Showing papers on "Spacecraft propulsion published in 2014"

Microfabricated electrospray emitter arrays with integrated extractor and accelerator electrodes for the propulsion of small spacecraft

Abstract: Microfabricated electrospray thrusters could revolutionize the spacecraft industry by providing efficient propulsion capabilities to micro and nano satellites (1–100 kg). We present the modeling, design, fabrication and characterization of a new generation of devices, for the first time integrating in the fabrication process individual accelerator electrodes capable of focusing and accelerating the emitted sprays. Integrating these electrodes is a key milestone in the development of this technology; in addition to increasing the critical performance metrics of thrust, specific impulse and propulsive efficiency, the accelerators enable a number of new system features such as power tuning and thrust vectoring and balancing. Through microfabrication, we produced high density arrays (213 emitters cm−2) of capillary emitters, assembling them at wafer-level with an extractor/accelerator electrode pair separated by micro-sandblasted glass. Through IV measurements, we could confirm that acceleration could be decoupled from the extraction of the spray—an important element towards the flexibility of this technology. We present the largest reported internally fed microfabricated arrays operation, with 127 emitters spraying in parallel, for a total beam of 10–30 µA composed by 95% of ions. Effective beam focusing was also demonstrated, with plume half-angles being reduced from approximately 30° to 15° with 2000 V acceleration. Based on these results, we predict, with 3000 V acceleration, thrust per emitter of 38.4 nN, specific impulse of 1103 s and a propulsive efficiency of 22% with <1 mW/emitter power consumption.

ESTCube-1 nanosatellite for electric solar wind sail in-orbit technology demonstration

Abstract: This paper presents the mission analysis, requirements, system design, system level test results, as well as mass andpower budgets of a 1-unit CubeSat ESTCube-1 built to perform the first in-orbit demonstration of electric solar wind sail (E-sail)technology. The E-sail is a propellantless propulsion system concept that uses thin charged electrostatic tethers for turning themomentum flux of a natural plasma stream, such as the solar wind, into spacecraft propulsion. ESTCube-1 will deploy and chargea 10 m long tether and measure changes in the satellite spin rate. These changes result from the Coulomb drag interaction with theionospheric plasma that is moving with respect to the satellite due to the orbital motion of the satellite. The following subsystemshavebeendevelopedtoperformandtosupporttheE-sailexperiment: atetherdeploymentsubsystembasedonapiezoelectricmotor;an attitude determination and control subsystem to provide the centrifugal force for tether deployment, which uses electromagneticcoils to spin up the satellite to one revolution per second with controlled spin axis alignment; an imaging subsystem to verify tetherdeployment, which is based on a 640 × 480 pixel resolution digital image sensor; an electron gun to keep the tether at a highpositive potential; a high voltage source to charge the tether; a command and data handling subsystem; and an electrical powersubsystem with high levels of redundancy and fault tolerance to mitigate the risk of mission failure.

High-Power Solar Electric Propulsion for Future NASA Missions

Abstract: NASA has sought to utilize high-power solar electric propulsion as means of improving the affordability of in-space transportation for almost 50 years. Early efforts focused on 25 to 50 kilowatt systems that could be used with the Space Shuttle, while later efforts focused on systems nearly an order of magnitude higher power that could be used with heavy lift launch vehicles. These efforts never left the concept development phase in part because the technology required was not sufficiently mature. Since 2012 the NASA Space Technology Mission Directorate has had a coordinated plan to mature the requisite solar array and electric propulsion technology needed to implement a 30 to 50 kilowatt solar electric propulsion technology demonstration mission. Multiple solar electric propulsion technology demonstration mission concepts have been developed based on these maturing technologies with recent efforts focusing on an Asteroid Redirect Robotic Mission. If implemented, the Asteroid Redirect Vehicle will form the basis for a capability that can be cost-effectively evolved over time to provide solar electric propulsion transportation for a range of follow-on mission applications at power levels in excess of 100 kilowatts.

Deep Throttle of a Nitrous Oxide and Hydroxyl-Terminated Polybutadiene Hybrid Rocket Motor

Abstract: Deep-throttle static test results from an N2O and hydroxyl-terminated polybutadiene hybrid rocket motor are presented. The nominal 800 N thrust level was turned down to less than 12 N while still maintaining stable and controlled combustion. This 67∶1 turndown was accomplished using a commercial off-the-shelf throttle valve and a solid rocket motor case adapted for hybrid rocket testing. During throttled motor tests, the pressure ratio across the injector grows from a nominal value of 2.0 to greater than 3.0. This feature contrasts with the observed behavior of liquid rockets, where the injector pressure ratio drops significantly during deep throttle. This characteristic likely supports the observed hybrid burn stability during deep throttle. Data comparisons with a physics-based, throttled, hybrid rocket burn model accurately match for combustor pressure, thrust, and propellant consumption. At throttle levels approaching 20% of nominal, the N2O exiting the throttle valve is entirely in a vapor state. The...

Peregrine Hybrid Rocket Motor Development

Abstract: To further develop and demonstrate the applicability of liquefying-fuel hybrid rocket technology to low-cost launch applications, a small team of engineers is developing a medium-scale liquefying-fuel hybrid sounding rocket using storable propellants (paraffin wax and N2O) that will propel a 5 kg payload to the edge of space. This rocket, known as the Peregrine Sounding Rocket, is being developed by engineers from NASA Ames, Stanford University, Space Propulsion Group Inc. (SPG, Sunnyvale, CA) and NASA Wallops, with a launch from Wallops anticipated at some point in the future. Results of ground testing performed using a heavy-weight configuration of the motor show that stable and efficient combustion has been achieved.

Sunjammer: A Solar Sail Demonstration

Abstract: NASA’s newly minted Space Technology Mission Directorate (STMD) is supporting the fabrication of a sail of this design in preparation of a planned 2014 flight. This mission, dubbed Sunjammer, will further advance the potential of propellantless solar sails. The Sunjammer mission is being led by the private company L’Garde Inc. of Tustin, CA. Sunjammer is named after a short story written by Sir Arthur C. Clarke. This ambitious project aims to prove the efficacy of a versatile and scalable solar sail design.

Replacement of chemical rocket launchers by beamed energy propulsion.

Abstract: Microwave Rocket is a beamed energy propulsion system that is expected to reach space at drastically lower cost. This cost reduction is estimated by replacing the first-stage engine and solid rocket boosters of the Japanese H-IIB rocket with Microwave Rocket, using a recently developed thrust model in which thrust is generated through repetitively pulsed microwave detonation with a reed-valve air-breathing system. Results show that Microwave Rocket trajectory, in terms of velocity versus altitude, can be designed similarly to the current H-IIB first stage trajectory. Moreover, the payload ratio can be increased by 450%, resulting in launch-cost reduction of 74%.

Two-Dimensional Particle-In-Cell Simulation of Magnetic Sails

Abstract: A magnetic sail is spacecraft propulsion that produces an artificial magnetosphere to block solar wind particles and thus impart momentum to accelerate a spacecraft. In the present study, the authors conducted two-dimensional particle-in-cell simulations on small-scale magnetospheres to investigate thrust characteristics of a magnetic sail and its derivative, magnetoplasma sail, in which the magnetosphere is inflated by an additional plasma injection. As a result, the authors found that the electron Larmor motion and the charge separation become significant on such a small-scale magnetosphere and the thrust of the magnetic sail is affected by the cross-sectional size of the charge-separated magnetosphere. The authors also reveal that the plasma injection, on the condition that the kinetic energy of plasma is smaller than the local magnetic field energy (β∼10−3), can significantly inflate the magnetosphere by inducing diamagnetic current in the same direction as the onboard coil current. As a result, the m...

An Overview of Solar Sail Propulsion within NASA

Abstract: Solar Sail Propulsion (SSP) is a high-priority new technology within The National Aeronautics and Space Administration (NASA), and several potential future space missions have been identified that will require SSP. Small and mid-sized technology demonstration missions using solar sails have flown or will soon fly in space. Multiple mission concept studies have been performed to determine the system level SSP requirements for their implementation and, subsequently, to drive the content of relevant technology programs. The status of SSP technology and potential future mission implementation within the United States (US) will be described.

Staged Combustion Cycle Rocket Engine Subsystem Definition for Future Advanced Passenger Transport

Abstract: DLR’s launcher systems analysis division is investigating since a couple of years a visionary, extremely fast passenger transportation concept based on rocket propulsion. Thanks to the multi-national collaboration, the technical lay-out of the SpaceLiner has now matured to Phase A conceptual design level. Full-flow staged combustion cycle rocket engines with a moderate 15 to 17 MPa range in chamber pressure have been selected as the baseline propulsion system. The expansion ratios of the engines are adapted to their respective optimums required by the stages; while the mass flow, turbo-machinery, and combustion chamber are assumed to remain identical. The paper describes the SpaceLiner 7 propulsion system: • The reference vehicle’s preliminary design, • Main propulsion system definition and architectural lay-out, • Thrust chamber geometries, • Pre-design of different turbomachinery and attached preburners, • Advanced ceramic material fuel- and oxidizer-rich pre-burners and injectors as an alternative to increase lifetime of components. The presented work is including preliminary sizing on component level and first mass estimation data.

Thrust Evaluation of Small-Scale Magnetic Sail Spacecraft by Three-Dimensional Particle-in-Cell Simulation

Abstract: A magnetic sail is a spacecraft propulsion system that generates an artificial magnetosphere to block solar wind particles and uses the imparted momentum to accelerate a spacecraft. In the present study, three-dimensional particle-in-cell simulations were conducted on small-scale magnetospheres to investigate the thrust characteristics of small-scale magnetic sails. The results show that electron Larmor motion and charge separation become significant in small-scale magnetospheres, and that the thrust of the magnetic sail is affected by the cross-sectional area of the charge-separated plasma cavity. Empirical formulas for the thrust are obtained by changing spacecraft design and solar wind parameters. These equations show that the thrust of a small-scale magnetic sail is approximately proportional to magnetic moment, solar wind density, and solar wind velocity. The empirical formulas enable determination of the trajectory of the spacecraft and performance of a mission analysis.

Development of a Three-Dimensional Printed, Liquid-Cooled Nozzle for a Hybrid Rocket Motor

Abstract: A DDITIVE manufacturing, or three-dimensional (3-D) printing, has rapidly changed from a means to produce component prototypes into a viable method of manufacturing complex, functional parts or devices [1]. The use of these techniques to produce fuel grains for hybrid rockets has previously been reported by several authors [2–4], and now, NASA Marshall Space Flight Center has begun an effort to use 3-D printing technology to make additional rocket components. The long-term objectives of this effort are to bring down manufacturing costs and thereby reduce launch costs for placing small payloads in orbit. As part of this effort, the University of Tennessee has, in collaboration with NASA personnel, designed, fabricated, assembled, and successfully tested a hybrid rocket motor that uses a printed nozzle with embedded cooling channels. The project was carried out to demonstrate the feasibility of using complex, printed components in the high-pressure, high-temperature sections of a rocket motor. This effort continues a longstanding research and education program in hybrid rocket propulsion at the University of Tennessee [5–7]. In its current version, the nozzle cooling system uses water, and the temperature rise of the coolant is measured to determine experimentally the heating rate distribution for comparison with initial analytical predictions. In future studies, the same tools used for the present motor will be employed to design a regeneratively cooled nozzle that will employ nitrous oxide in the cooling system. Experimental validation of the design methodology is desired so that future flight nozzles can be developed to be as thin-walled and lightweight as possible. Thin nozzle walls are advantageous not only due to their low weight, but also because they allow more effective cooling and lower inside surface temperatures.

A Combined Solar Electric and Storable Chemical Propulsion Vehicle for Piloted Mars Missions

Abstract: The Mars Design Reference Architecture (DRA) 5.0 explored a piloted Mars mission in the 2030 timeframe, focusing on architecture and technology choices. The DRA 5.0 focused on nuclear thermal and cryogenic chemical propulsion system options for the mission. Follow-on work explored both nuclear and solar electric options. One enticing option that was found in a NASA Collaborative Modeling for Parametric Assessment of Space Systems (COMPASS) design study used a combination of a 1-MW-class solar electric propulsion (SEP) system combined with storable chemical systems derived from the planned Orion crew vehicle. It was found that by using each propulsion system at the appropriate phase of the mission, the entire SEP stage and habitat could be placed into orbit with just two planned Space Launch System (SLS) heavy lift launch vehicles assuming the crew would meet up at the Earth-Moon (E-M) L2 point on a separate heavy-lift launch. These appropriate phases use high-thrust chemical propulsion only in gravity wells when the vehicle is piloted and solar electric propulsion for every other phase. Thus the SEP system performs the spiral of the unmanned vehicle from low Earth orbit (LEO) to E-M L2 where the vehicle meets up with the multi-purpose crew vehicle. From here SEP is used to place the vehicle on a trajectory to Mars. With SEP providing a large portion of the required capture and departure changes in velocity (delta V) at Mars, the delta V provided by the chemical propulsion is reduced by a factor of five from what would be needed with chemical propulsion alone at Mars. This trajectory also allows the SEP and habitat vehicle to arrive in the highly elliptic 1-sol parking orbit compatible with envisioned Mars landing concepts. This paper explores mission options using between SEP and chemical propulsion, the design of the SEP system including the solar array and electric propulsion systems, and packaging in the SLS shroud. Design trades of stay time, power level, specific impulse and propellant type are discussed.

Effects of Injector Design on Combustion Stability in Hybrid Rockets Using Self-Pressurizing Oxidizers

Abstract: Interest in nitrous oxide based hybrid rockets is at an all time high. Nitrous oxide (N2O) is a unique oxidizer because it exhibits a high vapor pressure at room temperature ( 730 psia or 5.03 MPa). Due to this high vapor pressure, liquid nitrous oxide can be expelled from a tank without the use of complicated pumps or pressurization systems required by most traditional liquid rocket systems. This results in weight savings and design simplicity. Additional benefits of nitrous oxide include storability, ease of handling, and relative safety compared to traditional liquid oxidizers. The design and modeling of injectors for use with high vapor pressure propellants such as nitrous oxide is made complicated due to the possibility of two-phase flow. The operating pressures within rocket propellant feed systems can often drop below the vapor pressure for these unique propellants, especially within the injector. Injectors operating under these conditions are likely to exhibit cavitation, resulting in significant vapor formation and limitation of mass flow rate. With the introduction of two-phase flow, a critical flow regime can be observed, where the flow rate is independent of backpressure (similar to choking). For a simple orifice style injector, it has been demonstrated that critical flow occurs when the downstream pressure falls su ciently below the vapor pressure, ensuring bulk vapor formation within the injector element. It has been proposed to leverage the insensitivity of critical mass flow rate to downstream pressure as a means of preventing the occurrence of feed system coupled combustion instabilities in hybrid rockets utilizing nitrous oxide. The Peregrine Sounding Rocket is a hybrid rocket that runs on para n wax and nitrous oxide. Its development is a joint e ort between NASA Ames Research Center, Stanford University, and Space Propulsion Group, Inc. For years, progress of the Peregrine program has been hampered by combustion instability problems. Based upon results from the aforementioned small scale injector experiments, a powerful, yet simple solution to the so-called feed system coupled combustion instability was discovered, the details of which are presented. This work also led to the invention of a new class of rocket propellant injectors designed specifically to decrease the likelihood of this type of combustion instability. An in-depth discussion of the proposed design and operation of this novel injection scheme is included, along with the presentation of some prototype cold flow testing results which served as a successful proof of concept.

Selection and Manufacturing of Membrane Materials for Solar Sails

Abstract: Commercial metallized polyimide or polyester films and hand-assembly techniques are acceptable for small solar sail technology demonstrations, although scaling this approach to large sail areas is impractical Opportunities now exist to use new polymeric materials specifically designed for solar sailing applications, and take advantage of integrated sail manufacturing to enable large-scale solar sail construction This approach has, in part, been demonstrated on the JAXA IKAROS solar sail demonstrator, and NASA Langley Research Center is now developing capabilities to produce ultrathin membranes for solar sails by integrating resin synthesis with film forming and sail manufacturing processes This paper will discuss the selection and development of polymer material systems for space, and these new processes for producing ultrathin high-performance solar sail membrane films

Reactants sprayed into plasma flow for rocket propulsion

Abstract: Specific impulse and rocket engine efficiency can be improved by injecting reactants, e.g., a propellant combination or a monopropellant and a catalyst, into a plasma flow of a rocket engine. In some aspects, a catalyst or a propellant is carried by plasma formed by passing a flow of a feed gas through an electrical arc. In some aspects, reactants are combusted in supersonic plasma flow to generate combustion ionization in the plasma flow.

Atmospheric Mining in the Outer Solar System:. [Aerial Vehicle Reconnaissance and Exploration Options

Abstract: Atmospheric mining in the outer solar system has been investigated as a means of fuel production for high energy propulsion and power. Fusion fuels such as Helium 3 (3He) and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy production. Helium 3 and hydrogen (deuterium, etc.) were the primary gases of interest with hydrogen being the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to investigate resource capturing aspects of atmospheric mining in the outer solar system. This included the gas capturing rate, storage options, and different methods of direct use of the captured gases. Additional supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues. While capturing 3He, large amounts of hydrogen and 4He are produced. With these two additional gases, the potential for fueling small and large fleets of additional exploration and exploitation vehicles exists. Additional aerospacecraft or other aerial vehicles (UAVs, balloons, rockets, etc.) could fly through the outer planet atmospheres, for global weather observations, localized storm or other disturbance investigations, wind speed measurements, polar observations, etc. Deep-diving aircraft (built with the strength to withstand many atmospheres of pressure) powered by the excess hydrogen or helium 4 may be designed to probe the higher density regions of the gas giants. Outer planet atmospheric properties, atmospheric storm data, and mission planning for future outer planet UAVs are presented.

Plume Impingement Analysis for the European Service Module Propulsion System

Abstract: Plume impingement analyses were performed for the European Service Module (ESM) propulsion system Orbital Maneuvering System engine (OMS-E), auxiliary engines, and reaction control system (RCS) engines. The heat flux from plume impingement on the solar arrays and other surfaces are evaluated. This information is used to provide inputs for the ESM thermal analyses and help determine the optimal configuration for the RCS engines.

Solar and Drag Sail Propulsion: From Theory to Mission Implementation

Abstract: Solar and drag sail technology is entering the mainstream for space propulsion applications within NASA and around the world. Solar sails derive propulsion by reflecting sunlight from a large, mirror- like sail made of a lightweight, reflective material. The continuous sunlight pressure provides efficient primary propulsion, without the expenditure of propellant or any other consumable, allowing for very high V maneuvers and long-duration deep space exploration. Drag sails increase the aerodynamic drag on Low Earth Orbit (LEO) spacecraft, providing a lightweight and relatively inexpensive approach for end-of-life deorbit and reentry. Since NASA began investing in the technology in the late 1990's, significant progress has been made toward their demonstration and implementation in space. NASA's Marshall Space Flight Center (MSFC) managed the development and testing of two different 20-m solar sail systems and rigorously tested them under simulated space conditions in the Glenn Research Center's Space Power Facility at Plum Brook Station, Ohio. One of these systems, developed by L'Garde, Inc., is planned for flight in 2015. Called Sunjammer, the 38m sailcraft will unfurl in deep space and demonstrate solar sail propulsion and navigation as it flies to Earth-Sun L1. In the Flight Center (MSFC) managed the development and testing of two different 20-m solar sail systems and rigorously tested them under simulated space conditions in the Glenn Research Center's Space Power Facility at Plum Brook Station, Ohio. One of these systems, developed by L'Garde, Inc., is planned for flight in 2015. Called Sunjammer, the 38m sailcraft will unfurl in deep space and demonstrate solar sail propulsion and navigation as it flies to Earth-Sun L1. In the interim, NASA MSFC funded the NanoSail-D, a subscale drag sail system designed for small spacecraft applications. The NanoSail-D flew aboard the Fast Affordable Science and Technology SATellite (FASTSAT) in 2010, also developed by MSFC, and began its mission after it was ejected from the FASTSAT into Earth orbit, where it remained for several weeks before deorbiting as planned. NASA recently selected two small satellite missions for study as part of the Advanced Exploration Systems (AES) Program, both of which will use solar sails to enable their scientific objectives. Lunar Flashlight, managed by JPL, will search for and map volatiles in permanently shadowed Lunar craters using a solar sail as a gigantic mirror to steer sunlight into the shaded craters. The Near Earth Asteroid (NEA) Scout mission will use the sail as primary propulsion allowing it to survey and image one or more NEA's of interests for possible future human exploration. Both are being studied for possible launch in 2017. The Planetary Society's privately funded LightSail-A and -B cubesat-class spacecraft are nearly complete and scheduled for launch in 2015 and 2016, respectively. MMA Design launched their DragNet deorbit system in November 2013, which will deploy from the STPSat-3 spacecraft as an end of life deorbit system. The University of Surrey is building a suite of cubesat class drag and solar sail systems that will be launched beginning in 2015. As the technology matures, solar sails will increasingly be used to enable science and exploration missions that are currently impossible or prohibitively expensive using traditional chemical and electric rockets. For example, the NASA Heliophysics Decadal Survey identifies no less than three such missions for possible flight before the mid-2020's. Solar and drag sail propulsion technology is no longer merely an interesting theoretical possibility; it has been demonstrated in space and is now a critical technology for science and solar system exploration.

High Input Voltage Discharge Supply for High Power Hall Thrusters Using Silicon Carbide Devices

Abstract: A power processing unit for a 15 kW Hall thruster is under development at NASA Glenn Research Center. The unit produces up to 400 VDC with two parallel 7.5 kW discharge modules that operate from a 300 VDC nominal input voltage. Silicon carbide MOSFETs and diodes were used in this design because they were the best choice to handle the high voltage stress while delivering high efficiency and low specific mass. Efficiencies in excess of 97 percent were demonstrated during integration testing with the NASA-300M 20 kW Hall thruster. Electromagnet, cathode keeper, and heater supplies were also developed and will be integrated with the discharge supply into a vacuum-rated brassboard power processing unit with full flight functionality. This design could be evolved into a flight unit for future missions that requires high power electric propulsion.

Mars Science Laboratory Descent-Stage Integrated Propulsion Subsystem: Development and Flight Performance

Abstract: On 5 August 2012, the Mars Science Laboratory mission successfully landed Curiosity, the largest interplanetary rover ever built, on the surface of Mars. The entry, descent, and landing phase of this mission was by far the most complex landing ever attempted on a planetary body. The descent-stage propulsion subsystem was explicitly developed for the guided-entry and sky-crane maneuvers that enabled precise landing of Curiosity. Development of the descent-stage propulsion system required a number of new propulsion hardware developments, incorporating technologies not normally found in spacecraft propulsion subsystems. The in-flight performance of the descent-stage propulsion system was consistent with expectations, with the exception of higher than expected delivered thrust from the Mars lander engines. The descent-stage propulsion system completed its mission with significant capability margin with respect to thruster life, maximum delivered thrust, and available propellant at touchdown.

Effect of Varying Design Options on the Transient Behavior of a Hybrid Rocket Motor

Abstract: Hybrid rockets provide compelling features for use in atmospheric and space rocket propulsion. One of the prominent applications of hybrid rockets which foster on its characteristics is the propulsion of micro air launch vehicles. In this paper, a set of design options of a hybrid rocket motor is evaluated for propulsion of micro air launch vehicles. In order to evaluate the various design options of a hybrid rocket, we developed design and performance simulation codes. A simulation code is based on a legacy interior ballistic model. MATLAB ® environment was used to develop the design and performance analysis codes and to visualize the temporal variation of performance characteristics and grain geometry during burning. We employ the developed codes to assess the replacement of solid rocket motors which are typically used in Air Launch Vehicles by hybrid rocket motors. A typical Micro Air Launch Vehicle mission to launch a 20-kg payload into a 400-km circular polar orbit is assumed. The results show that a hybrid rocket is a suitable candidate for micro air launch vehicles. The performance is improved in terms of specific impulse and thrust with smaller size in the same mission. Several design parameters of hybrid rocket motors were also evaluated and analyzed, including different fuel port geometry, type of fuels and oxidizers, number of ports, nozzle design and initial mass flux. These design parameters bring a significant effect on hybrid rocket performance and size.

Characterization on a magnetically levitated testbed for electrospray propulsion systems

Abstract: Small satellites are changing the space scene dramatically. By drastically reducing costs while still having impressive technological capabilities, their popularity among the space community is increasing at a very fast rate. Propulsion systems for these class of spacecraft are very limited. One promising technology is the ion Electrospray Propulsion System (iEPS) developed at the Space Propulsion Laboratory at MIT. Electrosprays accelerate ions present in the interface between an ionic liquid and vacuum using strong electric fields. Current thrust estimates for the iEPS modules land in the vicinity of tens of μNewtons. Measuring the small thrust produced by the devices is challenging to say the least. This thesis presents the design and development of a Magnetically Levitated Thrust Balance (MLTB) for thrust estimation of the iEPS devices. The MLTB levitates an engineering model of a small satellite using magnetic fields inside a vacuum chamber. The zero friction environment is exploited to measure the minute thrust levels produced by the electrospray thrusters. Additional sensors and actuators that provide added functionality to the instrument are also explained. A fully stand-alone Power Processing Unit (PPU) capable of generating and delivering the high voltage signals needed to drive the thrusters is explained in detail. Test results of charging behavior and lifetime characterization of the emitted current are presented as a preliminary exploration of these processes. Thesis Supervisor: Paulo C. Lozano Title: Associate Professor of Aeronautics and Astronautics

Additive Manufacturing of Low Cost Upper Stage Propulsion Components

Abstract: NASA is currently developing Additive Manufacturing (AM) technologies and design tools aimed at reducing the costs and manufacturing time of regeneratively cooled rocket engine components. These Low Cost Upper Stage Propulsion (LCUSP) tasks are funded through NASA's Game Changing Development Program in the Space Technology Mission Directorate. The LCUSP project will develop a copper alloy additive manufacturing design process and develop and optimize the Electron Beam Freeform Fabrication (EBF3) manufacturing process to direct deposit a nickel alloy structural jacket and manifolds onto an SLM manufactured GRCop chamber and Ni-alloy nozzle. In order to develop these processes, the project will characterize both the microstructural and mechanical properties of the SLMproduced GRCop-84, and will explore and document novel design techniques specific to AM combustion devices components. These manufacturing technologies will be used to build a 25K-class regenerative chamber and nozzle (to be used with tested DMLS injectors) that will be tested individually and as a system in hot fire tests to demonstrate the applicability of the technologies. These tasks are expected to bring costs and manufacturing time down as spacecraft propulsion systems typically comprise more than 70% of the total vehicle cost and account for a significant portion of the development schedule. Additionally, high pressure/high temperature combustion chambers and nozzles must be regeneratively cooled to survive their operating environment, causing their design to be time consuming and costly to build. LCUSP presents an opportunity to develop and demonstrate a process that can infuse these technologies into industry, build competition, and drive down costs of future engines.