Papers by Melissa McGuire
This paper captures trajectory analysis of a representative low thrust, high power Solar Electric... more This paper captures trajectory analysis of a representative low thrust, high power Solar Electric Propulsion (SEP) vehicle to move a mass around cislunar space in the range of 20 to 40 kW power to the Electric Propulsion (EP) system. These cislunar transfers depart from a selected Near Rectilinear Halo Orbit (NRHO) and target other cislunar orbits. The NRHO cannot be characterized in the classical two-body dynamics more familiar in the human spaceflight community, and the use of low thrust orbit transfers provides unique analysis challenges. Among the target orbit destinations documented in this paper are transfers between a Southern and Northern NRHO, transfers between the NRHO and a Distant Retrograde Orbit (DRO) and a transfer between the NRHO and two different Earth Moon Lagrange Point 2 (EML2) Halo orbits. Because many different NRHOs and EML2 halo orbits exist, simplifying assumptions rely on previous analysis of orbits that meet current abort and communication requirements for human mission planning. Investigation is done into the sensitivities of these low thrust transfers to EP system power. Additionally, the impact of the Thrust to Weight ratio of these low thrust SEP systems and the ability to transit between these unique orbits are investigated.
Concurrent Engineering Centers (CECs) are specialized facilities with a goal of generating and ma... more Concurrent Engineering Centers (CECs) are specialized facilities with a goal of generating and maturing engineering designs by enabling rapid design iterations. This is accomplished by co-locating a team of experts (either physically or virtually) in a room with a focused design goal and a limited timeline of a week or less. The systems engineer uses a model of the system to capture the relevant interfaces and manage the overall architecture. A single model that integrates other design information and modeling allows the entire team to visualize the concurrent activity and identify conflicts more efficiently, potentially resulting in a systems model that will continue to be used throughout the project lifecycle. Performing systems engineering using such a system model is the definition of model-based systems engineering (MBSE); therefore, CECs evolving their approach to incorporate advances in MBSE are more successful in reducing time and cost needed to meet study goals. This paper surveys space mission CECs that are in the middle of this evolution, and the authors share their experiences in order to promote discussion within the community. Concurrent Engineering Center (CEC) is an organization of people, tools, and facilities with a specific goal of rapidly generating and maturing engineering designs. Teams of experts are assembled and given a design goal
AIAA SPACE 2015 Conference and Exposition, Aug 28, 2015
CAC is analytical prediction program to study heat-transfer and fluid-flow characteristics of cir... more CAC is analytical prediction program to study heat-transfer and fluid-flow characteristics of circular coolant passage. Predicts, as function of time, axial and radial fluid conditions, temperatures of passage walls, rates of flow in each coolant passage, and approximate maximum material temperatures. Written in ANSI standard FORTRAN 77.
2015 IEEE Aerospace Conference, 2015
Ball Aerospace & Technologies Corp participated in a Space Act Agreement with NASA GRC to determi... more Ball Aerospace & Technologies Corp participated in a Space Act Agreement with NASA GRC to determine the fe asibility of accommodating enough Solar Electric Propulsion (SEP) on the Ball ESPA-c1ass bus to result in a mission of interest to Ball customers. The baseline for the study was the ESPA class BCP-I00 bus. Since the BCP-I00 bus has flight heritage on USAF programs, the approach for the study was to use the existing bus design and minimize changes to only those necessary to accommodate the SEP system. This approach maintains high heritage and mIDlmlzes the amount of Non-Recurring Engineering required for the bus. High heritage components were also selected for the SEP system when available, including an off-the-shelf Xenon tank, existing cathode, HET thruster and Xenon fe ed control, allowing fu ture development fu nding to be fo cused on a PPU compatible with the existing BCP-100 28 V power bus. The results of the study show that while meeting the ESPA envelope and mass requirements, the BCP-I00 can accommodate enough SEP capability to allow the orbit to be raised or lowered anywhere within LEO or change the inclination up to 10° fr om a LEO starting point. From a GTO starting point, an elliptical orbit with apogee at GEO is also possible.
This paper examines two low thrust insertion options for delivery of a 40-kW solar electric propu... more This paper examines two low thrust insertion options for delivery of a 40-kW solar electric propulsion spacecraft to a Near Rectilinear Halo Orbit (NRHO). One option considered is a trans-lunar injection launch as a co-manifested payload on the Space Launch System. For this option, a reference trajectory is designed and a scan of launch dates is completed to understand the propellant mass sensitivity. A 15-day period cyclical variation in required propellant is observed that is attributed to solar gravity effects. A second option considered is to launch on a smaller commercial launch vehicle to a less energetic elliptical orbit and use SEP to spiral out to NRHO. For this option, analysis is completed to understand the trades between delivered mass to NRHO, total propellant required, time of flight, and solar array degradation. Results show that, while launching to lower altitudes can deliver greater payload mass to NRHO, significant solar array degradation can occur. In addition to a generic dataset that can be applied to any launch vehicle, spiral trajectory results are presented specific to launch on an Atlas V 551 and Falcon 9.
NASA is currently developing the Asteroid Redirect Robotic Mission (ARRM) that would have the cap... more NASA is currently developing the Asteroid Redirect Robotic Mission (ARRM) that would have the capability to retrieve a boulder from a Near Earth Asteroid and place it in Lunar orbit where astronauts in an Orion spacecraft would rendezvous with the ARRM vehicle and explore the boulder. This mission is conceived as a capabilities demonstration mission that would path-find high power Solar Electric Propulsion (SEP) and Earth-independent human spaceflight operations for Mars missions in the 2030s, as part of NASA's Journey to Mars initiative. The high-power, light-weight solar arrays and high-power, magnetically-shielded hall thrusters being developed for ARRM will dramatically increase NASA's in-space transportation capability. These two technologies could propel affordable human missions to asteroids, Martian moons, and asteroids. In addition, these technologies could be used to enhance human access to cis-lunar space and the Lunar surface. This paper will provide an overview of ARRM and discuss how ARRM-developed technologies would feed forward to human deep space exploration missions.
AAS/AIAA Space Flight Mechanics Meeting, Feb 5, 2017
Part of NASA's new asteroid initiative would be a robotic mission to capture a roughly four to te... more Part of NASA's new asteroid initiative would be a robotic mission to capture a roughly four to ten meter asteroid and redirect its orbit to place it in translunar space. Once in a stable storage orbit at the Moon, astronauts would then visit the asteroid for science investigations, to test in space resource extraction, and to develop experience with human deep space missions. This paper discusses the mission design techniques that would enable the redirection of a 100-1000 metric ton asteroid into lunar orbit with a 40-50 kW Solar Electric Propulsion (SEP) system. Nomenclature ΔV = change in velocity C3 = v ∞ squared I sp = specific impulse v ∞ = hyperbolic excess velocity
The National Aeronautics and Space Administration’s (NASA’s) recently cancelled Asteroid Redirect... more The National Aeronautics and Space Administration’s (NASA’s) recently cancelled Asteroid Redirect Mission was proposed to rendezvous with and characterize a 100 m plus class near-Earth asteroid and provide the capability to capture and retrieve a boulder off of the surface of the asteroid and bring the asteroidal material back to cislunar space. Leveraging the best of NASA’s science, technology, and human exploration efforts, this mission was originally conceived to support observation campaigns, advanced solar electric propulsion, and NASA’s Space Launch System heavy-lift rocket and Orion crew vehicle. The asteroid characterization and capture portion of ARM was referred to as the Asteroid Redirect Robotic Mission (ARRM) and was focused on the robotic capture and then redirection of an asteroidal boulder mass from the reference target, asteroid 2008 EV5, into an orbit near the Moon, referred to as a Near Rectilinear Halo Orbit where astronauts would visit and study it. The purpose ...
Solar Electric Propulsion (SEP) offers fuel efficiency and mission robustness for spacecraft. The... more Solar Electric Propulsion (SEP) offers fuel efficiency and mission robustness for spacecraft. The combination of solar power and electric propulsion engines is currently used for missions ranging from geostationary stationkeeping to deep space science because of these benefits. Both solar power and electric propulsion technologies have progressed to the point where higher electric power systems can be considered, making substantial cargo missions and potentially human missions viable. This paper evaluates and compares representative lunar, Mars, and Sun-Earth Langrangian point missions using SEP and chemical propulsion subsystems. The potential benefits and limitations are discussed along with technology gaps that need to be resolved for such missions to become possible. The connection to NASA's human architecture and technology development efforts will be discussed.
AIP Conference Proceedings, 1999
The nuclear thermal rocket (NTR) is one of the leading propulsion options for future human missio... more The nuclear thermal rocket (NTR) is one of the leading propulsion options for future human missions to Mars due to its high specific impulse (Isp ∼850–1000 s) and attractive engine thrust-to-weight ratio (∼3–10). Because only a miniscule amount of enriched uranium-235 fuel is consumed in a NTR during the primary propulsion maneuvers of a typical Mars mission, engines configured for both propulsive thrust and modest power generation (referred to as “bimodal” operation) provide the basis for a robust, “power-rich” stage enabling propulsive Mars capture and reuse capability. A family of modular “bimodal” NTR (BNTR) vehicles are described which utilize a common “core” stage powered by three 66.7 kN (∼15 klbf) BNTRs that produce 50 kWe of total electrical power for crew life support, an active refrigeration/reliquification system for long term, “zero-boiloff” liquid hydrogen (LH2) storage, and high data rate communications. Compared to other propulsion options, a Mars mission architecture using BNTR transfer vehicles requires fewer transportation system elements which reduces mission mass, cost and risk because of simplified space operations. For difficult Mars options, such as a Phobos rendezvous and sample return mission, volume (not mass) constraints limit the performance of the “all LH2” BNTR stage. The use of “LOX-augmented” NTR (LANTR) engines, operating at a modest oxygen-to-hydrogen (O/H) mixture ratio (MR) of 0.5, helps to increase “bulk” propellant density and total thrust during the trans-Mars injection (TMI) burn. On all subsequent burns, the bimodal LANTR engines operate on LH2 only (MR=0) to maximize vehicle performance while staying within the mass limits of two ∼80 t “Magnum” heavy lift launch vehicles (HLLVs).
Recent human Mars exploration studies at NASA have focused on a split mission approach involving ... more Recent human Mars exploration studies at NASA have focused on a split mission approach involving predeployment of surface and orbital cargo elements followed by piloted missions with long surface stays (-500 days) and “l-way” transit times of -6 to 7 months. In the event an aborted landing or major surface system failure forces an early return to the crew transfer vehicle (CTV), astronauts could spend the entire mission duration (-900 days) in a weightless environment. An artificial gravity CTV design capable of countering the potentially debilitating physiological effects of “zero gravity” is described which uses “bimodal” nuclear thermal rocket (NTR) propulsion. With its high specific impulse (Isp -850-l 000 s), attractive engine thrust-to-weight ratio (-3-i 0) and demonstrated feasibility, the NTR is the most promising propulsion technology for future human exploration missions to the Moon, Mars and near Earth asteroids. Because only a minuscule amount of enriched uranium235 fuel is consumed in a NTR during the primary propulsion maneuvers of a typical Mars mission, engines configured for both propulsive thrust and modest power generation (referred to as “bimodal” operation) provide the basis for a robust, “power-rich” stage enabling a propulsive Mars capture capability for the CTV. A common “bimodal” NTR (BNTR) “core” stage powered by three -15 thousand pounds force (klbf) BNTRs supplies 50 kWe of total electrical power for crew life support and an active refrigeration system enabling long term, “zero-boiloff” liquid hydrogen (LH2) storage. On the piloted CTV, the bimodal NTR core stage is connected to the inflatable -----------------------------------------------------------------------*Ph.D./Nuclear Engineering, Senior Member AIAA ‘*Aerospace Engineer, Member AIAA “TransHab” crew module via an innovative, spinelike “saddle truss” (approximately 22 meters in length) which is open underneath to allow easy jettisoning of the “in-line” LH2 propellant tank following the trans-Mars injection (TMI) burn. The CTV then initiates vehicle rotation at o 4 revolutions per minute (rpm) to provide the TransHab crew with a Mars gravity field (-0.38 g E) during the outbound transit. A higher rotation rate (w 6 rpm) can provide -0.8 gE on the return leg to help reacclimate the crew to Earth’s gravity after their -500 day stay at Mars. In addition to supplying artificial gravity and abundant power for the crew, a Mars architecture using BNTR transfer vehicles also has a lower total launch mass, fewer transportation system elements and simpler mission operations than competing “non-nuclear” chemical and solar electric propulsion (SEP) options. INTRODUCTION AND BACKGROUND Over the last 3 years, NASA’s intercenter Mars Exploration Study Team has been evaluating a split cargo / piloted mission approach for sending humans to Mars in the 2014 timeframe. Payload masses have continued to be refined and updatedl, and a variety of space transportation technology options have been examined*,s. In the FY98 reference mission profile, the crew traveled to Mars under “zero gravity” conditions and landed on its surface in a common transit / habitat module integrated into an aerobraked lander configuration. Two cargo flights preceded the piloted mission and were used to predeploy surface assets and a separate transfer stage for returning the crew to Copyright
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Papers by Melissa McGuire