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NASA NTRS1992

Advanced Manned Launch System (AMLS) study

To assure national leadership in space operations and exploration in the future, NASA must be able to provide cost effective and operationally efficient space transportation. Several NASA studies and the joint NASA/DoD Space Transportation Architecture Studies (STAS) have shown the need for a multi-vehicle space transportation system with designs driven by enhanced operations and low costs. NASA is currently studying an advanced manned launch system (AMLS) approach to transport crew and cargo to the Space Station Freedom. Several single and multiple stage systems from air-breathing to all-rocket concepts are being examined in a series of studies potential replacements for the Space Shuttle launch system in the 2000-2010 time frame. Rockwell International Corporation, under contract to the NASA Langley Research Center, has analyzed a two-stage all-rocket concept to determine whether this class of vehicles is appropriate for the AMLS function. The results of the pre-phase A study are discussed.

Ehrlich, Carl F., Jr.↗
NASA NTRSDate not supplied

Structural Dynamics Observations in Space Launch System Green Run Hot Fire Testing

The Space Launch System (SLS) Core Stage (CS) Thrust Vector Control (TVC) system is comprised of eight mechanical feedback Shuttle heritage Type III TVC actuators and four RS-25 engines, each attached to a Shuttle heritage gimbal block/bearing. Two actuators are used to move each engine in two planes perpendicular to one another (i.e., pitch and yaw). The TVC system design leverages hardware from the Space Shuttle program as well as new hardware designed specifically for the Core Stage. The Green Run Hot Fire (GRHF) of the SLS Core Stage provided a flight-like ground test environment for verification of integrated vehicle TVC performance. A TVC model coupled to a vehicle structural dynamic model has been developed previously and incrementally validated in subsystem tests and simulations. Still, some aspects of TVC performance in GRHF were not anticipated. The ensuing investigation demonstrated the need for well-instrumented test environments, various levels of modeling fidelity, test-representative structural models, and caution in reuse of legacy components. This paper is the sixth installment in a seven-paper series surveying the design, engineering, test validation, and flight performance of the Core Stage Thrust Vector Control system. It introduces the salient structural dynamic phenomena uncovered in ambient and hot fire testing. During the Green Run test campaign, a comparison of ambient and hot fire step responses showed a significant change in apparent damping due to the presence of friction, challenging long standing assumptions that friction could be neglected. Additionally, the characteristic response of the engine and thrust structure during GRHF proved to be more complex than anticipated, as evidenced by the available actuator, thrust structure, and engine measurements. While the string-potentiometer based test instrumentation was intended to allow for reconstruction of the engine angles along the two control axes, the geometric placement, location uncertainty, and responses in overlapping frequency spectra revealed additional phenomena requiring further analysis and post-processing. The observations from both modal and frequency response testing during the Green Run ambient and hot fire configurations led to Engine and Core Stage FEM (finite element model) updates. When evidence of unexpected engine motion was found in engine section accelerometer data, the authors pursued additional structural analysis leading to FEM updates associated with the TVC gimbal and thrust structure. Through collaboration between structures, TVC, and flight control disciplines, the test-informed models and root-cause analysis led to confident flight rationale for the first flight of the SLS launch vehicle.

Richard K. Moore↗
NASA NTRSDate not supplied

Structural Dynamics Observations in Space Launch System Green Run Hot Fire Testing

The Space Launch System (SLS) Core Stage (CS) Thrust Vector Control (TVC) system is comprised of eight mechanical feedback Shuttle heritage Type III TVC actuators and four RS-25 engines, each attached to a Shuttle heritage gimbal block/bearing. Two actuators are used to move each engine in two planes perpendicular to one another (i.e., pitch and yaw). The TVC system design leverages hardware from the Space Shuttle program as well as new hardware designed specifically for the Core Stage. The Green Run Hot Fire (GRHF) of the SLS Core Stage provided a flight-like ground test environment for verification of integrated vehicle TVC performance. A TVC model coupled to a vehicle structural dynamic model has been developed previously and incrementally validated in subsystem tests and simulations. Still, some aspects of TVC performance in GRHF were not anticipated. The ensuing investigation demonstrated the need for well-instrumented test environments, various levels of modeling fidelity, test-representative structural models, and caution in reuse of legacy components. This paper is the sixth installment in a seven-paper series surveying the design, engineering, test validation, and flight performance of the Core Stage Thrust Vector Control system. It introduces the salient structural dynamic phenomena uncovered in ambient and hot fire testing. During the Green Run test campaign, a comparison of ambient and hot fire step responses showed a significant change in apparent damping due to the presence of friction, challenging long standing assumptions that friction could be neglected. Additionally, the characteristic response of the engine and thrust structure during GRHF proved to be more complex than anticipated, as evidenced by the available actuator, thrust structure, and engine measurements. While the string-potentiometer based test instrumentation was intended to allow for reconstruction of the engine angles along the two control axes, the geometric placement, location uncertainty, and responses in overlapping frequency spectra revealed additional phenomena requiring further analysis and post-processing. The observations from both modal and frequency response testing during the Green Run ambient and hot fire configurations led to Engine and Core Stage FEM (finite element model) updates. When evidence of unexpected engine motion was found in engine section accelerometer data, the authors pursued additional structural analysis leading to FEM updates associated with the TVC gimbal and thrust structure. Through collaboration between structures, TVC, and flight control disciplines, the test-informed models and root-cause analysis led to confident flight rationale for the first flight of the SLS launch vehicle.

Richard Moore↗
NASA NTRS2014

Space Launch System Implementation of Adaptive Augmenting Control

Given the complex structural dynamics, challenging ascent performance requirements, and rigorous flight certification constraints owing to its manned capability, the NASA Space Launch System (SLS) launch vehicle requires a proven thrust vector control algorithm design with highly optimized parameters to provide stable and high-performance flight. On its development path to Preliminary Design Review (PDR), the SLS flight control system has been challenged by significant vehicle flexibility, aerodynamics, and sloshing propellant. While the design has been able to meet all robust stability criteria, it has done so with little excess margin. Through significant development work, an Adaptive Augmenting Control (AAC) algorithm has been shown to extend the envelope of failures and flight anomalies the SLS control system can accommodate while maintaining a direct link to flight control stability criteria such as classical gain and phase margin. In this paper, the work performed to mature the AAC algorithm as a baseline component of the SLS flight control system is presented. The progress to date has brought the algorithm design to the PDR level of maturity. The algorithm has been extended to augment the full SLS digital 3-axis autopilot, including existing load-relief elements, and the necessary steps for integration with the production flight software prototype have been implemented. Several updates which have been made to the adaptive algorithm to increase its performance, decrease its sensitivity to expected external commands, and safeguard against limitations in the digital implementation are discussed with illustrating results. Monte Carlo simulations and selected stressing case results are also shown to demonstrate the algorithm's ability to increase the robustness of the integrated SLS flight control system.

Wall, John H.↗
NASA NTRS2014

Space Launch System Implementation of Adaptive Augmenting Control

Given the complex structural dynamics, challenging ascent performance requirements, and rigorous flight certification constraints owing to its manned capability, the NASA Space Launch System (SLS) launch vehicle requires a proven thrust vector control algorithm design with highly optimized parameters to robustly demonstrate stable and high performance flight. On its development path to preliminary design review (PDR), the stability of the SLS flight control system has been challenged by significant vehicle flexibility, aerodynamics, and sloshing propellant dynamics. While the design has been able to meet all robust stability criteria, it has done so with little excess margin. Through significant development work, an adaptive augmenting control (AAC) algorithm previously presented by Orr and VanZwieten, has been shown to extend the envelope of failures and flight anomalies for which the SLS control system can accommodate while maintaining a direct link to flight control stability criteria (e.g. gain & phase margin). In this paper, the work performed to mature the AAC algorithm as a baseline component of the SLS flight control system is presented. The progress to date has brought the algorithm design to the PDR level of maturity. The algorithm has been extended to augment the SLS digital 3-axis autopilot, including existing load-relief elements, and necessary steps for integration with the production flight software prototype have been implemented. Several updates to the adaptive algorithm to increase its performance, decrease its sensitivity to expected external commands, and safeguard against limitations in the digital implementation are discussed with illustrating results. Monte Carlo simulations and selected stressing case results are shown to demonstrate the algorithm's ability to increase the robustness of the integrated SLS flight control system.

VanZwieten, Tannen S.↗
NASA NTRS1991

Advanced manned launch system study status

Various concepts for advanced manned launch systems (AMLS) are examined for delivery missions to Space Station and polar orbit. Included are single- and two-stage winged systems with rocket and/or airbreathing propulsion systems. For near-term technologies, two-stage, reusable rocket systems are favored over single-stage rocket or airbreathing/rocket systems. Advanced technologies enable viable single-stage-to-orbit (SSTO) concepts. Although two-stage rocket systems continue to be lighter in dry weight than SSTOs, advantages in simpler operations may make SSTOs more cost-effective over the life cycle. Generally, rocket systems maintain a dry weight advantage over airbreathing systems at advanced technology levels, but to a lesser degree than when near-term technologies are used. More detailed understanding of vehicle systems and associated ground and flight operations requirements and procedures is essential in determining quantitative discrimination between these latter concepts.

Freeman, Delma C., Jr.↗
NASA NTRSDate not supplied

Space Launch System Artemis I CubeSats: SmallSat Vanguards of Exploration, Science and Technology

When NASA’s Space Launch System (SLS) rocket launches in 2021 with the Orion crew vehicle, it will lay the foundation for NASA’s goal of landing the first woman and the next man on the Moon as part of the Artemis program. This first flight—Artemis I—will also mark a milestone for smallsats. Thirteen6U CubeSats are manifested on the Artemis I flight, the first fleet of CubeSats carried as a ride share opportunity to deep space.(NASA’s first CubeSats to deep space, the twin Mars Cube One [MarCO] spacecraft, were an integral part of the InSight Mars lander mission). The Artemis I CubeSat manifest represents a diverse collection of smallsats performing an array of science missions and technology demonstrations. Payloads from NASA, international partners, academia and industry will execute a variety of experiments. Several smallsats will perform lunar-focused missions that may return data that addresses Strategic Knowledge Gaps (SKGs) in the agency’s lunar exploration program. Indeed, the Artemis I CubeSats will be in the vanguard of the agency’s 21st-century lunar program. The Artemis I missions will produce data to support space radiation awareness,crewed landings and in-situ resource utilization, helping to support a sustained human lunar presence. Several of the Artemis I CubeSats are demonstrating new technologies, including propulsion capabilities. Among the Artemis I CubeSats are three selected through NASA’s Cube Quest Challenge, part of the Centennial Challenges program. These three missions will compete for prize money while meeting specific technical development goals. Payloads from the Japanese and Italian space agencies provide an early opportunity for international involvement in the Artemis program. Student involvement in almost half of the payloads allow STEM engagement with NASA’s Artemis program. The SLS Block 1 vehicle for the Artemis I flight is manufactured with several elements delivered to Kennedy Space Center (KSC) and being prepared for stacking and integration. The new-development of the program, the 212-footcore stage with its four RS-25 engines installed is currently at Stennis Space Center (SSC) for “green run” testing. Following the green run test campaign, the stage will ship to KSC, where it will be integrated with the rest of the vehicle, including the upper stage adapter, where the Artemis I smallsats will be housed.

Kimberly F Robinson↗
NASA NTRSDate not supplied

Flight Performance and Stability of Space Launch System Core Stage Thrust Vector Control

The Space Launch System (SLS) Core Stage (CS) Thrust Vector Control (TVC) system is comprised of eight mechanical feedback Shuttle heritage Type III TVC actuators and four RS-25 engines, each attached to a Shuttle heritage gimbal block/bearing. The Core Stage TVC shares vehicle control authority with the SLS 5-segment Solid Rocket Boosters (SRBs) during boost phase flight, and is the sole means of vehicle flight control during in exoatmospheric flight following SRB separation. TVC responses during Green Run Hot Fire (GRHF) testing revealed that the TVC did not meet its performance specifications. Step and frequency responses exhibited unexpected departures from prior laboratory data and modeled behavior. Post-test analysis determined that the characteristics of the structure and gimbal friction are significantly influenced by the thrust-loaded conditions, and the command avionics exhibited a small but important gain nonlinearity. Using the available test data, the design team augmented the flight control TVC models to bound the observed results and include the additional fidelity needed for vehicle flight control analysis so as to build sufficient rationale for flight certification. Prior to the Green Run tests, “simplex” linear models typically used for flight control analysis did not include gimbal friction and other nonlinearities owing to long-standing assumptions that these effects were negligible in the Shuttle Orbiter TVC system. Following the Green Run findings, simulation analysis of the flight dynamics in the time and frequency domain revealed the propensity for a flight control limit cycle oscillation (LCO) if friction and structural compliances fell near the edges of test-predicted bounds. While the “most probable” models did not predict an in-flight LCO, the SLS Program conservatively proceeded with a system-wide evaluation and ultimate acceptance of the possibility for a small amplitude, low-frequency TVC LCO in flight. A final validation of the extensive test and modeling effort occurred when the first flight of SLS successfully demonstrated the fully integrated performance of the vehicle’s TVC system This paper is the final installment in a seven-paper series surveying the design, engineering, test validation, and flight performance of the Core Stage Thrust Vector Control system. In this paper, the development of flight rationale in light of the TVC responses observed in Green Run is discussed, along with a review of the flight telemetry illustrating the correlation of the preflight predictions with the observed performance.

John H. Wall↗
NASA NTRSDate not supplied

CubeSat Payloads on NASA’s Space Launch System Pave the Way for Artemis Moon Missions

Preparing for first launch in 2021, NASA’s Space Launch System (SLS) super heavy-lift launch vehicle will usher in a new era of human spaceflight, returning astronauts to the Moon as part of the Artemis program. Although designed to send crew in the Orion spacecraft and large payloads to the Moon and beyond, SLS also provides CubeSats with rideshare opportunities for missions to deep space. The first launch of SLS and Orion, Artemis I, has 13 6U CubeSats manifested. The payloads have been tested and will soon ship to Kennedy Space Center (KSC) to be integrated into commercial off-the-shelf (COTS) dispensers and integrated into the SLS Block 1 vehicle. Leveraging launches for the Artemis program to deploy rideshare smallsats to deep space provides a low-cost opportunity to perform missions that previously would have required a larger spacecraft and a dedicated launch, and offers additional benefits to both NASA and the smallsat community. CubeSats, including those manifested on the Artemis I flight, have a valuable role to play in the Artemis program, providing data to address NASA’s identified Strategic Knowledge Gaps (SKGs) in its plans to permanently establish humanity in deep space. Payload sponsors and developers for the Artemis I CubeSats hail from a variety of NASA industry partners and mission directorates, as well as international space agencies and universities. Several payloads destined for cislunar space will demonstrate propulsion systems and other technologies useful to future exploration. Science missions manifested on the Artemis I flight include characterizing the effects of deep space radiation on living organisms, searching for hydrogen and other volatiles on the Moon’s South Pole, and studying the lunar radiation environment. Three of the payloads were selected through NASA’s Centennial Challenges Program. Those payloads are competing for prize money while meeting specific technical development goals, such as communication with Earth from millions of miles in space. Student involvement in almost half of the Artemis I payload development allows STEM engagement with SLS and NASA’s Artemis program. As the initial vehicle to fly, the SLS Block 1 vehicle will lay the foundation for a generation of human and robotic deep space exploration missions. The Block 1 core stage is undergoing final testing at Stennis Space Center in 2020 before transportation to KSC for integration and launch in 2021. Following the Block 1 vehicle, the Block 1B and Block 2 vehicles will incorporate propulsion system upgrades and other changes to increase lift capability. In addition to sending the Orion vehicle to TLI, SLS can also be outfitted with large-diameter fairings to send robotic probes to deep space. With unparalleled lift, volume and departure energy, SLS is poised to usher in a new generation of spaceflight. In addition to launching Orion and large-volume missions, CubeSats may also be a part of Artemis missions to deep space.

Kimberly Robinson↗
NASA NTRS2017

NASA's Space Launch System: Deep-Space Delivery for Smallsats

Designed for human exploration missions into deep space, NASA's Space Launch System (SLS) represents a new spaceflight infrastructure asset, enabling a wide variety of unique utilization opportunities. While primarily focused on launching the large systems needed for crewed spaceflight beyond Earth orbit, SLS also offers a game-changing capability for the deployment of small satellites to deep-space destinations, beginning with its first flight. Currently, SLS is making rapid progress toward readiness for its first launch in two years, using the initial configuration of the vehicle, which is capable of delivering 70 metric tons (t) to Low Earth Orbit (LEO). On its first flight test of the Orion spacecraft around the moon, accompanying Orion on SLS will be small-satellite secondary payloads, which will deploy in cislunar space. The deployment berths are sized for "6U" CubeSats, and on EM-1 the spacecraft will be deployed into cislunar space following Orion separate from the SLS Interim Cryogenic Propulsion Stage. Payloads in 6U class will be limited to 14 kg maximum mass. Secondary payloads on EM-1 will be launched in the Orion Stage Adapter (OSA). Payload dispensers will be mounted on specially designed brackets, each attached to the interior wall of the OSA. For the EM-1 mission, a total of fourteen brackets will be installed, allowing for thirteen payload locations. The final location will be used for mounting an avionics unit, which will include a battery and sequencer for executing the mission deployment sequence. Following the launch of EM-1, deployments of the secondary payloads will commence after sufficient separation of the Orion spacecraft to the upper stage vehicle to minimize any possible contact of the deployed CubeSats to Orion. Currently this is estimated to require approximately 4 hours. The allowed deployment window for the CubeSats will be from the time the upper stage disposal maneuvers are complete to up to 10 days after launch. The upper stage will fly past the moon at a perigee of approximately 100km, and this closest approach will occur about 5 days after launch. The limiting factor for the latest deployment time is the available power in the sequencer system. Several NASA Mission Directorates were involved in the development of programs for the competition, selection, and development of EM-1 payloads that support directorate priorities. CubeSat payloads on EM-1 will include both NASA research experiments and spacecraft developed by industry, international and potentially academia partners. The Human Exploration and Operations Mission Directorate (HEOMD) Advanced Exploration Systems (AES) Division was allocated five payload opportunities on the EM-1 mission. Near Earth Asteroid (NEA) Scout is designed to rendezvous with and characterize a candidate NEA. A solar sail, an innovation the spacecraft will demonstrated for the CubeSat class, will provide propulsion. Lunar Flashlight will use a green propellant system and will search for potential ice deposits in the moon's permanently shadowed craters. BioSentinel is a yeast radiation biosensor, planned to measure the effects of space radiation on deoxyribonucleic acid (DNA). Lunar Icecube, a collaboration with Morehead State University, will prospect for water in ice, liquid, and vapor forms as well as other lunar volatiles from a low-perigee, highly inclined lunar orbit using a compact Infrared spectrometer. Skyfire, a partnership with Lockheed Martin, is a technology demonstration mission that will perform a lunar flyby, collecting spectroscopy, and thermography data to address questions related to surface characterization, remote sensing, and site selection. NASA's Space Technology Mission Directorate (STMD) was allocated three payload opportunities on the EM-1 mission. These slots will be filled via the Centennial Challenges Program, NASA's flagship program for technology prize competitions, which directly engages the public, academia, and industry in open prize competitions to stimulate innovation. The NASA Science Mission Directorate (SMD) was allocated two payload opportunities on the EM-1 mission. The CubeSat Mission to Study Solar Particles (CuSP) payload will study the sources and acceleration mechanisms of solar and interplanetary particles in near-Earth orbit, support space weather research by determining proton radiation levels during Solar Energetic Particle (SEP) events and identifying suprathermal properties that could help predict geomagnetic storms. The LunaH-Map payload will help scientists understand the quantity of H-bearing materials in lunar cold traps (~10 km), determine the concentration of H-bearing materials with 1m depth, and constrain the vertical distribution of H-bearing materials. The final three payload opportunities for the EM-1 mission were allocated for NASA's international space agency counterparts. The flight opportunities are intended to benefit the international space agency and NASA as well as further the collective space exploration goals. ArgoMoon is sponsored by ESA/ASI and will fly along with the ICPS on its disposal trajectory to perform proximity operations with the ICPS post-disposal, take external imagery of engineering and historical significance, and perform an optical communications demonstration. EQUULEUS, sponsored by JAXA, will fly to a libration orbit around the Earth-Moon L2 point and demonstrate trajectory control techniques within the Sun-Earth- Moon region for the first time by a nano spacecraft. The mission will also contribute to the future human exploration scenario by understanding the radiation environment in geospace and deep space, characterizing the flux of impacting meteors on the far side of the moon, and demonstrating the future deep space exploration scenario using the "deep space port" at Lagrange points. OMOTENASHI, also sponsored by JAXA, will land the smallest lunar lander to date on the lunar surface to demonstrate the feasibility of the hardware for distributed cooperative exploration system. Small landers will enable multi-point exploration, which is complimentary with large-scale human exploration. Once on the lunar surface, the OMOTENASHI spacecraft will observe the radiation and soil environments of the lunar surface by active radiation measurements and soil shear measurements. Following EM-1, Space Launch System will evolve to the more-powerful Block 1B configuration, which uses a new Exploration Upper Stage to increase the vehicle's LEO payload capability from 70 t to 105 t. With that transition, the Orion Stage Adapter, which will carry the secondary payloads on EM-1, will be phased out, and a new Universal Stage Adapter will be introduced, creating opportunities for flying larger secondary payloads. This paper will provide a brief status of SLS progress toward first launch; an overview of smallsat accommodations, integration, and operations on EM-1; information about the specific payloads flying on that launch; and a discussion of future accommodations and opportunities for secondary payloads on SLS for Exploration Mission-2 and beyond.

Robinson, Kimberly F.↗
NASA NTRS2017

NASA's Space Launch System: Deep-Space Opportunities for SmallSats

Designed for human exploration missions into deep space, NASA's Space Launch System (SLS) represents a new spaceflight infrastructure asset, enabling a wide variety of unique utilization opportunities. While primarily focused on launching the large systems needed for crewed spaceflight beyond Earth orbit, SLS also offers a game-changing capability for the deployment of small satellites to deep-space destinations, beginning with its first flight. Currently, SLS is making rapid progress toward readiness for its first launch in two years, using the initial configuration of the vehicle, which is capable of delivering 70 metric tons (t) to Low Earth Orbit (LEO). On its first flight test of the Orion spacecraft around the moon, accompanying Orion on SLS will be small-satellite secondary payloads, which will deploy in cislunar space. The deployment berths are sized for "6U" CubeSats, and on EM-1 the spacecraft will be deployed into cislunar space following Orion separate from the SLS Interim Cryogenic Propulsion Stage. Payloads in 6U class will be limited to 14 kg maximum mass. Secondary payloads on EM-1 will be launched in the Orion Stage Adapter (OSA). Payload dispensers will be mounted on specially designed brackets, each attached to the interior wall of the OSA. For the EM-1 mission, a total of fourteen brackets will be installed, allowing for thirteen payload locations. The final location will be used for mounting an avionics unit, which will include a battery and sequencer for executing the mission deployment sequence. Following the launch of EM-1, deployments of the secondary payloads will commence after sufficient separation of the Orion spacecraft to the upper stage vehicle to minimize any possible contact of the deployed cubesats to Orion. Currently this is estimated to require approximately 4 hours. The allowed deployment window for the cubesats will be from the time the upper stage disposal maneuvers are complete to up to 10 days after launch. The upper stage will fly past the moon at a perigee of approximately 100km, and this closest approach will occur about 5 days after launch. The limiting factor for the latest deployment time is the available power in the sequencer system. Several NASA Mission Directorates were involved in the development of programs for the competition, selection, and development of EM-1 payloads that support directorate priorities. CubeSat payloads on EM-1 will include both NASA research experiments and spacecraft developed by industry, international and potentially academia partners. The Human Exploration and Operations Mission Directorate (HEOMD) Advanced Exploration Systems (AES) Division was allocated five payload opportunities on the EM-1 mission. Near Earth Asteroid (NEA) Scout is designed to rendezvous with and characterize a candidate NEA. A solar sail, an innovation the spacecraft will demonstrated for the CubeSat class, will provide propulsion. Lunar Flashlight will use a green propellant system and will search for potential ice deposits in the moon's permanently shadowed craters. BioSentinel is a yeast radiation biosensor, planned to measure the effects of space radiation on deoxyribonucleic acid (DNA). Lunar Icecube, a collaboration with Morehead State University, will prospect for water in ice, liquid, and vapor forms as well as other lunar volatiles from a low-perigee, highly inclined lunar orbit using a compact Infrared spectrometer. Skyfire, a partnership with Lockheed Martin, is a technology demonstration mission that will perform a lunar flyby, collecting spectroscopy, and thermography data to address questions related to surface characterization, remote sensing, and site selection. NASA's Space Technology Mission Directorate (STMD) was allocated three payload opportunities on the EM-1 mission. These slots will be filled via the 2 Centennial Challenges Program, NASA's flagship program for technology prize competitions, which directly engages the public, academia, and industry in open prize competitions to stimulate innovation. The NASA Science Mission Directorate (SMD) was allocated two payload opportunities on the EM-1 mission. The CubeSat Mission to Study Solar Particles (CuSP) payload will study the sources and acceleration mechanisms of solar and interplanetary particles in near-Earth orbit, support space weather research by determining proton radiation levels during Solar Energetic Particle (SEP) events and identifying suprathermal properties that could help predict geomagnetic storms. The LunaH-Map payload will help scientists understand the quantity of H-bearing materials in lunar cold traps (~10 km), determine the concentration of H-bearing materials with 1m depth, and constrain the vertical distribution of H-bearing materials. The final three payload opportunities for the EM-1 mission were allocated for NASA's international space agency counterparts. The flight opportunities are intended to benefit the international space agency and NASA as well as further the collective space exploration goals. ArgoMoon is sponsored by ESA/ASI and will fly along with the ICPS on its disposal trajectory to perform proximity operations with the ICPS post-disposal, take external imagery of engineering and historical significance, and perform an optical communications demonstration. EQUULEUS, sponsored by JAXA, will fly to a libration orbit around the Earth-Moon L2 point and demonstrate trajectory control techniques within the Sun-Earth-Moon region for the first time by a nano spacecraft. The mission will also contribute to the future human exploration scenario by understanding the radiation environment in geospace and deep space, characterizing the flux of impacting meteors on the far side of the moon, and demonstrating the future deep space exploration scenario using the "deep space port" at Lagrange points. OMOTENASHI, also sponsored by JAXA, will land the smallest lunar lander to date on the lunar surface to demonstrate the feasibility of the hardware for distributed cooperative exploration system. Small landers will enable multi-point exploration, which is complimentary with large-scale human exploration. Once on the lunar surface, the OMOTENASHI spacecraft will observe the radiation and soil environments of the lunar surface by active radiation measurements and soil shear measurements. Following EM-1, Space Launch System will evolve to the more-powerful Block 1B configuration, which uses a new Exploration Upper Stage to increase the vehicle's LEO payload capability from 70 t to 105 t. With that transition, the Orion Stage Adapter, which will carry the secondary payloads on EM-1, will be phased out, and a new Universal Stage Adapter will be introduced, creating opportunities for flying larger secondary payloads. This paper will provide a brief status of SLS progress toward first launch; an overview of smallsat accommodations, integration, and operations on EM-1; information about the specific payloads flying on that launch; and a discussion of future accommodations and opportunities for secondary payloads on SLS for Exploration Mission-2 and beyond.

Robinson, Kimberly F.↗
NASA NTRS2016

NASA's Space Launch System Transitions From Design To Production

NASA's Space Launch System (SLS) successfully completed its Critical Design Review (CDR) in 2015, a major milestone on the journey to an unprecedented era of exploration for humanity. CDR formally marked the program's transition from design to production phase just four years after the program's inception and the first such milestone for a human launch vehicle in 40 years. While challenges typical of a complex development program lie ahead, CDR evaluators concluded that the design is technically and programmatically sound and ready to press forward to Design Certification Review (DCR) and readiness for launch of Exploration Mission 1 (EM-1) in the 2018 timeframe. SLS is prudently based on existing propulsion systems, infrastructure and knowledge with a clear, evolutionary path as required by mission needs. In its initial configuration, designated Block 1, SLS will a minimum of 70 metric tons (t) (154,324 pounds) of payload to low Earth orbit (LEO). It will evolve to a 130 t (286,601 pound) payload capacity by upgrading its engines, boosters, and upper stage, dramatically increasing the mass and volume of human and robotic exploration while decreasing mission risk, increasing safety, and simplifying ground and mission operations. CDR was the central programmatic accomplishment among many technical accomplishments that will be described in this paper. The government/industry SLS team successfully test-fired a flight-like five-segment solid rocket motor, as well as seven hotfire development tests of the RS-25 core stage engine. The majority of the major test article and flight barrels, rings, and domes for the core stage liquid oxygen, liquid hydrogen, engine section, intertank, and forward skirt were manufactured at NASA's Michoud Assembly Facility in New Orleans, Louisiana. Renovations to the B-2 test stand for stage green run testing were completed at NASA's Stennis Space Center (SSC), near Bay St. Louis, Mississippi. Core stage test stands are reaching completion at NASA's Marshall Space Flight Center in Huntsville, Alabama. The modified Pegasus barge for core stage transportation from manufacturing to testing and launch sites was delivered to SSC. The Interim Cryogenic Propulsion System test article was also completed. This paper will discuss these and other technical and programmatic successes and challenges over the past year and provide a preview of work ahead before the first flight of this new capability.

Askins, Bruce R.↗
NASA NTRS2017

NASA's Space Launch System: A Transformative Capability for Deep Space Missions

Already making substantial progress toward its first launches, NASA’s Space Launch System (SLS) exploration-class launch vehicle presents game-changing new opportunities in spaceflight, enabling human exploration of deep space, as well as a variety of missions and mission profiles that are currently impossible. Today, the initial configuration of SLS, able to deliver more than 70 metric tons of payload to low Earth orbit (LEO), is well into final production and testing ahead of its planned first flight, which will send NASA’s new Orion crew vehicle around the moon and will deploy 13 CubeSats, representing multiple disciplines, into deep space. At the same time, production work is already underway toward the more-capable Block 1B configuration, planned to debut on the second flight of SLS, and capable of lofting 105 tons to LEO or of co-manifesting large exploration systems with Orion on launches to the lunar vicinity. Progress being made on the vehicle for that second flight includes initial welding of its core stage and testing of one of its engines, as well as development of new elements such as the powerful Exploration Upper Stage and the Universal Stage Adapter “payload bay.” Ultimately, SLS will evolve to a configuration capable of delivering more than 130 tons to LEO to support humans missions to Mars. In order to enable human deep-space exploration, SLS provides unrivaled mass, volume, and departure energy for payloads, offering numerous benefits for a variety of other missions. For robotic science probes to the outer solar system, for example, SLS can cut transit times to less than half that of currently available vehicles or substantially increased spacecraft mass. In the field of astrophysics, SLS’ high payload volume, in the form of payload fairings with a diameter of up to 10 meters, creates the opportunity for launch of large-aperture telescopes providing an unprecedented look at our universe. This presentation will give an overview of SLS’ capabilities and its current status, and discuss the vehicle’s potential for human exploration of deep space and other game-changing utilization opportunities.

Creech, Stephen D.↗
NASA NTRSDate not supplied

Force and Moment Analysis for the High Reynolds Number Wind Tunnel Test of the Space Launch System at Ascent Conditions

A high Reynolds number test of the Space Launch System was performed at the NASA Langley National Transonic Facility (NTF). The objective of the test was to use the cryogenic testing capabilities of the NTF to acquire data over the largest range of Reynolds numbers possible with a specific focus on the Reynolds numbers closest to flight conditions. The test was performed at Mach numbers from 0.50 to 0.95 which corresponds to the ascent portion of flight for the SLS vehicle. Force and moment data showed that pitching and yawing moment were sensitive to Reynolds number effects over the full range of Mach and Reynolds numbers tested. Axial force also showed sensitivity to Reynolds number with the largest differences seen between Mach 0.50 to 0.90. Surface pressure data showed the highest sensitivity to Reynolds number in the vicinity of the solid rocket booster forward attach region.

Space Launch System↗
NASA NTRSDate not supplied

Force and Moment Analysis for the High Reynolds Number Wind Tunnel Test of the Space Launch System at Ascent Conditions

A high Reynolds number test of the Space Launch System was performed at the NASA Langley National Transonic Facility (NTF). The objective of the test was to use the cryogenic testing capabilities of the NTF to acquire data over the largest range of Reynolds numbers possible with a specific focus on the Reynolds numbers closest to flight conditions. The test was performed at Mach numbers from 0.50 to 0.95, which corresponds to the ascent portion of flight for the SLS vehicle. Force and moment data showed that pitching and yawing moment were sensitive to Reynolds number effects over the full range of Mach and Reynolds numbers tested. Axial force also showed sensitivity to Reynolds number with the largest differences seen between Mach 0.50 to 0.90. Surface pressure data showed the highest sensitivity to Reynolds number in the vicinity of the solid rocket booster forward attach region.

Space Launch System↗
NASA NTRS1992

HL-20 personnel launch system - A concept definition case study

For several years, the NASA Langley Research Center has been involved in defining options for future space transportation systems. As part of this effort, for the past 2 years, an analysis of a candidate Personnel Launch System to deliver and return people and small payloads to and from Space Station Freedom has been conducted. This effort has involved a government/industry/university team in conducting an indepth analysis of the HL-20 lifting body concept to provide a technically viable, affordable Personnel Launch System. This paper will use the HL-20 PLS definition activity to illustrate the process that is used by Langley to mature vehicle concepts to identify technical/development risks and costs for future transportation systems.

Freeman, Delma C., Jr.↗
NASA NTRSDate not supplied

NASA’s Space Launch System: Artemis I Results and the Path Forward

On Nov. 16, 2022, NASA launched the Artemis I mission on the agency’s new SLS (Space Launch System) rocket. The debut launch of the integrated vehicle sent an uncrewed Orion spacecraft into a distant retrograde (DRO) orbit about the Moon to accomplish multiple mission objectives, including evaluating Orion’s heatshield at lunar return velocities and collecting critical data from the first flight of the new superheavy lift launch vehicle. Post-flight data analyses show that the rocket performed with a high degree of precision and accuracy. In addition to completing testing and launch of the Artemis I SLS in 2022, notable progress was made on hardware for future launch vehicles that will support Artemis missions II, III, IV, and V. The Artemis II core stage is mostly complete, and its RS-25 engines were integrated in the fall of 2023. The Artemis II solid rocket booster motor segments were shipped to the launch site in September 2023. Propellant tanks are being manufactured for additional missions, solid booster segments are being cast and prepared, software is being developed, and production of new RS-25 engines is underway. A more capable upper stage is in development, as well as a large adapter to encapsulate a 10-metric ton (t) co-manifested payload. This paper will provide details on the Artemis I flight as well as cover hardware progress for the future flights as available.

John Honeycutt↗
NASA NTRSDate not supplied

NASA Space Launch System Completes Green Run Testing, Begins Assembly

NASA’s Space Launch System (SLS) Program is poised in 2021 to shift its focus to the launch site with the completion of its last major integrated hardware and software test. SLS is NASA’s evolvable super heavy-lift launch vehicle for deep space exploration. Using proven propulsion technologies, SLS will be the most powerful launch vehicle in the world. That capability translates not only into more mass and volume to destinations but also simplified payload design and mission operations and greater opportunity for mission success. These capabilities will be important for the Artemis program, NASA’s plan to return humans to the Moon to stay in a sustainable way in order to develop and test technologies and operations needed for human missions to Mars and other destinations. SLS will anchor the transportation leg of an innovative, sustainable program of lunar exploration with commercial and international partners as the first step of human exploration of deep space. While all major hardware and software efforts made significant progress in 2020 and 2021, the most visible was the Green Run test series of the Artemis I core stage conducted at NASA’s Stennis Space Center (SSC) on the B-2 test stand. The series validated core stage design, performance, workmanship, and readiness for shipment to NASA Kennedy Space Center (KSC) for final processing, integration and launch. The core stage provides the backbone for SLS’ main propulsion system, consisting of two five-segment solid rocket boosters and four RS-25 liquid hydrogen (LH2)/liquid oxygen (LOX) engines. SLS also includes an Interim Cryogenic Propulsion Stage (ICPS) that will insert the Orion crew spacecraft into a lunar trajectory.

John Honeycutt↗