbit to interplanetary transfer.

11:06

AAS Earth-to-Mars Low Energy Transfers from Cislunar Direct Retrograde Orbits
21-330 Colas Chevailler, ISAE-SUPAERO; Emmanuel Blazquez, ISAE-SUPAERO; Stéphanie LizyDestrez
The scope of this research is to propose new impulsive transfer strategies from Earth-Moon DROs
to Sun-Mars planar Lyapunov Orbits, making use of low-energy pathways and weak stability
boundaries. The trajectory is optimized in three patched Three-Body systems to make use of anintermediary phasing planar Lyapunov Orbit of the Sun-Earth system. Firstly, a new strategy forcost-efficient departure from DROs is showcased, by injection into the unstable invariant manifold
of a tangential planar Lyapunov Orbit. Secondly, a systematic hybrid optimization procedure is
proposed to design fuel and time efficient DRO-to-Mars trajectories easily corrected in high-fidelity
models.

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31st AAS/AIAA Space Flight Mechanics Meeting11:18AAS DEEP SPACE TRANSFERS OF PIGGY-BACK MICRO SPACE PROBES USING
21-295 HYBRIDROCKET
KICK
MOTOR
Daichi Ito, The Graduate University for Advanced Studies, SOKENDAI; Nishanth
Pushparaj, The Graduate University for Advanced Studies, SOKENDAI; Kotaro Fujiwara,
Hokkaido University; Yasuhiro Kawakatsu, JAXA / ISAS
Geostationary Transfer Orbit (GTO) is a good launching point for deep space missions. Although"piggy-back" is a low-cost approach for inserting micro space probes into a GTO, the main mission
primarily determines GTOs' nature and the launch window. Therefore, the piggy-back probes' kickmotor must have the necessary capacity to cope with arbitrary launch dates and GTOs. Preliminary
studies suggest that GTO to Moon transfer requires a ∆V of 1.81km/s. This study extends the transfer
case to Mars, utilizing an Earth swing-by via 1:1 resonant orbit from a GTO. These results provide
useful insights for designing and planning low-cost missions.

11:30

AAS EVALUATION OF ITERATIVE ANALYTICAL TECHNIQUESFOR THE
21-230 TRAJECTORY
DESIGN OF A DIRECT JUPITER ORBITER MISSION
Parvathi S P, Indian Institute of Science; Ramanan R V, Indian Institute of Space Scienceand Technology
For a direct orbiter mission to Jupiter, it is understood that the velocity impulse required will be huge.
To surpass this expenditure, usually gravity assist missions are attempted for a Jupiter mission.
However, in this research, an evaluation is carried out for the trajectory design of a direct Jupiterorbiter mission. The iterative analytical techniques based on the patched conic and the pseudostate
concepts are used to obtain the trajectory design for the minimum energy opportunity of 2022. A
comparison is made on the initial states of the departure trajectory and the achieved target parameters.

11:42

AAS Solar
Sail
Trajectories
forInterstellar
ObjectRendezvous
21-370 Daniel Miller, Massachusetts Institute of Technology; Damon Landau, Jet Propulsion
Laboratory; Richard Linares, Massachusetts Institute of Technology; Benamin Weiss,
Department of Earth, Atmospheric and Planetary Sciences; Paulo Lozano, Department of
Aeronautics and Astronautics
Using the “statite” concept, this paper presents a potential solar sail mission to study Interstellar
Objects (ISOs). These objects are tantalizing scientific targets but challenging to study due to theirshort lead time and high heliocentric velocities. By using its solar sail to “hover” in place, a statite isable to await the discovery of an ISO and, when called upon, convert the enormous potential energyof its state into the velocity necessary to rendezvous with the object. In this investigation, solar sailtrajectories to known ISOs will be produced and launch trajectories to the initial statite state will
investigated.

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Feb 1, 2021Virtual Room #2
02 - Debris Clouds, Debris Densities, and Space Environment
Chair: Alinda Mashiku, NASA GSFC
10:30

Waves
in
DebrisCloudsAAS Density
21-269 Ken Chan, Chan Aerospace Consulting
This paper shows the existence of waves of varying densities travelling through a debris cloud. It
deals with the formulation of analytical expressions describing the formation and evolution of these
density waves. It is well-known that the Earth’s oblateness causes a precession of the Ascending
Node of the orbital plane of each debris fragment. However, in contrast, these density waves arecaused by differenl rates between the fastest and the slowest precessions belonging to the same debris
cloud so as to form a band initially. As the width of this band expands, it gradually fills the Earth’s
360o girth.

10:42

AAS Some Topological Properties of Keplerian Parametric Scatter Diagrams of Debris
21-268 Clouds
Ken Chan, Chan Aerospace Consulting
This paper discusses some topological properties exhibited by scatter diagrams such as semi-major
axis/eccentricity, semi-major-axis/inclination and eccentricity/inclination of the debris fragments
produced either in a collision between two orbiting objects or the explosion of an orbiting object.
These properties are useful in the study of debris clouds such as their evolution and decay of various
fragments due to atmospheric drag. The approach circumvents the need to perform time-consuming
numerical simulations which mask certain features so important in the prediction of the life span ofthese debris clouds. Moreover, it leads to the forecast of density waves and their eventual decay.

10:54

Risk
Truth
Data
Generation
for
Model
ValidationAAS Debris
21-200 Brian Hansen, The Aerospace Corporation
Assessing satellite risk from breakup debris has become increasingly important. Several different
risk models have been developed, but there are still no truth data available for their evaluation. We
present a limited set of debris risk “truth” data generated by performing massive Monte Carlo runs,
preserving close approaches small enough to collide with actual satellites. Resulting risk values witherror bars are presented for the FY-1C ASAT, run against three high-risk satellites. Comparisonswith the corresponding risk predicted by models developed at The Aerospace Corporation show them
to be conservative and accurate to within about half an order of magnitude.

11:06

AAS Effect of perturbations on orbital density using Eulerian orbit dynamics
21-217 Liam Healy, Naval Research Laboratory; Blake Halpin, Naval Research Laboratory; Scott
Kindl, Naval Research Laboratory; Patric Hoskins, Naval Research Laboratory
The behavior of object density after a fragmentation has been analyzed using "Eulerian orbit
dynamics", our term for the propagation of densities in contrast to the traditional propagation ofindividual objects. We previously pioneered a technique that propagates the spatial density of orbital
objects exactly. In the present work, we show the effects of perturbations, principally the J2
gravitational and atmospheric drag, on orbits in low-earth, geosynchronous, and highly ellipticalorbits. The results are compared with unperturbed results on a continuous scale, with the perturbation

Page 1431st AAS/AIAA Space Flight Mechanics Meetingparameter (such as J2 coefficient) varied from zero (unperturbed), to much larger than realistic
values.

11:18

AAS Secular Dynamics based Features for the Characterization of Small Debris Clouds
21-286 after
Fragmentation
Di Wu, UC San Diego; Aaron Rosengren
Current characterization of space debris usually neglects fragments smaller than 10cm because of thelimited numbers of infrastructure capable of doing so. Yet, the threat from small debris objects could
not be less dangerous to satellites than any other debris. This work conducts an investigation forspace debris clouds and proposes a set of features based secular dynamics to characterize them.
Meanwhile these features’ evolutions are further illustrated. As a result, these features allow the
representation of small debris clouds and the prediction of their evolution.

11:30

Drag
Data
AAS Assessing Thermospheric Densities Derived from Orbital
21-354 Valerie Bernstein, University of Colorado Boulder; Marcin Pilinski, Laboratory for
Atmospheric and Space Physics, CU Boulder; Eric Sutton, University of Colorado Boulder
Two-Line Element (TLE) entries provide an expansive record of orbital element information for
most known Earth-orbiting objects and can be used to derive thermospheric densities. We compare
TLE-derived and accelerometer-derived densities for 8+ years of CHAMP and GRACE satellite data.
Results indicate that TLE processing choices, as well as the relative positioning of the twin GRACE
satellites, significantly impact agreement between the different density datasets. Additionally, TLE
density variability is greater in low-drag environments. This analysis reveals the uncertainty inherent
in long-term density datasets inferred from TLEs used to construct empirical models, which are thenfed into orbit determination schemes.

11:42

AAS Density
estimation
using
second-order
Gauss
Markovprocesses
21-340 Vishal Ray, CU Boulder; Daniel Scheeres, University of Colorado Boulder; Eric Sutton,
University of Colorado Boulder; Marcin Pilinski, Laboratory for Atmospheric and Space
Physics, CU Boulder
Atmospheric density estimates derived from satellite data play an important role in determining asatellite’s location in orbit and studying the evolution of the Earth’s atmosphere. But they are plaguedby biases resulting from simplifying assumptions pertaining the satellite drag-coefficient. In thiswork, we leverage previous work on simultaneous estimation of atmospheric density and ballisticcoefficient from satellite tracking data using first-order Gauss-Markov processes. We extend themethod to utilize second-order Gauss Markov processes that are more suitable for periodicallyvarying parameters and estimate the drag-coefficient using Fourier models.

11:54

AAS Impact of Driver and Model Uncertainty on Drag and Orbit Prediction
21-415 Richard Licata, West Virginia University; Piyush Mehta, West Virginia University; W. Kent
Tobiska, Space Environment Technologies
Space Weather (SW) has a strong influence on satellite tracking, orbital decay, and collision
avoidance in low Earth orbit (LEO). Specifically, satellite position Probability Density Functions(PDFs) essential for probability of collision, Pc, estimates are heavily dependent on drag. These
PDFs are used in satellite conjunction analyses; therefore, confidence in them isparamount. However, these density forecastshave multiple sources of uncertainty that can lessen ourPage 15

31st AAS/AIAA Space Flight Mechanics Meetingconfidence in the resulting PDFs. These include SW driver uncertainty, model uncertainty,
and subgrid uncertainty. In this paper, we quantify the impact of both SW driver uncertainty andmodel uncertainty and analyze their contributions.

Feb 1, 2021Virtual Room #3
03 - Rendezvous
Chair: Fabio Curti, School of Aerospace Engineering, Sapienza University of Rome
10:30

AAS Bearings-Only
Guidance for Rendezvous in a
Cis-Lunar
NRHO
21-209 Giordana Bucchioni, University of Pisa Dip.Ingegneria Informazione; Mario Innocenti,
University of Pisa - Department of Information Engineering; Fabio D'Onofrio, Universityof Pisa, Dip. Ingegneria dell'Informazione
The current plans of returning to the Moon, involve rendezvous and docking/berthing with the Lunar
Gateway, whose targeted orbit is a Near Rectilinear Halo Orbit(NRHO). The aim of this work is todesign and validate a guidance algorithm for the close-range rendezvous phase, assuming that thechaser can only measure relative angles to the target. The navigation performance is affected by the
maneuvers performed because their execution is necessary to make the problem observable. The
relative motion equations with third body perturbation are considered directly in the guidancealgorithm, with the additional aim of improving observability during the approach trajectory.

10:42

AAS Analytical Description of Relative Position and Velocity on J2-Perturbed Eccentric21-235 Orbits
Matthew Willis, Stanford University; Simone D'Amico, Stanford University
A new solution is introduced for the relative position and velocity of two spacecraft on eccentric
orbits perturbed by Earth oblateness. The equations of relative motion subject to an arbitrary
perturbing force are derived and this general framework is used to develop a partial solution for thecase of perturbation by the second zonal harmonic of Earth’s gravitational potential. The
performance of the new solution is compared with several prominent translational and orbital
element-based solutions from the literature, and the inability of variation of parameters to produce acomplete, closed-form solution for the J2 corrections is discussed.

10:54

AAS Non-Cooperative Rendezvous and Proximity Operations for Active Debris Removal
21-281 Missions
TAKAHIRO SASAKI, Japan Aerospace Exploration Agency; Naomi Murakami, JAXA; Yu
Nakajima, JAXA; Moeko Hidaka; Ryo Nakamura, Japan Aerospace Exploration Agency;
Toru Yamamoto, Japan Aerospace Exploration Agency
As the amount of debris in orbit increases, so does the risk of collisions and their seriousness. One
solution receiving increased attention is active debris removal (ADR). The first step in such missions
would be to approach the debris. This study addresses the practical rendezvous scenario for the ADR
mission and clarifies the requirements for the navigation system, by using the Linear Covariance
Analysis, while newly taking bias errors into account. It also considers trajectory safety in bothnominal and off-nominal situations. Finally, it is shown that the proposed rendezvous trajectory is
sufficiently safe from the viewpoint of collision.

Page 16

31st AAS/AIAA Space Flight Mechanics Meeting11:06

AAS Optimal Trajectory Control of J2 Perturbed Spacecraft Relative Motion in Elliptical
21-357 Orbit
Ayansola Ogundele, National Space Research and Development Agency; Olufemi Agboola,
National Space Research and Development Agency, Nigeria
The proper functioning of aerospace systems and their ability to achieve the mission objectives
depend largely on proper understanding of their relative motion dynamics and ability to keep themin the required mission operation configurations through proper control. In this paper, nonlinear
dynamics and control of J2 perturbed spacecraft formation flying are developed via Euler-Lagrange
and State Dependent Riccati Equation (SDRE) approach. J2 perturbed nonlinear dynamic relative
motion model containing quadratic nonlinear terms is obtained from the original nonlinear J2
perturbed equation. Then, SDRE technique is applied to the model. Efficiency of the controller isvalidated using numerical simulations.

11:18

AAS Challenge
Problem:
AssuredSatellite
Proximity
Operations
21-419 Christopher D. Petersen, Air Force Research Laboratory; Kerianne Hobbs, Air Force
Research Laboratory; Kendra Lang, Verus Research; Sean Phillips, AFRL
Assuring safety of a spacecraft during autonomous rendezvous, proximity operations, and docking
is a non-trivial, multi-constraint challenge. To address this, we formulate a challenge problem
relating to autonomous rendezvous and docking of a basic 6U CubeSat model with thrust in one axis,
a reaction wheel for attitude control, and a gimballed sensor. To assure safety of the vehicle during
operations, a variety of constraints are introduced. Several different solutions to the challenge
problem are discussed, with benefits and disadvantages being highlighted.

11:30

AAS Autonomous Satellite Rendezvous and Proximity Operations via Model Predictive
21-423 Control
Methods
Anonto Zaman, Georgia Institute of Technology; Alexander Soderlund, National Academyof Sciences / Air Force Research Laboratory; Christopher D. Petersen, Air Force ResearchLaboratory; Sean Phillips, AFRLThis work examines the autonomous rendezvous, proximity operations, and docking (ARPOD)
problem wherein a “chaser” spacecraft with a single thruster must maneuver and dock with a “target”
spacecraft whilst maintaining safety constraints. The challenge lies in the fact that the chaser satellite
is underactuated, and there is coupling in both its translational and rotational dynamics. To drive theinputs of the chaser we leverage non-linear model predictive control (MPC) in order to construct anefficient control policy while incorporating nonlinear dynamics and constraints. In-depth simulation
analyses demonstrate successful safe docking through this MPC-driven approach.

11:42

Relative
MotionUsing
theClohessy-Wiltshire
EquationsAAS Forced
21-438 Brendan Hennessey Rose, USAFA; Blair F. Thompson, The Aerospace Corporation; Daniel
ShowalterIn this paper we present a novel method for the development and analysis of forced motion relative
trajectories between two spacecraft. The method is based on Lambert targeting in the natural relative
motion space of the Clohessy-Wiltshire (CW) equations. The desired relative motion trajectory is
discretized over time of flight. The method can then be used to determine the feasibility of thedesired relative trajectory compared to the thrust availability for a particular spacecraft, and to modify

Page 17

31st AAS/AIAA Space Flight Mechanics Meetingthe trajectory and time of flight to satisfy maneuvering constraints such as line of sight, position
relative to the sun, etc. This method

Feb 1, 2021Virtual Room #4
04 - Satellite Formations & Collision Avoidance
Chair: Christopher Roscoe, Tiger Innovations
10:30

AAS Optimizing
Formation
Flying
Orbit
Designs
21-410 James Ragan, California Institute of Technology; Soon-Jo Chung, California Institute ofTechnology; Kai Matsuka, California Institute of Technology; Marco Lavelle, JPL; Razi
Ahmed, JPL; Ilgin Seker, JPLGroups of spacecraft flying in formation in Earth orbit have the potential to perform more complex
tasks and produce higher quality science but introduce increased design complexity. This study
attempts to optimize the design of spacecraftformations subject to dynamic constraints in the context
of an Earth observing Synthetic Aperture Radar mission, in terms of the quality of science produced.
Building on preliminary trajectories found using genetic algorithm-based methods, a simplified
version of the design problem will be solved to give an analytic solution, to be used to approximate
the global solution via further machine learning based algorithms.

10:42

AAS Structural Design and Impact Analysis of a 1.5U CubeSat on the Lunar Surface
21-417 Christopher Hays, Embry-Riddle Aeronautical University; Troy Henderson, Embry-Riddle
Aeronautical University; Daniel Posada, Embry-Riddle Aeronautical University; Aryslan
Malik, Embry-Riddle Aeronautical University
Ahead of the United States' crewed return to the moon in 2024, Intuitive Machines, under a NASA
Commercial Lunar Payload Services contract, will land their Nova-C lunar lander in October 2021.
At 30 meters altitude during the terminal descent, EagleCam will be deployed, and will capture andtransmit the first-ever third-person images of a spacecraft making an extraterrestrial landing. This
paper will focus on the structural design, modeling, and impact analysis of a 1.5U CubeSat payload
to withstand a ballistic, soft-touch landing on the lunar surface.

10:54

AAS Securing
Distributed
MicroSatellites
fromCyber-attacks
21-313 Mizanul Chowdhury, MIT
The large-scale development and deployment of small satellite systems in the modern aerospacesector motivates the parallel development of new flight software and avionics systems to meet thedemands of modern spaceflight operations. Cyber-attacks are a growing threat to future robots. The
shift towards automatization has increased relevance and reliance on robots. Securing robots has
been secondary or ternary priority and thus robots are vulnerable to cyber-attacks. I am proposing afederated policy enforcement point using Attribute Based Access Control (ABAC) basedarchitecture, using cryptography mechanism, which addresses the most common ROS safety issues.

11:06

AAS STATE-SPACE CONTROLLER
21-361 CONSTELLATIONSPage 18FORLEO,

LOW-THRUSTSATELLI TE

31st AAS/AIAA Space Flight Mechanics Meeting

Mario Contreras, MIT; David Arnas, Massachusetts Institute of Technology; Richard
Linares, Massachusetts Institute of Technology
Due to the increased use of satellite constellations some altitudes in LEO have experienced a large
increase in number of satellites. This is a trend expected to continue in the future, which could
potentially lead to an increased risk of collision between satellites. Collision avoidance is therefore
paramount to maintain normal operations and to prevent runaway growth of space debris in LEO.
This work develops a state-space controller for LEO satellites operating in nearly-circular orbits with
low-thrust engines. This is done using a linearized model of the dynamics under the Earthgravitational potential and atmospheric drag.

11:18

AAS Determination of Efficient Quantities of Interest for Space Situational Awareness and21-276 Adaptive
Monte
Carlo
Andrew VanFossen, The Ohio State University; Mrinal Kumar, The Ohio State University
Space situational awareness (SSA) integrates space surveillance, environmental monitoring, thecurrent status of satellite systems, and analysis of the space domain to provide decision-making
entities with a quantifiable and timely body of evidence. The feasibility of utilizing probability ofcollision as a quantity of interest within an adaptive Monte Carlo (AMC) platform to controltransient
performance is investigated. The computationalefficiency of each method is evaluated and comparedas timely and actionable intelligence is a requirement of SSA. A parallel approach is also
implemented to further alleviate computational bottlenecks within the AMC platform.

11:30

AAS Design of Collision Avoidance Maneuvers using Optimal Control Theory and Convex
21-311 OptimizationÁlvaro Martínez Chamarro, ISAE-SUPAERO; Carlos Belmonte Hernandez, ISAE-Supaero;
Roberto Armellin, ISAE-SUPAERO
This work presents two methods to compute low-thrust collision avoidance maneuvers for short term
encounters. The first method is based on a minimum-energy optimal control problem. In thesecond method, the design of the maneuver is formulated as a convex optimization problem. In bothcases, constraints on either an approximated value of the collision probability, the miss distance, or
the maximum collision probability are considered. The methods are compared on a large set of
realistic conjunctions in low Earth Orbit.

11:42

AAS Velocimeter LIDAR Systems for Automated Rendezvous, Proximity Operation and21-440 Debris
RemovalApplications
Manoranjan Majji, Texas A&M University, College Station

11:54

AAS Collision
Probability
forGeneralSpacecraft
21-267 Ken Chan, Chan Aerospace Consulting
This paper deals with the formulation of analytical expressions (up to the fourth order in a Taylor’s
series expansion of the Gaussian probability density function) for computing the collision probabilityof a general spacecraft whose cross-section can be described by combinations of circles, ellipses,
rectangles, parallelograms and polygons of any shape. These polygons may be convex or concave
simply connected or even multiply connected regions. Since any spacecraft cross-section can be

Page 19

31st AAS/AIAA Space Flight Mechanics Meetingdecomposed into these elemental cross sections to any degree of accuracy, this formulation yields
the collision probability of an actual collision cross-section of an entire spacecraft with space debris.

Feb 1, 2021Virtual Room #5
05 - Asteroids I
Chair: Roberto Furfaro, The University of Arizona
10:30

AAS Trajectory Evolution of the Spherical Rover in Different Asteroid Terrains
21-206 Ziwen Li, Beijing Institute of Technology; Xiangyuan Zeng, Beijing Institute of Technology
The paper presents the trajectory evolution of the sphericalrover under the different asteroid terrains.
As for the rubble-pile asteroids, the influence of topography on the hopping rover should be taken
into account. Taking comet 133P as the central body, three different local terrains are constructedbased on the corresponding smooth polyhedron model. The large-scale trajectories are simulated toanalyze the evolution of the sphericalrover in these different terrains. The distribution of the terminal
longitudes and latitudes of trajectories are recorded and compared to discuss the influence of asteroid
terrain on the spherical rover.

10:42

AAS HIGH-FIDELI TY SIMULATIONS OF SMALL BODY LANDERS WITH
21-227 ARBITRARY SHAPES BASED ON THE POLYGONAL CONTACT
Yonglong Zhang, Tsinghua University; Tongge Wen, Beijing Institute of Technology; Ziwen
Li, Beijing Institute of Technology; Xiangyuan Zeng, Beijing Institute of Technology; Li
Junfeng
The high-fidelity simulations of a lander on and above the surface of a small body is still an open
problem. In this study, both the lander and the small body are modeled as polyhedrons. The
Polygonal Contact Model (PCM) is used to calculate the contact force and torque between landers
and small bodies. Together with orbital and attitude dynamics, the 6 degrees of freedom motion of alander on and above the surface of a small body can be simulated. More details about them arepresented in our full paper. The advantages of our method are also given.

10:54

AAS Asteroid Landing with a Solar Sail: Lander Deployment and Sail Descent to Surface
21-296 Iain Moore, Universityof Glasgow; Colin McInnes, Universityof Glasgow; Matteo Ceriotti,
University of Glasgow
Solar sails have been proposed as the primary propulsion system for multiple Near-Earth Asteroid(NEA) rendezvous missions. The propellant-less nature of the sail makes then uniquely placed toachieve the high energy requirements of such a mission. This work investigates the landing phase of
the mission, presenting both the lander deployment from the sail and the descent of the sail to thesurface of the asteroid. Deployment of significant mass from the sail brings a change in sailperformance. This brings a change in the dynamics of the system, which is investigated here.

11:06

AAS On-board small-body semantic segmentation based on morphological features with U21-378 Net

Page 20

31st AAS/AIAA Space Flight Mechanics Meeting

Mattia Pugliatti, Politecnico di Milano; Michele Maestrini, Politecnico di Milano; Pierluigi
Di Lizia, Politecnico di Milano; Francesco Topputo, Politecnico di Milano
Small-bodies exhibit a great variability in morphological features which are often unknown a priori,
but rich in information that can be exploited for landing, planning and navigation. However,obtaining a database with such features often involves labor intensive processes. This work proposesa methodology that exploits image rendering and processing techniques which allows to automatize
the labelling of semantic segmentation of small-bodies’ procedurally generated surface features. The
database is then used to train a Convolutional Neural Network for semantic segmentation, whose
performances are evaluated in 3 scenarios of growing complexity, concluding with an analysis ofreal images.

11:18

AAS End to End Asteroid ISRU Using an On-Orbit CubeSat Centrifuge
21-442 Jekan Thangavelautham, University of Arizona
In this paper, we present a coherent plan to combine several existing component technologies tosimulate asteroid surface conditions in space on a 12U CubeSat using a mature, low-speed centrifuge
laboratory. Using this centrifuge, our development plan will prove the principle feasibility of an
excavating mechanism design (1) to access and continuously collect regolith on an asteroid surface
using a bucket wheel excavator and (2) provide process technologies to extract water (as aresource). Our approach of simulating an asteroid surface using a relatively simple centrifuge
concept offers a unique, low-cost, low-risk alternative to further refine and validate asteroid ISRU
technology.

11:30

AAS Visual Reconnaissance of Tumbling Asteroids with Mother Daughter Swarms
21-443 Jekan Thangavelautham, University of Arizona
Small satellites are emerging as a promising new tool for interplanetary exploration. This work
develops small satellite swarm architectures for reconnaissance mission concepts to tumblingasteroids. The tumbling dynamics of the asteroid, coupled with its irregular shape, make the mission
concept design process complex and unintuitive. We present the design of swarm architectures thatminimized the number of spacecraft required and generate a global surface map of the asteroid frommultiple flyby encounters. The presented architectures are then demonstrated using a case study of asimulated
missionconcept
totheasteroid
4179
Toutatis.

11:42

AAS The Perturbative Effects of Gas Drag at Active Comets: Equations of Motion for the
21-411 Mean
Elements
under
Periodic
Inverse-Square
Perturbations
Mark Moretto, University of Colorado Boulder; Jay McMahon, University of Colorado
BoulderThis paper derives equations of motion for the mean elements under a general, periodic, inversesquare, perturbing acceleration and applies these equations to a comet-orbiter. Equations of motion
for the mean elements are first derived with a perturbing acceleration described by Fourier series intrue anomaly. Fourier series in true anomaly are found for spherical harmonics expansions of theperturbing acceleration in the radial, in-track, cross-track (RIC) frame where the perturbing
acceleration are be linked to an inertial frame. Additionally, the rotation of a perturbing acceleration
described using spherical harmonics expansions in the inertial frame into the RIC frame isdemonstrated.

Page 2131st AAS/AIAA Space Flight Mechanics Meeting

Feb 1, 2021Virtual Room #1
06 - Low Thrust Trajectories I
Chair: Natasha Bosanac, University of Colorado, Boulder
13:30

AAS Low Thrust Trajectory Design with Convex Optimization for Libration Point Orbits
21-231 Yuki Kayama, Kyushu University; Kathleen C. Howell, Purdue University; Mai Bando,
Kyushu University; Shinji Hokamoto, Kyushu University
Convex optimization has been attracting attention because it is highly robust and requires shortcomputation times. This paper considers to apply the convex optimization to trajectory design using
three-body dynamics in cis-lunar space and verify that it does work well even for the region near the
Lagrange points involves instability and nonlinearity. Specifically, the convex optimization scheme
is applied in the transfer from a halo orbit to the near-rectilinear halo orbit which is a periodic orbit
defined in the CR3BP. As a further step, the transfer problem is transitioned to an ephemeris model.

13:42

AAS FUEL OPTIMIZATION OF LOW-THRUST SATELLITES USING A SEMI21-242 ANALYTIC
APPROACH
Axel Garcia, MIT; Richard Linares, Massachusetts Institute of Technology; Paul J. Cefola,
University at Buffalo (SUNY); Zachary Folcik, Arlington, MA; David Gondelach,
Massachusetts Institute of Technology; Christopher Jewison, Draper; Juan Félix San-Juan,
University of La Rioja
The main goal of this research is to optimize low-thrust collision avoidance maneuvers for both theprobability of collision between satellites and the propellant expenditure considering a J2
perturbation model. An indirect control method combining the minimum fuel optimal control
problem with the probability of collision taken as a terminal constraint is presented in this paper. We
apply analytical and semi-analytical propagation techniques to efficiently compute optimal collision
avoidance maneuvers. These techniques will be compared with another implementation of theindirect method using a full numerical solution. Efficiency, accuracy robustness and computational
speed trades among these models are analyzed.

13:54

AAS Exploration
of
Low-Thrust
Lunar
Swingby
EscapeTrajectories
21-273 Jackson Shannon, University of Maryland; Donald Ellison, NASA Goddard Space Flight
Center; Christine Hartzell
Spiral escape trajectories enable a spacecraft to escape Earth’s gravity and travel into interplanetary
space under its own power. This analysis demonstrates how to design spiral escape trajectories thatleverage single and double Lunar gravity assists and compares the effectiveness of each trajectory
type. The trajectories are constructed by combining backwards propagated Q-Law and a perturbed
Sims-Flanagan transcription to design the spiral and interplanetary phases, respectively. We
demonstrate that these mission types result in significant propellant savings when compared to aconventional, no Lunar swingby spiral escape, and are highly beneficial for the interplanetaryrideshare mission concept.

14:06

AAS A Hybrid Closed-Loop Guidance Strategy for Low-Thrust Spacecraft Enabled by
21-302 Neural
Networks

Page 2231st AAS/AIAA Space Flight Mechanics MeetingNicholas LaFarge, Purdue University; Kathleen C. Howell, Purdue University; Richard
Linares, Massachusetts Institute of Technology
Recent advancements demonstrate machine learning as a potentially effective approach for onboard
guidance. Neural network controllers overcome challenging dynamical regions of space and, in
contrast to traditional iterative approaches, evaluate in constant time. However, neural networks
frequently behave unpredictably, and the resulting control solution is likely to violate practical limits.
This investigation proposes a hybrid guidance approach that simultaneously benefits from the speedof neural networks and the robustness of traditional iterative methods to ensure all mission criteria
are met. In this paradigm, the neural network rapidly produces accurate startup solutions that improve
the performance of onboard targeting.

14:18

AAS Autonomous Guidance for Multi-revolution Low-thrust Orbit Transfer via
21-315 Reinforcement
Learning
Hyeokjoon Kwon, Korea Advanced Institute of Science and Technology (KAIST); Snyoll
Oghim, KAIST ; Hyochoong Bang, Korea Advanced Institute of Science and Technology(KAIST)
In this paper, we propose low-thrust spacecraft guidance for multi-revolution orbit transfer using theSoft Actor-Critic reinforcement learning (RL) algorithm. Assuming the thrust magnitude is constant,
we built the RL agent that decides the thrust direction over the entire multi-revolution orbit transfer,satisfying the terminal boundary condition and minimizing the flight time simultaneously. The
reward function was designed as a gradient form to achieve efficient training. With the same step
size between action changes, the proposed method outperformed Q-law guidance.

14:30

AAS INITIAL MANEUVER TARGETING AROUND SMALL BODIES USING LOW21-331 THRUSTPROPULSION
Donald Kuettel, Colorado Center for Astrodynamics Research; Jay McMahon, Universityof Colorado Boulder
Low-thrust propulsion is natural choice for spacecraft propulsion around small bodies. However, thefinite, continuous maneuvers associated with low-thrust propulsion are not able to be accomplishedwith a traditional open-loop GNC ap- proach. As such, an autonomous spacecraft GNC architectureis necessary. This paper focuses on developing a variety of autonomous maneuver targeting capabilities in the small body environment using low-thrust propulsion. This is accom- plished by using a
Lambert solver, a parametric bilinear tangent control law cou- pled with a Newton-Raphsonpredictor-corrector, and a Brent-Dekker root-finding method.

14:42

AAS A MODIFIED ORBIT CHAINING FRAMEWORK FOR LOW-THRUST
21-344 TRANSFERS
BETWEEN
ORBITSINCISLUNAR
SPACE
Bonnie Prado Pino, Purdue University; Kathleen C. Howell, Purdue University; David
Folta, NASA Goddard Space Flight Center
In an effort to explore further extended mission options for the Lunar IceCube (LIC) spacecraft, newinterest arises into the problem of constructing a general framework for initial guess generation of
low-thrust trajectories in cislunar space, that is independent of the force models in which the orbitsof interest are defined. In this investigation, a generalized strategy for constructing initial guesses for
low-thrust spacecraft traveling between lunar orbits is presented. These trajectories are converged as
mass-optimal solutions in lower fidelity models, that are easily transitioned to a higher fidelity
ephemeris model, while evolving entirely within the cislunar region.

Page 23

31st AAS/AIAA Space Flight Mechanics Meeting14:54

AAS Toward On-Board Guidance of Low-Thrust Spacecraft in Deep Space Using
21-350 Sequential
Convex
Programming
Christian Hofmann, Politecnico di Milano; Francesco Topputo, Politecnico di Milano
A robust and lightweight algorithm based on convex programming is developed to solve the lowthrust fuel-optimal trajectory optimization problem. We convexify the problem and use a hp-adaptive
flipped Radau Pseudospectral discretization. Switching times are determined and added as
optimization variables in a subsequent optimization process to obtain accurate on-off control
structures. The overall robustness is assessed by varying the quality of the initial guess through ashape-based method and compared to results in the literature and state-of-the-art solvers. The method
is a promising first step towards autonomous guidance in real space missions due to its rapid speed
and excellent robustness.

Feb 1, 2021Virtual Room #2
07 - Attitude Dynamics and Control
Chair: Andrew J. Sinclair, Air Force Research Laboratory
13:30

AAS Design of Time-Optimal Slew Maneuvers with Boolean Star Tracker Availability
21-237 Constraints
Elliott VonWeller, Naval Postgraduate School; Mark Karpenko, Naval Postgraduate
School; Ronald J. Proulx, Naval Postgraduate School
Path constraints in continuous-time optimal control problems must currently be satisfied as a set of
logical conjunctions. In many applications, constraints may contain non-conjunction operators. This
paper explores attitude maneuver designs in which at least one of two star tracker must remain always
unocculted by bright objects. The usual AND constraint is relaxed in favor of an exclusivedisjunctive (NAND) path constraint when developing solutions for time-optimal slews. This solution
embeds a continuous representation of the discrete logic as part of the optimal control problem
formulation. An analysis of the necessary conditions for optimality is developed.

13:54

AAS Modified State Observer for Attitude Synchronization of Formation Flying Spacecraft
21-371 Garba Subedi, Wichita State University; Atri Dutta, Wichita State University
This paper considers the problem of attitude tracking for synchronization of spacecraft in formation
flying network, taking into consideration communication time delay, system uncertainties
and external disturbances. Our methodology utilizes a graph theory based model for thecommunication network to determine the desired reference attitude profile for synchronization andan inverse-controller design for tracking the desired attitude profile. The inverse controller isaugmented with Chebyshev neural network based modified state observer to account for system
uncertainties and external disturbances. Numerical simulations are presented to demonstrate theperformance of the controller.

Page 24

31st AAS/AIAA Space Flight Mechanics Meeting14:06

AAS EXAMINTION OF MAGNETIC DIRECTIONAL CONTROL BY FORCE USING
21-387 SUPERCONDUCTING
DIAMAGNETIC
EFFECT
Shogo Tochimoto, Graduate School of Frontier Sciences, The University of Tokyo, Master2nd grade; Sakai Shin-ichiro, Japan Aerospace Exploration Agency
In recent years, the image resolution required for space telescopes has dramatically increased, and itis necessary to prevent vibration disturbance and heat generated from various devices frompropagating to the observation equipment. Therefore, our laboratory proposes a mechanism that
separates the telescope part and the bus part equipped with various devices and passively controls
the relative position using magnetic flux pinning. Regarding this mechanism, we estimated and madean experiment with the repulsive and attractive force due to the superconducting diamagnetic effect.

14:30

Using
Stochastic
Expansions
AAS Attitude State Uncertainty Propagation
21-409 Brandon Jones, The University of Texas at Austin; Trevor Wolf, The University of Texas atAustinThis paper presents an approach to propagating attitude uncertainty when the state is parameterizedusing a quaternion with a probability density function defined on the four-dimensional sphere. Using
stochastic expansions, such as polynomial chaos expansions, in this context require orthogonal
polynomials to satisfy proofs of convergence. To generate the basis functions, we first evaluate
hypersphericalharmonics and apply a numeric orthogonalization procedure. This procedure requires
approximation of moments of the harmonics with respect to the initial density, with accuracy of thebasis determined by the quality of the moments. Performance of the approach is demonstrated fortorque-free and torqued motion.

Feb 1, 2021Virtual Room #3
08 - Navigation
Chair: Brian Gunter, Georgia Institute of Technology
13:30

Evolution
of
Deep
Space
Navigation:
2014-2016
AAS The21-211 Lincoln Wood, Jet Propulsion Laboratory, Caltech
The exploration of the planets of the solar system using robotic vehicles has been underway since
the early 1960s. During this time the navigational capabilities employed have increased greatly inaccuracy, as required by the missions' scientific objectives and as enabled by improvements intechnology. This paper is the eighth in a chronological sequence dealing with the evolution of deep
space navigation, covering the time interval 2014 to 2016. The paper focuses on the observational
techniques used to obtain navigational information, propellant-efficient means for modifying
spacecraft trajectories, and the computational methods employed, tracing their evolution through 11
planetary missions.

13:42

AAS Spacecraft Terrain Relative Navigation with Synthetic Aperture Radar
21-254 Bryan Pogorelsky, The University of Texas at Austin; Renato Zanetti, The University ofPage 25

31st AAS/AIAA Space Flight Mechanics MeetingTexas at Austin; Jingyi Chen, The University of Texas at Austin; Scott Jenkins, Sandia
National Laboratories
A spacecraft terrain relative navigation system is presented relying on measurements obtained froma synthetic aperture radar that are fused with inertial measurements and attitude determination systemdata in a multiplicative extended Kalman filter. The method of processing the SAR images to retrieve
measurements for the navigation filter is shown, including autofocusing and image geolocation steps.
Monte Carlo simulation results are presented demonstrating that the SAR based terrain relative
navigation system produces consistent state estimates and successfully bounds, or in some instances,significantly reduces the navigation uncertainty of the spacecraft throughout its trajectory by up to
98%.

13:54

Filtering
with
Intrinsic
Fault
ResistanceAAS Nonlinear
21-266 Gunner Fritsch, Texas A&M University; Kyle DeMars, Texas A&M University
Fault tolerance methods are critical to spaceflight navigation systems, where residual editing is themost common practice to screen out erroneous sensor data. This work investigates an alternative
approach, where sensor returns classified as faulty are not simply rejected, but are accounted forwithin the measurement model of the sensor, ultimately leading to a filter with intrinsic fault
resistance. Several different faulty measurement models are examined by comparing the
proposed filter to a baseline filter outfitted with residual editing, where analysis is performed to test
relative performance, robustness, and approximation ability of the proposed filter.

14:06

AAS Position Estimation Method by Asteroid Shape Images and Image Coding Method for
21-298 On-board
OpticalNavigation
Shuya Kashioka, SOKENDAI; Genki Ohira, SOKENDAI; Yuki Takao, Japan Aerospace
Exploration Agency; Takatoshi Iyota, Soka University; Yuichi Tsuda, Japan Aerospace
Exploration Agency
Optical navigation is one of the most rising technologies for the autonomous control of deep space
exploration. It is difficult to perform image matching actual images with pre-set images because theappearance of boulders or its shading varies depending on the illumination conditions or the position
and attitude of the spacecraft. In this paper, we describe a method for predefining shadow map
relating to an asteroid shape model, then defining the regions to be arbitrarily selected image
matching. We obtain results that pixel errors are within about one pixel on the image coordinates inshaded object image varying SAP angles

14:18

Navigation
Using
A
Planet's
Illumination
Conditions
AAS Relative
Kalani
Danas
Rivera,MechanicalandAerospace
Engineering,
Cornell
University;
Mason
21-359Peck
The observed illuminated phases of a planet are used for onboard estimation of the planet-sun unit
vector. Onboard optical instruments also provide the spacecraft with unit vectors to the sun andplanet. The relative spacecraft-planetary body-sun position and orientation are estimated from theseunit vectors. This paper addresses the singularities and limitations of a closed-form estimation
process. The proposed relative navigation technology is promising for spacecraft operating in
cislunar space and without access to Earth ranging capabilities.

Page 26

31st AAS/AIAA Space Flight Mechanics Meeting14:30

about
irregular
bodiesthroughsegmentation
maps
AAS Navigation
21-383 Mattia Pugliatti, Politecnico di Milano; Francesco Topputo, Politecnico di Milano
Small-bodies exhibit a great variability in terms of morphological features, containing richinformation that can be exploited amongst other things for autonomous optical navigation.
Observables can be taken from the body’s outline or from correlation with natural features. In an
attempt to strike a balance between the two family of techniques, in this work an end-to-end
navigation algorithm operating on segmentation maps is illustrated. Two different architectures arepresented and their performances are evaluated in close-proximity scenarios about Didymos, Lutetia
and HW1, assuming the shape model of the bodies is available beforehand.

14:42

AAS Gaussian Mixture Particle Flow Modeling Using Information Potential
21-321 Kari Ward, Missouri University of Science and Technology; Kyle DeMars, Texas A&M
University
Recursive filtering methodologies typically require some form of model to define the underlying
probability density function (pdf). One such filter family, particle flow, introduces an update``dynamics’’ model to describe the evolution of the pdf over an update. Implementing a Gaussian
mixture model for the pdf allows for estimation in a wide array of problems and increases thecapabilities of the particle flow framework. This work builds upon previous research that leverages
the incorporation of information to define a flow based on information potential to account forchanges and interactions in the Gaussian mixture model.

14:54

AAS Navigation at Active Comets: The Time Varying and Stochastic Coma
21-413 Mark Moretto, University of Colorado Boulder; Jay McMahon, University of Colorado
BoulderSpacecraft orbiting active comets are subject to a number of perturbing forces including nonspherical gravity, solar radiation pressure, third-body effects, and drag from the coma. Estimation of
the spacecraft state is complicated by the fact that the coma is time varying and the parameters related
to coma drag are highly uncertain. The coma varies stochastically and periodically, with daily,
seasonal, and orbital timescales, and multi-orbit variations. This is a challenge to spacecraft
navigators. This paper discusses several approaches to estimating time varying coma properties,
piecewise batch and functional approximations. Additionally, lower limits for variation magnitude
and duration are explored.

Feb 1, 2021Virtual Room #4
09 - Atmospheric Reentry Guidance and Control
Chair: Pradipto Ghosh, Northrop Grumman Corporation
13:30

AAS Numerical Predictor-Corrector Based Guidance Scheme for Aero-Gravity Assist at
21-201 Titan
for
Enceladus
Missions
Daniel Engel, University of Illinois at Urbana-Champaign Department of Aerospace
Engineering; Soumyo Dutta, NASA Langley Research Center; Zachary Putnam, University
of Illinois at Urbana-Champaign

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The Fully Numerical Predictor-Corrector Aerocapture Guidance algorithm was modified to workwith a direct force control blunt body vehicle, executing an aero-gravity assist maneuver at Titan toenter a Saturnian orbit and conduct fly-by at Enceladus. Additionally, a proportional-integralderivative controller was implemented to command sideslip angles for control of the orbital
inclination. Numerical simulation showed the developed guidance scheme was capable ofminimizing the energy and inclination error at atmospheric exit, allowing Saturnian moon tour
trajectories and Enceladus exploration at a small delta-V cost, on the order of 100 m/s in the nominal
case.

13:42

AAS Flight Control Methodologies for Neptune Aerocapture
Trajectories
21-202 Rohan Deshmukh, Purdue University; David Spencer; Soumyo Dutta, NASA LangleyResearch CenterIn this work, a comparison of potential flight control methodologies for a Neptune aerocapture
mission are presented. Lifting trajectories pertaining to bank angle modulation and direct force
control as well as ballistic trajectories pertaining to continuously-variable drag modulation areinvestigated. A parametric study of vehicle configurations is explored to quantitatively compare theflight envelope between lifting and ballistic trajectories. A closed-loop numerical predictor-corrector
aerocapture guidance architecture is utilized to unify each flight control technique for trajectorycomparisons. Results from a series of Monte Carlo simulations of blunt body Neptune aerocapture
trajectories using each flight control methodology are presented.

13:54

AAS Nonlinear Set-Membership Filtering-Based State Estimation of Reentry Vehicles
21-306 Diganta Bhattacharjee, The University of Texas at Arlington; Kamesh Subbarao, Universityof Texas at Arlington
We propose a nonlinear set-membership filtering-based state estimation technique for reentry
vehicles. The recursive set-membership filter utilizes the state dependent
coefficientparameterization to acquire a pseudo-linear description of the governing nonlinear system. At every
recursion, the filter requires solutions to two convex optimization problems and these solutions canbe efficiently obtained. We have included details of the filter design, the nonlinear motion model forthe reentry vehicle, and the nonlinear measurement model in the extended abstract. In the final
version, we would include simulation results corresponding to the set-membership filter and would
provide comparisons with other nonlinear state estimation techniques.

14:06

AAS Analytical Guidance for Mars
Aerocapturevia
Drag
Modulation
21-308 Ibrahim Halil Cihan, University of Missouri, Columbia; Craig Kluever, University ofMissouri
A new analytical predictor-corrector guidance algorithm has been developed for the Mars
aerocapture problem. Ballistic coefficient is the only control variable for shaping the vehicle's flightpath. Velocity during the aerocapture maneuver is modeled by a hyperbolic tangent function of flightpath angle. This formulation results in a closed-loop control law for ballistic coefficient. Guidance
periodically updates the velocity profile so that the correct exit conditions are achieved. Two different
apoapsis-targeting scenarios are investigated for the Mars aerocapture problem. Monte-Carlosimulations demonstrate the performance and robustness of the proposed algorithm.

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31st AAS/AIAA Space Flight Mechanics Meeting14:30AAS Stochastic
Predictor-Corrector
Guidance
21-400 Jay McMahon, University of Colorado Boulder; Davide Amato, University of Colorado
Boulder
Many guidance algorithms are built on a predictor-corrector algorithm for adjusting guidance
parameters to meet terminal trajectory constraints. However these methods classically ignore the factthat the system is in fact stochastic as they solve for the guidance solution. In this paper, we discuss
recent developments in a robust predictor-correctormethodology for addressing the stochastic natureof guidance problems. This uncertainty is due to the fact that the navigation solution is imperfect, as
well as considering uncertainty in the dynamic models and vehicle performance parameters. We
demonstrate the methods on EDL and orbital transfer problems.

Feb 1, 2021Virtual Room #5
10 - Artificial Intelligence in Astrodynamics
Chair: Peter Lai, LinQuest Corporation
13:30

AAS Designing Impulsive Station-Keeping Maneuvers near a Sun-Earth L2 Halo Orbit via
21-216 Reinforcement
Learning
Stefano Bonasera, CU Boulder; Ian Elliott, University of Colorado Boulder; Christopher
Sullivan, Colorado Center for Astrodynamics; Natasha Bosanac, University of Colorado,
Boulder; Nisar Ahmed, University of Colorado Boulder; Jay McMahon, University ofColorado Boulder
Reinforcement learning is used to plan station-keeping maneuvers for a spacecraft operating near a
Sun-Earth L2 halo orbit and subject to perturbations from momentum unloads. This scenario istranslated into a reinforcement learning problem that reflects the desired goals, variables, anddynamical environment. Proximal Policy Optimization is used to train policies that generate stationkeeping maneuvers in the circular restricted three-body problem and a point mass ephemeris model.
These policies successfully produce bounded trajectories with small maneuver requirements,
motivating further development of autonomous maneuver planning technologies for spacecraft
operating in complex gravitational environments.

13:42

AAS Image-Based Lunar Landing Hazard Detection
via
Deep
Learning
21-249 Luca Ghilardi, University of Arizona; Andrea Scorsoglio, University of Arizona; Andrea
D'Ambrosio, Sapienza Università di Roma; Roberto Furfaro, The University of Arizona;
Fabio Curti, School of Aerospace Engineering, Sapienza University of Rome
As part of NASA’s Vision for Space Exploration program, future human missions to the moon will
require an increased automation level. In particular, it will be essential to perform safe landing
autonomously in the presence of hazards. This work deals with an image-based hazard detection forboth 3DOF (Degrees of Freedom) and 6DOF lunar landing. The proposed approach relies on the new
deep learning semantic segmentation for image classification. Images are rendered using a detailed
Digital Terrain Model (DTM) from which terrain features are extracted.

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31st AAS/AIAA Space Flight Mechanics Meeting13:54

AAS Uncertainty-Aware Deep Learning for Safe Landing
Site
Selection
21-253 Katherine Skinner, University of Michigan; Kento Tomita, Georgia Institute of Technology;
Koki Ho, Georgia Institute of Technology
Hazard detection is critical for enabling autonomous landing on planetary surfaces. Current state-ofthe-art methods leverage traditional computer vision approaches to automate identification of safe
terrain from input digital elevation models (DEMs). However, performance for these methods
degrades for noisy DEMs. Alternatively, deep learning can outperform traditional approaches forhazard detection on noisy DEMs. Estimating network uncertainty can provide further insight
regarding reliability of network output. This work proposes an uncertainty-aware learning-based
method for hazard detection, with an algorithm that takes network predictions and uncertainty maps
to produce uncertainty-aware safety maps forlanding. Experiments are presented with simulated datawith varying noise parameters.

14:06

AAS The Application of Streaming Clustering to Spacecraft Identification and Tracking in
21-381 Formation
and
Swarm
Missions
Jill Davis, Missouri University of Science and Technology; Henry Pernicka, Missouri
University of Science and Technology
The continued development of small satellites has made them an increasingly viable mission
alternative to traditional monolithic spacecraft. While Earth orbiting missions can rely on GNSS datafor high-accuracy inertial and relative navigation, deep space missions will require new navigation
techniques.This research presents a solution to the spacecraft identification and data association
problem by using an unsupervised learning (clustering) architecture that classifies spacecraft frommonocular camera images. Results show high levels of classification accuracy as well as the abilityof the algorithm to adapt as the swarm configuration changes throughout the simulation.

14:18

AAS Applications of Physics Informed Neural Networks for Gravity Field Modeling21-393 John Martin, University of Colorado Boulder; Hanspeter Schaub, University of Colorado
This paper introduces the use of Physics Informed Neural Networks (PINN) as a tool to unify
flexible machine learning representations of the gravity field with the underlying analytic dynamics.
By injecting the formal differential equations governing gravity into the neural network training
process using automatic differentiation, this paper demonstrates that machine learning gravity
models can be held to a higher level of rigor and accuracy than previously explored. Moreover thispaper aims to demonstrate that PINNs can be a viable alternative to current analytic models both forapplications
inastrodynamics
simulation
andgravityfield
recovery.

14:30

AAS Artificial Neural Network Based Prediction of Solar Array Degradation during
21-424 Electric
Orbit-RaisingTanzimul Farabi, Wichita State University; Atri Dutta, Wichita State University
This paper presents an artificial neural network based approach for predicting the power loss of allelectric satellites during low-thrust orbit-raising through the Van Allen radiation belts. The developed
network can be beneficial in computing thrust availability of a satellite within low-thrust mission
design tools. The network is trained on data generated using the AP/E9 models for radiation flux
calculation and SPENVIS for power loss computation. Finally, the application of the network to asequential low-thrust orbit-raising solver is demonstrated through numerical simulations for orbitraising of telecommunication satellites starting from different geosynchronous transfer orbits.

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31st AAS/AIAA Space Flight Mechanics Meeting14:42

AAS DeepLearning
HSGP4:
Hyperparameters
analysis21-241 Juan Félix San-Juan, University of La Rioja; Edna Viviana Segura Alvarado, University of
La Rioja; Hans Carrillo, Universityof La Rioja; Rosario López, Universityof La Rioja; Iván
Pérez, University of La Rioja; Montserrat San-Martín, University of Granada
The hybrid orbit propagation methodology is used to model the error of any type of orbit propagatorwith the aim of improving its perturbation model or integration technique and hence enhancing its
accuracy. In this work, we present an application of the hybrid methodology, in which the time-series
forecasting processis performed using deep learning method to SGP4. We have adjusted the resulting
Hybrid SGP4 propagator, HSGP4, to the case of Galileo-type orbits. We will describe the hyperparameter selection, which is an important part of the development of HSGP4, and show how HSGP4
can improve the accuracy of SGP4.

Feb 2, 2021Virtual Room #1
11 - Low Thrust Trajectories II
Chair: Arnaud Boutonnet, European Space Agency / ESOC
10:30

AAS Indirect Optimization for Low-Thrust Transfers with Earth-Shadow Eclipses
21-368 Yang Wang, Politecnico di Milano; Francesco Topputo, Politecnico di Milano
An efficient indirect method is presented for low-thrust transfers in presence of Earth-shadow
eclipses. The key feature of our method is the capability to offer accurate Jacobian of problem
functions with respect to all decision variables, which is pivotal for robust convergence. Particularattention is paid to handling the discontinuity conduced by Earth-shadow eclipses. The statetransition matrix at shadow entrance and exit is compensated using calculus of variations. A
systematic framework for solving both time-optimal and fuel-optimal problems is established. The
GTO to GEO transfers transfers are simulated to illustrate the effectiveness and efficiency of themethod developed.

10:42

AAS A new methodology for the solution to the stiffness problem applied to low-thrust21-369 trajectory optimisation in terms of orbital elements using the Differential Dynamic
Programming
Marco Nugnes, Politecnico di Milano; Camilla Colombo, Politecnico di Milano
The largest part of direct and indirect methods exploits Cartesian coordinates as state representation
for the optimisation of dynamical systems. However, for specific dynamical systems such as orbit
dynamics, orbital elements represent a reasonable alternative. Orbital elements provide a physicalinsight together with the time evolution of the orbit geometry. The introduction of the orbital
elements makes the dynamical system stiff because of the different time evolution between fast andslow variables. This paper defines a solution to the stiffness problem for the low-thrust trajectory
optimisation using orbital elements as state representation and the Differential Dynamic
Programming as optimization method.

Page 3131st AAS/AIAA Space Flight Mechanics Meeting10:54

AAS Low-Thrust Trajectory Optimization Using the Kustaanheimo-Stiefel Transformation
21-374 Kevin Tracy, Carnegie Mellon University; Zachary Manchester, Carnegie Mellon
University
We present a novel trajectory optimization formulation for the low thrust orbital transfer problem
that utilizes the Kustaanheimo-Stiefel transformation. For the unperturbed case, this transformation
maps the nonlinear three-dimensional two-body dynamics to a four-dimensional linear harmonic
oscillator. These new dynamics, even when perturbed, are significantly more linear than alternative
state representations, and therefore a better candidate for trajectory optimization. By formulating a
low thrust trajectory optimization problem with this model, a thrust plan can be solved for without
an initial guess, and with fewer knot points than alternative state representations.

11:06

AAS Low-thrust Transfer Trajectories to Earth-Moon Near Rectilinear Halo Orbits
21-384 Emmanuel Blazquez, ISAE-SUPAERO; Alberto Fossà, Institut Supérieur de l'Aéronautiqueet de l'Espace (ISAE-SUPAERO); Tom Semblanet, ISAE-SUPAERO; Stéphanie LizyDestrez
Low-thrust propulsion is a promising technology for station-keeping maneuvers and fuel-efficientcargo delivery to the Gateway.This work proposes new methodologies to design fuel-optimal lowthrust propulsion transfers to EML-2 Near Rectilinear Halo Orbits (NRHOs) from Low Earth, Low
Lunar Orbits and other Earth-Moon NRHOs. Trajectories are computed as solutions of continuoustime optimal control problems, minimizing the propellant mass consumption. The paper introduces
a novel trajectory stacking procedure to generate initial guesses for the optimization problem,
patching together segments of carefully selected trajectories in the vicinity of the departure andarrival orbits. This initialization, easily automatized, converges towards fuel-efficient transfers with
reduced time of flight.

11:18

AAS Comparison of Costate Initialization Techniques For Fuel-Optimal Low-Thrust21-385 Trajectory
DesignPraveen Jawaharlal Ayyanathan, Auburn University; Ehsan Taheri, Auburn University
In this paper, two methodologies are investigated for generating missing initial costate values ofboundary-value problems associated with fuel-optimal low-thrust trajectories. Solving the resulting
boundary-value problems can become quite challenging due to 1) the presence of complex, nonsmooth, bang-off-bang control structures, 2) small domain of convergence, and 3) lack of
information about the value of missing costates. For three-dimensional fuel-optimal problems, thestandard method of ``random initialization'' is compared against a method in which the missing initialcostates are constrained to lie on a unit 8-dimensional hyper-sphere. The results will be summarized
for multi-revolution, fuel-optimal, low-thrust trajectories.

11:30

AAS Hybrid Evolutionary-Indirect Multiple-Gravity-Assist Low-Thrust Interplanetary
21-388 Trajectory
DesignNicholas Nurre, Auburn University; Ehsan Taheri, Auburn University
In this work, an enhanced indirect optimization method is implemented as the inner-level solver
within a hybrid dual-level algorithm. The input to the algorithm is a user-defined sequence of planets.
The outer-level of the algorithm set the bounds for the design variables automatically and uses a
global search algorithm (particle swarm optimization (PSO)) to generate problem boundary andgravity-assist parameters. The inner-level solver finds a fuel-optimal trajectory for each segment of
the trajectory by solving a two-point boundary-value problem. The algorithm is capable of finding

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31st AAS/AIAA Space Flight Mechanics Meeting

candidate optimal trajectories for interplanetary missions with forced coast arcs prior and post
gravity-assist maneuvers.

11:42

AAS Reachable set of low delta-v trajectories following a gravity-assist flyby
21-422 Chun-Yi Wu, University of Texas at Austin; Ryan Russell, The University of Texas at Austin
Icy moons flyby tours are challenging to design due to the extraordinarily large search space. Stateof-the-practice approaches rely on discretized grid searches over a reduced domain, and often waste
computation on solutions with excessively high delta-v. A new method is proposed that (a) considers
the full domain of reachable bodies and transfer types (VILT, resonant, non-resonant, even- and oddNpi), (b) finds interpolatable families of solutions when degrees of freedom are available, and (c)structures the search to only find solutions within a delta-v threshold. This new approach is designed
to inform an outer loop pathfinding scheme.

Feb 2, 2021Virtual Room #2
12 - Trajectory Design I
Chair: James Thorne, Institute for Defense Analyses (IDA)
10:30

AAS Invariant
Funnelsfor
Resonant
Landing
Orbits21-221 Jared Blanchard, Stanford University
We discovered a simple, two-part solution to the problem of finding resonant orbits to land on highlatitudes of Ocean Worlds. First, we apply a standard planar Poincar\'e map in the spatial problem toidentify a resonant landing orbit. Next we generate an "invariant funnel" of trajectories that converge
to the orbit, which acts as an attractor. The funnel has a wide mouth, thousands of kilometers wide,that shrinks to a small disc at a landing site only a few kilometers (or less) wide. These funnels aregoverned by "resonant rings" of landing trajectories, and will make navigation more simple.

10:42

AAS Expected Thrust Fraction: Resilient Trajectory Design Applied to the Earth Return21-232 Orbiter
Ari Rubinsztejn, University of Alabama; Rohan Sood, The University of Alabama; Frank
Laipert, Jet Propulsion Laboratory
Electric propulsion is an enabling technology for NASA's Mars Sample Return mission.
Unfortunately, electric propulsion makes spacecraft susceptible to missed thrust events. This paper
investigates the application of expected thrust fraction to the Earth Return Orbiter's outbound Earthto-Mars trajectory. Through the use of expected thrust fraction, a trajectory with a baseline 65.4%
success rate is improved to an 86.6% success rate at the cost of only 12 kgs of delivered mass.
Additionally, when expected thrust fraction is used in conjunction with other missed thrust event
mitigation techniques, a 96.0% success rate is achieved.

10:54

AAS Mission Analysis and Design of VMMO: The Volatile Mineralogy Mapping Orbiter
21-251 Nicola Baresi, University of Surrey; Harry Holt, Surrey Space Centre; Nicolò Bernardinin;
Xiaoyu Fu, University of Surrey; Mansur Tisaev; Yang Gao; Christopher Bridges; Andrea

Page 33

31st AAS/AIAA Space Flight Mechanics MeetingLucca Fabris; Roberto Armellin, ISAE-SUPAERO; Piotr Murzionak, MPB
Communications; Roman Kruzelecky, MPB Communications
Water ice and other volatile compounds found in permanently shadowed regions near the lunar poles
have attracted the interests of space agencies and private companies due to their great potential for
in-situ resource utilization and scientific breakthroughs. This paper presents the mission design andtrade-off analyses of the Volatile Mineralogy Mapping Orbiter, a 12U CubeSat to be launched in
2023 with the goal of understanding the composition and distribution of water ice near the lunar
South pole. Spacecraft configurations based on chemical and electric propulsion systems areinvestigated and compared for different candidate science orbits and rideshare opportunities.

11:06

AAS Functional Interpolation Method to Compute Period Orbits in the Circular Restricted21-257 Three-Body
Problem
Hunter Johnston, Texas A&M University; Martin Wen-Yu Lo, Jet Propulsion Laboratory;
Daniele Mortari, Texas A&M University
Computing Halo orbits, finding nonlinear periodic orbits in general, has become an important part ofmodern mission design. In this paper, we introduce a novel, simple, and efficient method for finding
periodic orbits by analytically embedding the boundary-conditions using the Theory of Functional
Connections.

11:18

AAS Analytical Partial Derivatives of the Q-Law
Guidance
Algorithm
21-274 Jackson Shannon, University of Maryland; Donald Ellison, NASA Goddard Space Flight
Center; Christine Hartzell
One method of producing low-thrust trajectories is the closed-loop Q-Law guidance algorithm. This
work wraps Q-Law inside a nonlinear programming problem to search for locally optimal gain
combinations and enforce nonlinear constraints on the initial state. Gradient-based trajectory
optimization has been shown to benefit greatly when analytical partial derivatives are supplied to the
optimizer. This paper presents the Q-Law optimization problem setup and derives the Q-Law thrust
vector partial derivatives for the State Transition Matrix required by standard nonlinear optimization
software.

11:30

AAS I’ll have the Porter: Interactively Visualizing the Results of Statistical Maneuver
21-334 Analysis
Rohan Patel, California State Polytechnic University, Pomona; Jimmy Moore, University of
Utah, School of Computing; Jeffrey Stuart, Jet Propulsion Laboratory; Sonia Hernandez,
Jet Propulsion Laboratory; Emine Basak Alper Ramaswamy, NASA Jet Propulsion
Laboratory
Statistical maneuver analysis is a key part of mission design and navigation, ensuring adequate
margins on propellant and mission safety. Maneuver plans are validated through the use of Monte
Carlo analysis simulating a variety of error sources and outputting a large quantity of data. We aredeveloping a visual interface, Porter, focused on providing mission analysts the ability to probe thedetailed results of a single Monte Carlo run. We discuss the development and core features of thePorter interface, detailing the design decisions both in the user-oriented interface as well as the backend data organization for the raw outputs.

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31st AAS/AIAA Space Flight Mechanics Meeting11:42

AAS Robust Multi-body Slewing Trajectories via Unscented Optimal Control
21-405 Brian Bishop, Air Force Institute of Technology; Richard Cobb, Air Force Institute ofTechnology; Costantinos Zagaris, Air Force Institute of Technology
Traditional trajectory generation for multi-body reorientation maneuvers rely upon simplified
kinematic principles employing conservative constraints on maximum gimbal torque and velocity tominimize disturbances. Techniques such as notch filtering or input shaping are utilized to increase
robustness and reduce excitation of structural modes. This manuscript investigates the use of
unscented optimal control techniques to generate maneuvers robust against uncertain parameters
while simultaneously decreasing maneuver length and minimizing system vibrational excitation. The
proposed method employs pseudospectral optimal control while leveraging the unscented transformto account for parameter uncertainty. The performance and robustness of the resulting trajectories
are compared against standard maneuvers.

11:54

AAS ExplorationofDeimosandPhobosleveraging
resonant
orbits.
21-234 David Canales Garcia, Purdue University; Maaninee Gupta, Purdue University; Beom
Park, Purdue; Kathleen C. Howell, Purdue University
While the interest in future missions devoted to Phobos and Deimos rises, missions that explore both
moons are expensive in terms of maneuver capabilities due to the lack of low-energy transfers. The
proposed approach in this investigation includes Mars-Deimos resonant orbits that offer repeatedDeimos flybys as well as access to libration point orbits in the Phobos vicinity. A strategy to selectthe candidate orbits is discussed and associated costs are analyzed, both for impulsive and low-thrustengine models, within the context of the coupled spatial circular restricted three body problem, which
are then validated into a higher-fidelity ephemeris model.

Feb 2, 2021Virtual Room #3
13 - Spacecraft Control I
Chair: Francesco Topputo, Politecnico di Milano
10:30

AAS MODIFYING AND OPTIMIZING THE INVERSE OF THE
FREQUENCY
21-210 RESPONSE CIRCULANT MATRIX AS AN ITERATIVE LEARNING CONTROL
LAW
Shuo Liu, Columbia University; Richard Longman, Columbia University
Feedback control systems do not do what you ask. Bandwidth tells what commands can be handled.
Iterative Learning Control (ILC) seeks to perform high precision motions along a desired path for al
frequencies after a few learning iterations. Use in spacecraft include performing highly accurate
sensor scanning. ILC is finite time and therefore has initial transients. The purpose of this paper is tocreate a method of designing ILC compensators based on steady state frequency response, and havethe ILC converge to zero error in spite of transients and bandwidth. A method of doing this isdemonstrated with good performance.

10:42

AAS Iterative Learning Control Inverse Problem Using Harmonic Frequency Filters
21-239 Jer-Nan Juang, National Cheng Kung Univ; Richard Longman, Columbia University

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31st AAS/AIAA Space Flight Mechanics Meeting

Basic learning laws with the design of a filter are summarized and their input convergence conditions
are described. This paper presents a cliff harmonic-frequency filter with a frequency cutoff and aweighted harmonic-frequency filter with frequency weighting for iterative learning control inverse
problem. Filter matrices based on the state-space modelof a finite-difference digital filter are derived
for Matlab’s and Gustafsson’s forward and backward filtering which are commonly called filtfilt
methods. Furthermore, filter matrices for Matlab’s and Gustafsson’s filtfilts are revised to make theinput convergence matrix to be monodically stable.

10:54

AAS Identification of the Dynamics in the Singular Vectors of the System Toeplitz Matrix
21-272 ofMarkovParameters
Jer-Nan Juang, National Cheng Kung Univ; Richard Longman, Columbia University
Singular value decomposition of a Toeplitz matrix plays a major role in designing an iterative
learning controller. It is found that each left or right singular vector can be considered as a free-decay
response of a linear model. A linear system identification method is then used to identify the modalparameters such as frequencies and damping ratios. Each singular vector decomposed from a
Toeplitz matrix contains at least one pure frequency. Numerical examples for several different sizesof system orders are used to discuss the characteristics of identified eigenvalues embedded in the
singular vectors.

11:06

AAS DESIGN TRADEOFFS USING SECOND ORDER REPETITIVE CONTROL TO
21-278 REDUCESENSITIVITYTODISTURBANCEPERIOD
Ayman Ismail, Columbia University; Richard Longman, Columbia University
Repetitive control is widely used for tracking a periodic command and/or eliminating a periodic
disturbance of known period. Two issues can be encountered in applications: disturbance period is
not known to high precision or is subject to fluctuations from random unmodeled effects. Second
order repetitive control is developed as a method to widen notches and make the performance lesssensitive to accurate knowledge or fluctuations in the period. To obtain best performance, tradeoffs
related to error produced at addressed and intermediate frequencies must be made during design.
This paper analyzes these tradeoffs and offers approaches to intelligently address each tradeoff.

11:18

AAS Controller
Designfor
LaunchVehiclewithInternal
Torque21-279 Ryan Kinzie, Embry-Riddle Aeronautical University; Dongeun Seo, Embry-Riddle
Aeronautical University
This paper seeks to create a robust linear controller to compensate for a torque that is generated
internally on a launch vehicle due to its engine design. A mathematical model of the internal torquesof a general engine along with the torque's coupled nature to the throttle setting of the engine will becreated and then analyzed in a six degree-of-freedom rigid-body modelof the launch vehicle. Modern
control methods will then be utilized to generate a robust quaternion-based linear-quadratic regulator
control algorithm, which is expected to be able to sufficiently compensate for the vehicle's internal
torque and coupled forces.

11:30

AAS Reduced Control Authority in a Dispersed Satellite Formation Antenna Array
21-263 Mason Nixon, Leidos Inc. / University of Alabama in Huntsville Department of ElectricalEngineering; Yuri Shtessel, University of Alabama in Huntsville Department of ElectricalEngineering

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31st AAS/AIAA Space Flight Mechanics Meeting

Key technologies in small satellites, spacecraftcontrol, and antenna arrays have come about in recent
years. Previously, we described new control techniques for a novel satellite formation architecture
wherein each satellite acts as an independent antenna in a satellite formation. This has the potential
to facilitate increased data transmission performance, reconfigurability, adaptive beamforming,robustness to noise and interference, increased gain, and other benefits. For small satellites,
propulsion and/or actuation can be limited within each dimension or axis, leading to reduced control
authority. We address the control problem for this type of system with perturbations using adaptive
sliding mode control techniques.

11:42

AAS Lyapunov-Based Control of Kinematically Coupled Close-Proximity Spacecraft
21-390 Feature
Point
Dynamics
Eric Butcher, University of Arizona; Chad Wenn, University of Arizona
A nonlinear Lyapunov-based strategy for the 6-DOF control of kinematically coupled closeproximity spacecraft feature point dynamics is presented in which the feature point is an off-centerof-mass point of interest such as a docking port. The relative dynamics of the spacecraft centers-ofmass are described by the Hill-Clohessy-Wiltshire equations or other standard equations of relative
motion, while additional terms account for the kinematic orbit/attitude coupling. Either global oralmost global asymptotic stability is achieved depending on the attitude-dependent part of the control
law. Monte Carlo simuluations demonstrate the success of the proposed technique.

11:54

AAS A Near-Optimal Attitude Control
for anEarth
Imaging
Satellite
21-255 Giovanni Lavezzi, South Dakota State University; Marco Ciarcia, South Dakota State
University
This paper describes a near-optimal attitude control strategy for an Earth observation satellite. The
proposed approach combines a direct method, the Inverse Dynamics in the Virtual Domain, and anonlinear programming solver, the Sequential Gradient-Restoration Algorithm, for the fastcalculation of the solution trajectory, enabling a closed-loop implementation. Optimality andpointing accuracy are assessed for several target acquisitions and tracking maneuvers performed ina high-fidelity simulation environment. Both minimum time and minimum control energy criteria
are considered. Comparison against conventional attitude controllers, a quaternion feedback PD
controller and a LQR, is also provided.

Feb 2, 2021Virtual Room #4
14 - Cislunar Space Situational Awareness
Chair: Brandon Jones, The University of Texas at Austin
10:30

AAS Ground-Based Navigation Trades for Operations in Gateway's Near Rectilinear Halo
21-450 Orbit
Matthew Bolliger, Advanced Space; Michael Thompson, Advanced Space; Nathan (Parrish)
Ré, Advanced Space, LLC; Diane Davis, a.i. solutions, Inc.
This paper presents an analysis of ground-based tracking during operations in a 9:2 synodic-resonant
Earth-Moon L2 southern NRHO. The performance of different tracking configurations is comparedin terms of the annual orbit maintenance ?V, state uncertainties, state errors, and filter reliability.

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31st AAS/AIAA Space Flight Mechanics MeetingTracking configurations are parameterized based on track durations, locations within the NRHO, andnumber of tracks per revolution. Monte Carlo analysis with simulated observations is performed oneach of 44 tracking configurations. Different filter setups are leveraged to identify outliers. The
resulting filter solutions are compared to a notional reference requirement of 10 km, 10 cm/s 3? state
uncertainty.

10:42

AAS Assessing Observer Location Schemes for Cis-Lunar Space Domain Awareness
21-225 Michael Rosenof, Air Force Institute of Technology; Bryan Little, Air Force Institute ofTechnology
With renewed worldwide interest in cis-lunar space, the need for reliable domain awareness in that
extended region of space is clear. This investigation quantifies the suitability of several possible
stations for observer satellites in cis-lunar space by calculating the specific irradiance each would
observe as they track satellites in various realistic lunar free-return trajectories across a decade. Early
indications are that the combination of stations resulting in the best overall observation op-portunities
is a single satellite orbiting L4 or L5, and a single satellite in low lunar orbit out of the plane of the
Moon’s orbit.

10:54

AAS Cislunar
Space
Situational
Awareness
21-290 Carolin Frueh, Purdue University; Kathleen C. Howell, Purdue University; Kyle DeMars,
Texas A & M University
Classically, space situational awareness and space traffic management focuses on the near earth
region, which is highly populated by satellites and space debris objects. With the expansion of spacefairing further in the cislunar space, the problems of space situational awareness arises anew inregions fa away from the near earth realm. This paper investigates the conditions for successfulSpace
Situational Awareness and Space Traffic Management in the Cislunar region by drawing directcomparison to the known challenges and solutions in the near-Earth realm, highlighting similarities
and differences and their implication on Space Traffic Management engineering solutions.

11:18

AAS Observability Metrics
forSpace-Based
Cislunar
DomainAwareness
21-406 Erin Fowler, University of Maryland College Park; Derek Paley, University of MarylandCollege Park; Stella Hurtt, University of Maryland College Park
We present a dynamic simulation framework of the cislunar environment for use in numericalanalysis of various pairings of resident space objects and observer satellites intended for cislunar
space domain awareness. The paper’s contributions include analysis of orbit families for the missionof space-based cislunar domain awareness and a set of metrics that can be used to inform the specificorbit parameterization for cislunar SDA constellation design. The empirical observability Gramian,along with several heuristic metrics, is computed for observations of satellites on trajectories in the
Earth-Moon system to assess their degree of observability for a given observer-target orbit pair.

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31st AAS/AIAA Space Flight Mechanics Meeting

Feb 2, 2021Virtual Room #5
15 Dynamical System Theory I
Chair: Donghoon Kim, University of Cincinnati
10:30

AAS Quasi-Periodic Orbits in the Sun-Earth-Moon Bicircular Restricted Four-Body
21-270 Problem
Brian McCarthy, Purdue University; Kathleen C. Howell, Purdue University
Examining properties of quasi-periodic orbits provides insight into the Sun-perturbed environment
in cislunar space. In this investigation, quasi-periodic trajectories and their properties are explored in
the Sun-Earth-Moon Bicircular Restricted Four-Body Problem (BCR4BP).
Additionally,
computation and stability of invariant torus families in the BCR4BP are outlined. Understanding quasiperiodic behavior in the BCR4BP expands available options for path planning and potential
destinations in the lunar vicinity.

10:42

AAS DESIGN OF SOLAR SAILING IN SUN-EARTH-MOON
SYSTEM AND
21-307 TRANSFERTO
INTERPLANETARYREGION
Toshihiro Chujo, Tokyo Institute of Technology; Yuki Takao, Japan Aerospace Exploration
AgencyLunar Orbital Platform-Gateway in NASA’s Artemis program is expected to provide more
opportunities of deep space flight for micro probes or CubeSats in the Sun-Earth-Moon system. To
extend lifetime of such small missions saving propellant consumption, solar sails are suitable
propulsion systems, applicable to station keeping of halo orbits and transfer among them. They canalso help escaping to the interplanetary region to reach other celestial bodies. This paper shows thedesign process and some possible examples of solar sailing in the Sun-Earth-Moon system andtransfer to the interplanetary region, especially for missions released on NRHO.

10:54

AAS On the use of zero-momentum surfaces to identify transport opportunities to planar
21-310 Lyapunov
orbitsRoshan Thomas Eapen, Texas A&M University; Kathleen C. Howell, Purdue University;
Kyle T. Alfriend, Texas A&M University
Transfer trajectory design in the restricted three-body problem is largely dependent on the topologyof the invariant manifolds. In this paper, the behavior of such manifolds are studied through the useof a Poincaré map generated from a zero-momentum subspace of the third-body motion. Such maps
characterize the regions of allowed motions of the invariant manifolds to occupy the space boundedby quasi-periodic orbits. The dynamical structures arising from these zero-momentum surfaces are
instrumentalin identifying transport opportunities to planar Lyapunov orbits and give an upper boundon the manifold insertion angle for tangential transfers.

11:06

AAS Theory of low-energy transit orbits in the periodically-perturbed restricted three-body
21-317 problem
Joshua Fitzgerald, Virginia Tech; Shane Ross
In the circular restricted three-body problem, low-energy transit orbits are revealed by linearizing thegoverning differential equations about the Lagrange points. This procedure fails when time-periodic
perturbations are considered, such as perturbation of the sun (ie., the bicircular problem) or orbital

Page 39

31st AAS/AIAA Space Flight Mechanics Meetingeccentricity of the primaries. For this case, the Lagrange point is replaced by a periodic orbit, viewed
as an index-1 saddle fixed point of a symplectic map. In analogy with the geometry about an index1 saddle equilibrium point, transit and non-transit orbits are identified in the saddle canonical plane.
Furthermore, the linearized symplectic map admits a conserved quadratic Hamiltonian.

11:18

AAS Defining the Fundamental Frequencies of Quasi-Periodic Invariant Tori
21-343 Luke Peterson, University of Colorado Boulder; Daniel Scheeres, University of Colorado
Boulder
Quasi-periodic orbits are higher-dimensional solutions of Hamiltonian dynamical systems that lie on
the surface of invariant tori. Quasi-periodic motion on the torus is fully described by the frequencies
of motion on the torus; however, any unimodular mapping of the frequency vector offers anequivalent representation. This work presents an approach to uniquely define the frequencies of aquasi-periodic invariant torus. The group-theoretic approach exploits the action of unimodular
matrices on the set of frequencies so that the fundamental frequencies are closest to resonance. We
include examples applied to center manifolds emanating off of periodic orbits in the Hill three-bodyproblem.

11:30

AAS Using GPUs and the Parameterization Method for Rapid Search and Refinement of
21-349 Connections between Tori in Periodically Perturbed Planar Circular Restricted 3Body
Problems
Bhanu Kumar, Georgia Institute of Technology; Rodney L. Anderson, Jet Propulsion
Laboratory/Caltech; Rafael de la Llave, Georgia Institute of Technology
When the planar circular restricted 3-body problem is periodically perturbed, most unstable periodic
orbits become invariant tori. However, 2D Poincaré sections no longer work to find their manifolds’
intersections; new methods are needed. In this study, we first review a method of restricting theintersection search to only certain manifold subsets. We then implement this search using Julia and
OpenCL, representing the manifolds as triangular meshes and gaining a 30x speedup using GPUs.
We finally show how to use manifold parameterizations to refine the approximate connections foundin the mesh search. We demonstrate the tools on the planar elliptic RTBP.

11:42

AAS HYPERCOMPLEX UNIVERSAL VARIABLES APPROACH FOR THE STATE
21-363 TRANSITION MATRIX IN THE GENERAL KEPLERIAN RELATIVE ORBITAL
MOTION
Daniel Condurache, Technical University of Iasi; Vladimir Martinusi, Technion - Israel
Institute of Technology
The paper presents a unified approach to the explicit computation of the state transition matrix (STM)
associated to the relative orbital motion in Keplerian arbitrary orbits. The use of the hypercomplex
universal variables allows the unified formulation of the STM, regardless the elliptic, parabolic or
hyperbolic nature of their inertial trajectories. The universal variables approach offers aparameterization of the geodesics in the constant curvature phase space on which the inertial motion
takes place. The parameterization is made with the help of the generalized trigonometric functions ina space of constant mean curvature.

11:54

AAS Navigating Low-Energy Trajectories to Land on the Surface of Europa
21-360 Sonia Hernandez, Jet Propulsion Laboratory; Rodney L. Anderson, Jet Propulsion

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31st AAS/AIAA Space Flight Mechanics Meeting

Laboratory/Caltech; Yu Takahashi, Jet Propulsion Laboratory; Duane Roth, Jet Propulsion
Laboratory; Tim McElrath, JPL/Caltech
Navigation strategies typically use linearized techniques to predict maneuver statistics and perform
orbit determination. A linearized approach works well for high-energy trajectories, since the “true”
trajectory is well approximated by a linearized trajectory when propagated for short periods of time.
On the other hand, low-energy trajectories, such as those needed to explore planetary moons, arehighly nonlinear and sensitive to small perturbations; thus the typical linearized navigation
techniques are no longer valid. In this paper we explore different approaches to performing maneuver
design for low-energy trajectories, with an emphasis on the approach phase of a Europa lander
concept mission.

Feb 2, 2021Virtual Room #1
16 - Trajectory Design II
Chair: Powtawche Valerino, NASA Marshall Space Flight Center
13:30

AAS Escape Trajectories from Lagrangian Points with Electric Propulsion
21-252 Luigi Mascolo, Politecnico di Torino; Lorenzo Casalino, Politecnico di Torino - DIMEAS
An indirect method to determine optimal low-thrust trajectories for the escape from Earth’s sphereof influence, starting from L2 and NRHO, is developed. The highly chaotic and non-linear dynamics
of motion close to Lagrangian points challenges the remarkable precision of the indirect method:
new approaches and improvements to handling these numerical problems are identified andimplemented, as a multifield and multi-shooting method in which the trajectory splits at the highvelocity gradient points. The dynamic model considers 4-body gravitation, JPL' ephemeris, and may
include spherical harmonic models for Earth and Moon; solar radiation pressure is also considered.

13:42

AAS Multidisciplinary System Design Optimization of Lunar Surface Access from Cislunar
21-291 Orbit via Surrogate-Assisted Evolutionary Algorithms Using Highly-Parallel GPU
Architecture
Kyuto Furutachi, Kyushu University; Hideaki Ogawa, Kyushu University; Satoshi Ueda,
Japan Aerospace Exploration Agency
Global optimization draws increasing attention with the advancement of space missions andincreasing complexity of spacecraft
systems.
A Multidisciplinary
SystemDesignOptimization (MSDO) framework has been developed for the lunar surface accessmission consisting of NRHO-LLO transfer and lunar landing phases by performing orbit propagationand surrogate modeling on GPU (graphics processing unit) cores in conjunction with surrogateassisted evolutionary algorithms. A distinct Pareto optimal front has resulted from a largescale MSDO study exploiting a highly parallelized architecture enabled by GPUs, which would
otherwise be prohibitive for traditional approaches using CPUs. The results have been scrutinized
and a global sensitivity analysis has been conducted to gain insights into the key design factors andinteractions between subsystems and orbital transfer.

Page 41

31st AAS/AIAA Space Flight Mechanics Meeting13:54

AAS Global Trajectory Optimization of Earth-NRHO Transfer Using Weak Stability
21-320 BoundaryVia
GPU-Based
Super-Parallelization
Satoshi Ueda, Japan Aerospace Exploration Agency; Hideaki Ogawa, Kyushu University
This paper presents a global trajectory optimization framework via a multi-fidelity approach thatutilizes a GPU for low-fidelity initial solution search and a CPU to determine high-fidelity feasible
solutions. A multi-fidelity approach is proposed to enable global trajectory optimization of EarthNRHO transfer. The present study employs a weak stability boundary transfer that utilizes solar tidal
force for velocity increment saving. The knowledge and insights are summarized for the resultant
global structure of feasible solutions, while verifying the capability and effectiveness of the global
design framework enabled by a GPU-based highly-parallel architecture.

14:06

AAS Recovery Trajectories for Inadvertent Departures
from
an
NRHO
21-345 Emily Zimovan-Spreen, Purdue University; Diane Davis, a.i. solutions, Inc.; Kathleen C.
Howell, Purdue University
The current Gateway baseline orbit, an NRHO, is a nearly-stable orbit that requires regular orbit
maintenance (OM) maneuvers for a spacecraft to remain in the orbit long-term. With extended
missed OM maneuvers, spacecraft will depart from the baseline orbit. In response, a strategy torecover inadvertent departure trajectories and return a spacecraft to the NRHO is developed. A
Monte Carlo-based approach is used to analyze departures that are recoverable using a standard OM
approach. Dynamical structures in the vicinity of the NRHO are used to design recovery trajectories
for spacecraft that have departed further from the baseline.

14:30

AAS EFFECTS OF V-INFINITY LEVERAGING WITH LUNAR-EARTH GRAVITY
21-392 ASSISTON
INTERPLANETARYTRAJECTORI ES
Giuliana Elena Miceli, ISAE SUPAERO; Stefano Campagnola, Jet Propulsion Laboratory
This works evaluates the effects of Lunar-Earth Gravity Assist on mission design and Δv budget,using V-infinity leveraging. The Earth is often exploited for flybys during interplanetary trajectories.
The use of the Moon, in combination with the Earth, provides additional deviation of the hyperbolic
excess velocity with respect to the Earth and modifies its magnitude, increasing the overall flyby
performance. The Lunar-Earth Gravity Assist has been evaluated for external leveraging, both for
Short and Long transfers. Asample mission to Jupiter is showcased and results suggest that the Moon
effect during the flyby reduces the leveraging Δv by 5.3%.

14:42

AAS Periapsis Targeting with Weak Stability Boundary Transfers for Orbiting around21-403 Planetary
Moons
Yuri Shimane, Georgia Institute of Technology
This work proposes an alternative approach for periapsis targeting with Weak Stability Boundarytransfers (WSBT). This is conducted in the circular restricted three body problem (CR3BP) togenerate preliminary solutions for subsequent trajectory refinement in higher-fidelity models.
Specifically, a design procedure for targeting the periapsis of a celestial body with a WSBT is
proposed based on a grid-based manifold sampling technique. Compared to conventional hyperbolic
approaches, WSBT offers a significant reduction in delta-V required for insertion into a destination
orbit, thus providing an attractive alternative approach for mission designers.

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31st AAS/AIAA Space Flight Mechanics Meeting14:54

AAS Lunar Impact Probability for Spacecraft in Near Rectilinear Halo Orbits
21-452 Diane Davis, a.i. solutions, Inc.; Rolfe Power, Purdue University; Kathleen C. Howell,
Purdue University; Jeffrey Gutkowski
Near Rectilinear Halo Orbits (NRHOs) near the Moon are of recent interest for missions including
Gateway and CAPSTONE. To address planetary protection considerations during long-term NRHO
operations, the probability of impact on the lunar surface following a wide range of ?v perturbations
is assessed. The effects of disturbance distribution around the NRHO and the short-term destinationof escaping particles are explored. The likelihoods of collision across the entire lunar surface andwithin sensitive polar regions are considered in both the Circular Restricted Three-Body model andin the higher-fidelity ephemeris force model.

Feb 2, 2021Virtual Room #2
17 - Spacecraft Control II
Chair: Ossama Abdelkhalik, Iowa State University
13:30

AAS Study on Autonomous Gravity-Assists with a Path Following Control
21-247 Rodolfo Batista Negri, National Institute for Space Research; Antonio Fernando Bertachini
Prado, INPE
An autonomous control of gravity-assist hyperbolic trajectories is studied. In order to do so, it isapplied a path following control law that uses sliding mode control theory to guarantee robustness tobounded disturbances. Other advatange is that this path following is specially derived to maintainany Keplerian motion. The control strategy is tested in the Jovian system, with multiple flybys by all
Galilean moons.

13:42

AAS Adaptive control for proximity maneuvers around asteroids using Extreme Learning
21-262 Machine-based
gravityfield
estimation
Andrea D'Ambrosio, Sapienza Università di Roma; Gabriele Conforti, School of Aerospace
Engineering, Sapienza University of Rome; Ivan Agostinelli, School of Aerospace
Engineering, Sapienza University of Rome; Fabio Curti, School of Aerospace Engineering,
Sapienza University of Rome
Proximity operations around asteroids are challenging because of the difficulties in the real-time
estimation of their gravity field. A direct adaptive control is employed to study proximity maneuvers
around asteroids. The adaptive control law is directly adjusted to minimize the error between plant
and reference trajectory outputs. The control law’s gains are tuned to obtain the desired
performances. Furthermore, to consider a fast and accurate estimation of the gravity, Extreme
Learning Machine is exploited to map the position vector into the gravity vector in the asteroid bodyfixed frame. Finally, all the framework is applied to proximity maneuvers around asteroid Gaspra

13:54

AAS Robust Adaptive Control for Attitude Control of Spacecraft Formation Flying
21-294 Soobin Jeon, Yonsei University, Korea; Hancheol Cho, Bradley University; Sang-Young
Park, Yonsei University
A continuous adaptive sliding mode controller is proposed for precise attitude control of spacecraft
formation flying. The time continuity of controlinput successfully eliminates chattering and achieves

Page 43

31st AAS/AIAA Space Flight Mechanics Meetingfinite-time convergence in the presence of unknown bounded uncertainties. To automatically updates
the control gain without prior knowledge of the disturbances, a simple adaptive law is developed.
Numerical simulations are conducted for three types of attitude control problems and suggest therobustness and accuracy of the proposed controller while successfully compensating disturbancesfrom uncertainties of the momentum of inertia and external environments.

14:06

AAS Physics-Informed Neural Network Solutionof Hamilton-Jacobi-Bellman Equations for
21-319 a
Class
of
Space
OptimalControl
Problems
Roberto Furfaro, The University of Arizona; Andrea Scorsoglio, University of Arizona;
Enrico Schiassi, University of Arizona
In this paper, finite and infinite horizon optimal control problems for general and space applications
are solved via a dynamic programming approach using Physics-Informed Neural Networks(PINNs).
In particular, the arising Hamilton Jacobi Bellman partial differential equation, that guarantees anecessary and sufficient condition for the optimality and provides a closed loop solution, is solved
via
PINNs.
PINNs are particular neural networks where the training is regulated by the physics of the problem,
modeled through differential equations.

14:18

AAS Closed-Loop Optimal Control for Spacecraft Rendezvous and Proximity Operations
21-355 Using
Second-Order
Cone
Programming
Michael Devore, Barron Associates Inc; Richard Adams, Barron Associates Inc; Adam
Reed, Barron Associates Inc; Alexander Lewis , San Diego State University; Ping Lu, San
Diego State University
Autonomous guidance and control solutions for spacecraft rendezvous and proximity operations(RPO) must be robust to modeling uncertainties, unmodeled dynamics, errors in thruster output andalignment, sensor bias and noise, and environmental disturbances. An autonomous control system
may also have to contend with emerging debris or other obstacles. This paper presents a closed-loop
control approach based on second-order cone programming (SOCP) that supports continuous regeneration of a fuel-optimal control solution that satisfies inequality constraints as well as equality
constraints on interior points and terminal conditions within a multi-phase mission.

14:30

AAS Modeling and Control of an Electromagnetic Docking System for the SAS-SAT
21-391 CubeSat
MissionKyle Rankin, New Mexico State University; Hyeongjun Park, New Mexico State University;
Steven Stochaj, New Mexico State University
The Satellite Alignment System SATellite (SAS-SAT) demonstrates a low-cost system to performthe final approach to docking between two CubeSats utilizing electromagnets. This paper shows thedevelopment of the dynamics model. Additionally, this paper goes into a detailed analysis of thecontrolsystem's required, including PID, LQR, and MPC controllers. This paper presents an analysisof the viability of such a system looking at variables such as the required magnet size, and the range
at which the magnetic docking system becomes viable. Finally, this paper will estimate the sizing of
the electromagnets, and the attitude control system.

Page 44

31st AAS/AIAA Space Flight Mechanics Meeting14:42AAS Attitude and Orbit Control System for a High-Resolution FIREFLY Satellite
21-412 Karthic Balasubramanian, Syzygy Space Technologies (Pixxel Space Technologies Inc);
Piruthvi Chendur Palanisamy, Syzygy Space Technologies Pvt Ltd (Pixxel Space)
High resolution earth imaging satellites have traditionally been large satellites. The companies like
Pixxel are achieving high resolution requirement with a microsatellite as small as 30 kilogram insize. The authors explore the development of high precision Attitude and Orbit Control System(AOCS) for such a Low Earth Orbit (LEO) microsatellite mission. The satellite will be launched by
Falcon-9 and it is positioned in a circular Sun-Synchronous Polar Orbit of altitude 550km above
earth’s surface by an Orbit Transfer Vehicle (OTV). The satellite is to be deployed with an orbit
inclination of 97.5 deg.

14:54

AAS Three-Axis Reaction Wheel Desaturation using Two-Axis Gimbaled Thruster on a
21-418 non-Diagonal
Inertia
Satellite
Carlos Montalvo; William Sherman, University of South Alabama
For institutions with satellite missions limited by budget and dimensional constraints, having
redundant control authority over all three rotational axes might prove challenging by only having
means of secondary attitude control actuation on two axes. This develops an inherent problem whenreaction wheel saturation occurs. A control system is developed in this paper that allows for full
three-axis desaturation of a spacecraft’s reaction wheels via a gimbaled thruster with only two axesof rotation. This is accomplished by utilizing the property that a non-diagonal inertia matrix willcause rotation in one axis to transfer momentum to another axis. The full manuscript will include fullcontrol law derivation.

Feb 2, 2021Virtual Room #3
18 - Space Object Characterization and Independent Attitude Determination
Chair: Piyush Mehta, West Virginia University
13:30

AAS Multi-Scale Convolutional Neural Networks for Inference of Space Object Attitude
21-246 Status
from
Detrended
Geostationary
Light
CurvesGregory Badura, GTRI; Brian Gunter, Georgia Institute of Technology; Christopher
Valenta, Georiga Tech Research Institute; Brian Shoffeitt, Georgia Tech Research InstituteConvolutional neural network architectures were utilized to classify simulated geo-stationary RSO
light curves into one of three operational states: controlled, maneuvering, or tumbling. Two different
architectures were trained on a dataset of full- and partial-night light curves: (1) a Multi-scale
Convolutional Neural Network (MCNN), and (2) a deep Convolutional Neural Network (CNN). The
MCNN incorporates frequency domain pre-processing and multi-scale feature extraction, allowing
it to extract behaviors occurring on different timescales. Our results show that the MCNN does not
out-perform the deep-CNN, suggesting that it is potentially better to utilize model architectures thatfully automate the process of feature extraction.

13:54

AAS Empirical
Approaches
toUltra-Wide
Angle
Lens
Calibration
21-327 Sam Wishnek, CU Boulder; Marcus Holzinger, University of Colorado Boulder

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31st AAS/AIAA Space Flight Mechanics Meeting

Optical data pre-processing for space situational awareness requires lens calibration where thedistortion induced by the optical system is accounted for in extracting the angular measurements ofa target. Existing methods for image calibration attempt to fit the data to a function-based model.
This approach does not perform well for lenses with a very large field of view or asymmetricdistortions. Here is presented an algorithm for empirically calibrating night sky images taken withultra-wide angle lenses in order to generate mappings between pixels and inertially registered line- ofsight beams better than existing functional methods.

14:06

AAS Light-Robust Shape-from-Silhouette Algorithmfor Autonomous Optical Navigation to
21-323 an
Unknown
Small
Body
Saptarshi Bandyopadhyay, Jet Propulsion Laboratory, California Institute of Technology;
Jacopo Villa, University of Colorado Boulder; Alan Osmundson, University of Southern
California, ; Benjamin Hockman, Jet Propulsion Laboratory, California Institute ofTechnology; Benjamin Morrell, NASA Jet Propulsion Laboratory; Daniel Lubey, Jet
Propulsion Laboratory, California Institute of Technology; Shyam Bhaskaran, Jet
Propulsion Laboratory; David Bayard, Jet Propulsion Laboratory; Issa Nesnas, Jet
Propulsion Laboratory, California Institute of Technology
We present an advanced Shape-from-Silhouette (SFS) algorithm, which is robust to illumination
conditions and non-zero sun phase. SFS is an important step in the optical navigation pipeline for anautonomous
small
spacecraft
toapproachanunknown
small
body.
The algorithm estimates the rotation-axis pole and 3D shape (visual hull) of the small body using
only the lit pixels within the silhouette of the small body, rotation rate, and spacecraft-target relative
poses
from
orbit
determination.
We present detailed numerical simulations and multiple sensitivity analyses to demonstrate theeffectiveness of our proposed SFS algorithm.

14:18

AAS Modeling and Simulation of Rotary Sloshing in Launch Vehicles
21-433 Jeb Orr, Mclaurin Aerospace
Recent experience has reemphasized the risk of rotary sloshing limit cycles in launch vehicle
propellant tanks. A detailed analysis of mechanical analogs for the simulation of nonlinear fluid
dynamic coupling in axisymmetric containers is presented. A novel formulation is derived that is
easily coded for simulation and incorporates damping asymmetry for tanks with ringbaffles. Theoretical and simulation results are compared with historical test data. High-fidelity
Monte Carlo simulation of a liquid-propellant vehicle is used to compare the present approach withtraditional mechanical models of propellant slosh.

14:30

AAS Real-Time, Flight-Ready, Non-Cooperative Spacecraft Pose Estimation Using
21-283 Monocular
Imagery
Kevin Black, Texas Spacecraft Laboratory; Shrivu Shankar, Texas Spacecraft Laboratory;
Daniel Fonseka, Texas Spacecraft Laboratory; Jacob Deutsch, Texas Spacecraft
Laboratory; Abhimanyu Dhir, Texas Spacecraft Laboratory; Maruthi R. Akella, The
University of Texas at Austin
A key requirement for autonomous on-orbit proximity operations is the estimation of a spacecraft’s
pose (position and orientation). It is desirable to employ monocular cameras for this problem due totheir low cost, weight, and power requirements. This work presents a novel convolutional neuralnetwork (CNN)-based monocular pose estimation system that achieves state-of-the-artaccuracy with

Page 46

31st AAS/AIAA Space Flight Mechanics Meetinglow computational demand. In combination with a Blender-based synthetic data generation scheme,
the system demonstrates the ability to generalize from purely synthetic training data to real in-space
imagery of the Northrop Grumman Enhanced Cygnus spacecraft. Additionally, the system achieves
real-time performance on low-power hardware.

Feb 2, 2021Virtual Room #4
19 - Asteroids II & Mars
Chair: Anil Rao, University of Florida
13:30

AAS Flexible and single-impulse transfers for asteroid retrieval using the invariantofthe
Circular-Restricted
Three-bodyProblem
21-245 manifolds
Jack Tyler, University of Southampton; Alexander Wittig, University of Southampton
Recent studies have used the invariant manifolds of the Circular-Restricted Three-Body Problem toretrieve Near-Earth Objects, classifying those retrievable below a cost of 500m/s as Easily
Retrievable Objects (EROs). We significantly extend on the previous literature, both in the number
of EROs and their optimal solutions: 44 EROs are found, including four new EROs below 100m/s.
We also study the Pareto fronts of the EROs for the first time, demonstrating that the retrieval cost
is approximately constant for any transfer time, including single-impulse transfers for only
marginally higher cost than two-impulse transfers for many EROs.

13:42

AAS Deimos Flyby Observation Analysis using Resonant Flybys for the MMX Mission
21-299 Ferran Gonzalez-Franquesa, SOKENDAI, The Graduate University for Advanced Studies;
Naoya Ozaki, ISAS, JAXA; Yasuhiro Kawakatsu, JAXA / ISAS
JAXA's next flagship mission Martian Moons eXploration (MMX) will visit Phobos and Deimos.
The mission aims to provide answers on the formation and evolution of the moons and, by extension,
the the inner Solar System. Due to the nature of the Mars-Deimos system and mission constraints,
the exploration of Deimos will be carried out via multiple resonant flybys. This approach allows the
MMX probe to perform close-up observations of largely unexplored regions of the moon underdesired solar illumination conditions, maximizing the scientific output.

13:54

AAS Observability-Aware Trajectory Optimization for Small-body Gravity Estimation
21-304 Masahiro Fujiwara, The University of Tokyo; Ryu Funase, The University of Tokyo
In small-body explorations, gravity estimation is a critical task to design trajectories for main
operations and identify some characteristics of the target body. The gravity field can be recovered bytracking perturbed spacecraft'strajectory around the body. For more effective gravity estimation, thisresearch proposes the sampling-based optimization method to find the trajectory where a trace of thegravity coefficients' covariance matrix or a trace of the inverse of observability gramian is thesmallest. Numerical simulations show the optimal trajectories are different between the covariancematrix and observability gramian.

14:06

AAS Comparing Optical Tracking Techniques in Distributed Asteroid Orbiter Missions
21-336 Using
Ray-Tracing

Page 47

31st AAS/AIAA Space Flight Mechanics MeetingKaitlin Dennison, Stanford University Space Rendezvous Laboratory; Simone D'Amico,
Stanford University
Keypoint descriptors are compared to a characteristic-specific landmark descriptor (craters) for
optical tracking within a monolithic and distributed space system orbiting an asteroid. Additionally,a novel method to validate correlations between any landmark descriptors using ray-tracing isdeveloped. Optical tracking methods are evaluated in simulation to identify tracking limitations.
Simulated test cases are validated using the ray-trace matching technique. Ray-trace matching andoptical tracking are further validated using images from a robotic testbed and real images from NEAR
Shoemaker. Craters are shown to be at least comparable to keypoint descriptors. Ray-trace matchingshows great potential for optical tracking validation.

14:18

AAS Station Keeping of Satellites in Areostationary Mars Orbit using Model Predictive
21-358 Control
Robert Halverson, Department of Aerospace Engineering and Mechanics, University of
Minnesota - Twin Cities; Avishai Weiss, MERL; Ryan Caverly, University of Minnesota
In this paper, a model predictive control (MPC) station keeping policy is applied to a spacecraft
orbiting Mars in an areostationary orbit. A high-fidelity orbital model is presented that considers thesignificant orbital perturbations caused by Mars' non-Keplerian gravitational potential, the presenceof the Sun and Mars’ moons, and solar radiation pressure. An MPC policy is implemented with theobjective of minimizing fuel consumption while remaining within a prescribed station keeping
window. Simulation results at a stable longitude demonstrate the MPC policy meets the defined
objectives, while providing a benchmark for the annual fuel required for Martian station keeping.

14:30

AAS GNC of a Tethered Robotic Explorer for Accessing Cliffs, Canyons, and Craters on the
21-444 surfaceofMars
Jekan Thangavelautham, University of Arizona

14:42

AAS Advancing Asteroid Surface Mobility Using Machine Learning and the SPIKE
21-445 Spacecraft
Concept
Jekan Thangavelautham, University of ArizonaFeb 2, 2021Virtual Room #5
20 - Space Robotics and Autonomous Operation & Lunar
Chair: Manoranjan Majji, Texas A&M University, College Station
13:30

AAS DYNAMIC MODELING AND CONTROL FOR A TETHER-DRIVEN MULTI 21-285 MANIPULATORSSYSTEMCAPTURINGA
TUMBLING
TARGET

Page 48

31st AAS/AIAA Space Flight Mechanics MeetingQiming Luo, School of Aerospace Engineering,Beijing Institute of Technology; Quan Hu,
School of Aerospace Engineering, Beijing Institute of Technology
A novel mechanism is proposed in this work for tumbling target capture — tether-driven multimanipulators system. It is consisted of four 2-DOFs manipulators, and a tether connecting the tips ofthe manipulators. The tether length can be controlled by a motor at one manipulator’s tip, so theconfiguration and motion of the system are controlled by the tether, as well as the joint motor in the
manipulators. We investigate the dynamic modeling and trajectory tracking control for this tetherdriven multi-manipulators system.Numerical simulations demonstrates the proposed mechanism iseffective in capturing a non-cooperative target.

13:42

AAS Sustained Low-Altitude Lunar Orbital Mission (SLALOM) Navigation Concept
21-337 Jeff Parker, Advanced Space, LLC; James Thomas, Advanced Space; Sai Chikine, Advanced
Space; Charles Cain, Advanced Space; Matthew Bolliger, Advanced SpaceThis paper describes the autonomous navigation system that is being developed to demonstrate theautonomous navigation of a spacecraft traversing an incredibly low-altitude lunar orbit. The
Sustained Low-Altitude Lunar Orbital Mission (SLALOM) is a proposed mission concept that would
place a spacecraft into an orbit with a mean altitude of < 10 km and maintain it there for multiple
months. The autonomous navigation system includes a collection of onboard orbit determination
filters and an autonomous maneuver design system, each of which must operate without any groundinputs for sustained periods of time, through multiple maneuvers.

13:54

AAS Methods in Triangulation for Image-Based Terrain Relative Navigation
21-401 Kevin Kobylka, Rensselaer Polytechnic Institute; John Christian, Rensselaer Polytechnic
Institute
Imagery obtained by a spacecraft in orbit around a celestial body can provide directional
measurements from the spacecraft to multiple landmarks on the surface of the body. These
measurements may be used to estimate the spacecraft location by triangulation. While the direct
linear transform (DLT) method allows for a non-iterative solution for spacecraft localization, it
creates a least squares problem with sometimes undesirable error characteristics. This work explores
several solutions to the triangulation problem and evaluates their relative efficacy within the context
of spacecraft terrain relative navigation (TRN).

14:06

AAS LIBRATION REDUCTION DURING PARTIAL SATELLITE RETRIEVAL OF
21-284 VERTICAL
THREE-MASSTETHEREDSYSTEMS
Derek Bourabah, University at Buffalo; Eleonora Botta, University at Buffalo
Tether retraction in a three-mass tethered satellite system is an unstable process in which libration
angle increases over time. A simple control method is proposed to significantly reduce libration
during a partial retraction maneuver. The proposed method introduces short periods of extension
during retrieval. Simulations with varying initial conditions and number of extension/retraction
cycles show that the controlalgorithm is effective. It is found that performing the maneuver too manytimes will diminish the efficiency. Ideally, the proposed methodology is applied to the two tethers,
but if only one tether is to be controlled, the lower tether should be maneuvered.

14:18

AAS Design and Analysis of Deployment Mechanics for a Self-Folding, Spiral Based Space21-333 Borne
Interferometer

Page 49

31st AAS/AIAA Space Flight Mechanics MeetingKanak Parmar, Auburn University; Manuel Indaco; Ryan Long; Will Taylor; Nathaneal
Adkins; Deepika Singla; Russell Mailen; Davide Guzzetti, Auburn University
Ground observation of the Dark Ages signal is impeded by the Earth's atmosphere, which induces
significant signal distortions at frequencies below 30 MHz. Compared to traditional methods, we
propose a space-borne interferometer comprised of dipole antennas, embedded within a deployable,
kilometer-size orbiting spiral in cislunar space. This structure is composed of shape memory polymer
material marked by ink hinges that absorb solar radiation, triggering a temperature gradient thatcauses the material to fold. In this work, we initiated the design and analysis the spiral deployment
mechanics and the resulting array performance to propose the appropriate space-borne interferometerarchitecture.

14:30

AAS Slant Range Measurements for Lunar
21-435 Randall Christensen, Utah State University

Terrain

Relative

Navigation

14:42

MasconGlobalLunar
Gravity
ModelsAAS Point
21-453 Sean McArdle, University of Texas at Austin
Lunar gravitational models are generated using sets of point mass potentials fit to the recent, highly
resolved GRGM1200A representation derived from GRAIL mission data. Point mass ensembles arehighly parallelizable and can encode the gravitational potential and its gradients to an arbitrary order.
A new model generation algorithm uses nonlinear optimization to assign point mass positions thatbest reproduce the gravitational field. The new technique generates models with improved numericalstability, memory cost, and evaluation runtime speed. A database of point mascon models is released,
including driver routines that evaluate the gravitational potential gradients up to third order.

14:54

AAS Nearly Constant-Time SLAM-based Terrain Relative Navigation for Landing on an
21-425 Uncharted
World
Matthew Givens, University of Colorado Boulder; Jay McMahon, University of Colorado
Boulder
Solutions to the Terrain Relative Navigation (TRN) estimation problem have traditionally relied onlandmark or image-based maps built from pre-existing orbital imagery to generate absolute positionand velocity estimates of a landing vehicle. Insights and advances from the field of Simultaneous
Localization and Mapping (SLAM) have produced algorithms that can efficiently estimate both thepose of the vehicle and the environment around it. This work applies one such algorithm, the Exactly
Sparse Extended Information Filter (ESEIF), to the TRN problem and compares it to the more
traditional Extended Kalman Filter (EKF) approach on the grounds of accuracy and computational
efficiency.

Feb 3, 2021Virtual Room #1
21 - Trajectory Optimization
Chair: Sonia Hernandez, Jet Propulsion Laboratory
Page 50

31st AAS/AIAA Space Flight Mechanics Meeting10:30AAS Quantum-inspired Diffusion Monte Carlo Optimization Algorithm applied to Space
21-207 Trajectories
Federico De Grossi, Sapienza University of Rome; Christian Circi, Sapienza University ofRome
In this work, an algorithm for optimization is proposed, inspired by the principles of Quantum
Mechanics. The algorithm is based on the Diffusion Monte Carlo method, commonly used for thecomputation of ground states of many-particles systems. The optimization problem is reconductedto sampling the ground state wave function of a particle subject to a potential based on the function
to be minimized. The algorithm is applied to the problem of transfer between circular orbits and to
the problem of rendezvous with the asteroid Pallas, where the results are compared to results obtainedwith PSO.

10:42

AAS Global Optimization of Manifold-Based Transfers to Halo and Butterfly Orbits Using
21-293 Highly-ParallelGPU
Architecture
Yang Foo, Kyushu University; Hideaki Ogawa, Kyushu University; Satoshi Ueda, Japan
Aerospace Exploration Agency; Mai Bando, Kyushu University
Cis-lunar libration point orbits are prime candidates for forthcoming lunar and deep space missions.
The present study focuses on transfers between the Earth and highly inclined lunar halo orbits, alongwith the bifurcated butterfly family via invariant manifolds. Multi-objective genetic optimization has
been performed separately employing a direct and hybrid approach, incorporating surrogate
modeling in the former and a highly-parallel GPU (graphics processing units) architecture in thelatter. Pareto-optimal solutions exhibiting different attributes have been identified and representative
trajectories are shortlisted. These solutions provide a better understanding of the trade-off between
maneuver costs and time, while elucidating interesting dynamical properties in the Moon's vicinity.

10:54

AAS Optimal injection into Quasi-Satellite Orbits around Phobos: application to MMX
21-297 mission
Nicola Marmo, The Graduate University for Advanced Studies (SOKENDAI) - ISAS/JAXA;
Diogene Alessandro Dei Tos, JAXA; Hitoshi Ikeda, Japan Aerospace Exploration Agency;
Yasuhiro Kawakatsu, JAXA / ISAS
The Japan Aerospace Exploration Agency is aiming to launch in 2024 the Martian Moons
eXploration mission. The main scientific objective is to survey the two Martian moons and to returna sample from the surface of Phobos. As nominal scientific orbits, several Quasi-Satellite Orbits
around Phobos have been computed and adopted in consideration of the complex dynamical
environment characteristic of the Mars--Phobos system. This paper explores the performancecapability of a multi-impulsive control strategy to inject the MMX probe into a host of QSOs aroundPhobos, after a heliocentric journey from the Earth. A perturbation analysis in the vicinity of

11:06

AAS Spacecraft Trajectory-Propulsion Co-optimization Using Enhanced Regularized
21-318 Indirect
Methods
Vishala Arya, Texas A & M University; Ehsan Taheri, Auburn University; John L. Junkins,
Texas A&M University
Application of idealized constant-specific-impulse, constant-thrust electric thruster performancemodels or curve-fitted polynomials is quite common. In this paper, a framework is developed for cooptimization of 1) spacecraft trajectory, 2) operations modes of multi-mode propulsion systems, and3) solar array size. The selection of the most optimal operation modes is in accordance toPage 51

31st AAS/AIAA Space Flight Mechanics MeetingPontryagin’s minimum principle for solving a payload-mass-maximization problem. The novelty
is enhanced by solving a mixed-integer featuring user-defined constraints on the maximum numberof operating modes used along the trajectory. Utility of the framework is demonstrated through amulti-year trajectory from Earth to Gerasimenko using an SPT-140 thruster with 21 operating modes.

11:18

AAS Optimal Maneuver Targeting Using State Transition Tensors with Variable Time-of21-404 FlightSpencer Boone, University of Colorado Boulder; Jay McMahon, University of Colorado
BoulderThis paper presents a methodology for expanding the higher-order state transition tensors (STTs) of
a reference trajectory with respect to the final time over which the trajectory is propagated. Following
this, a maneuver targeting and optimization scheme with a variable time-of-flight is developed using
only the STTs of the reference trajectory. The algorithm is used to efficiently compute accurate andnear-optimal stationkeeping maneuvers for a spacecraft operating in a halo orbit in the Earth-Moonsystem. The optimization scheme is computationally lightweight, and could be suitable for on-board
use in highly nonlinear dynamical systems.

11:30

JupiterGravity
Assists–
Analytic
Approximations
AAS Optimized
21-407 Ralph McNutt, JHU Applied Physics Laboratory
The use of the planet Jupiter to effect gravity assists for aiding propulsive requirements forinterplanetary trajectories is well known. In mission proposals and mission planning, typicallyspecific launch opportunities are targets and detailed mission designs developed. However, thisapproach can be costly in both time and resources if a less specific design space is known. By making
use of appropriate, small approximations, we derive general analytic solutions for the performanceof both passive and active, i.e. powered, Jupiter gravity assists as a function of initial launch energy
and available rocket stage capability during a close flyby of the planet.

11:42

AAS CostateTransformationforIndirectTrajectory
Optimization
21-408 Ehsan Taheri, Auburn University; Vishala Arya, Texas A & M University; John L. Junkins,
Texas A & M University
A methodology is proposed to establish costate transformation between any two sets of coordinates.
It has utility for solving optimal control problems using indirect methods. The Jacobian of thenonlinear map between any two sets of coordinates/elements turns out to be the critical component
in the costate vector transformation theory. Application of the proposed method and its utility aredemonstrated through a number of time- and fuel-optimal trajectory optimization problems.

Feb 3, 2021Virtual Room #2
22 - Formation Flying
Chair: Robert Melton, Pennsylvania State University
10:30

Page 52

AAS Spacecraft Close-Range Trajectory Planning via
21-282 Guaranteed

Convex Optimization with
Convergence

31st AAS/AIAA Space Flight Mechanics Meeting

Guoxu Zhang, Beijing Institute of Technology; Changxuan Wen, Beijing Institute ofTechnology; Qiao Dong, Beijing Institute of Technology
A novel convexization method is proposed to solve both fuel-optimal and time-optimal spacecraft
close-range trajectory planning problems. First, the nonlinear terms in dynamics are transformed into
path constraints through the redefinition of variables. Then, the introduction of intermediate variables
and convex-concave decomposition are adopted to handle path constraints. In this manner, theobjective is linear after discretization, the equality constraints are affine, and the nonlinearity isconcentrated in cone constraints and concave inequality constraints. Then, concave inequality
constraints are linearized. Furthermore, a general sequential solution algorithm is proposed and theconvergence of the algorithm can be proved.

10:42

AAS DISTRIBUTED PATH PLANNING METHOD FOR LARGE-SCALE SWARM
21-287 SAFEMIGRATION
Xingyu Zhou, Beijing Institute of Technology; Qiao Dong, Beijing Institute of Technology;
Changxuan Wen, Beijing Institute of Technology; Hongwei Han, Beijing Institute ofTechnology
This paper proposes a distributed sequential convex optimization (DSCO) method for large-scale
fuel-optimal swarm migration problems. The optimal control problem (OCP) under collision
avoidance constraints is formulated. The coupled collision avoidance constrains are decoupled in an
iterative framework based on the nominal trajectory. An iterative update strategy and a convergencejudgment strategy are proposed to improve the robustness and efficiency of the algorithm. Thensequential convex programming (SCP) is used to solve the distributed sub-problems. Finally, theproposed DSCO is successfully applid to a 100-spacecrafts swarm migration problem.

10:54

AAS Nonlinear Mapping of Orbit Element Differences for Spacecraft Formation Flying
21-341 Ayansola Ogundele, National Space Research and Development Agency; Olufemi Agboola,
National Space Research and Development Agency, Nigeria
The increase in interest in spacecraft formation flying concept necessitated the need to design anddevelop a high fidelity dynamical models for future space missions. In this paper, to improve thedynamics fidelity, higher order relative motion model is developed using orbit element differences.
The nonlinear mapping between orbit element differences and Hill coordinates are established using
Taylor series expansion. Using the nonlinear mapped relationship, radial, along-track and cross-track
positions and velocities are developed. Afterward, new state transition matrix and bounded relative
motion are developed for both circular and elliptical chief orbits. A comparison is made with theexisting models.

11:06

AAS Satellite Formation Reconfiguration and the Traveling Salesman Problem
21-348 Kyle T. Alfriend, Texas A&M University
The problem being investigated is: Given a formation of msatellites and a set of desired Nformations
from a group of typical formations develop the methodology for determining the optimal sequencefor visiting each formation such that the total impulsive Dvrequired for the set of reconfigurations is
minimized. It is shown that the solution reduces to a Traveling Salesman Problem using a Manhattan(L1) norm. With Nformations there are Npoints and the axes are the in-plane and out-ofplane Dv’sfor achieving the reconfiguration from the initial formation.

Page 53

31st AAS/AIAA Space Flight Mechanics Meeting11:18AAS Closed Form Solution of Nonlinear J2 Perturbed Spacecraft Formation Flying in
21-373 Elliptical
Orbit
Ayansola Ogundele, National Space Research and Development Agency; Olufemi Agboola,
National Space Research and Development Agency, Nigeria
In this paper, closed form solution of nonlinear J2 perturbed spacecraft formation flying in ellipticalorbit is developed via power series approach. The power series method is one of the most widelyused and powerful analytic methods for constructing solutions of linear and nonlinear differential
equations. Quadratic approximation form of the J2 perturbed relative motion was formulated byretaining quadratic nonlinear terms. Afterward, power series solution technique was applied todevelop analytical solutions of the motion. The new model is compared numerically with thenonlinear J2 perturbed motion.

11:30

AAS Spacecraft Formation Control Near a Periodic Orbit Using Geometric Relative
21-451 Coordinates
Ian Elliott, University of Colorado Boulder; Natasha Bosanac, University of Colorado,
Boulder
A nonlinear feedback control law is introduced to establish relative motion about a periodic orbit
with oscillatory modes in the circular restricted three-body problem. The control law feeds backerrors in terms of geometric relative coordinates defined using nearby quasi-periodic motion. Thisdefinition of the tracking error enables straightforward feedbackgain selection via geometric insight.
The control law is used to stabilize a spacecraft to follow first-order quasi-periodic motion relative
to a periodic orbit, requiring low control effort to maintain long-term bounded relative motion in thecircular restricted three-body problem.

11:42

AAS Spacecraft
Swarmsfor
Monitoring
ActiveEarth
Features21-448 Jekan Thangavelautham, University of Arizona
In this work, we develop swarm mission conceptsfor monitoring active Earth features with Synthetic
Aperture Radar (SAR). To achieve this, we develop probabilistic coverage algorithms for different
operational modes of SAR. These algorithms are used to design the seed spacecraft orbits, which arethen used to design a constellation that maximizes the spatio-temporal coverage. We then examine
the reconfiguration problem, where once an active feature is detected, the spacecraft performmaneuvers to maximize the temporal coverage of the feature. Finally, we demonstrate the algorithms
through numerical simulations to design a SAR-based swarm to detect and monitor volcanoes.

Feb 3, 2021Virtual Room #3
23 - Guidance, Navigation, and Control
Chair: Marcus Holzinger, University of Colorado Boulder
10:30

AAS Optimal reference orbit tracking around asteroids via Particle Swarm Optimization
inversedynamics
technique21-260 and
Andrea D'Ambrosio, Sapienza Università di Roma; Andrea Carbone, School of Aerospace
Engineering, Sapienza University of Rome; Marco Mastrofini, School of Aerospace

Page 54

31st AAS/AIAA Space Flight Mechanics Meeting

Engineering, Sapienza University of Rome; Fabio Curti, School of Aerospace Engineering,
Sapienza University of Rome
Optimal proximity operations around asteroids are very challenging because of their irregular gravity
field. This paper focuses on optimal control applied to asteroids proximity maneuvers obtained
thanks to the combination of Particle Swarm Optimization, inverse dynamics and B-splines, used toapproximate the trajectory. Furthermore, an Extreme Learning Machine-based algorithm is
employed to estimate the gravity vector from the position vector in the asteroid body-fixed frame.
This choice allows to achieve a good accuracy while decreasing the computational time that otherprecise methods, like the polyhedron model, would require. Finally, the proposed framework is
applied to reference orbit tracking around asteroids.

10:42

AAS Direct Visual SLAM with a Filter-Based Lidar Measurement Incorporation
21-347 Corey Marcus, The University of Texas at Austin; Renato Zanetti, The University of Texas
at Austin
In this paper we present a Direct Monocular SLAM system which is augmented with flash LIDAR
images. The LIDAR measurements are incorporated with an Extended Kalman Filter and utilizationof the Gamma and Inverse Gamma probability distribution functions. The system produces metricpose and map estimates. Monte Carlo methods are used to demonstrate that incorporating LIDAR
measurements into the system provides significant performance improvements over a system without
LIDAR in simulation. Experimental results using the EuRoC dataset are then presented which show
improved system performance in real-time operation.

10:54

AAS Covariance Estimation using geometric optimization on symmetric positive definite
21-353 manifolds
Rahul Moghe, The University of Texas at Austin; Maruthi R. Akella, The University of Texas
at Austin; Renato Zanetti, The University of Texas at Austin
This paper provides a significant extension to our previous work on adaptive covariance estimationthat estimates the noise covariance matrices of a discrete linear system with simultaneous guarantees
for convergence of the noise covariance estimates and the state estimates. The specific advanceestablished in this work is that the estimates of the covariance are calculated using a differential
geometric optimization framework that ensures that the covariance estimates lie restricted to thesymmetric positive definite (SPD) manifold. This property is desirable since the covariance estimatesused in calculating the state estimates have to be SPD at all times for them

11:06

Maintenance
StrategyforEarth-Moon
Halo
OrbitsAAS Orbit
21-366 Vivek Muralidharan, Purdue University; Kathleen C. Howell, Purdue University
The L1 and L2 Near Rectilinear Halo Orbits (NRHOs) are suitable long horizon trajectories for cislunar exploration missions. Due to unmodeled forces as well as orbit determination errors in thisdynamically sensitive region, the spacecraft deviates from the desired path. The current investigation
focuses on an impulsive stationkeeping technique to maintain the spacecraft near a long horizon
virtual reference orbit. The dynamics in the halo orbit region are explored to identify suitablemaneuver and target locations for orbit maintenance. Furthermore, phasing constraints areincorporated to maintain spacecrafts on orbits where states are sensitive to epoch time.

Page 55

31st AAS/AIAA Space Flight Mechanics Meeting11:18AAS INVESTIGATION
OF
KEY
GYRO
PERFORMANCE
CRITERIA:
21-397 OPTIMIZATIONVIA
META-ANALYSISCORRELATIONSMartin Hasha, Lockheed Martin Space Company
Inertial Reference Units (IRUs) are crucialto achieving spacecraft Line-of-Sight (LOS) fine-pointing
performance. Allocated criteria (e.g. drift, bias, etc.) present profound challenges for assessing unit
limits and trade-off weighting lacking statistically-significant data. A unique data-mining metaanalysis is performed on large datasets of in-family, flight-accepted Hemispherical Resonating Gyros(HRGs), addressing multiple parameters. Evaluation via bivariate correlations(Pearson's
coefficients) is intended to extract previously unexplored/unknown insights. Cost reductions, while
meeting overall limits, is discussed. Data aggregations, conclusions, and methods are valuable in
LOS jitter models, analyses, and optimizing wide-ranging space applications: e.g. steering mirrors,
cryocoolers, moving antenna, microgravity platforms, planetary flybys, etc.

11:30

AAS Estimation Of The Conditional State And Covariance with Taylor Polynomials
21-416 Simone Servadio, The Universityof Texas at Austin; Renato Zanetti, The Universityof Texas
at Austin
A novel estimator is presented that expands the typical state and covariance update laws of Kalmanfilters to polynomial updates in the measurement. The filter employs Taylor series approximationsof the nonlinear dynamic and measurement functions. All polynomials (functions approximation,state update, and covariance update) can be made to arbitrary order to trade between filter's
accuracy/consistency and computational time. The performance of the algorithm is tested innumerical simulations.

11:42

AAS Orion GN&C Sequencing for Off-Nominal Rendezvous, Proximity Operations, and21-439 Docking
Jordan Abell, University of Colorado Boulder; Peter Schulte, The Charles Stark Draper
Laboratory, Inc.; Fred Clark, Draper; Peter Spehar, NASA Johnson Space Center; David
Woffinden, NASA Johnson Space Center
This paper discusses the Concept of Operations of the nine contingency strategies available for offnominal Rendezvous, Proximity Operations, and Docking of Orion with the Gateway in a NearRectilinear Halo Orbit around the Moon. Explanations are provided for each contingency strategy,
how they are initiated, when they can be initiated, and how they are designed to protect the crew.
Then an overview is provided of the sequencing of the Guidance, Navigation, and Control flight
software used to achieve each contingency strategy, in the form of Phases, Segments, Activities, andModes. These off-nominal scenarios require the definition of new Segments and Activities.

Feb 3, 2021Virtual Room #4
24 - Orbit Determination
Chair: Kyle DeMars, Texas A&M University
10:30

AAS Comparison and Error Modeling of Velocity Initial Orbit Determination Algorithms
21-280 Linyi Hou, University of Illinois at Urbana-Champaign; Kevin Lohan, University of Illinois
at Urbana-Champaign; Zachary Putnam, University of Illinois at Urbana-Champaign

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31st AAS/AIAA Space Flight Mechanics Meeting

Recently, Christian and Hollenberg proposed and solved a new class of initial orbit determination
problems whereby a spacecraft's orbit is determined using only velocity measurements. This paper
introduces a modification to the velocity initial orbit determination algorithm that improves bothaccuracy and computationalefficiency. Changes in the orbit determination error with respect to semimajor axis, eccentricity, true anomaly, sensor noise, measurement duration, and number ofmeasurements are then analytically modeled using the orbit hodograph. Finally, the analytic model
is compared against Monte Carlo simulations using the improved algorithm. Results show theanalytic model accurately predicts changes in orbit determination error.

10:42

AAS Towards Accurate Orbit Determination using Semi-analytical Satellite Theory
21-309 Bryan Cazabonne, CS GROUP; Paul J. Cefola, University at Buffalo (SUNY)
Space agencies generally use numerical methods to meet their orbit determination needs. Due to theever increasing number of observed space objects, the development of new orbit determination
methods becomes essential. DSST is an orbit propagator based on a semi-analytical theory. It
combines the accuracy of numerical propagation and the speed of analytical propagation. The paper
presents an open-source DSST orbit determination application included in the Orekit library.
Accuracy of the DSST orbit determination is demonstrated by comparison with a numerical method.
Both the satellite’s state vector estimation and the measurement residuals are used as comparison
metrics.

10:54

AAS Nonlinear
Set-Membership
Filtering-Based
Orbit
Estimation
21-314 Diganta Bhattacharjee, The University of Texas at Arlington; Kamesh Subbarao, Universityof Texas at Arlington
We propose a nonlinear set-membership filtering-based orbit estimation technique for Earth-orbiting
satellites. The recursive set-membership filter utilizes the state dependent coefficientparameterization to acquire a pseudo-linear description of the governing nonlinear system. At every
recursion, the filter requires solutions to two convex optimization problems and these solutions canbe efficiently obtained. We have included details of the filter design, the nonlinear motion model forthe satellite in orbit, and the nonlinear measurement model in the extended abstract. In the final
version, we would include simulation results corresponding to the set-membership filter and would
provide comparisons with other state estimation techniques.

11:06

AAS Optimally Convergent Minimum-Time Space Object Search and Recovery
21-326 Sam Fedeler, Universityof Colorado at Boulder; Marcus Holzinger, Universityof Colorado
Boulder; William Whitacre, Charles Starck Draper Laboratory
A critical challenge in Space Domain Awareness (SDA) is gaining custody of newly detected or
maneuvering objects. The dynamically feasible location of one such object may be represented as anadmissible region or reachable set. This paper proposes techniques for exploring search sets using
sample-based planning. Several methods for sampling feasible regions of measurement space aredeveloped, and Monte Carlo Tree Search (MCTS) is applied over a limited horizon to determine
time-optimal sets of actions. Tree search aids in overcoming local minima in solutions found withtraditional optimization methods.

Page 57

31st AAS/AIAA Space Flight Mechanics Meeting11:30

Determination
Via
Physics
Informed
NeuralNetworksAAS Orbit
21-338 Andrea Scorsoglio, University of Arizona; Roberto Furfaro, The University of Arizona
In this paper, a set of orbit determination problems are solved via Physics-Informed Neural
Networks. The classical least squares estimate is used a baseline for the loss function using a set ofnoisy measurements. The state of the spacecraft is estimated at each epoch using a deep neuralnetwork. A penalizing term based on the differential equations modelling the dynamics of the
problem is then added to the loss as a regularizing term. This ensure that the learned relationshipbetween input and output is compliant with the physics of the problem.

11:42

AAS The Improvement of Satellite Constellation GNSS Orbit Determination through the
21-362 IncorporationofIntersatellite
Ranging
Measurements
Byron Davis, Georgia Institute of Technology; Brian Gunter, Georgia Institute ofTechnology
Satellite-based Global Navigation Satellite System (GNSS) Precision Orbit Determination (POD)
uses relative measurements of distance to GNSS satellites with known positions and velocities toestimate the overall state of the non-GNSS satellite. This study seeks to determine whether an overall
gain can be made to the performance of a high-fidelity orbit determination scheme through theaddition of relative intersatellite measurements between non-GNSS satellites in a constellation. The
authors develop a simulation and estimation environment in JPL’s Monte software to assess thecapabilities of nanosatellites to perform POD with GNSS only and quantify gains to POD withadditional crosslink observations.

11:54

AAS Process Noise Covariance Modeling for Absolute and Relative Orbit Determination
21-248 Nathan Stacey, Stanford University; Simone D'Amico, Stanford University
This paper develops analytical process noise covariance models for both absolute and relative orbit
determination in a discrete-time Kalman filtering framework. A model of the process noise
covariance of a Cartesian spacecraft state is obtained for near-circular orbits by leveraging thesolution of the Hill-Clohessy-Wiltshire equations parameterized in curvilinear coordinates. Absolute
orbital element process noise covariance models are obtained by either assuming a near-circular orbit
or a small propagation interval. Process noise covariance models for relative spacecraft states arethen constructed from the developed absolute spacecraft state process noise covariance models. The
presented models are validated through numerical simulations.

Feb 3, 2021Virtual Room #5
25 - Orbital Dynamics, perturbations and Stability
Chair: Diane Davis, a.i. solutions, Inc.
10:30

AAS Including
theclosed-form$J_2^2$effectin
DSST
21-233 Juan Félix San-Juan, University of La Rioja; Rosario López, University of La Rioja; Iván
Pérez, University of La Rioja; Paul J. Cefola, University at Buffalo (SUNY)
A second-order closed-form semi-analytical solution of the main problem of the artificial satellite
theory (J2 problem) compatible with the Draper Semi-analytic Satellite Theory (DSST) is presented.
The short-period terms are removed by means of an extension of the Lie-Deprit method using

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31st AAS/AIAA Space Flight Mechanics Meeting

Delaunay variables. The averaged equations of motion are given explicitly and transformed to thenon-singular equinoctial elements. Finally, the second-order terms in the mean element equationsof motion are included in the C/C++ version of the DSST orbit propagator.

10:42

AAS Koopman operator theory applied to the J2 perturbed motion around an oblate planet
21-240 David Arnas, Massachusetts Institute of Technology; Richard Linares, Massachusetts
Institute of Technology
This manuscript analysis the solution provided by the Koopman operator methodology in its
application to the main satellite problem. In this regard, this work performs an spectral study of thesolution generated and compares it with the solution provided by the Poincar\'e-Lindstedt method.
In addition, this manuscript introduces a perturbation methodology based on the Koopman
operator to study perturbed systems. Several examples of application of these methodologies areincluded to show their performance under different conditions.

10:54

AAS Modern Numerical Programming with Julia for Astrodynamic Trajectory Design
21-303 Dan Padilha, University of Tokyo / JAXA Institute of Space and Astronautical Science;
Diogene Alessandro Dei Tos, JAXA; Nicola Baresi, University of Surrey; Junichiro
Kawaguchi, JAXA
A programming toolkit is developed to leverage Julia, a high-performance numerical programming
language, in the generation, optimisation, and analysis of orbital trajectories. Julia combines highlevel abstraction with the computational efficiency of dynamic compilation, enabling highly
composable and extensible programs and state-of-the-art performance in differential systems,
statistical analysis, and machine learning. This paper outlines the motivations and consequences ofJulia's multiple dispatch and meta-programming capabilities, and demonstrates new techniques
enabled in the design of ballistic capture trajectories for a JAXA planetary exploration mission. The
resulting toolkit's composability, extensibility, and performance is compared to JAXA's in-house
jTOP trajectory propagation and optimisation tool.

11:06

AAS The Terrestrial Exoplanet Simulator: An orbital propagator with optimal error
21-335 growthfollowing
Brouwer'slawPeter Bartram, University of Southampton; Alexander Wittig, University of Southampton
We present the TES, a new error-optimal n-body integrator for propagating systems dominated by acentral mass that permits close encounters and achieves a relative energy error at machine precision,i.e. $10^{-16}$, for $10^5$ orbits. TES refines the classicalEncke method with a series of numericalimprovements that reduce both integration runtime and numerical error. The performance of TES ishighly favourable for long-term evolution and close encounters of near Earth objects, such as
Apophis, are propagated precisely. TES can be extended to support arbitrary perturbing forces,
making it suitable for highly accurate long-term integration of satellites in the LEO environment.

11:18

AAS Energy and Phasing Considerations for Low-Energy Transfers from Cislunar to
21-352 HeliocentricSpace
Kenza Boudad, Purdue University; Kathleen C. Howell, Purdue University; Diane Davis,
a.i. solutions, Inc.
In the next decades, multiple missions are proposed or planned to originate in the vicinity of theMoon and be delivered to heliocentric space, such as departures from Gateway to interplanetary

Page 59

31st AAS/AIAA Space Flight Mechanics Meetingdestinations. The Earth-Moon-Sun transit dynamics are complex, primarily influenced by the Earthand the Moon in cislunar space; the gravitational influence of the Sun becomes significant after
departure from the Earth-Moon vicinity. The current investigation leverages an Earth-Moon-Sunspacecraft four-body model, the Bicircular Restricted Four-Body Problem, including dynamical
structures in this regime to explore natural motion between the lunar vicinity and orbits near the SunEarth libration points.

11:30

AAS An Analysis of Koopman-based Perturbation Theory Applied to the Motion About an
21-365 Oblate
PlanetDavid Arnas, Massachusetts Institute of Technology; Richard Linares, Massachusetts
Institute of Technology; Kyle T. Alfriend, Texas A&M University
This paper investigates perturbation methods for satellite motion using the Koopman Operator (KO)in combination with Lie Series methods. The goal of this work is to compute near-identity CanonicalTransformations (CT) that simplifies Hamiltonian systems and allows for the removal of fast periodic
terms. The KO is used to numerically compute the CT that achieves the intend simplification. This
work applies the proposed approach to the motion about an oblate planet were only the zonal terms
are considered.

11:42

AAS SRP-J2 Resonances in Low Earth Orbits for Objects with a Time-Variant Area-to21-375 Mass
Ratio
Catherine Massé, McGill University; Inna Sharf, Mcgill University; Florent Deleflie,
IMCCE / Paris Observatory
In this work, we study the effect of the rotational motion on the SRP-J2 resonance phenomenon andwe suggest that a resonance effect of considerable strength could be achieved for non-sphericalspacecraft in any orbit, by adopting an appropriate spin scenario. In this way, it would be possible
for a spacecraft to exploit the resonance to accelerate its de-orbitation. Using Gauss' singly-averaged
planetary equations, we present a derivation of the spin scenario that would generate a resonance,
simulation results verifying this analysis, as well as a detailed analysis of the phase plots to provide
more insight into the eccentricity evolution.

Feb 3, 2021Virtual Room #1
26 - Trajectory Design III
Chair: Rohan Sood, The University of Alabama
13:30

AAS Aerocapture Trajectories for Earth Orbit Technology Demonstration and Orbiter
Missionsat
Venus,Mars,
andNeptune21-229 Science
William Strauss, Jet Propulsion Laboratory; Alex Austin, Jet Propulsion
Laboratory/California Institute of Technology
The use of aerocapture to provide the delta-v needed to capture a spacecraft into orbit can provide
significant fuel savings compared to a propulsive orbit insertion. The aerocapture guidance method
described in this paper uses drag modulation, which deploys a drag skirt in the atmosphere until theamount of delta-v needed to capture into the desired orbit is obtained, at which time the drag skirt isseparated from the spacecraft. By modulating the time of drag skirt jettison, the vehicle can target a

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31st AAS/AIAA Space Flight Mechanics Meetingspecific orbit apoapsis in the presence of uncertainties such as entry targeting errors and unknown
atmospheric conditions.

13:42

AAS A Rapid Target-Search Techniquefor
KBO Exploration Trajectories
21-243 Miguel Benayas Penas, Catholic University of America ; Kyle Hughes, NASA Goddard
Space Flight Center; Bruno Sarli, NASA/GSFC Science Collaborator; Donald Ellison,NASA Goddard Space Flight Center; Kevin Cowan, Delft University of Technology
A rapid, grid-based, target-search algorithm is presented to find candidate sequences of small-body
encounters for mission design. The algorithm is especially relevant for cases with large combinatorial
spaces. In this paper, the algorithm is used to identify candidate flyby sequences of multiple KuiperBelt Objects (KBOs). The target-search algorithm consists of four sequential steps: (1) parameter
definition, (2) fine-tuned Lambert-based grid search of ballistic trajectories visiting one KBO, (3)rapid, delta V-based proximity search for additional KBOs using the state transition matrices, and(4) trajectory optimization of the most promising KBO sequences using the Evolutionary Mission
Trajectory Generator (EMTG).

13:54

AAS Combined b-plane and Picard-Chebyshev approach for the continuous design of
21-289 perturbed
interplanetary
resonant
trajectories
Alessandro Masat, Politecnico di Milano; Matteo Romano, Politecnico di Milano; Camilla
Colombo, Politecnico di Milano
Orbital resonances have been exploited in different contexts, with the latest interplanetary application
being the ESA/NASA mission Solar Orbiter, which uses repeated flybys of Venus to change theecliptic inclination with low fuel consumption. The b-plane formalism is a smart framework todesign flybys at the boundaries of the sphere of influence with. The theory is applied in conjunction
with the Picard-Chebyshev integration method as optimal pruning to the continuous design ofperturbed resonant interplanetary trajectories in reverse cascade, based on models and analyses fromprevious works. This semi-analytical strategy may allow to surf generic perturbing effects before
optimizing artificial control actions. Applications include designing both planetary andinterplanetary quasi-ballistic trajectories.

14:06

launchwindow
analysisandmissiondesignAAS EQUULEUS
21-292 Diogene Alessandro Dei Tos, JAXA; Takuya Chikazawa, University of Tokyo; Yosuke
Kawabata, The Universityof Tokyo; Kota Kakihara, The Universityof Tokyo; Nicola Baresi,
University of Surrey; Stefano Campagnola, Jet Propulsion Laboratory; Yasuhiro
Kawakatsu, JAXA / ISAS
This paper presents the trajectory design of EQUULEUS, a CubeSat scheduled to launch as a
piggyback of Artemis 1. EQUULEUS will maneuver to a quasi-halo in 1-to-4 resonance with theMoon. As a secondary payload, the trajectory must be compatible with the requirements of the
primary mission, but also robust against disturbances and changes in the deployment state. Realistic
initial conditions are processed and the solution structure for optimal lunar transfers is analyzed. A
host of candidate solutions is presented, compatibly with fuel and power limitations.
The understanding of the solution space is shown to be insightful for the design of robust trajectories
for limited spacecraft.

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31st AAS/AIAA Space Flight Mechanics Meeting14:18AAS Study on Interplanetary Trajectories towards
Uranusand
Neptune21-372 Francesco Sena, Department of Mechanical and Aerospace Engineering, Sapienza
Universityof Rome; Andrea D'Ambrosio, Sapienza Università di Roma; Fabio Curti, Schoolof Aerospace Engineering, Sapienza University of Rome
To better understand the origin and evolution of our Solar System, the Ice Giants could represent a
coveted destination in future decades. In this work, possible trajectories towards Uranus and Neptune
have been investigated. Using PyKEP and PyGMO, the Multiple Gravity-Assist (MGA) and theMultiple Gravity Assist with One Deep-Space-Maneuver per leg (MGA-1DSM) problems have beensolved. In the simple MGA case, also a powered gravity-assist has been considered. Our analysis
shows that feasible trajectories towards Uranus and Neptune can be obtained with a propellant usage
in term of ∆v the order of 2 km/s.

14:30

AAS Preliminary
MissionDesignfor
Proposed
NuSol
Probe
21-377 Kyle Messick, Wichita State University; Atri Dutta, Wichita State University; Holger Meyer;Mark Christl; Nick Solomey
A solar neutrino detector has never flown in space. NuSolis a proposed mission to fly a solar neutrino
detector close to the Sun in order to carry out unique science objectives that cannot be realized bydetectors on Earth. The paper presents a preliminary trajectory design for the NuSol mission in orderto accomplish the science goals, taking into account specified mission cost constraints, a given launch
window, and an overall mission duration. Numerical simulations are presented to compare different
mission scenarios and to identify a trajectory design that realizes the science goals of the mission.

14:42

AAS Acceleration-Based Indirect Method for Continuous and Impulsive Trajectory Design
21-399 Ehsan Taheri, Auburn University; Vishala Arya, Texas A & M University
A novel acceleration-based formulation is proposed to construct minimum-$\Delta v$ bang-off-bang
thrust profiles and impulsive maneuvers in a rapid manner. Substantial simplifications are achievedby removing mass as one of the states and thrust magnitude and specific impulse value as parametersfrom problem formulation. Standard acceleration-based optimization problems lead to trajectories
whose solution lie entirely on a singular arc. To enforce bang-off-bang controlstructures, a maximum
acceleration parameter is introduced to obtain impulsive solutions. Utility of the method isdemonstrated for transfer maneuvers between orbits in two-body dynamics and in the circular
restricted three-body problem.

14:54

AAS Interplanetary Trajectory Design for a Hybrid Photonic-Electric Propulsion System
21-426 Departingfrom
Cislunar
OrbitsYuki Takao, Japan Aerospace Exploration Agency; Toshihiro Chujo, Tokyo Institute ofTechnology
A hybrid system consisting of solar photonic-electric propulsion for use in deep space exploration isinvestigated. The simultaneous use of photonic and electric propulsion, which is accomplished by asolar sail equipped with thin-film solar cells, enhances the thrust performance of a space probe.
Making use of each propulsion system depending on the sun distance can cover a wide area in deep
space, which in turn extends the possible regions to be explored. In this study, assuminginterplanetary missions departing from an exploration base on cislunar orbits, a trajectory design
method for the hybrid propulsion system is presented.

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31st AAS/AIAA Space Flight Mechanics Meeting

Feb 3, 2021Virtual Room #2
27 - Guidance and Control
Chair: Atri Dutta, Wichita State University
13:30

AAS Autonomous Spacecraft Obstacle Avoidance and Trajectory Tracking in a Dense
21-208 Debris
Field
Madhur Tiwari, Embry-Riddle Aeronautical University; David Zuehlke, Embry-Riddle
Aeronautical University; Richard Prazenica, Embry-Riddle Aeronautical University ; Troy
Henderson, Embry-Riddle Aeronautical University
An autonomous path planning technique using artificial potential functions paired with a direct
adaptive controller is implemented for spacecraft trajectory tracking through a dense debris field.
The debris field is modeled using relative orbital dynamics with disturbances and the spacecraft ismodeled using two-body nonlinear dynamics and perturbations. The spacecraft is assumed to be inproximity to a dense debris field that it must navigate through to reach a goal destination. A direct
adaptive controller is implemented to track generated trajectories using artificial potential functions
to achieve robust tracking in the presence of model and path uncertainties.

13:42

AAS Class of Optimal Space Guidance Problems solved via Indirect Methods and Physics21-258 Informed
NeuralNetworks
Enrico Schiassi, University of Arizona; Andrea D'Ambrosio, Sapienza Università di Roma;Andrea Scorsoglio, University of Arizona; Roberto Furfaro, The University of Arizona;
Fabio Curti, School of Aerospace Engineering, Sapienza University of RomeIn this work, optimal space guidance control problems are faced using indirect methods and PhysicsInformed Neural Networks (PINNs), whose training is driven by the dynamics equations.
The boundary value problem arising from the Pontryagin Minimum Principle is solved both via
standard PINNs and the Extreme Theory of Functional Connections (X-TFC). With X-TFC, theboundary conditions are analytically satisfied thanks to the so-called Constrained Expressions,introduced with the original Theory of Functional Connections (TFC). These expressions are a sumof a free-function, expanded as a neural network trained via Extreme Learning Machine, and afunctional that analytically satisfies the boundary constraints.

13:54

AAS Physics-Informed Neural Networks Appliedto a Series of Constrained Space Guidance
21-259 Problems
Andrea D'Ambrosio, Sapienza Università di Roma; Enrico Schiassi, University of Arizona;
Roberto Furfaro, The Universityof Arizona; Fabio Curti, School of Aerospace Engineering,
Sapienza University of Rome
Extreme Theory of Functional Connections (X-TFC) is exploited to solve constrained optimal
control problems (COCP) via indirect method. The latent solutions are approximated using the socalled Constrained Expressions, which are the sum of a free-chosen function, represented by a single
layer neural network trained via Extreme Learning Machine, and a functional that analyticallysatisfies the boundary conditions. Moreover, inequality constraints are considered and the COCP istransformed into an unconstrained optimal controlproblem introducing new variables and employing
saturation functions. X-TFC is then used to solve the related boundary value problem. Results show
great accuracy and low computational time.

Page 63

31st AAS/AIAA Space Flight Mechanics Meeting14:06

AAS REACTIONWHEEL
VIBRATIONALJITTER
META-ANALYSIS:
21-386 INTEGRATIVEINSIGHTSVIASTATISTICAL
CORRELATIONSMartin Hasha, Lockheed Martin Space Company
Reaction Wheel Assemblies (RWAs) are crucial to achieve stringent spacecraft Line-of-Sight (LOS)
fine-pointing limits. Induced Vibrations (IVs) are judiciously allocated to contain deleterious
jitter: handicapped when lacking sufficient statistically-significant data. An IV meta-analysis isundertaken via same-family dataset mining. Directionality, harmonics, and source diagnostics utilizebivariate correlations (Pearson’s coefficients). Multiple key parameters are enlisted to discoverpreviously unknown/unresolved relationships. Proven optimization methodologies, data results,
issues, and conclusions are presented. Prior findings are expanded to extend to current/future RWAs.
Data aggregations and insights are valuable for wide-ranging spacecraft applications: e.g. steering
mirrors, cryocoolers, moving antenna, microgravity platforms, planetary flybys, etc.

14:18

AAS Precision Attitude
Stabilization
withIntermittent
External
Torque21-402 Arjun Ram Subramani Purushothaman, The University of Texas at Austin; Maruthi R.
Akella, The University of Texas at Austin
The attitude stabilization of a microsatellite employing a variable-amplitude cold-gas thruster whichreflects as a time varying gain on the controlinput is considered. Existing literature uses a persistence
filter based approach that typically leads to large control gains and torque inputs during specific timeintervals corresponding to the "off" phase of the external actuation. This work aims at reducing thetransient spikes placed upon the torque commands by the judicious introduction of an additional timevarying scaling factor as part of the control law.

14:42

AAS Perceptron Based Orbital Guidance in a Low Gravity Asteroid Environment
21-441 Leonard Vance, University of ArizonaFeb 3, 2021Virtual Room #3
28 - Dynamical System Theory II
Chair: Amanda Haapala , Johns Hopkins University Applied Physics Laboratory
13:30

AAS Global
L2
Quasi-Halo
Familyand
theirCharacteristics
21-212 David Lujan, University of Colorado Boulder; Daniel Scheeres, University of Colorado
Boulder
A preexisting algorithm for computing quasi-periodic orbits called GMOS is used to explore theboundaries of the L2 quasi-halo family in the Earth-Moon system. An algorithm is developed to
explore the family utilizing one-dimensional straight line continuation in frequency space. This work
provides insight into the family's boundaries and characteristics, including their frequencies, Jacobi
energies, perilunes, and apolunes. The affects of resonances between the frequencies of quasiperiodic orbits is clearly observed, highlighting their importance when computing these class oforbits. A method for obtaining canonical family tangent vectors and continuing families of quasiperiodic orbits along lines of constant slopes in frequency space isPage 64

31st AAS/AIAA Space Flight Mechanics Meeting13:42AAS A Rapid Method For Orbital Coverage Statistics With J2 Using Ergodic Theory
21-222 Andrew Graven, Cornell University; Alan Barr, Department of Computing andMathematical Sciences, California Institute of Technology; Martin Wen-Yu Lo, Jet
Propulsion Laboratory
Quantifying long-term statistical properties of satellite trajectories typically entails time-consuming
trajectory propagation. We present a fast, ergodic method of analytically estimating these for J2perturbed elliptical orbits, broadly agreeing with trajectory propagation-derived results. We extend
the approach in Graven and Lo (2019) to estimate: (1) Satellite-ground station coverage with limited
satellite field of view and ground station elevation angle with numerically optimized formulae, and(2) long-term averages of general functions of satellite position. This method is fast enough tofacilitate real-time, interactive tools for satellite constellation and network design, with anapproximate 1000x GPU speedup.

13:54

AAS Low-Energy Transfers between Planar and Spatial Periodic Orbits via Vertical
21-244 Instability
aroundEarth-Moon
L1
Kenta Oshima, Hiroshima Institute of Technology
This paper presents a method of designing low-energy transfers changing the out-of-plane amplitude
substantially around a libration point L1 via the vertical instability of planar Lyapunov orbits in the
Earth-Moon circular restricted three-body problem. A sequence of optimizations onto short-term
stable manifolds associated with the weak vertical instability emanating from planar Lyapunov orbits
generates multi-revolutional, low-energy trajectories reaching substantial out-of-plane amplitudes
against the stronger horizontal instability. As applications, the trajectories are used to computetransfers between planar Lyapunov orbits and three-dimensional vertical Lyapunov and halo orbits
with wide ranges of time-of-flight and delta-v.

14:18

AAS Quasi-periodic
Orbit
Transfers
Via
Intersecting
Torus
Whiskers
21-256 Damennick Henry, University of Colorado at Boulder; Daniel Scheeres, University ofColorado Boulder
The ability to transfer between orbits is a necessary component of many space missions. Transfers
between the most abundant type of orbit, quasi-periodic orbits (QPOs), remain largely
unstudied. This paper presents a methodology for transferring between hyperbolic QPOs bycomputing position intersections between their invariant manifolds. Fundamental to themethodology is the treatment of QPOs as quasi-periodic tori and the manifolds as the associatedwhiskers. The approach is general and can be applied to a wide variety of dynamicalsystems. Numerical examples are given in the circular restricted three body problem model of the
Earth-Moon system.

14:30

AAS CubeSat
Lunar Transfer Design via
Weak Stability Boundaries
21-265 Danny Owen, University College London; Xiaoyu Fu, University of Surrey; Nicola Baresi,
University of Surrey
CubeSat ride-share opportunities to lunar transfer orbit are becoming increasingly common. Low
propellant budgets mean many of these CubeSats would benefit from low-energy trajectories. Designof such trajectories can be computationally intensive. We propose an investigation into patterns oforbital parameters mapped to the Moon B-plane that allow for low-energy lunar trajectory design
for CubeSats that are initially placed into a free-return trajectory as secondary payloads. This will

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31st AAS/AIAA Space Flight Mechanics Meetingresult in tools to make such trajectory design quicker and easier. This is achieved via a grid searchmethod in which forward and backward propagated trajectories are paired at a mutual patching point.

Feb 3, 2021Virtual Room #4
29 - Space Robotics and Autonomous Operation
Chair: Jay McMahon, University of Colorado Boulder
13:30

AAS A Unique Robotic Manipulator for Application in Hardware-In-The-Loop Simulations
21-213 ofOn-Orbit
Servicing
Missions
Anirudh Chhabra, University of Cincinnati; Donghoon Kim, University of Cincinnati
Autonomous on-orbit servicing missions require high precision because any unwanted contact forces
can cause damage to space systems. This makes the on-ground hardware-in-the-loop simulations
necessary as operations must be thoroughly evaluated before such missions are carried out in space.
A unique robotic structure is proposed where a robotic arm is linked with a Stewart platform.
Mathematical models are developed for systems with different robotic arms having varying degrees
of freedom and the corresponding dynamics are formulated. Simulation studies are conducted for
capturing scaled-down orbitaltrajectories by using an optimal controlscheme and identify the systemwith desired range and accuracy.

13:42

of
Spacecraft
Deployables
FailuresAAS Study
21-224 Alejandro Rivera, NASA Goddard Space Flight Center
Unsuccessful deployments of solar arrays, antennas and other spacecraft deployable appendages are
one of the main causes of initial satellite failures and reduction in their capabilities withapproximately one failure every two years, which result in extremely large insurance claims. This
paper examines publically known spacecraft deployables failures and anomalies that have occurredsince 1968 on a total of 40 different spacecraft, and that can be directly attributed to deployment
issues. Information is used to build a case for a robotic servicing mission. Concepts for three possible
robotic tools and the novel technologies they employ are then briefly described.

13:54

AAS Genetic Fuzzy System-Based Multi-Robot Coordination for Planetary Missions
21-238 Daegyun Choi, University of Cincinnati; Donghoon Kim, University of Cincinnati
In the planet exploration missions, experimental devices without mobility may require relocating toperform further missions. To transport objects like experimental devices, a multi-robot system(MRS) has become popular in recent decades due to its benefits. In this research, an object
transportation problem with an MRS is dealt with by using a fuzzy inference system in the mannerof decentralized control. The parameters of membership functions and the rule-base are trained by agenetic algorithm with various training scenarios to find the best fit solution, and the trained fuzzy
inference system is validated by using several testing scenarios.

14:06

AAS COLLISION AVOIDANCE AND FORMATION FLYING FOR NASA ASTROBEE
21-382 ROBOTS USING PREDICTIVE CONTROL AND MACHINE LEARNI NG

Page 66

31st AAS/AIAA Space Flight Mechanics MeetingIsuru Basnayake, New Maxico State University; Hyeongjun Park, New Mexico State
University
Using multiple NASA Astrobee robots in a confined space such as the International Space Station(ISS) increases the chance of a collision. This requires employing a formation control and collision
avoidance framework for the three Astrobees operating in the ISS. Model predictive control (MPC)would be the best candidate for this task. However, machine learning techniques can be utilized toreduce the online computation burden of MPC. In this paper, we develop a control framework basedon nonlinear MPC with improved for efficient online control by employing machine learningtechniques, for the formation control and collision avoidance of the Astrobees in ISS.

14:18

AAS Safe and Uncertainty-Aware Robotic Motion Planning Techniques for Agile On-Orbit
21-421 Assembly
Bryce Doerr, Massachusetts Institute of Technology; Keenan Albee, Massachusetts Instituteof Technology; Monica Ekal, Instituto Superior Técnico; Richard Linares, Massachusetts
Institute of Technology; Rodrigo Ventura, Instituto Superior Técnico, University of Lisbon
As access to space and robotic autonomy capabilities move forward, there is simultaneously agrowing interest in deploying large, complex space structures to provide new on-orbit capabilities.
New space-borne observatories, large orbital outposts, and even futuristic on-orbit manufacturing
will be enabled by robotic assembly of space structures using techniques like on-orbit additive
manufacturing which can provide flexibility in constructing and even repairing complex hardware.
The contribution of this work is to address both the motion planning and controlfor robotic assemblywith consideration of the inertial estimation of the combined robotic assembler and additively
manufactured component system.

14:30

AAS Catalyst: A Platform for Autonomous Tactical Multi-Spacecraft Aggregation
21-446 Jekan Thangavelautham, University of Arizona

14:42

AAS MAXIMIZING DUST DEVIL FOLLOW-UP OBSERVATIONS ON MARS USING
21-449 CUBESATS
AND
ON-BOARDSCHEDULI NG
Robyn Woollands, University of Illinois at Urbana-Champaign; Federico Rossi, Jet
Propulsion Laboratory, California Institute of Technology; Tiago Stegun Vaquero, Jet
Propulsion Laboratory, California Institute of Technology; Marc Sanchez Net, Jet
Propulsion Laboratory, California Institute of Technology; Suyun Bae, Jet Propulsion
Laboratory, California Institute of Technology; Joshua Vander Hook, Jet Propulsion
Laboratory, California Institute of Technology
Several million dust devil events occur on Mars every day. These events last about 30 minutes andrange in size from meters to hundreds of meters in diameter. Designing low-cost missions that will
improve our knowledge of dust devil formation and evolution is fundamental to informing futurecrewed Mars lander missions about surface conditions. In this paper we present a mission design
methodology for a constellation of low orbiting Mars cubesats, each carrying imagers with agile
pointing capabilities. The goal is to maximize the number of dust devil follow-up observations
through real-time, on-board scheduling.

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31st AAS/AIAA Space Flight Mechanics Meeting14:54

AAS FemtoSats for Exploring Permanently Shadowed
21-447 Jekan Thangavelautham, University of Arizona

Regions on

the Moon

Feb 3, 2021Virtual Room #5
30 - Multi Object Tracking
Chair: Richard Linares, Massachusetts Institute of Technology
13:30

AAS Space
Object Tracking at the Purdue
Optical Ground
Station21-236 Patrick Kelly, Texas A&M University; Carolin Frueh, Purdue University
The resident space object population in the near-Earth vicinity has steadily increased since the dawnof the space age. The resultant congestion in near-Earth space necessitates the availability of more
complete and more accurate satellite tracking information to ensure the continued sustainable use ofthis environment. This paper outlines the development of an operational system for the delivery ofaccurate satellite tracking information by means of optical observation conducted at the Purdue
Optical Ground Station (POGS). The capability of this system is demonstrated using observations of
the Wide Area Augmentation System (WASS) satellites, for which independent ephemeris
information is obtained.

13:42

AAS Joint Probabilistic Data Association Filter Using Alternate Equinoctial Orbital
21-339 Elements
John Helmuth, Texas A&M University; Kyle DeMars, Texas A&M University
Space surveillance is a challenging problem, which grows more difficult with each new object inorbit. Loss of satellite custody can lead to dangerous consequences such as collisions resulting in
destruction of expensive resources and a dramatic increase in debris. This paper merges the joint
probabilistic data association filter with alternate equinoctial orbital elements to create an improved
framework for space object tracking and comparesthe approach to a JPDAfilter with Cartesian statesin numerical experiments.

14:06

AAS Autonomous Spacecraft Tasking using Monte Carlo Tree Search Methods
21-228 Adam Herrmann, University of Colorado, Boulder; Hanspeter Schaub, University ofColoradoThis work explores the use of Monte Carlo tree search (MCTS) methods as a form of value iteration
to solve the Earth-observing satellite scheduling problem, expanding on prior work by comparing
neural network regression over MCTS state-action pairs to a variation of AlphaZero, which
continually improves upon the value network by executing it as the rollout policy in MCTS. An indepth hyperparameter search is conducted for both algorithms, which are compared on the basis ofperformance, safety, and downlink opportunity utilization. Furthermore, each trained network is
executed in a stochastic version of the Earth-observing satellite environment to measure robustness
to uncertainty.

Page 68

31st AAS/AIAA Space Flight Mechanics Meeting14:18AAS Autonomous Satellite Detection and Tracking using
OpticalFlow
21-364 David Zuehlke, Embry-Riddle Aeronautical University; Daniel Posada, Embry-Riddle
Aeronautical University; Madhur Tiwari, Embry-Riddle Aeronautical University; Troy
Henderson, Embry-Riddle Aeronautical University
In this paper, an autonomous method of satellite detection and tracking in images is implemented
using optical flow. Optical flow is used to estimate the image velocities of detected objects in a seriesof space images. Given that most objects in an image will be stars, the overall image velocity fromstar motion is used to estimate the image frame-to-frame motion. Objects seen to be moving withvelocity profiles distinct from the overall image velocity are then classified as potential resident space
objects. The detection algorithm is exercised using both simulated star images and ground-based
imagery of satellites.

14:30

AAS APPLICATIONS OF A MCMC SAMPLING AND CLUSTERING METHODS
21-427 BASED RANDOMIZED-FINITE SET STATISTICS TECHNIQUE (R-FISST II)
Utkarsh Mishra, Texas A&M University; Suman Chakravorty, Texas A&M University;
Weston Faber, Applied Defense Solutions; Islam Hussein, Thornton TomasettiThis paper presents a novel approach to keeping the Random Finite Set (RFS)based Bayesianrecursions tractable. We propose a randomized scheme using aMetropolis-Hastings, Markov Chain
Monte Carlo (MCMC), based technique and Finite Set Statistics (FISST), termed Randomized FISSTII (R-FISST II). This technique samples highly probable target-observation association hypotheses
and uses them to approximate the posterior RFS based multi-object Probability Den-sity Function(PDF). Finally, we demonstrate the performances of this tracker for a multiple space object tracking
problem with heavy clutter. We compare and contrast this method with a Multi target tracking
method based on Murthy's K-best assignment algorithm.

14:42

AAS Orbit Determination Using the Probability Hypothesis Density Filter and Alternate
21-271 Equinoctial
OrbitalElements
James Brouk, Texas A &M University; Kyle DeMars, Texas A&M University
Accurate and efficient orbit determination is imperative to effective utilization of the near-Earthenvironment. This paper formulates the Gaussian mixture probability hypothesis density (GM-PHD)
filter using alternate equinoctial orbital elements (AEOEs). The GM-PHD filter, born of random
finite set statistics, allows greater flexibility than the extended Kalman filter (EKF). AEOEs are a setof coordinates strategically chosen to produce an efficient parameterization for estimation purposes.
The proposed filter is tested through Monte Carlo simulation and analysis, examining the effects ofreduced inter-object spacing on filter performance in comparison to an EKF using joint probabilistic
data association in Cartesian coordinates.

Page 69

31st AAS/AIAA Space Flight Mechanics Meeting

Authors(Parrish) Ré, Nathan 14 - Cislunar Space Situational Awareness
Abell, Jordan 23 - Guidance, Navigation, and Control
Adams, Richard 17 - Spacecraft Control II
Adkins, Nathaneal 20 - Space Robotics and Autonomous Operation & Lunar
Agboola, Olufemi 03 - Rendezvous , 22 - Formation Flying
Agostinelli, Ivan 17 - Spacecraft Control II
Ahmed, Nisar 10 - Artificial Intelligence in Astrodynamics
Ahmed, Razi 04 - Satellite Formations & Collision Avoidance
Akella, Maruthi R. 18 - Space Object Characterization and Independent Attitude Determination , 23 Guidance, Navigation, and Control , 27 - Guidance and Control
Albee, Keenan 29 - Space Robotics and Autonomous Operation
Alfriend, Kyle T. 15 Dynamical System Theory I , 22 - Formation Flying , 25 - Orbital Dynamics,
perturbations and Stability
Alper Ramaswamy, Emine Basak 12 - Trajectory Design I
Amato, Davide 09 - Atmospheric Reentry Guidance and Control
Anderson, Rodney L. 15 Dynamical System Theory I
Armellin, Roberto 04 - Satellite Formations & Collision Avoidance , 12 - Trajectory Design I
Arnas, David 04 - Satellite Formations & Collision Avoidance , 25 - Orbital Dynamics, perturbations andStability
Arya, Vishala 21 - Trajectory Optimization , 26 - Trajectory Design III
Austin, Alex 26 - Trajectory Design III
Badura, Gregory 18 - Space Object Characterization and Independent Attitude Determination
Bae, Suyun 29 - Space Robotics and Autonomous Operation
Balasubramanian, Karthic 17 - Spacecraft Control II
Bando, Mai 01 - Interplanetary Trajectories , 06 - Low Thrust Trajectories I , 21 - Trajectory Optimization
Bandyopadhyay, Saptarshi 18 - Space Object Characterization and Independent Attitude Determination
Bang, Hyochoong 06 - Low Thrust Trajectories I
Baresi, Nicola 12 - Trajectory Design I , 25 - Orbital Dynamics, perturbations and Stability , 26 - Trajectory
Design III , 28 - Dynamical System Theory II
Barr, Alan 28 - Dynamical System Theory II
Bartram, Peter 25 - Orbital Dynamics, perturbations and Stability
Basnayake, Isuru 29 - Space Robotics and Autonomous Operation
Batista Negri, Rodolfo 17 - Spacecraft Control II
Bayard, David 18 - Space Object Characterization and Independent Attitude Determination
Belmonte Hernandez, Carlos 04 - Satellite Formations & Collision Avoidance
Benayas Penas, Miguel 26 - Trajectory Design III
Bernardinin, Nicolò 12 - Trajectory Design I
Bernstein, Valerie 02 - Debris Clouds, Debris Densities, and Space Environment
Bhaskaran, Shyam 18 - Space Object Characterization and Independent Attitude Determination
Bhattacharjee, Diganta 09 - Atmospheric Reentry Guidance and Control , 24 - Orbit Determination
Bishop, Brian 12 - Trajectory Design I
Black, Kevin 18 - Space Object Characterization and Independent Attitude Determination
Blanchard, Jared 12 - Trajectory Design I
Blazquez, Emmanuel 01 - Interplanetary Trajectories , 11 - Low Thrust Trajectories II
Bolliger, Matthew 14 - Cislunar Space Situational Awareness , 20 - Space Robotics and Autonomous
Operation & Lunar
Bonasera, Stefano 10 - Artificial Intelligence in Astrodynamics
Boone, Spencer 21 - Trajectory Optimization
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31st AAS/AIAA Space Flight Mechanics MeetingBosanac, Natasha 10 - Artificial Intelligence in Astrodynamics , 22 - Formation Flying
Botta, Eleonora 20 - Space Robotics and Autonomous Operation & Lunar
Boudad, Kenza 25 - Orbital Dynamics, perturbations and Stability
Bourabah, Derek 20 - Space Robotics and Autonomous Operation & Lunar
Bridges, Christopher 12 - Trajectory Design I
Brouk, James 30 - Multi Object Tracking
Bucchioni, Giordana 03 - Rendezvous
Butcher, Eric 13 - Spacecraft Control I
Cain, Charles 20 - Space Robotics and Autonomous Operation & Lunar
Campagnola, Stefano 16 - Trajectory Design II , 26 - Trajectory Design III
Canales Garcia, David 12 - Trajectory Design I
Canalias, Elisabet 01 - Interplanetary Trajectories
Carbone, Andrea 23 - Guidance, Navigation, and Control
Carrillo, Hans 10 - Artificial Intelligence in Astrodynamics
Casalino, Lorenzo 16 - Trajectory Design II
Caverly, Ryan 19 - Asteroids II & Mars
Cazabonne, Bryan 24 - Orbit Determination
Cefola, Paul J. 06 - Low Thrust Trajectories I , 24 - Orbit Determination , 25 - Orbital Dynamics,
perturbations and Stability
Ceriotti, Matteo 05 - Asteroids I
Chakravorty, Suman 30 - Multi Object Tracking
Chan, Ken 02 - Debris Clouds, Debris Densities, and Space Environment , 04 - Satellite Formations &Collision Avoidance
Charkoutsis, Stefanos 01 - Interplanetary Trajectories
Chen, Jingyi 08 - Navigation
Chevailler, Colas 01 - Interplanetary Trajectories
Chhabra, Anirudh 29 - Space Robotics and Autonomous Operation
Chikazawa, Takuya 26 - Trajectory Design III
Chikine, Sai 20 - Space Robotics and Autonomous Operation & Lunar
Cho, Hancheol 17 - Spacecraft Control II
Choi, Daegyun 29 - Space Robotics and Autonomous Operation
Chowdhury, Mizanul 04 - Satellite Formations & Collision Avoidance
Christensen, Randall 20 - Space Robotics and Autonomous Operation & Lunar
Christian, John 20 - Space Robotics and Autonomous Operation & Lunar
Christl, Mark 26 - Trajectory Design III
Chujo, Toshihiro 15 Dynamical System Theory I , 26 - Trajectory Design III
Chung, Soon-Jo 04 - Satellite Formations & Collision Avoidance
Ciarcia, Marco 13 - Spacecraft Control I
Cihan, Ibrahim Halil 09 - Atmospheric Reentry Guidance and Control
Circi, Christian 21 - Trajectory Optimization
Clark, Fred 23 - Guidance, Navigation, and Control
Cobb, Richard 12 - Trajectory Design I
Colombo, Camilla 11 - Low Thrust Trajectories II , 26 - Trajectory Design III
Condurache, Daniel 15 Dynamical System Theory I
Conforti, Gabriele 17 - Spacecraft Control II
Contreras, Mario 04 - Satellite Formations & Collision Avoidance
Cowan, Kevin 26 - Trajectory Design III
Curti, Fabio 10 - Artificial Intelligence in Astrodynamics , 17 - Spacecraft Control II , 23 - Guidance,
Navigation, and Control , 26 - Trajectory Design III , 27 - Guidance and Control
D'Ambrosio, Andrea 10 - Artificial Intelligence in Astrodynamics , 17 - Spacecraft Control II , 23 - Guidance,
Navigation, and Control , 26 - Trajectory Design III , 27 - Guidance and Control
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31st AAS/AIAA Space Flight Mechanics MeetingD'Amico, Simone 03 - Rendezvous , 19 - Asteroids II & Mars , 24 - Orbit Determination
D'Onofrio, Fabio 03 - Rendezvous
Danas Rivera, Kalani 08 - Navigation
Davis, Byron 24 - Orbit Determination
Davis, Diane 14 - Cislunar Space Situational Awareness , 16 - Trajectory Design II , 25 - Orbital Dynamics,
perturbations and Stability
Davis, Jill 10 - Artificial Intelligence in Astrodynamics
De Grossi, Federico 21 - Trajectory Optimizationde la Llave, Rafael 15 Dynamical System Theory I
Dei Tos, Diogene Alessandro 21 - Trajectory Optimization , 25 - Orbital Dynamics, perturbations andStability , 26 - Trajectory Design III
Deleflie, Florent 25 - Orbital Dynamics, perturbations and Stability
DeMars, Kyle 08 - Navigation , 14 - Cislunar Space Situational Awareness , 30 - Multi Object Tracking
Dennison, Kaitlin 19 - Asteroids II & Mars
Deshmukh, Rohan 09 - Atmospheric Reentry Guidance and Control
Deutsch, Jacob 18 - Space Object Characterization and Independent Attitude Determination
Devore, Michael 17 - Spacecraft Control II
Dhir, Abhimanyu 18 - Space Object Characterization and Independent Attitude Determination
Di Lizia, Pierluigi 05 - Asteroids I
Doerr, Bryce 29 - Space Robotics and Autonomous Operation
Dong, Qiao 22 - Formation Flying
Dutta, Atri 07 - Attitude Dynamics and Control , 10 - Artificial Intelligence in Astrodynamics , 26 Trajectory Design III
Dutta, Soumyo 09 - Atmospheric Reentry Guidance and Control
Dutta, Soumyo 09 - Atmospheric Reentry Guidance and Control
Eapen, Roshan Thomas 15 Dynamical System Theory I
Ekal, Monica 29 - Space Robotics and Autonomous Operation
Elliott, Ian 10 - Artificial Intelligence in Astrodynamics , 22 - Formation Flying
Ellison, Donald 06 - Low Thrust Trajectories I , 12 - Trajectory Design I , 26 - Trajectory Design III
Engel, Daniel 09 - Atmospheric Reentry Guidance and Control
Faber, Weston 30 - Multi Object Tracking
Fang, Liping 28 - Dynamical System Theory II
Farabi, Tanzimul 10 - Artificial Intelligence in Astrodynamics
Fedeler, Sam 24 - Orbit Determination
Fitzgerald, Joshua 15 Dynamical System Theory I
Folcik, Zachary 06 - Low Thrust Trajectories I
Folta, David 06 - Low Thrust Trajectories I
Fonseka, Daniel 18 - Space Object Characterization and Independent Attitude Determination
Foo, Yang 21 - Trajectory Optimization
Fossà, Alberto 11 - Low Thrust Trajectories II
Fowler, Erin 14 - Cislunar Space Situational AwarenessFritsch, Gunner 08 - Navigation
Frueh, Carolin 14 - Cislunar Space Situational Awareness , 30 - Multi Object Tracking
Fu, Xiaoyu 12 - Trajectory Design I , 28 - Dynamical System Theory II
Fujiwara, Kotaro 01 - Interplanetary Trajectories
Fujiwara, Masahiro 19 - Asteroids II & Mars
Funase, Ryu 19 - Asteroids II & Mars
Furfaro, Roberto 10 - Artificial Intelligence in Astrodynamics , 17 - Spacecraft Control II , 24 - Orbit
Determination , 27 - Guidance and Control
Furutachi, Kyuto 16 - Trajectory Design II
Gao, Yang 12 - Trajectory Design I
Page 72

31st AAS/AIAA Space Flight Mechanics MeetingGarcia, Axel 06 - Low Thrust Trajectories I
Ghilardi, Luca 10 - Artificial Intelligence in Astrodynamics
Givens, Matthew 20 - Space Robotics and Autonomous Operation & Lunar
Gondelach, David 06 - Low Thrust Trajectories I
Gonzalez-Franquesa, Ferran 19 - Asteroids II & Mars
Graven, Andrew 28 - Dynamical System Theory II
Gunter, Brian 18 - Space Object Characterization and Independent Attitude Determination , 24 - Orbit
Determination
Gupta, Maaninee 12 - Trajectory Design I
Gutkowski, Jeffrey 16 - Trajectory Design II
Guzzetti, Davide 20 - Space Robotics and Autonomous Operation & Lunar
Halpin, Blake 02 - Debris Clouds, Debris Densities, and Space Environment
Halverson, Robert 19 - Asteroids II & Mars
Han, Hongwei 22 - Formation Flying
Hansen, Brian 02 - Debris Clouds, Debris Densities, and Space Environment
Hartzell, Christine 06 - Low Thrust Trajectories I , 12 - Trajectory Design I
Hasha, Martin 23 - Guidance, Navigation, and Control , 27 - Guidance and Control
Hays, Christopher 04 - Satellite Formations & Collision Avoidance
Healy, Liam 02 - Debris Clouds, Debris Densities, and Space Environment
Helmuth, John 30 - Multi Object Tracking
Henderson, Troy 04 - Satellite Formations & Collision Avoidance , 27 - Guidance and Control , 30 - Multi
Object Tracking
Hennessey Rose, Brendan 03 - Rendezvous
Henry, Damennick 28 - Dynamical System Theory II
Hernandez, Sonia 12 - Trajectory Design I , 15 Dynamical System Theory I
Herrmann, Adam 30 - Multi Object Tracking
Hidaka, Moeko 03 - Rendezvous
Ho, Koki 10 - Artificial Intelligence in Astrodynamics
Hobbs, Kerianne 03 - Rendezvous
Hockman, Benjamin 18 - Space Object Characterization and Independent Attitude Determination
Hofmann, Christian 06 - Low Thrust Trajectories I
Hokamoto, Shinji 01 - Interplanetary Trajectories , 06 - Low Thrust Trajectories I
Holt, Harry 12 - Trajectory Design I
Holzinger, Marcus 18 - Space Object Characterization and Independent Attitude Determination , 24 - Orbit
Determination
Hoskins, Patric 02 - Debris Clouds, Debris Densities, and Space Environment
Hou, Linyi 24 - Orbit Determination
Howell, Kathleen C. 06 - Low Thrust Trajectories I , 12 - Trajectory Design I , 14 - Cislunar Space
Situational Awareness , 15 Dynamical System Theory I , 16 - Trajectory Design II , 23 - Guidance,
Navigation, and Control , 25 - Orbital Dynamics, perturbations and Stability
Hu, Quan 20 - Space Robotics and Autonomous Operation & Lunar , 28 - Dynamical System Theory II
Hughes, Kyle 26 - Trajectory Design III
Hurtt, Stella 14 - Cislunar Space Situational Awareness
Hussein, Islam 30 - Multi Object Tracking
Ikeda, Hitoshi 21 - Trajectory Optimization
Indaco, Manuel 20 - Space Robotics and Autonomous Operation & Lunar
Innocenti, Mario 03 - Rendezvous
Ismail, Ayman 13 - Spacecraft Control I
Ito, Daichi 01 - Interplanetary Trajectories
Iyota, Takatoshi 08 - Navigation
Jawaharlal Ayyanathan, Praveen 11 - Low Thrust Trajectories II
Page 73

31st AAS/AIAA Space Flight Mechanics MeetingJenkins, Scott 08 - Navigation
Jeon, Soobin 17 - Spacecraft Control II
Jewison, Christopher 06 - Low Thrust Trajectories I
Johnston, Hunter 12 - Trajectory Design I
Jones, Brandon 07 - Attitude Dynamics and Control
Juang, Jer-Nan 13 - Spacecraft Control I
Junfeng, Li 05 - Asteroids I
Junkins, John L. 21 - Trajectory Optimization
Kakihara, Kota 26 - Trajectory Design III
Karpenko, Mark 07 - Attitude Dynamics and Control
Kashioka, Shuya 08 - Navigation
Kawabata, Yosuke 26 - Trajectory Design III
Kawaguchi, Junichiro 25 - Orbital Dynamics, perturbations and Stability
Kawakatsu, Yasuhiro 01 - Interplanetary Trajectories , 19 - Asteroids II & Mars , 21 - Trajectory
Optimization , 26 - Trajectory Design III
Kayama, Yuki 06 - Low Thrust Trajectories I
Kelly, Patrick 30 - Multi Object Tracking
Kim, Donghoon 29 - Space Robotics and Autonomous Operation
Kindl, Scott 02 - Debris Clouds, Debris Densities, and Space Environment
Kinzie, Ryan 13 - Spacecraft Control I
Kluever, Craig 09 - Atmospheric Reentry Guidance and Control
Kobylka, Kevin 20 - Space Robotics and Autonomous Operation & Lunar
Kruzelecky, Roman 12 - Trajectory Design I
Kuettel, Donald 06 - Low Thrust Trajectories I
Kumar, Bhanu 15 Dynamical System Theory I
Kumar, Mrinal 04 - Satellite Formations & Collision Avoidance
Kwon, Hyeokjoon 06 - Low Thrust Trajectories I
LaFarge, Nicholas 06 - Low Thrust Trajectories I
Laipert, Frank 12 - Trajectory Design I
Landau, Damon 01 - Interplanetary Trajectories
Lang, Kendra 03 - Rendezvous
Lavelle, Marco 04 - Satellite Formations & Collision AvoidanceLavezzi, Giovanni 13 - Spacecraft Control I
Lewis , Alexander 17 - Spacecraft Control II
Li, Ziwen 05 - Asteroids I
Licata, Richard 02 - Debris Clouds, Debris Densities, and Space Environment
Linares, Richard 01 - Interplanetary Trajectories , 04 - Satellite Formations & Collision Avoidance , 06 - Low
Thrust Trajectories I , 25 - Orbital Dynamics, perturbations and Stability , 29 - Space Robotics andAutonomous Operation
Little, Bryan 14 - Cislunar Space Situational AwarenessLiu, Shuo 13 - Spacecraft Control I
Lizy-Destrez, Stéphanie 01 - Interplanetary Trajectories , 11 - Low Thrust Trajectories II
Lo, Martin Wen-Yu 12 - Trajectory Design I , 28 - Dynamical System Theory II
Lohan, Kevin 24 - Orbit Determination
Long, Ryan 20 - Space Robotics and Autonomous Operation & Lunar
Longman, Richard 13 - Spacecraft Control I
López, Rosario 10 - Artificial Intelligence in Astrodynamics , 25 - Orbital Dynamics, perturbations andStability
Lozano, Paulo 01 - Interplanetary Trajectories
Lu, Ping 17 - Spacecraft Control II
Lubey, Daniel 18 - Space Object Characterization and Independent Attitude Determination
Page 74

31st AAS/AIAA Space Flight Mechanics MeetingLucca Fabris, Andrea 12 - Trajectory Design I
Lujan, David 28 - Dynamical System Theory II
Luo, Qiming 20 - Space Robotics and Autonomous Operation & Lunar
Maestrini, Michele 05 - Asteroids I
Mailen, Russell 20 - Space Robotics and Autonomous Operation & Lunar
Majji, Manoranjan 04 - Satellite Formations & Collision Avoidance
Malik, Aryslan 04 - Satellite Formations & Collision Avoidance
Manchester, Zachary 11 - Low Thrust Trajectories II
Marcus, Corey 23 - Guidance, Navigation, and Control
Marmo, Nicola 21 - Trajectory Optimization
Martin, John 10 - Artificial Intelligence in Astrodynamics
Martínez Chamarro, Álvaro 04 - Satellite Formations & Collision AvoidanceMartinusi, Vladimir 15 Dynamical System Theory I
Masat, Alessandro 26 - Trajectory Design III
Mascolo, Luigi 16 - Trajectory Design II
Massé, Catherine 25 - Orbital Dynamics, perturbations and Stability
Mastrofini, Marco 23 - Guidance, Navigation, and Control
Matsuka, Kai 04 - Satellite Formations & Collision Avoidance
McArdle, Sean 20 - Space Robotics and Autonomous Operation & Lunar
McCarthy, Brian 15 Dynamical System Theory I
McElrath, Tim 15 Dynamical System Theory I
McInnes, Colin 05 - Asteroids I
McMahon, Jay 05 - Asteroids I , 06 - Low Thrust Trajectories I , 08 - Navigation , 09 - Atmospheric Reentry
Guidance and Control , 10 - Artificial Intelligence in Astrodynamics , 20 - Space Robotics and Autonomous
Operation & Lunar , 21 - Trajectory Optimization
McNutt, Ralph 21 - Trajectory Optimization
Mehta, Piyush 02 - Debris Clouds, Debris Densities, and Space Environment
Messick, Kyle 26 - Trajectory Design III
Meyer, Holger 26 - Trajectory Design III
Miceli, Giuliana Elena 16 - Trajectory Design II
Miller, Daniel 01 - Interplanetary Trajectories
Mishra, Utkarsh 30 - Multi Object Tracking
Moghe, Rahul 23 - Guidance, Navigation, and Control
Montalvo, Carlos 17 - Spacecraft Control II
Moore, Iain 05 - Asteroids I
Moore, Jimmy 12 - Trajectory Design I
Moretto, Mark 05 - Asteroids I , 08 - Navigation
Morrell, Benjamin 18 - Space Object Characterization and Independent Attitude Determination
Mortari, Daniele 12 - Trajectory Design I
Murakami, Naomi 03 - Rendezvous
Muralidharan, Vivek 23 - Guidance, Navigation, and Control
Murzionak, Piotr 12 - Trajectory Design I
Nakajima, Yu 03 - Rendezvous
Nakamura, Ryo 03 - Rendezvous
Nesnas, Issa 18 - Space Object Characterization and Independent Attitude Determination
Nixon, Mason 13 - Spacecraft Control I
Nugnes, Marco 11 - Low Thrust Trajectories II
Nurre, Nicholas 11 - Low Thrust Trajectories II
Ogawa, Hideaki 01 - Interplanetary Trajectories , 16 - Trajectory Design II , 21 - Trajectory Optimization
Oghim, Snyoll 06 - Low Thrust Trajectories I
Ogundele, Ayansola 03 - Rendezvous , 22 - Formation Flying
Page 75

31st AAS/AIAA Space Flight Mechanics MeetingOhira, Genki 08 - Navigation
Orr, Jeb 18 - Space Object Characterization and Independent Attitude Determination
Oshima, Kenta 28 - Dynamical System Theory II
Osmundson, Alan 18 - Space Object Characterization and Independent Attitude Determination
Owen, Danny 28 - Dynamical System Theory II
Ozaki, Naoya 19 - Asteroids II & Mars
Padilha, Dan 25 - Orbital Dynamics, perturbations and Stability
Palanisamy, Piruthvi Chendur 17 - Spacecraft Control II
Paley, Derek 14 - Cislunar Space Situational Awareness
Park, Beom 12 - Trajectory Design I
Park, Hyeongjun 17 - Spacecraft Control II , 29 - Space Robotics and Autonomous Operation
Park, Sang-Young 17 - Spacecraft Control II
Parker, Jeff 20 - Space Robotics and Autonomous Operation & Lunar
Parmar, Kanak 20 - Space Robotics and Autonomous Operation & Lunar
Patel, Rohan 12 - Trajectory Design I
Peck, Mason 08 - Navigation
Pérez, Iván 10 - Artificial Intelligence in Astrodynamics , 25 - Orbital Dynamics, perturbations and Stability
Pernicka, Henry 10 - Artificial Intelligence in Astrodynamics
Petersen, Christopher D. 03 - Rendezvous
Peterson, Luke 15 Dynamical System Theory I
Phillips, Sean 03 - Rendezvous
Pilinski, Marcin 02 - Debris Clouds, Debris Densities, and Space Environment
Pogorelsky, Bryan 08 - Navigation
Posada, Daniel 04 - Satellite Formations & Collision Avoidance , 30 - Multi Object Tracking
Power, Rolfe 16 - Trajectory Design II
Prado, Antonio Fernando Bertachini 17 - Spacecraft Control II
Prado Pino, Bonnie 06 - Low Thrust Trajectories I
Prazenica, Richard 27 - Guidance and Control
Proulx, Ronald J. 07 - Attitude Dynamics and Control
Pugliatti, Mattia 05 - Asteroids I , 08 - Navigation
Pushparaj, Nishanth 01 - Interplanetary Trajectories
Putnam, Zachary 09 - Atmospheric Reentry Guidance and Control , 24 - Orbit Determination
R V, Ramanan 01 - Interplanetary Trajectories
Ragan, James 04 - Satellite Formations & Collision
Avoidance Rankin, Kyle 17 - Spacecraft Control II
Ray, Vishal 02 - Debris Clouds, Debris Densities, and Space Environment
Reed, Adam 17 - Spacecraft Control II
Rivera, Alejandro 29 - Space Robotics and Autonomous Operation
Romano, Matteo 26 - Trajectory Design III
Rosengren, Aaron 02 - Debris Clouds, Debris Densities, and Space Environment
Rosenof, Michael 14 - Cislunar Space Situational AwarenessRoss, Shane 15 Dynamical System Theory I
Rossi, Federico 29 - Space Robotics and Autonomous Operation
Roth, Duane 15 Dynamical System Theory I
Rubinsztejn, Ari 12 - Trajectory Design I
Russell, Ryan 11 - Low Thrust Trajectories II
S P, Parvathi 01 - Interplanetary Trajectories
San-Juan, Juan Félix 06 - Low Thrust Trajectories I , 10 - Artificial Intelligence in Astrodynamics , 25 Orbital Dynamics, perturbations and Stability
San-Martín, Montserrat 10 - Artificial Intelligence in Astrodynamics
Sanchez Net, Marc 29 - Space Robotics and Autonomous Operation
Page 76

31st AAS/AIAA Space Flight Mechanics MeetingSarli, Bruno 26 - Trajectory Design III
SASAKI, TAKAHIRO 03 - Rendezvous
Schaub, Hanspeter 10 - Artificial Intelligence in Astrodynamics , 30 - Multi Object Tracking
Scheeres, Daniel 02 - Debris Clouds, Debris Densities, and Space Environment , 15 Dynamical System
Theory I , 28 - Dynamical System Theory II
Schiassi, Enrico 17 - Spacecraft Control II , 27 - Guidance and Control
Schulte, Peter 23 - Guidance, Navigation, and Control
Scorsoglio, Andrea 10 - Artificial Intelligence in Astrodynamics , 17 - Spacecraft Control II , 24 - Orbit
Determination , 27 - Guidance and Control
Segura Alvarado, Edna Viviana 10 - Artificial Intelligence in Astrodynamics
Seker, Ilgin 04 - Satellite Formations & Collision Avoidance
Semblanet, Tom 11 - Low Thrust Trajectories II
Sena, Francesco 26 - Trajectory Design III
Seo, Dongeun 13 - Spacecraft Control I
Servadio, Simone 23 - Guidance, Navigation, and Control
Shankar, Shrivu 18 - Space Object Characterization and Independent Attitude Determination
Shannon, Jackson 06 - Low Thrust Trajectories I , 12 - Trajectory Design I
Sharf, Inna 25 - Orbital Dynamics, perturbations and Stability
Sherman, William 17 - Spacecraft Control II
Shimane, Yuri 16 - Trajectory Design II
Shin-ichiro, Sakai 07 - Attitude Dynamics and Control
Shoffeitt, Brian 18 - Space Object Characterization and Independent Attitude Determination
Showalter, Daniel 03 - Rendezvous
Shtessel, Yuri 13 - Spacecraft Control I
Singla, Deepika 20 - Space Robotics and Autonomous Operation & Lunar
Skinner, Katherine 10 - Artificial Intelligence in Astrodynamics
Soderlund, Alexander 03 - Rendezvous
Soldini, Stefania 01 - Interplanetary Trajectories
Solomey, Nick 26 - Trajectory Design III
Sood, Rohan 12 - Trajectory Design I
Spehar, Peter 23 - Guidance, Navigation, and Control
Spencer, David 09 - Atmospheric Reentry Guidance and Control
Stacey, Nathan 24 - Orbit Determination
Stegun Vaquero, Tiago 29 - Space Robotics and Autonomous Operation
Stochaj, Steven 17 - Spacecraft Control II
Strauss, William 26 - Trajectory Design III
Stuart, Jeffrey 12 - Trajectory Design I
Subbarao, Kamesh 09 - Atmospheric Reentry Guidance and Control , 24 - Orbit Determination
Subedi, Garba 07 - Attitude Dynamics and Control
Subramani Purushothaman, Arjun Ram 27 - Guidance and Control
Sullivan, Christopher 10 - Artificial Intelligence in Astrodynamics
Sutton, Eric 02 - Debris Clouds, Debris Densities, and Space Environment
Taheri, Ehsan 11 - Low Thrust Trajectories II , 21 - Trajectory Optimization , 26 - Trajectory Design III
Takahashi, Yu 15 Dynamical System Theory I
Takao, Yuki 08 - Navigation
Takao, Yuki 15 Dynamical System Theory I
Takao, Yuki 26 - Trajectory Design III
Taylor, Will 20 - Space Robotics and Autonomous Operation & Lunar
Thangavelautham, Jekan 05 - Asteroids I , 19 - Asteroids II & Mars , 22 - Formation Flying , 29 - Space
Robotics and Autonomous Operation
Thomas, James 20 - Space Robotics and Autonomous Operation & Lunar
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31st AAS/AIAA Space Flight Mechanics Meeting

Thompson, Blair F. 03 - Rendezvous
Thompson, Michael 14 - Cislunar Space Situational Awareness
Tisaev, Mansur 12 - Trajectory Design I
Tiwari, Madhur 27 - Guidance and Control , 30 - Multi Object Tracking
Tobiska, W. Kent 02 - Debris Clouds, Debris Densities, and Space Environment
Tochimoto, Shogo 07 - Attitude Dynamics and Control
Tomita, Kento 10 - Artificial Intelligence in Astrodynamics
Topputo, Francesco 05 - Asteroids I , 06 - Low Thrust Trajectories I , 08 - Navigation , 11 - Low Thrust
Trajectories II
Tracy, Kevin 11 - Low Thrust Trajectories II
Tsuda, Yuichi 08 - Navigation
Tyler, Jack 19 - Asteroids II & Mars
Ueda, Satoshi 16 - Trajectory Design II , 21 - Trajectory Optimization
Valenta, Christopher 18 - Space Object Characterization and Independent Attitude Determination
Vance, Leonard 27 - Guidance and Control
Vander Hook, Joshua 29 - Space Robotics and Autonomous Operation
VanFossen, Andrew 04 - Satellite Formations & Collision Avoidance
Ventura, Rodrigo 29 - Space Robotics and Autonomous Operation
Villa, Jacopo 18 - Space Object Characterization and Independent Attitude Determination
VonWeller, Elliott 07 - Attitude Dynamics and Control
Wang, Yang 11 - Low Thrust Trajectories II
Ward, Kari 08 - Navigation
Weiss, Avishai 19 - Asteroids II & Mars
Weiss, Benamin 01 - Interplanetary Trajectories
Wen, Changxuan 22 - Formation Flying
Wen, Tongge 05 - Asteroids I
Wenn, Chad 13 - Spacecraft Control I
Whitacre, William 24 - Orbit Determination
Willis, Matthew 03 - Rendezvous
Wishnek, Sam 18 - Space Object Characterization and Independent Attitude Determination
Wittig, Alexander 19 - Asteroids II & Mars , 25 - Orbital Dynamics, perturbations and Stability
Woffinden, David 23 - Guidance, Navigation, and Control
Wolf, Trevor 07 - Attitude Dynamics and Control
Wood, Lincoln 08 - Navigation
Woollands, Robyn 29 - Space Robotics and Autonomous Operation
Wu, Chun-Yi 11 - Low Thrust Trajectories II
Wu, Di 02 - Debris Clouds, Debris Densities, and Space Environment
Xu, Zhe 01 - Interplanetary Trajectories
Yamamoto, Toru 03 - Rendezvous
Zagaris, Costantinos 12 - Trajectory Design I
Zaman, Anonto 03 - Rendezvous
Zanetti, Renato 08 - Navigation , 23 - Guidance, Navigation, and Control
Zeng, Xiangyuan 05 - Asteroids I
Zhang, Guoxu 22 - Formation Flying
Zhang, Yonglong 05 - Asteroids I
Zhou, Xingyu 22 - Formation Flying
Zimovan-Spreen, Emily 16 - Trajectory Design II
Zuehlke, David 27 - Guidance and Control , 30 - Multi Object Tracking

Page 78

31st AAS/AIAA Space Flight Mechanics MeetingChairs

Abdelkhalik, Ossama 17 - Spacecraft Control II (Author)
Blazquez, Emmanuel 11 - Low Thrust Trajectories II
Bosanac, Natasha 06 - Low Thrust Trajectories I (Author)
Boudad, Kenza 25 - Orbital Dynamics, perturbations and Stability (Author)
Boutonnet, Arnaud 11 - Low Thrust Trajectories II (Author)
Choi, Daegyun 15 Dynamical System Theory I (Author)
Curti, Fabio 03 - Rendezvous (Author) , 13 - Spacecraft Control I (Author)
Davis, Diane 25 - Orbital Dynamics, perturbations and Stability (Author)
DeMars, Kyle 24 - Orbit Determination (Author)
Dutta, Atri 27 - Guidance and Control (Author)
Furfaro, Roberto 05 - Asteroids I (Author) , 17 - Spacecraft Control II (Author)
Ghosh, Pradipto 09 - Atmospheric Reentry Guidance and Control (Author)
Gunter, Brian 08 - Navigation (Author)
Haapala , Amanda 28 - Dynamical System Theory II (Author)
Hernandez, Sonia 21 - Trajectory Optimization (Author)
Holzinger, Marcus 23 - Guidance, Navigation, and Control (Author)
Howell, Kathleen C. 01 - Interplanetary Trajectories (Author)
Jones, Brandon 14 - Cislunar Space Situational Awareness (Author)
Kim, Donghoon 15 Dynamical System Theory I (Author)
Lai, Peter 10 - Artificial Intelligence in Astrodynamics (Author)
Linares, Richard 30 - Multi Object Tracking (Author)
Majji, Manoranjan 20 - Space Robotics and Autonomous Operation & Lunar (Author)
Mashiku, Alinda 02 - Debris Clouds, Debris Densities, and Space Environment (Author) , 18 - Space Object
Characterization and Independent Attitude Determination (Author)
McMahon, Jay 29 - Space Robotics and Autonomous Operation (Author)
Mehta, Piyush 02 - Debris Clouds, Debris Densities, and Space Environment (Author) , 18 - Space Object
Characterization and Independent Attitude Determination (Author)
Melton, Robert 22 - Formation Flying (Author)
Rao, Anil 19 - Asteroids II & Mars (Author)
Roscoe, Christopher 04 - Satellite Formations & Collision Avoidance (Author)
Rubinsztejn, Ari 26 - Trajectory Design III (Author)
Sinclair, Andrew J. 07 - Attitude Dynamics and Control (Author)
Sood, Rohan 01 - Interplanetary Trajectories (Author) , 26 - Trajectory Design III (Author)
Thorne, James 12 - Trajectory Design I (Author)
Topputo, Francesco 03 - Rendezvous (Author) , 13 - Spacecraft Control I (Author)
Valerino, Powtawche 16 - Trajectory Design II (Author)

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31st AAS/AIAA Space Flight Mechanics Meeting