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compass final report: nuclear electric propulsion (nep)-chemical vehicle 1.2Many previous studies have examined sending crews to and from Mars. The most economical involved a ‘conjunction’ class whereby the crew spends around 500 days on Mars waiting for a ‘cheap’ return. The total mission time results in over a 1000-day mission duration (about 3 years). Given the current experience level of only one year on the International Space Station (ISS), it of interest to reduce that time to only two years, thus reducing risk and minimizing required Mars surface infrastructure. The Phase 1.1 Study goal was stated as follows, “Determine the feasibility of a two-year roundtrip class Mars mission concept of operation that enables boots on Mars no later than 2036.” While the Phase1 study did show feasibility for the NEP-Chemical option, the 2036 Opposition opportunity was found to stress the schedule due to proposed technology development schedules. A 2039 Opposition (which requires even more energy than the 2036 case) was chosen as representative for Phase 1.2. Phase 1.2 also sought to further refine the concept, building on the feasibility, but addressing several challenges brought by the red team and habitat team. Given the date of 2039, nearer term technologies, primarily nuclear thermal and nuclear electric were deemed as the most viable for these missions. As will be shown, the energy required to perform such a mission in only two years (for the 2039 opportunity at least) is about three times that of the three-year conjunction mission. The rocket equation shows that this mission would then require several times the propellant of the three-year mission unless the specific impulse (ISP) of the propulsion system can be increased. Based on lunar needs, a limit of five Space Launch System (SLS) launchers with 8.4m fairings was imposed for the piloted transportation portion of the mission, limiting the size of the system. When using nuclear electric propulsion, the main limiting factor was packaging the required radiator area. The higher Isp nuclear electric propulsion (NEP) system option is described herein but with a twist: in order to keep the size of radiators packageable in one SLS and use proven reactor power system technology (~1200K reactor outlet temperature and superalloy-class Brayton) the NEP system had to be combined with a chemical propulsion system. This combination of electric propulsion and high thrust chemical was found to be useful in previous design studies combining solar electric propulsion (SEP) and chemical propulsion. Such a combination allowed the low-thrust system to provide significant change in velocity (∆V) during the interplanetary portions of the mission, thereby notably reducing the ∆V required by the high thrust system to capture and depart from the Mars gravity well. Here the high thrust ‘impulsive’ system is more efficient due to the Oberth Effect. A plethora of trades, both at the mission and system level, as well as the subsystem level were performed to develop these vehicle concepts. An entire family of NEP-Chemical transportation vehicles is described herein. The main driver and the primary focus was the piloted vehicle but additional concepts for cargo were performed using the same ‘building blocks’ in order to reduce costs and provide commonality.
Document ID
20210017131
Document Type
Technical Memorandum (TM)
Authors
Steven R Oleson
(Glenn Research Center Cleveland, Ohio, United States)
Laura M Burke
(Glenn Research Center Cleveland, Ohio, United States)
Lee S Mason
(National Aeronautics and Space Administration Washington D.C., District of Columbia, United States)
Elizabeth R Turnbull
(Glenn Research Center Cleveland, Ohio, United States)
Steven Mccarty
(Glenn Research Center Cleveland, Ohio, United States)
Anthony J Colozza
(HX5, LLC)
James E Fittje
(Science Applications International Corporation (United States) McLean, Virginia, United States)
John T Yim
(Glenn Research Center Cleveland, Ohio, United States)
Michael Smith
(Oak Ridge National Laboratory Oak Ridge, Tennessee, United States)
Thomas W Packard
(HX5, LLC)
Brandon T Klefman
(Glenn Research Center Cleveland, Ohio, United States)
John Z Gyekenyesi
(HX5, LLC)
Brent F Faller
(Glenn Research Center Cleveland, Ohio, United States)
Paul C Schmitz
(Power Computing Solutions Inc. Avon Lake, Ohio, USA)
David A Smith
(HX5, LLC)
Lucia Tian
(Glenn Research Center Cleveland, Ohio, United States)
Caroline R Austin
(Glenn Research Center Cleveland, Ohio, United States)
W Peter Simon
(Glenn Research Center Cleveland, Ohio, United States)
Christopher R Heldman
(Glenn Research Center Cleveland, Ohio, United States)
Onoufrios Theofylaktos
(Glenn Research Center Cleveland, Ohio, United States)
Christine L Schmid
(Glenn Research Center Cleveland, Ohio, United States)
Thomas J Parkey
(Glenn Research Center Cleveland, Ohio, United States)
Natalie J Weckesser
(Glenn Research Center Cleveland, Ohio, United States)
Lee A Jackson
(HX5, LLC)
Date Acquired
June 8, 2021
Publication Date
June 11, 2021
Subject Category
Spacecraft Propulsion and Power
Report/Patent Number
CD-2020-181
E-19978
Funding Number(s)
WBS: 039889.04.01.02.22
CONTRACT_GRANT: 80GRC020D0003
Distribution Limits
Public
Copyright
Public Use Permitted.
Technical Review
NASA Peer Committee
Keywords
Nuclear Power
Electric Propulsion
Hall Thrusters
Mars Transportation
Opposition Class

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