Barry Nakazono

The Ion Propulsion System For Dawn

Summary The Dawn mission will be the first use of ion propulsion on a full up science mission for NASA. The ion propulsion system for Dawn is based on that demonstrated on Deep Space 1 with modifications necessary to accommodate multiple thrusters, to make the system single fault tolerant, to reduce the mass of the mechanical gimbals, and to accommodate a much larger propellant load. To rendezvous with the two heaviest main-belt asteroids, Vesta and Ceres, Dawn will carry 450 kg of xenon, whereas DS 1 carried only 8 1.5 kg of xenon. Acknowledgements The work described in this paper was conducted, in part, by the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration. References 1. 2. 3. 4. 5. 6. M. D. Rayman, P. Varghese, D. H. Lehman, and L. L. Livesay, “Results From The Deep Space 1 Technology Validation Mission,’D IAA-99- IAA. 1 1.2.01, Presented at the 50th International Astronautical Congress, Amster#am, The Netherlands, 4-8 October, 1999, Acta Astronautica 47, p. 475 (2000). M. D. Rayman and P. Varghese, “The Deep Space 1 Extended Mission,” Acta Astronautica Brophy, J. R., et al., “Ion Propulsion System (NSTAR) DS 1 Technology Validation Report,” JPL Publication 00-1 0, October 2000. J. E. Polk, et al., “Validation of the NSTAR Ion Propulsion System on the Deep Space One Mission: Overview and Initial Results,” AIAA 99-2274, presented at the 35th Joint Propulsion Conference and Exhibit, 20-24 June 1999, Los Angeles, California. J. E. Polk, et al., “Demonstration of the NSTAR Ion Propulsion System on the Deep Space One Mission, IEPC-01-075, Presented @t the 27th International Electric Propulsion iconference, Pasadena, CA, 15- 19 October, 2001. Brophy,

A Hybrid Mars Ascent Vehicle Concept for Low Temperature Storage and Operation

A hybrid propulsion system presents many advantages for a potential Mars Ascent Vehicle including high specific impulse, restartability and predicted excellent low temperature survivability. This additional benefit of low temperature storage and operation could substantially reduce the power required to maintain the system while on Mars and therefore decrease the total landed system mass required for the system. A new wax-based hybrid fuel has been formulated to realize these low temperature benefits, while still preserving high performance (Isp). The freezing point of the oxidizer can be selected to match the capabilities of the fuel, in this case Mixed Oxides of Nitrogen has been selected. The main disadvantages of this system are associated with the relatively low technology readiness level of the selected hybrid propulsion system for operation on Mars. However, technology development efforts are currently underway to advance the hybrid propulsion system to a level where it could potentially compete with heritage propulsion systems. An internal study completed at JPL in 2015 identified the single stage to orbit hybrid MAV as the lowest gross liftoff mass case from a large range of potential propulsion systems. Updates to this design are presented here.

Hybrid Propulsion In-Situ Resource Utilization Test Facility Results for Performance Characterization

Hybrid propulsion presents a promising alternative to conventional systems for in-space propulsion applications using In-Situ Propellant Production (ISPP). A hybrid propulsion test facility has been built at the NASA Jet Propulsion Laboratory (JPL) with the capability to evaluate ISPP oxidizers (gaseous mixtures of O2 and CO2) and modify fuel type and chamber geometry. This work is the result of a continuing effort at JPL to characterize the burn characteristics and performance of different propellant combinations and motor configurations in order to refine and support preliminary designs. Twelve tests using gaseous oxygen and two paraffin based fuels (Black Paraffin and SP1X) from the 2015 campaign are presented. Different reduction techniques are compared in an effort to determine the uncertainty associated with deriving a regression rate law and evaluating c* efficiency with the collected data.

Technology development and design of a hybrid Mars ascent vehicle concept

Hybrid propulsion has been investigated as an enhancing technology for a Mars Ascent Vehicle (MAV) concept as part of potential Mars Sample Return (MSR) because of its high specific impulse, restartability, and the ability to operate and survive at extremely low temperatures. A new wax-based hybrid fuel formulation has been developed that could withstand the harsh and variable Mars environment protected solely by a minimal layer of passive insulation. This formulation could provide substantial energy savings for a notional lander and is critical for rover mobility. Preliminary thermal cycle testing has determined that the formulation can survive the expected temperature extremes and lifetime thermal testing is currently underway. A complete preliminary design using this new fuel formulation combined with a low temperature oxidizer such as Mixed Oxides of Nitrogen (MON30) is presented. Several key features associated with a complete hybrid MAV concept are investigated to determine their mission suitability (e.g. Thrust Vector Control and restartable ignition options). Potential challenges along a path towards developing such a system are outlined and future work is suggested as a means of technology maturation. The hybrid design presented here was the lowest Gross Lift Off Mass (GLOM) result of a 2015 Jet Propulsion Laboratory (JPL) led MAV concept study [1].

Hybrid Propulsion In-Situ Resource Utilization Test Facility Development

Hybrid propulsion could be a potential game changing technology for several Mars applications, such as Mars Sample Return (MSR) and human exploration. A flexible hybrid test facility has been built at the Jet Propulsion Laboratory to provide data relevant to the design of such systems. This paper presents the motivations for such a system and its design. The facility is capable of testing 5 cm diameter fuel grains with gaseous oxygen and Mars in situ propellant production simulating oxidizer (varying mixtures of GO2, CO2 and CO). All currently planned tests utilize paraffin based fuels; however, alternative hybrid fuels may be used in the future. Variable length to outer diameter (L/D) ratios may also be tested to give insight on potential packaging constraints. The goal of this research is to enable the inclusion of hybrid propulsion systems in future mission design studies by determining the empirical constants in the regression rate equation for paraffin-based fuels with space storable and/or in situ oxidizers and to investigate the effect of L/D on combustion efficiency. Test results will be reported separately.

A hybrid mars ascent vehicle design and FY 2016 technology development

Hybrid propulsion is currently favored for a Mars Ascent Vehicle (MAV) concept from a thermal performance and Gross Lift Off Mass standpoint. However, it is at a relatively low level of maturity compared to conventional propulsion options. Technology development efforts are currently underway to bring hybrid propulsion to a technology readiness level that would enable its infusion into potential Mars Sample Return. A new propellant combination is being considered for this design that has excellent low temperature behavior. Preliminary results of two ground test campaigns are currently underway to characterize this propellant combination. Hotfire testing is being carried out in parallel at Parabilis Space Technologies and Space Propulsion Group. In addition to the new propellant combination, several other technologies are being pursued for a potential hybrid MAV: hypergolic ignition and Liquid Injection Thrust Vector Control. Both of these technologies have been applied in other rocket applications, e.g. liquid propulsion commonly uses hypergolic propellants and missiles, such as the Minuteman II, have used LITVC in the past. Hypergolic ignition, when oxidizer and fuel combust upon contact, is highly desirable for multiple starts required by the MAV concept. Therefore, testing at Penn State and Purdue is being completed in this area. An updated hybrid propulsion system design for a Mars Ascent Vehicle concept based on JPLs current understanding of potential Mars Sample Return requirements will be presented, leveraging the advances in technology development as well as updated understanding of how requirements may evolve.

Hybrid propulsion Mars Ascent Vehicle concept flight performance analysis

A high-fidelity simulation of a conceptual Mars Ascent Vehicle has been developed for end-to-end performance evaluation. The simulation environment is the Dynamics Simulator for Entry, Descent and Surface landing (DSENDS). The simulation work includes the modeling of the multi-body components, Martian environment, flight software and mission timeline. Using this simulation environment, the end-to-end MAV flight performance is evaluated, both in the nominal scenario and in perturbed off-nominal scenarios where model uncertainties are taken into account.

Hybrid Propulsion In-Situ Resource Utilization Test Facility Results

Hybrid rockets present a promising alternative to conventional chemical propulsion systems for In-Situ Resource Utilization (ISRU) and in-space applications. While they have many benefits for these applications, there are still many small details that require research before they can be adopted into flight systems. A flexible test facility was developed at JPL to test operation of hybrid motors at small scale (5 cm outer diameter fuel grains) over a range of conditions. Specifically, this paper studies two of the major advantages: low temperature performance and throttling. Paraffin-based hybrid rockets are predicted to have good performance at low temperatures. This could significantly decrease the overall system mass by minimizing the thermal conditioning required for Mars or outer planet applications. Therefore, the coefficient of thermal expansion and glass transition of paraffin are discussed. Additionally, deep throttling has been considered for several applications. This was a natural starting point for hotfire testing using the hybrid propulsion ISRU test facility. Additionally, short length to diameter ratio (L/D) fuel grains are tested to determine if these systems can be packaged into geometrically constrained spaces.

VAMOS: a SmallSat mission concept for remote sensing of Venusian seismic activity from orbit

The apparent youthfulness of Venus’ surface features, given a lack of plate tectonics, is very intriguing; however, longduration seismic observations are essentially impossible given the inhospitable surface of Venus. The Venus Airglow Measurements and Orbiter for Seismicity (VAMOS) mission concept uses the fact that the dense Venusian atmosphere conducts seismic vibrations from the surface to the airglow layer of the ionosphere, as observed on Earth. Similarly, atmospheric gravity waves have been observed by the European Venus Express’s Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument. Such observations would enable VAMOS to determine the crustal structure and ionospheric variability of Venus without approaching the surface or atmosphere. Equipped with an instrument of modest size and mass, the baseline VAMOS spacecraft is designed to fit within an ESPA Grande form factor and travel to Venus predominantly under its own power. Trade studies have been conducted to determine mission architecture robustness to launch and rideshare opportunities. The VAMOS mission concept was studied at JPL as part of the NASA Planetary Science Deep Space SmallSat Studies (PSDS3) program, which has not only produced a viable and exciting mission concept for a Venus SmallSat, but has also examined many issues facing the development of SmallSats for planetary exploration, such as SmallSat solar electric propulsion, autonomy, telecommunications, and resource management that can be applied to various inner solar system mission architectures.

Precision cleaning samples for science analysis using a gas-based dust removal tool

Current Mars science goals require the removal of dust from the surface of samples to expose the rock beneath the dust layer for imaging. A simple cold gas system is proposed to fill this need. A series of tests were conducted to investigate the dust suspension and entrainment phenomena under the influence of a cold gas jet in the near vacuum conditions at Mars. This paper describes the experimental set-up and results of these tests. Data was collected for more than 400 different tests in order to evaluate the influence of mass flow rate, molecular weight of the working gas, back pressure of the ambient gas, height of the nozzle above the surface, and the nozzle design. The results of these tests are summarized and presented. The test program showed that the use of a cold gas system is an effective means of clearing dust from the surface of samples and determined which design parameters are key for system performance.