Leveraging Existing EP Capabilities for the Emirates Mission to the Asteroid Belt

Leveraging Existing EP Capabilities for the Emirates Mission to the Asteroid Belt | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Leveraging Existing EP Capabilities for the Emirates Mission to the Asteroid Belt S. Green, B. Reese, R. Riley, M. Alhammadi, M. Al Ameri, O. Duchemin This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9161149/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 9 You are reading this latest preprint version Abstract The Emirates Mission to the Asteroid Belt (EMA), scheduled for launch in 2028, will conduct an eight-year, multi-target tour of seven main-belt asteroids, requiring over 10 km/s total delta-v and operations out to 3 AU. To meet these demands, the Laboratory for Atmospheric and Space Physics (LASP), in partnership with the United Arab Emirates Space Agency (UAESA), developed a Solar Electric Propulsion (SEP) architecture integrating two Safran Spacecraft Propulsion PPS®5000 Hall Effect Thrusters (HETs), a single Power Processing Unit (PPU), and Xenon Flow Controllers (XFCs) with a novel dual-pressure regulation strategy. The PPS®5000, originally developed for commercial use, has undergone extensive qualification and lifetime testing, demonstrating a cumulative impulse of 17.24 MN·s per thruster, throttling capability from 0.3 kW to 5 kW, and operational margins supporting EMA's power, xenon throughput, and lifetime requirements. The dual inlet-pressure XFC configuration enables precise flow control across the full thruster operating range while remaining within thermothrottle current qualification limits. System-level coupled tests confirmed full PPU–XFC–HET compatibility across the extended operating range and current environments. This heritage-unit based SEP system minimizes technical risk while delivering the efficiency, scalability, and flexibility required for EMA and future deep-space missions with similar high-delta-v needs. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 1. Introduction The United Arab Emirates (UAE) has rapidly expanded its role in space exploration, achieving a major milestone in 2021 with the successful Mars orbit insertion of the Emirates Mars Mission's Hope probe. Building on this momentum, and in alignment with the UAE National Space Strategy 2030 to foster scientific and technological advancement among future generations, the UAE Space Agency (UAESA) is now developing the Emirates Mission to the Asteroid Belt (EMA). Scheduled for launch in 2028, EMA will visit seven main-belt asteroids to deepen our understanding of the early solar system, the origins of water on terrestrial planets, and the potential for resource utilization within the asteroid belt [ 1 ]. To support the mission's demanding propulsion and trajectory requirements, including a high delta-v profile reaching up to 3 AU, the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder has designed a solar electric propulsion system, developed in partnership with UAESA, and specifically tailored to meet the needs of EMA. The primary scientific objective of EMA is to investigate the origin and evolution of water-rich asteroids. The mission aims to determine where these bodies formed, how they relate to meteorite populations, and what their chemical composition reveals about the history of the main asteroid belt. Scientific investigations will include mapping volatile content and surface mineralogy, studying geological history and internal structure, and characterizing thermophysical properties. In parallel, EMA will assess the resource potential of these asteroids to support future in-situ resource utilization. The mission will also monitor solar energetic particles throughout its journey to contribute new insights into heliospheric dynamics [ 1 ]. 2. Mission Trajectory The EMA mission design features a complex interplanetary trajectory that includes three planetary gravity assists (Venus, Earth, and Mars), six asteroid flybys, and a rendezvous with a seventh target. This trajectory enables EMA to encounter a diverse selection of main-belt asteroids, including (623) Chimaera, (13294) Rockox, and (10253) Westerwald, as well as three additional objects: (88055) 2000 VA28, (23871) 1998 RC76, and (59980) 1999 SG6. Following an initial flyby of the seventh target, (269) Justitia, the spacecraft will conduct proximity operations at the final rendezvous target, allowing for refined navigation and detailed scientific observations at multiple orbital altitudes [ 1 ]. The full trajectory and cruise phase delta-v and propellant budgets, shown in Fig. 1 and Table 1 , respectively, highlight the mission's propulsion requirements and the relative timing of major events. Table 1 EMA cruise phase delta-v and xenon propellant budget [ 2 ] Thrust Arc Delta-v (m/s) Xenon Mass (kg) Cruise to Earth 1,155 152 Thruster Characterizations 71 9.9 Cruise to Westerwald 1,865 224 Cruise to Chimaera 483 58 Cruise to Rockox 956 109 Cruise to Mars 1,670 169 Cruise to 88055 1,630 155 Cruise to 23871 342 37 Cruise to 59980 526 60 Cruise to Justitia 1,340 131 Cruise Phase Subtotal 10,003 1,104.9 3. Mission System Drivers EMA relies on a high-efficiency Solar Electric Propulsion (SEP) system for all primary trajectory and proximity operations maneuvers. This architecture is complemented by a hydrazine blowdown system, which supports early Trajectory Correction Maneuvers near Venus, assists with momentum management, and enables safe mode recovery. The mission's ambitious trajectory necessitates approximately 1,200 kg of xenon propellant over more than eight years to deliver nearly 10 km/s of delta-v, far exceeding the qualified maximum throughput of most existing Hall Effect Thrusters (HETs). Standard 5 kW-class HETs are typically optimized for GTO/GEO applications, operating efficiently at fixed power levels between 3 kW and 5 kW. In contrast, EMA demands a flexible propulsion system capable of supporting a broad operating range from 1 kW to 5 kW to accommodate variable mission phases and power availability. To address these requirements, candidate thruster technologies were evaluated with an emphasis on throughput capability, throttling flexibility, and heritage. This process identified the PPS®5000 Hall Effect Thruster as the most promising option. Although not originally designed for deep-space missions, this hardware has demonstrated capabilities that make it well-suited to this class of mission. The following section summarizes its performance characteristics and relevance to EMA's operational profile. 4. Thruster Performance and Applicability Comprehensive testing performed by Safran Spacecraft Propulsion (SSP) across the mission's power range provides valuable insights into the PPS®5000's versatility, robustness, and suitability for EMA. The thruster was originally qualified to ten reference operating points to support a broader operating domain than typically required for traditional commercial missions (see Fig. 2 ). This wide domain enables flexible integration with variable power architectures, a key requirement for deep-space operations. The PPS®5000's lifetime qualification exceeds the mission's requirements, with a demonstrated total impulse capability of 17.24 MN·s, supported by 19,460 hours of accumulated firing time and 974.5 kg of xenon throughput per thruster (Table 2 ). This qualified throughput nearly doubles that of previous high-capability thrusters, such as the SPT-140, which was qualified to 500 kg [ 3 – 4 ]. Table 2 PPS®5000 Cumulative Life Qualification Summary [ 5 ] Total Impulse (MN.s) Total Hours of Operation (Hrs) ON/OFF Cycles (#) Total Xenon Throughput (kg) 17.24 19,460 9,595 974.5 4.1. Mission Requirements for Thruster Life A summary comparison between EMA's electric propulsion demands and the PPS®5000's certified capabilities is provided in Table 3 . This comparison demonstrates that all key parameters, including power range, total impulse, and xenon throughput, are met with sufficient margins. Table 3 Comparison of EMA EP System Requirements vs PPS®5000 Qualified Performance Parameter EMA Mission Requirement PPS®5000 Capability Power Range 1-5kW 0.3-5kW Total Impulse (two thrusters) 22.4 MN.s 34.4 MN.s Xenon Throughput Up to 1250kg Up to 1949 kg Thrust/Isp Performance Varies by phase Meets Requirement A detailed review of the PPS®5000 lifetime qualification campaign confirmed that EMA's planned operational profile is well within the bounds of certified performance. The qualification campaign includes a 50% margin on total impulse, providing ample buffer to accommodate potential variations in wear rates or operational conditions over the course of the mission. The qualification testing strategy was intentionally designed to conservatively envelope a wide range of operating points. Following the standard rule of thumb that wear mechanisms are bounded by the highest qualified power at a given discharge voltage, operation at 300 V is fully covered by OP5 (5 kW, 300 V), while operation at 375–400 V is encompassed by OP8 (4.5 kW, 375 V). Lifetime testing was split approximately evenly between OP5 and OP8, ensuring that wear mechanisms associated with both low- and high-voltage regimes were thoroughly exercised [ 5 ]. EMA's expected usage, with roughly half of the mission in the 300 V regime and half in the 375–400 V regime, is therefore fully encompassed within the demonstrated qualification envelope. Additionally, SSP has observed no unexpected or voltage-specific degradation modes across these conditions. While minor differences in wear rates between voltages may exist at constant power, long-duration testing to date has revealed no measurable divergence in overall lifetime or erosion behavior [ 5 ]. This consistency supports the conclusion that the certified qualification envelope, with its built-in margin, provides high confidence that EMA's thruster performance will remain stable and predictable across the full mission duration. 4.2. Nominal and Extended Power Range Performance In its mission-relevant power range of 1 kW to 5 kW, the PPS®5000 has demonstrated thrust levels from 51 mN to 290 mN and specific impulse values ranging from 1231 s to 1975 s (Fig. 3 ) [ 5 ]. This wide performance envelope enables propellant-efficient maneuvering during both higher- and lower-power cruise phases and proximity operations, even at reduced solar flux levels at distances up to 3 AU. The ability to deliver adequate thrust across this range is essential for deep-space missions requiring continuous trajectory shaping and flexible power allocation. While high-power performance defines the cruise-phase capability, EMA's trajectory also includes extended periods with reduced available power, particularly at greater heliocentric distances. To ensure continuous thrusting during these phases, the PPS®5000's low-power behavior was characterized to confirm stability, efficiency, and predictable performance across the full mission envelope. 4.3. Low-Power Characterization and Adaptive Operation Additional short-duration test campaigns characterized the PPS®5000's low-power performance across a range of wear states, simulating conditions expected during mission phases with limited power availability. These tests demonstrated stable operation from 2 kW down to 0.3 kW, with predictable efficiency, reduced current oscillation amplitudes, and effective performance at low flowrates and current levels. This confirmed the thruster's ability to function reliably across a wide power spectrum. Notably, the thruster maintained stable discharge and efficiency using a fixed cathode-to-anode flowrate split ratio over the entire extended operating domain (Fig. 4 ), eliminating the need for additional cathode flow adjustments at low power [ 5 ]. In parallel with performance mapping, a review of potential degradation modes was conducted to assess whether extended operation at low power could influence thruster lifetime. This evaluation is crucial to ensuring the PPS®5000's certified margins remain valid over the mission's full eight-year operational period. 4.4. Failure Mechanisms This thorough review of credible failure mechanisms indicated that extended operation at reduced power levels does not degrade the thruster's total impulse capability over its qualified lifetime [ 5 ]. This combination of low-power adaptability, stable performance, and proven qualification margins makes the PPS®5000 a high-performance and low-risk solution for long-duration, propellant-constrained missions such as EMA. To further ensure long-term reliability and justify mission extensions or off-nominal operations, the PPS®5000 program also implemented an extensive cathode life testing campaign. Multiple qualification and flight-standard hollow cathodes were operated under varying throttling and cycling profiles, with some subjected to Destructive Physical Analysis (DPA) to identify and characterize wear modes. These tests confirmed robust performance across all profiles, including operation with oxygen-contaminated xenon, and supported lifetime modeling, material equivalence qualification, and process validation. Cathode CD024, tested extensively both in thruster and stand-alone modes, was successfully re-coupled with the EQM1 thruster at the end of the qualification program, demonstrating preserved functionality after prolonged use [ 5 ]. With thruster performance and life capability validated, attention shifted to integrating the electric propulsion system into a single-string spacecraft architecture to minimize mass, complexity, and power system overhead while meeting mission reliability requirements. This required careful coordination between power processing, xenon storage and delivery, and mechanical gimbaling to maintain precise thrust vector control. 5. System Description 5.1. EP Overview To implement EMA's EP system approach in a cost-effective, single-string configuration, the system integrates a single PPU, two XFCs, and two PPS®5000 HETs. Power generation across heliocentric distances from 1 AU to 3 AU is provided by two 20-kW solar arrays paired with a 100 V regulated power bus. As shown in the Electric Propulsion System Block Diagram (Fig. 5 ), the PPU delivers regulated electrical power from the spacecraft main power architecture, conditioning it to support a thruster discharge operational power range from as low as 1 kW up to 5 kW. The PPU contains an internal switching unit which allows selection between the two HETs. 5.2. Xenon Propulsion System The Xenon Propulsion System Pneumatic Block Diagram is presented in Fig. 6 . A single composite overwrap pressure vessel (COPV) provides storage for up to 1,250 kg of xenon at a maximum launch pressure of 1,250 psia (8.6 MPa). Two fill/drain valves provide access for ground testing and propellant loading operations. The Pressure Management Assembly consists of two independent circuits, each with two latch valves in series for propellant isolation and a single-stage mechanical pressure regulator. Pressure transducers provide redundant state-of-health monitoring both at the tank and at the regulated pressure outlets. Downstream, the flow splits to the two XFCs providing the necessary inlet pressure. The XFCs consist of an inlet filter and two in-series solenoid valves, providing flow isolation. Finer flow regulation is performed by controlling the current to the thermothrottle. Two orifices or flow restrictors within each XFC provide the appropriate cathode-to-anode flow ratio to the HETs. The HETs are also mounted on gimbal platforms which provide thrust vector control. The design relies on compatible, flight-qualified units for the HETs, XFCs (Fig. 7 ), and the PPU. To mitigate development and schedule risks, the project's objective was to use proven flight hardware wherever possible. This was especially important because the PPU performs closed-loop control of the XFC's thermothrottle current to regulate xenon flow to the thruster. To support this control architecture, it was necessary to retain the existing XFC thermothrottle design and control interface. 5.3. XFC Impacts The XFC's flow regulation capability depends primarily on inlet pressure, reference temperature, and the applied thermothrottle current. The electrical current I _tt governs the amount of heat transferred to the xenon gas, which affects gas viscosity due to its temperature dependence and, in turn, modifies the Reynolds number. As a result, increasing I _tt raises the capillary temperature and reduces the xenon flow rate; conversely, decreasing I _tt reduces capillary temperature and increases xenon flowrate [ 7 ]. Figure 8 illustrates how the typical XFC flow rate varies with thermal and inlet pressure setpoints across the full range of input current, enabling a broad flow capability [ 6 ]. A key challenge in operating across the full 1 kW to 5 kW power range is the need to approximately double the typical XFC flow rate range provided by a single inlet pressure setpoint. This wide dynamic range must be met while staying within the bounds of qualified thermothrottle current settings. To address this, the proper selection of XFC inlet pressure was found to be critical. EMA collaborated with SSP to identify and characterize two inlet pressure setpoints capable of supporting the required expanded flow range while maintaining compatibility with flight-qualified thermothrottle operation [ 3 ]. Figures 9 and 10 illustrate the concept and demonstrate that the two inlet pressure setpoints encompass the desired mass flowrate range throughout EMA's expected operating-temperature range. These results formed the basis for adopting a dual inlet pressure strategy that balances technical performance with cost and risk considerations. Implementing dual inlet pressures required an extensive trade study to assess architectural changes that could meet flow rate requirements while minimizing technical risk, cost, and schedule impacts. The selected approach, using a dual-setpoint mechanical regulator, offered a unique, cost-effective, and simple solution to support the full flow range. This decision was validated through a recently completed PPU–XFC–HET coupling test, which confirmed critical system compatibility across the extended operating domain and demonstrated that the XFCs, under closed-loop PPU control, can reliably deliver the required flow rates when supplied by the Pressure Management Assembly's dual-regulator setpoint design. The combination of a high-performance thruster, precise xenon flow control, and flight-qualified SEP units provides a complete solution to EMA's propulsion challenges. System-level validation efforts have confirmed hardware compatibility and stable operation across a range of thermal conditions, flow rates, and power levels. These results demonstrate that the propulsion system is ready to support EMA's dynamic mission profile, including its extended cruise and proximity operations. The integrated design balances innovation with heritage hardware, providing a reliable foundation for deep-space missions with similar technical constraints and performance goals. 6. Conclusion The Emirates Mission to the Asteroid Belt (EMA) demonstrates how a flight-qualified Hall Effect Thruster system can be adapted to meet the demands of a long-duration, high-delta-v interplanetary mission. The PPS®5000-based EP architecture, with its extended throttle range and validated dual-pressure xenon flow control, offers a low-risk, high-performance approach that balances capability, cost, and operational simplicity. This work underscores the value of collaborative development, exemplified by the partnership between LASP and the UAE Space Agency, and the role of rigorous ground validation in reducing mission risk and expanding the reach of electric propulsion. EMA's electric-propulsion and xenon-management systems form a proven blueprint for deep-space missions with high delta-v and variable power requirements. The experience gained will fuel the development of scalable, adaptable solar electric propulsion architectures that open new frontiers for science, logistics, and resource utilization across the solar system. Abbreviations Symbol Definition A amperes AU astronomical unit hrs hours I_d discharge current I_tt thermothrottle current kg kilogram km/s kilometers per second kW kilowatt mN millinewton MN·s meganewton seconds MPa megapascal m/s meters per second mg/s milligrams per second psia pounds per square inch absolute s seconds U_d discharge voltage V volts W watts Declarations Funding: Funding for the co-development of the Emirates Mission to Explore the Asteroid Belt is provided by the United Arab Emirates Space Agency to its knowledge partner, the University of Colorado Boulder's Laboratory for Atmospheric and Space Physics. Competing interests: The authors have no relevant financial or non-financial interests to disclose. Data availability: Not applicable. Code availability: Not applicable. Authors' contributions: S. Green led propulsion systems engineering and manuscript preparation. B. Reese contributed to spacecraft systems management and manuscript review. R. Riley contributed to electrical power systems analysis and manuscript review. M. Alhammadi contributed to xenon propellant analysis and manuscript review. M. Al Ameri contributed to spacecraft management and manuscript review. O. Duchemin provided thruster qualification data and contributed to manuscript review. All authors read and approved the final manuscript. References Al Maxmia H, Hayne PO, Alsaed N, Landis M, Bottke WF (2024) Harish. The Emirates Mission to the Asteroid Belt: Science Overview. IAC-24-A3-4B-3-x86216. 75th International Astronautical Congress, Milan, Italy https://doi.org/10.52202/078357-0085 Alhammadi M, Green S (2025) Pre-flight Assessments of Xenon Propellant Usage Uncertainties for the Emirates Mission to the Asteroid Belt. IEPC 2025 – 501. 39th International Electric Propulsion Conference, London, UK Duchemin O, Rabin J, Coduti G, Diome M, Cavelan X, Leroi V, Le Meur P, Edwards C, Fallis B (2022) Extended Qualification Life Test of the PPS®5000 Hall Thruster Unit. SP 2022 – 364. 8th Space Propulsion Conference, Estoril, Portugal Snyder JS, Goebel DM et al (2019) Electric Propulsion for the Psyche Mission. IEPC 2019 – 244. 36th International Electric Propulsion Conference, Vienna, Austria Duchemin O, Coduti G, Rabin J, Krzymushi T, Leroi V (2024) Extended Throttling Range Characterization of the PPS®5000 Hall Thruster. SP 2024 – 583. 9th Space Propulsion Conference, Glasgow, Scotland Diome M, Rabin J, Duchemin O, Balika L, Lonchard JM, Cavelan X (2017) Development of a Xenon Flow Controller for the PPS®5000 Hall Thruster Unit. IEPC 2017 – 417. 35th International Electric Propulsion Conference, Atlanta, Georgia Duchemin O, Rabin J, Balika L, Coduti G, Vial V, Vuglec D, Cavelan X (2019) Qualification Status of the PPS®5000 Hall Thruster Unit. IEPC 2019 – 906. 36th International Electric Propulsion Conference, Vienna, Austria Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 13 May, 2026 Reviews received at journal 13 May, 2026 Reviews received at journal 08 May, 2026 Reviewers agreed at journal 06 Apr, 2026 Reviewers agreed at journal 30 Mar, 2026 Reviewers invited by journal 24 Mar, 2026 Editor assigned by journal 22 Mar, 2026 Submission checks completed at journal 22 Mar, 2026 First submitted to journal 18 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9161149","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":611570859,"identity":"797effdf-ce35-44b4-8dcc-6c3c9c35a031","order_by":0,"name":"S. Green","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABJklEQVRIiWNgGAWjYJADxgcPoIwDIKIBSEgQ0MJskABlEa2FTYIoLfIz0h9+LmCozedn7z1WkVBTl8fAfvjAgY977GT7GZgP3ubB1GJwIyFZegbDccuZPefSbiQcO1zMwJOWcHDGs2TjmQ1sydbYtEgkHJDmYThmYHAjx+xGAtuBxAYJHoPDPAeYEzcc4DGTxqJFfkZi82+QFvv7b8wKEv7VwbTUA7Xwf8OmheFGMhtQvMbAQILHjCGxjRmm5TDIFjZsWgzOPGOz5jE4YCBxJsdYIrHvcDEb2C8HjhvPbGYztpyDxWHt6Y9v81TUGfC3nzH88OFbXR4/++GDDz4cqJbtZ29+eOMNFodB7DoMZyawwZnMuJSDQR1CC151o2AUjIJRMCIBAGSUZ7hrn/D4AAAAAElFTkSuQmCC","orcid":"","institution":"Laboratory for Atmospheric and Space Physics","correspondingAuthor":true,"prefix":"","firstName":"S.","middleName":"","lastName":"Green","suffix":""},{"id":611570862,"identity":"2f4b3242-6a83-46d6-b5f9-73ddc79015b3","order_by":1,"name":"B. Reese","email":"","orcid":"","institution":"Laboratory for Atmospheric and Space Physics","correspondingAuthor":false,"prefix":"","firstName":"B.","middleName":"","lastName":"Reese","suffix":""},{"id":611570864,"identity":"69909d85-3147-4ef3-8e8d-a59cc1e834ae","order_by":2,"name":"R. Riley","email":"","orcid":"","institution":"Laboratory for Atmospheric and Space Physics","correspondingAuthor":false,"prefix":"","firstName":"R.","middleName":"","lastName":"Riley","suffix":""},{"id":611570866,"identity":"463f8516-4978-4c26-8118-b45cb59ca832","order_by":3,"name":"M. Alhammadi","email":"","orcid":"","institution":"Technology Innovation Institute","correspondingAuthor":false,"prefix":"","firstName":"M.","middleName":"","lastName":"Alhammadi","suffix":""},{"id":611570881,"identity":"f6f04c20-0050-4337-9fbd-9a52d90cb3ff","order_by":4,"name":"M. Al Ameri","email":"","orcid":"","institution":"United Arab Emirates Space Agency","correspondingAuthor":false,"prefix":"","firstName":"M.","middleName":"Al","lastName":"Ameri","suffix":""},{"id":611570882,"identity":"c9c436ce-cfe3-4de7-913b-cb449ff21523","order_by":5,"name":"O. Duchemin","email":"","orcid":"","institution":"Safran Spacecraft Propulsion","correspondingAuthor":false,"prefix":"","firstName":"O.","middleName":"","lastName":"Duchemin","suffix":""}],"badges":[],"createdAt":"2026-03-18 15:38:29","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9161149/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9161149/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105470367,"identity":"8d3f2468-3c81-4e1c-8690-f4ca95a0ff01","added_by":"auto","created_at":"2026-03-26 11:43:16","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":285138,"visible":true,"origin":"","legend":"\u003cp\u003eEMA Mission Flight Trajectory\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-9161149/v1/194b316c4f7382d2272e99ee.png"},{"id":105470357,"identity":"f455edbf-90f4-4e53-8219-1d1d444f112f","added_by":"auto","created_at":"2026-03-26 11:43:14","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":80003,"visible":true,"origin":"","legend":"\u003cp\u003ePPS®5000 qualified operating domain [5]\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-9161149/v1/2a572ed7c8fda6e4eddaed1c.png"},{"id":105470366,"identity":"fa6c9f39-af45-46aa-875f-b8ace45e5627","added_by":"auto","created_at":"2026-03-26 11:43:16","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":88598,"visible":true,"origin":"","legend":"\u003cp\u003ePPS®5000 performance at BOL over extended range [5]\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-9161149/v1/5e0ae0a3494dd98a4c891fd5.png"},{"id":105470382,"identity":"729f2e4d-68d9-49e6-8e15-04c0d8fb454f","added_by":"auto","created_at":"2026-03-26 11:43:28","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":42349,"visible":true,"origin":"","legend":"\u003cp\u003eExtended\u003cstrong\u003e \u003c/strong\u003ePPS®5000 operating domain [5]\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-9161149/v1/326dfdfba465046030c0d572.png"},{"id":105470369,"identity":"d7a0c204-a9cd-4a12-958e-65002c2529a6","added_by":"auto","created_at":"2026-03-26 11:43:18","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":24974,"visible":true,"origin":"","legend":"\u003cp\u003eElectric propulsion system block diagram\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-9161149/v1/325869600b81c4fd9b272ec8.png"},{"id":105470371,"identity":"c6db2524-c9c3-40c6-8925-17822d45210f","added_by":"auto","created_at":"2026-03-26 11:43:18","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":43879,"visible":true,"origin":"","legend":"\u003cp\u003eEMA electric propulsion system pneumatic block diagram\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-9161149/v1/e7f0af8c62aa4901971f6f45.png"},{"id":105470379,"identity":"d40c0500-fcc8-4faa-9e5a-89e044cf7780","added_by":"auto","created_at":"2026-03-26 11:43:28","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":540088,"visible":true,"origin":"","legend":"\u003cp\u003ePPS®5000 Hall Thruster Unit (a) and\u003cstrong\u003e \u003c/strong\u003eXFC-5000 (b) [6]\u003c/p\u003e","description":"","filename":"image7.png","url":"https://assets-eu.researchsquare.com/files/rs-9161149/v1/394064914cc93f1299604836.png"},{"id":105470380,"identity":"396d84f0-2d26-4947-8ba8-21a2d5704b92","added_by":"auto","created_at":"2026-03-26 11:43:28","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":232059,"visible":true,"origin":"","legend":"\u003cp\u003eTypical XFC flowrate as function of thermothrottle current [6]\u003c/p\u003e","description":"","filename":"image8.png","url":"https://assets-eu.researchsquare.com/files/rs-9161149/v1/ffad269f811a6eb36a8f3559.png"},{"id":105752093,"identity":"89a7ca9c-c587-4931-a397-df6a514c42fb","added_by":"auto","created_at":"2026-03-30 15:54:45","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":84131,"visible":true,"origin":"","legend":"\u003cp\u003eDual pressure setpoint concept\u003c/p\u003e","description":"","filename":"image9.png","url":"https://assets-eu.researchsquare.com/files/rs-9161149/v1/2f09ac08caf4089ab076047b.png"},{"id":105470337,"identity":"16455ea8-5104-4eb2-a704-05726ef622fd","added_by":"auto","created_at":"2026-03-26 11:43:12","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":86321,"visible":true,"origin":"","legend":"\u003cp\u003eEMA XFC flowrate characterization testing\u003c/p\u003e","description":"","filename":"image10.png","url":"https://assets-eu.researchsquare.com/files/rs-9161149/v1/243d84fd6f4a2771f140cb32.png"},{"id":105753240,"identity":"1f86064b-f27a-4aa2-aa12-415e2afca40b","added_by":"auto","created_at":"2026-03-30 16:08:15","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2053988,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9161149/v1/594fc7e5-8acb-492c-a22d-27e01373a918.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Leveraging Existing EP Capabilities for the Emirates Mission to the Asteroid Belt","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThe United Arab Emirates (UAE) has rapidly expanded its role in space exploration, achieving a major milestone in 2021 with the successful Mars orbit insertion of the Emirates Mars Mission's \u003cem\u003eHope\u003c/em\u003e probe. Building on this momentum, and in alignment with the UAE National Space Strategy 2030 to foster scientific and technological advancement among future generations, the UAE Space Agency (UAESA) is now developing the Emirates Mission to the Asteroid Belt (EMA). Scheduled for launch in 2028, EMA will visit seven main-belt asteroids to deepen our understanding of the early solar system, the origins of water on terrestrial planets, and the potential for resource utilization within the asteroid belt [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTo support the mission's demanding propulsion and trajectory requirements, including a high delta-v profile reaching up to 3 AU, the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder has designed a solar electric propulsion system, developed in partnership with UAESA, and specifically tailored to meet the needs of EMA.\u003c/p\u003e \u003cp\u003eThe primary scientific objective of EMA is to investigate the origin and evolution of water-rich asteroids. The mission aims to determine where these bodies formed, how they relate to meteorite populations, and what their chemical composition reveals about the history of the main asteroid belt. Scientific investigations will include mapping volatile content and surface mineralogy, studying geological history and internal structure, and characterizing thermophysical properties. In parallel, EMA will assess the resource potential of these asteroids to support future in-situ resource utilization. The mission will also monitor solar energetic particles throughout its journey to contribute new insights into heliospheric dynamics [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"2. Mission Trajectory","content":"\u003cp\u003eThe EMA mission design features a complex interplanetary trajectory that includes three planetary gravity assists (Venus, Earth, and Mars), six asteroid flybys, and a rendezvous with a seventh target. This trajectory enables EMA to encounter a diverse selection of main-belt asteroids, including (623) Chimaera, (13294) Rockox, and (10253) Westerwald, as well as three additional objects: (88055) 2000 VA28, (23871) 1998 RC76, and (59980) 1999 SG6. Following an initial flyby of the seventh target, (269) Justitia, the spacecraft will conduct proximity operations at the final rendezvous target, allowing for refined navigation and detailed scientific observations at multiple orbital altitudes [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe full trajectory and cruise phase delta-v and propellant budgets, shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, respectively, highlight the mission's propulsion requirements and the relative timing of major events.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEMA cruise phase delta-v and xenon propellant budget [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThrust Arc\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDelta-v (m/s)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eXenon Mass (kg)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCruise to Earth\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1,155\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e152\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThruster Characterizations\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCruise to Westerwald\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1,865\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e224\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCruise to Chimaera\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e483\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e58\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCruise to Rockox\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e956\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e109\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCruise to Mars\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1,670\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e169\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCruise to 88055\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1,630\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e155\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCruise to 23871\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e342\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCruise to 59980\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e526\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e60\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCruise to Justitia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1,340\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e131\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCruise Phase Subtotal\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e10,003\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e1,104.9\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"3. Mission System Drivers","content":"\u003cp\u003eEMA relies on a high-efficiency Solar Electric Propulsion (SEP) system for all primary trajectory and proximity operations maneuvers. This architecture is complemented by a hydrazine blowdown system, which supports early Trajectory Correction Maneuvers near Venus, assists with momentum management, and enables safe mode recovery.\u003c/p\u003e \u003cp\u003eThe mission's ambitious trajectory necessitates approximately 1,200 kg of xenon propellant over more than eight years to deliver nearly 10 km/s of delta-v, far exceeding the qualified maximum throughput of most existing Hall Effect Thrusters (HETs). Standard 5 kW-class HETs are typically optimized for GTO/GEO applications, operating efficiently at fixed power levels between 3 kW and 5 kW. In contrast, EMA demands a flexible propulsion system capable of supporting a broad operating range from 1 kW to 5 kW to accommodate variable mission phases and power availability.\u003c/p\u003e \u003cp\u003eTo address these requirements, candidate thruster technologies were evaluated with an emphasis on throughput capability, throttling flexibility, and heritage. This process identified the PPS\u0026reg;5000 Hall Effect Thruster as the most promising option. Although not originally designed for deep-space missions, this hardware has demonstrated capabilities that make it well-suited to this class of mission. The following section summarizes its performance characteristics and relevance to EMA's operational profile.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"4. Thruster Performance and Applicability","content":"\u003cp\u003eComprehensive testing performed by Safran Spacecraft Propulsion (SSP) across the mission's power range provides valuable insights into the PPS\u0026reg;5000's versatility, robustness, and suitability for EMA. The thruster was originally qualified to ten reference operating points to support a broader operating domain than typically required for traditional commercial missions (see Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This wide domain enables flexible integration with variable power architectures, a key requirement for deep-space operations.\u003c/p\u003e \u003cp\u003eThe PPS\u0026reg;5000's lifetime qualification exceeds the mission's requirements, with a demonstrated total impulse capability of 17.24 MN\u0026middot;s, supported by 19,460 hours of accumulated firing time and 974.5 kg of xenon throughput per thruster (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This qualified throughput nearly doubles that of previous high-capability thrusters, such as the SPT-140, which was qualified to 500 kg [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePPS\u0026reg;5000 Cumulative Life Qualification Summary [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal Impulse (MN.s)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTotal Hours of Operation (Hrs)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eON/OFF Cycles (#)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTotal Xenon Throughput (kg)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e17.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19,460\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9,595\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e974.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e4.1. Mission Requirements for Thruster Life\u003c/h2\u003e \u003cp\u003eA summary comparison between EMA's electric propulsion demands and the PPS\u0026reg;5000's certified capabilities is provided in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. This comparison demonstrates that all key parameters, including power range, total impulse, and xenon throughput, are met with sufficient margins.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of EMA EP System Requirements vs PPS\u0026reg;5000 Qualified Performance\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eEMA Mission Requirement\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePPS\u0026reg;5000 Capability\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePower Range\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1-5kW\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.3-5kW\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal Impulse (two thrusters)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22.4 MN.s\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e34.4 MN.s\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eXenon Throughput\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUp to 1250kg\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eUp to 1949 kg\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThrust/Isp Performance\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eVaries by phase\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMeets Requirement\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eA detailed review of the PPS\u0026reg;5000 lifetime qualification campaign confirmed that EMA's planned operational profile is well within the bounds of certified performance. The qualification campaign includes a 50% margin on total impulse, providing ample buffer to accommodate potential variations in wear rates or operational conditions over the course of the mission.\u003c/p\u003e \u003cp\u003eThe qualification testing strategy was intentionally designed to conservatively envelope a wide range of operating points. Following the standard rule of thumb that wear mechanisms are bounded by the highest qualified power at a given discharge voltage, operation at 300 V is fully covered by OP5 (5 kW, 300 V), while operation at 375\u0026ndash;400 V is encompassed by OP8 (4.5 kW, 375 V). Lifetime testing was split approximately evenly between OP5 and OP8, ensuring that wear mechanisms associated with both low- and high-voltage regimes were thoroughly exercised [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. EMA's expected usage, with roughly half of the mission in the 300 V regime and half in the 375\u0026ndash;400 V regime, is therefore fully encompassed within the demonstrated qualification envelope.\u003c/p\u003e \u003cp\u003eAdditionally, SSP has observed no unexpected or voltage-specific degradation modes across these conditions. While minor differences in wear rates between voltages may exist at constant power, long-duration testing to date has revealed no measurable divergence in overall lifetime or erosion behavior [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. This consistency supports the conclusion that the certified qualification envelope, with its built-in margin, provides high confidence that EMA's thruster performance will remain stable and predictable across the full mission duration.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e4.2. Nominal and Extended Power Range Performance\u003c/h2\u003e \u003cp\u003eIn its mission-relevant power range of 1 kW to 5 kW, the PPS\u0026reg;5000 has demonstrated thrust levels from 51 mN to 290 mN and specific impulse values ranging from 1231 s to 1975 s (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. This wide performance envelope enables propellant-efficient maneuvering during both higher- and lower-power cruise phases and proximity operations, even at reduced solar flux levels at distances up to 3 AU. The ability to deliver adequate thrust across this range is essential for deep-space missions requiring continuous trajectory shaping and flexible power allocation.\u003c/p\u003e \u003cp\u003eWhile high-power performance defines the cruise-phase capability, EMA's trajectory also includes extended periods with reduced available power, particularly at greater heliocentric distances. To ensure continuous thrusting during these phases, the PPS\u0026reg;5000's low-power behavior was characterized to confirm stability, efficiency, and predictable performance across the full mission envelope.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e4.3. Low-Power Characterization and Adaptive Operation\u003c/h2\u003e \u003cp\u003eAdditional short-duration test campaigns characterized the PPS\u0026reg;5000's low-power performance across a range of wear states, simulating conditions expected during mission phases with limited power availability. These tests demonstrated stable operation from 2 kW down to 0.3 kW, with predictable efficiency, reduced current oscillation amplitudes, and effective performance at low flowrates and current levels. This confirmed the thruster's ability to function reliably across a wide power spectrum. Notably, the thruster maintained stable discharge and efficiency using a fixed cathode-to-anode flowrate split ratio over the entire extended operating domain (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e), eliminating the need for additional cathode flow adjustments at low power [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn parallel with performance mapping, a review of potential degradation modes was conducted to assess whether extended operation at low power could influence thruster lifetime. This evaluation is crucial to ensuring the PPS\u0026reg;5000's certified margins remain valid over the mission's full eight-year operational period.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e4.4. Failure Mechanisms\u003c/h2\u003e \u003cp\u003eThis thorough review of credible failure mechanisms indicated that extended operation at reduced power levels does not degrade the thruster's total impulse capability over its qualified lifetime [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. This combination of low-power adaptability, stable performance, and proven qualification margins makes the PPS\u0026reg;5000 a high-performance and low-risk solution for long-duration, propellant-constrained missions such as EMA.\u003c/p\u003e \u003cp\u003eTo further ensure long-term reliability and justify mission extensions or off-nominal operations, the PPS\u0026reg;5000 program also implemented an extensive cathode life testing campaign. Multiple qualification and flight-standard hollow cathodes were operated under varying throttling and cycling profiles, with some subjected to Destructive Physical Analysis (DPA) to identify and characterize wear modes. These tests confirmed robust performance across all profiles, including operation with oxygen-contaminated xenon, and supported lifetime modeling, material equivalence qualification, and process validation. Cathode CD024, tested extensively both in thruster and stand-alone modes, was successfully re-coupled with the EQM1 thruster at the end of the qualification program, demonstrating preserved functionality after prolonged use [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWith thruster performance and life capability validated, attention shifted to integrating the electric propulsion system into a single-string spacecraft architecture to minimize mass, complexity, and power system overhead while meeting mission reliability requirements. This required careful coordination between power processing, xenon storage and delivery, and mechanical gimbaling to maintain precise thrust vector control.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"5. System Description","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e5.1. EP Overview\u003c/h2\u003e \u003cp\u003eTo implement EMA's EP system approach in a cost-effective, single-string configuration, the system integrates a single PPU, two XFCs, and two PPS\u0026reg;5000 HETs. Power generation across heliocentric distances from 1 AU to 3 AU is provided by two 20-kW solar arrays paired with a 100 V regulated power bus. As shown in the Electric Propulsion System Block Diagram (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e), the PPU delivers regulated electrical power from the spacecraft main power architecture, conditioning it to support a thruster discharge operational power range from as low as 1 kW up to 5 kW. The PPU contains an internal switching unit which allows selection between the two HETs.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e5.2. Xenon Propulsion System\u003c/h2\u003e \u003cp\u003eThe Xenon Propulsion System Pneumatic Block Diagram is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. A single composite overwrap pressure vessel (COPV) provides storage for up to 1,250 kg of xenon at a maximum launch pressure of 1,250 psia (8.6 MPa). Two fill/drain valves provide access for ground testing and propellant loading operations. The Pressure Management Assembly consists of two independent circuits, each with two latch valves in series for propellant isolation and a single-stage mechanical pressure regulator. Pressure transducers provide redundant state-of-health monitoring both at the tank and at the regulated pressure outlets. Downstream, the flow splits to the two XFCs providing the necessary inlet pressure. The XFCs consist of an inlet filter and two in-series solenoid valves, providing flow isolation. Finer flow regulation is performed by controlling the current to the thermothrottle. Two orifices or flow restrictors within each XFC provide the appropriate cathode-to-anode flow ratio to the HETs. The HETs are also mounted on gimbal platforms which provide thrust vector control.\u003c/p\u003e \u003cp\u003eThe design relies on compatible, flight-qualified units for the HETs, XFCs (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e), and the PPU. To mitigate development and schedule risks, the project's objective was to use proven flight hardware wherever possible. This was especially important because the PPU performs closed-loop control of the XFC's thermothrottle current to regulate xenon flow to the thruster. To support this control architecture, it was necessary to retain the existing XFC thermothrottle design and control interface.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e5.3. XFC Impacts\u003c/h2\u003e \u003cp\u003eThe XFC's flow regulation capability depends primarily on inlet pressure, reference temperature, and the applied thermothrottle current. The electrical current \u003cem\u003eI\u003c/em\u003e_tt governs the amount of heat transferred to the xenon gas, which affects gas viscosity due to its temperature dependence and, in turn, modifies the Reynolds number. As a result, increasing \u003cem\u003eI\u003c/em\u003e_tt raises the capillary temperature and reduces the xenon flow rate; conversely, decreasing \u003cem\u003eI\u003c/em\u003e_tt reduces capillary temperature and increases xenon flowrate [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Figure\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e illustrates how the typical XFC flow rate varies with thermal and inlet pressure setpoints across the full range of input current, enabling a broad flow capability [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eA key challenge in operating across the full 1 kW to 5 kW power range is the need to approximately double the typical XFC flow rate range provided by a single inlet pressure setpoint. This wide dynamic range must be met while staying within the bounds of qualified thermothrottle current settings. To address this, the proper selection of XFC inlet pressure was found to be critical. EMA collaborated with SSP to identify and characterize two inlet pressure setpoints capable of supporting the required expanded flow range while maintaining compatibility with flight-qualified thermothrottle operation [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Figures\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e and \u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e illustrate the concept and demonstrate that the two inlet pressure setpoints encompass the desired mass flowrate range throughout EMA's expected operating-temperature range. These results formed the basis for adopting a dual inlet pressure strategy that balances technical performance with cost and risk considerations.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eImplementing dual inlet pressures required an extensive trade study to assess architectural changes that could meet flow rate requirements while minimizing technical risk, cost, and schedule impacts. The selected approach, using a dual-setpoint mechanical regulator, offered a unique, cost-effective, and simple solution to support the full flow range. This decision was validated through a recently completed PPU\u0026ndash;XFC\u0026ndash;HET coupling test, which confirmed critical system compatibility across the extended operating domain and demonstrated that the XFCs, under closed-loop PPU control, can reliably deliver the required flow rates when supplied by the Pressure Management Assembly's dual-regulator setpoint design.\u003c/p\u003e \u003cp\u003eThe combination of a high-performance thruster, precise xenon flow control, and flight-qualified SEP units provides a complete solution to EMA's propulsion challenges. System-level validation efforts have confirmed hardware compatibility and stable operation across a range of thermal conditions, flow rates, and power levels. These results demonstrate that the propulsion system is ready to support EMA's dynamic mission profile, including its extended cruise and proximity operations. The integrated design balances innovation with heritage hardware, providing a reliable foundation for deep-space missions with similar technical constraints and performance goals.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"6. Conclusion","content":"\u003cp\u003eThe Emirates Mission to the Asteroid Belt (EMA) demonstrates how a flight-qualified Hall Effect Thruster system can be adapted to meet the demands of a long-duration, high-delta-v interplanetary mission. The PPS\u0026reg;5000-based EP architecture, with its extended throttle range and validated dual-pressure xenon flow control, offers a low-risk, high-performance approach that balances capability, cost, and operational simplicity.\u003c/p\u003e \u003cp\u003eThis work underscores the value of collaborative development, exemplified by the partnership between LASP and the UAE Space Agency, and the role of rigorous ground validation in reducing mission risk and expanding the reach of electric propulsion. EMA's electric-propulsion and xenon-management systems form a proven blueprint for deep-space missions with high delta-v and variable power requirements. The experience gained will fuel the development of scalable, adaptable solar electric propulsion architectures that open new frontiers for science, logistics, and resource utilization across the solar system.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Abbreviations","content":"\u003ctable border=\"0\" cellspacing=\"3\" cellpadding=\"0\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eSymbol\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e\u003cstrong\u003eDefinition\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eamperes\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eAU\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eastronomical unit\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003ehrs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003ehours\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eI_d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003edischarge current\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eI_tt\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003ethermothrottle current\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003ekg\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003ekilogram\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003ekm/s\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003ekilometers per second\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003ekW\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003ekilowatt\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003emN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003emillinewton\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eMN\u0026middot;s\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003emeganewton seconds\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eMPa\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003emegapascal\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003em/s\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003emeters per second\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003emg/s\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003emilligrams per second\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003epsia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003epounds per square inch absolute\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003es\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003eseconds\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eU_d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003edischarge voltage\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003evolts\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eW\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003ewatts\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e Funding for the co-development of the Emirates Mission to Explore the Asteroid Belt is provided by the United Arab Emirates Space Agency to its knowledge partner, the University of Colorado Boulder\u0026apos;s Laboratory for Atmospheric and Space Physics.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u003c/strong\u003e The authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability:\u003c/strong\u003e Not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCode availability:\u003c/strong\u003e Not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions:\u003c/strong\u003e S. Green led propulsion systems engineering and manuscript preparation. B. Reese contributed to spacecraft systems management and manuscript review. R. Riley contributed to electrical power systems analysis and manuscript review. M. Alhammadi contributed to xenon propellant analysis and manuscript review. M. Al Ameri contributed to spacecraft management and manuscript review. O. Duchemin provided thruster qualification data and contributed to manuscript review. All authors read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAl Maxmia H, Hayne PO, Alsaed N, Landis M, Bottke WF (2024) Harish. The Emirates Mission to the Asteroid Belt: Science Overview. IAC-24-A3-4B-3-x86216. 75th International Astronautical Congress, Milan, Italy \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.52202/078357-0085\u003c/span\u003e\u003cspan address=\"10.52202/078357-0085\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlhammadi M, Green S (2025) Pre-flight Assessments of Xenon Propellant Usage Uncertainties for the Emirates Mission to the Asteroid Belt. IEPC 2025\u0026thinsp;\u0026ndash;\u0026thinsp;501. 39th International Electric Propulsion Conference, London, UK\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDuchemin O, Rabin J, Coduti G, Diome M, Cavelan X, Leroi V, Le Meur P, Edwards C, Fallis B (2022) Extended Qualification Life Test of the PPS\u0026reg;5000 Hall Thruster Unit. SP 2022\u0026thinsp;\u0026ndash;\u0026thinsp;364. 8th Space Propulsion Conference, Estoril, Portugal\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSnyder JS, Goebel DM et al (2019) Electric Propulsion for the Psyche Mission. IEPC 2019\u0026thinsp;\u0026ndash;\u0026thinsp;244. 36th International Electric Propulsion Conference, Vienna, Austria\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDuchemin O, Coduti G, Rabin J, Krzymushi T, Leroi V (2024) Extended Throttling Range Characterization of the PPS\u0026reg;5000 Hall Thruster. SP 2024\u0026thinsp;\u0026ndash;\u0026thinsp;583. 9th Space Propulsion Conference, Glasgow, Scotland\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDiome M, Rabin J, Duchemin O, Balika L, Lonchard JM, Cavelan X (2017) Development of a Xenon Flow Controller for the PPS\u0026reg;5000 Hall Thruster Unit. IEPC 2017\u0026thinsp;\u0026ndash;\u0026thinsp;417. 35th International Electric Propulsion Conference, Atlanta, Georgia\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDuchemin O, Rabin J, Balika L, Coduti G, Vial V, Vuglec D, Cavelan X (2019) Qualification Status of the PPS\u0026reg;5000 Hall Thruster Unit. IEPC 2019\u0026thinsp;\u0026ndash;\u0026thinsp;906. 36th International Electric Propulsion Conference, Vienna, Austria\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-electric-propulsion","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"joeprop","sideBox":"Learn more about [Journal of Electric Propulsion](https://www.springer.com/journal/44205)","snPcode":"44205","submissionUrl":"https://submission.nature.com/new-submission/44205/3","title":"Journal of Electric Propulsion","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-9161149/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9161149/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe Emirates Mission to the Asteroid Belt (EMA), scheduled for launch in 2028, will conduct an eight-year, multi-target tour of seven main-belt asteroids, requiring over 10 km/s total delta-v and operations out to 3 AU. To meet these demands, the Laboratory for Atmospheric and Space Physics (LASP), in partnership with the United Arab Emirates Space Agency (UAESA), developed a Solar Electric Propulsion (SEP) architecture integrating two Safran Spacecraft Propulsion PPS®5000 Hall Effect Thrusters (HETs), a single Power Processing Unit (PPU), and Xenon Flow Controllers (XFCs) with a novel dual-pressure regulation strategy. The PPS®5000, originally developed for commercial use, has undergone extensive qualification and lifetime testing, demonstrating a cumulative impulse of 17.24 MN·s per thruster, throttling capability from 0.3 kW to 5 kW, and operational margins supporting EMA's power, xenon throughput, and lifetime requirements. The dual inlet-pressure XFC configuration enables precise flow control across the full thruster operating range while remaining within thermothrottle current qualification limits. System-level coupled tests confirmed full PPU–XFC–HET compatibility across the extended operating range and current environments. This heritage-unit based SEP system minimizes technical risk while delivering the efficiency, scalability, and flexibility required for EMA and future deep-space missions with similar high-delta-v needs.\u003c/p\u003e","manuscriptTitle":"Leveraging Existing EP Capabilities for the Emirates Mission to the Asteroid Belt","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-26 11:42:43","doi":"10.21203/rs.3.rs-9161149/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-05-13T20:29:36+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-13T19:47:10+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-08T19:13:41+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"228805651319290264264936533958491943998","date":"2026-04-06T13:54:28+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"86902682999407833196331250964052148403","date":"2026-03-31T00:56:58+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-24T18:31:07+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-23T00:12:02+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-22T11:27:37+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Electric Propulsion","date":"2026-03-18T15:27:38+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-electric-propulsion","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"joeprop","sideBox":"Learn more about [Journal of Electric Propulsion](https://www.springer.com/journal/44205)","snPcode":"44205","submissionUrl":"https://submission.nature.com/new-submission/44205/3","title":"Journal of Electric Propulsion","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"40b1d018-ba8d-494d-89d6-49a6fb798937","owner":[],"postedDate":"March 26th, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Revision requested","date":"2026-05-13T20:29:36+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-13T19:47:10+00:00","index":15,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-08T19:13:41+00:00","index":14,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-05-14T09:04:40+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-26 11:42:43","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9161149","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9161149","identity":"rs-9161149","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}