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Trajectory Design Considerations for Exploration Mission 1Exploration Mission 1 (EM-1) will be the first mission to send an uncrewed Orion Multi-Purpose Crew Vehicle (MPCV) to cislunar space in the fall of 2019. EM-1 was originally conceived as a lunar free-return mission, but was later changed to a Distant Retrograde Orbit (DRO) mission as a precursor to the Asteroid Redirect Mission. To understand the required mission performance (i.e., propellant requirement), a series of trajectory optimization runs was conducted using JSC's Copernicus spacecraft trajectory optimization tool. In order for the runs to be done in a timely manner, it was necessary to employ a parallelization approach on a computing cluster using a new trajectory scan tool written in Python. Details of the scan tool are provided and how it is used to perform the scans and post-process the results. Initially, a scan of daily due east launched EM-1 DRO missions in 2018 was made. Valid mission opportunities are ones that do not exceed the useable propellant available to perform the required burns. The initial scan data showed the propellant and delta-V performance patterns for each launch period. As questions were raised from different subsystems (e.g., power, thermal, communications, flight operations, etc.), the mission parameters or data that were of interest to them were added to the scan output data file. The additional data includes: (1) local launch and landing times in relation to sunrise and sunset, (2) length of eclipse periods during the in-space portion of the mission, (3) Earth line of sight from cislunar space, (4) Deep Space Network field of view looking towards cislunar space, and (5) variation of the downrange distance from Earth entry interface to splashdown. Mission design trades can also be performed based on the information that the additional data shows. For example, if the landing is in darkness, but the recovery operations team desires a landing in daylight, then an analysis is performed to determine how to change the mission design to meet this request. Also, subsystems request feasibility of alternate or contingency mission designs, such as adding an Orion main engine checkout burn or Orion completing all of its burns using only its auxiliary thrusters. This paper examines and presents the evolving trade studies that incorporate subsystem feedback and demonstrate the feasibility of these constrained mission trajectory designs and contingencies.
Document ID
20180001259
Document Type
Conference Paper
Authors
Dawn, Timothy F.
(NASA Johnson Space Center Houston, TX United States)
Gutkowski, Jeffrey P.
(NASA Johnson Space Center Houston, TX United States)
Batcha, Amelia L.
(NASA Johnson Space Center Houston, TX United States)
Williams, Jacob
(Jacobs Technology, Inc. Houston, TX, United States)
Pedrotty, Samuel M.
(NASA Johnson Space Center Houston, TX United States)
Date Acquired
February 15, 2018
Publication Date
January 8, 2018
Subject Category
Astrodynamics
Report/Patent Number
JSC-E-DAA-TN50136
Meeting Information
AIAA/AAS Space Flight Mechanics Meeting(Kissimmee, FL)
Funding Number(s)
CONTRACT_GRANT: NNJ13HA01C
Distribution Limits
Public
Copyright
Public Use Permitted.

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