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At least 91 records · Page 5

Propulsive Trajectory Optimization to Minimize Surface Contamination

Descent retroburns using hydrazine thrusters will generate contaminants in their exhaust that can alter underlying samples, such as water-rich surfaces coinciding with possible life signatures or other science measurements of interest. We present an optimization technique that aims to autonomously minimize contamination during surface approach and landing for propulsive vehicles. In addition to short-range hoppers, the optimization technique is also fully applicable to traditional orbit-to-surface landers. This study addresses scenarios where surface alterations from propulsion events are counterproductive or hazardous to the mission objectives. This is of interest for landers (whether human or robotic), that may rely on pristine soils collected in the immediate vicinity of landing sites to accomplish science investigations, mining, or In Situ Resource Utilization (ISRU) surface operations. Such missions are averse to various surface-plume interactions such as thermal scoring, physical agitation, and contamination. The capability can be applied with minimal impact to the baseline concept.

Plume↗

Replication of Segments of STS-94 as a Lunar Surface Mission

The Artemis exploration plan will progress from initial Commercial Lunar Payloads Services (CLPS) landers to human landings to an established surface infrastructure supporting four crew for surface missions of a month or greater. NASA teams are currently working with partners to define the surface assets that will comprise this infrastructure, including habitation and laboratory facilities. However, design engineers often have limited insight into the laboratory capabilities needed inside a pressurized habitat or the demands such a facility will place upon crew availability. The Space Shuttle STS-94 Microgravity Science Laboratory (MSL-1) mission is used as an intravehicular activity science analog for the Surface Habitat. The STS-94 primary physical science instruments and crew activity in support of physical science investigations will be examined. Based on recent reference concepts for the Surface Habitat, options for incorporating the instruments and options for dividing physical science tasks among the Surface Habitat crew are discussed, based on STS94 crew tasks and assumptions for Surface Habitat operations. Crew size considerations are raised along with recommendations to reassess some of the current assumptions. Having shown that STS-94’s physical science investigations can be applied to a lunar surface mission, recommendations are made for increased attention to pressurized laboratory objectives, capabilities, and crew size.

Surface Habitat↗

A Permanent Human Lunar Surface Presence Enabled by a CLV Class JUMP Lander

There are compelling advantages of a human presence on the surface of the Moon, as evidenced partly by the preponderance of lunar surface architectures that have existed throughout NASA, industry, and academia since the Apollo program. This paper specifically advocates and illustrates an example of a permanent human lunar surface presence enabled by a commercial launch vehicle (CLV) class Joinable Undercarriage to Maximize Payload (JUMP) lunar lander. The paper will discuss purposes for such a surface presence, including SPD-1 fulfillment, global collaboration, US industry advancement, US government leadership in spaceflight, a Mars dress rehearsal, Mars collaborative exploration, and lunar village development. An architectural description will be presented, including site selection, primary elements, and surface configuration. Element and lander allocation to CLV and Space Launch System (SLS) rockets will be discussed in terms of launch vehicle selection philosophy and allocation to specific launch manifests. This will enable a presentation of a lunar campaign spanning the period from 2026 to 2056. In conclusion, various aspects of the architecture will be suggested for further study.

Howard, Robert L., Jr.↗

Effects of Spatial Resolution on Retropropulsion Aerodynamics in an Atmospheric Environment

Development of a powered descent capability for atmospheric environments is heavily reliant on computational simulation. The prohibitive computational cost of such simulations motivates an improvement in the understanding of the minimum computational fidelity re-quired to accurately characterize aerodynamic-propulsive interference for such applications. This work examines the applicability of detached eddy simulation methods for retropropulsion in atmospheric environments through utilization of a GPU-accelerated computational framework, yielding data that are largely unachievable with conventional high-performance computing resources. This effort was specifically designed to quantitatively assess the effects of spatial resolution on vehicle aerodynamics for nominal operation of a low lift-to-drag ratio, human-scale Mars lander concept. The test matrix and scaling approach span relevant nozzle expansion conditions as well as mid-supersonic to high-subsonic operating conditions. Solutions were generated using computational grids ranging from 143 million to 1.14 billion grid points (degrees of freedom). This paper will provide an overview of the computational campaign, approach, and discussion of preliminary results focused on a range of operating conditions for a conceptual low lift-to-drag, human-scale Mars lander.

Ashley M Korzun↗

NASA’s Initial and Sustained Artemis Human Landing Systems

On March 26, 2019, in keeping with President Trump’s Space Policy Directive-1, Vice President Pence charged NASA with landing the first woman and the next man on the South Pole of the Moon by 2024, followed by a sustained presence on and around the Moon by 2028. NASA’s Human Landing System (HLS) Program is responsible for the final mode of transportation in deep space that will carry humans to and from the surface of the Moon, to be designed and developed by American companies for NASA’s Artemis lunar exploration program. This paper examines the approach for Artemis human landing systems for both the initial missions and future sustained missions. While achieving the 2024 goal requires a focus on speed and the use of mature technologies, planning toward sustained operations to and from the lunar surface requires a focus on reliability and reusability. The two approaches, however, are not mutually exclusive, as demonstrated by the HLS prime contractors’ integrated lander system proposals. On April 30, 2020, NASA announced that Blue Origin of Kent, Washington, Dynetics (a Leidos company) of Huntsville, Alabama, and SpaceX of Hawthorne, California, were the awardees for NASA’s Human Landing System contracts under Appendix H of the NextSTEP-2 Broad Agency Announcement. The companies began work in a 10-month base period during which NASA teams worked with the companies to streamline the review of required products and to share the agency’s expertise in human spaceflight systems development. Following the base period, NASA will determine which company or companies will develop the human landers for the initial missions, including the 2024 landing, and which companies will develop landers for future sustained missions toward the end of the decade.

HLS↗

NASA’s Human Landing System: Enabling the Next Generation of Lunar Science

The Human Landing System (HLS) is the mode of transportation that will take astronauts to the lunar surface as part of NASA's Artemis exploration program. HLS also serves as a research platform both on the surface and in lunar orbit, enabling critical scientific investigations on and of the Moon. With support at NASA centers around the country, the HLS program, based at Marshall Space Flight Center in Huntsville, Alabama, is working closely with its commercial partners throughout the development process to design and build innovative and technically advanced lunar landers – new vehicles designed for the modern era of space travel – leveraging decades of human spaceflight experience and the speed of the commercial sector. In 2019, NASA asked U.S. industry for proposals to design and develop a human lander for the first human mission to the lunar surface under Artemis. Initial contracts were awarded to Blue Origin Federation, Dynetics, and SpaceX to advance their designs. Following the execution of the ten-month Base Period, NASA announced in April 2021 that the agency selected SpaceX to move forward with its human landing system [1] and land the first two astronauts on the lunar surface during the Artemis III mission. Following two protest periods, NASA awarded the contract, known as Option A, to SpaceX in July 2021 and resumed work in November 2021 (Fig. 1). In parallel, the HLS program has been preparing for the acquisition that will procure regular crewed transportation to the lunar surface following Artemis III. NASA released a request for information (RFI) in July 2021 asking U.S. industry for feedback to help inform the future solicitation, known as Lunar Exploration Transportation Services (LETS) [2]. Also in July 2021, NASA released the NextSTEP-2 Appendix N broad agency announcement soliciting new work from U.S. industry to mature their HLS designs and perform risk reduction activities in advance of the LETS procurement [3]. NASA selected Blue Origin Federation, Dynetics, Lockheed Martin, Northrop Grumman, and SpaceX to participate [4]. This work will also help better inform the LETS procurement and prepare industry to propose. NASA hopes to release a draft request for proposals (RFP) in Spring 2022.

R C Weber↗

Red Dragon: Low-cost Access to the Surface of Mars using Commercial Capabilities

We will discuss the feasibility of using a minimally-modified variant of a SpaceX Dragon capsule as a low-cost, large-capacity, near-term, Mars lander for scientific and human-precursor missions. We have been evaluating such a Red Dragon platform as an option for a Discovery Program mission concept. A Red Dragon lander has the potential to be low cost primarily because it would be derived from a routinely-flying spacecraft. Dragon is being developed to ferry cargo and crew to and from the International Space Station (ISS). The cargo variant is currently undergoing test flights, which will be followed by standard ISS cargo missions and, eventually, crewed flights. The human variant, unlike other Earth-return vehicles, appears to also have most of the capabilities necessary to land on Mars. In particular, it has a set of high-thrust, throttleable, storable bi-propellant Super- Draco engines integrated directly into the capsule which are intended for launch abort and powered landings on Earth. These thrusters suggest the possibility of a parachute-free, fully-propulsive deceleration at Mars from supersonic speeds to the surface. Concepts for large, human-relevant landers (see, e.g., [1]) also often employ supersonic retro-propulsion; Red Dragon's entry, descent, and landing approach would scale to those landers. Further, SpaceX's Falcon Heavy launch vehicle, currently under development and expected to have its first flight in 2013, will be capable of sending Dragon on a trajectory to Mars. We will discuss our motivation for exploring a Red Dragon lander, the primary technical questions which determine its feasibility, and the current results of our analysis. In particular, we will examine entry, descent, and landing (EDL) in detail. We will describe the modifications to Dragon necessary for interplanetary cruise, EDL, and operations on the Martian surface.

Karcz, John↗

MarsLab: A HEDS Lander Concept

Recognizing that the human exploration of Mars will be a science-focused enterprise, the Human Exploration and Development of Space (HEDS) program set out three years ago to develop a mix of science and technology Lander payloads as a first step toward a human mission. With three experiments ready for flight and four more in development, the HEDS Mars program has the capability to stage missions with considerable impact. This presentation describes one such mission design by no means unique. Ambitious in scope, it encompasses elements of all seven HEDS payloads in a configuration with a uniquely HEDS character. Pragmatically, a subset of these elements could be selected for existing small Lander platforms. Bristling with scientific experiments, technology demonstrations, and outreach elements, MarsLab represents a prototype of a manned science station or scientific outpost. A cartoon overview of MarsLab defines its major elements, explained more fully in the sections that follow. The concept is endorsed by PI's of the various HEDS payloads, details of which are presented elsewhere at this workshop.

Hecht, M. H.↗

Level of Automation and Failure Frequency Effects on Simulated Lunar Lander Performance

A human-in-the-loop experiment was conducted at the NASA Ames Research Center Vertical Motion Simulator, where instrument-rated pilots completed a simulated terminal descent phase of a lunar landing. Ten pilots participated in a 2 x 2 mixed design experiment, with level of automation as the within-subjects factor and failure frequency as the between subjects factor. The two evaluated levels of automation were high (fully automated landing) and low (manual controlled landing). During test trials, participants were exposed to either a high number of failures (75% failure frequency) or low number of failures (25% failure frequency). In order to investigate the pilots' sensitivity to changes in levels of automation and failure frequency, the dependent measure selected for this experiment was accuracy of failure diagnosis, from which D Prime and Decision Criterion were derived. For each of the dependent measures, no significant difference was found for level of automation and no significant interaction was detected between level of automation and failure frequency. A significant effect was identified for failure frequency suggesting failure frequency has a significant effect on pilots' sensitivity to failure detection and diagnosis. Participants were more likely to correctly identify and diagnose failures if they experienced the higher levels of failures, regardless of level of automation

performance↗

Sustaining Human Presence on Mars Using ISRU and a Reusable Lander

This paper presents an analysis of the impact of ISRU (In-Site Resource Utilization), reusability, and automation on sustaining a human presence on Mars, requiring a transition from Earth dependence to Earth independence. The study analyzes the surface and transportation architectures and compared campaigns that revealed the importance of ISRU and reusability. A reusable Mars lander, Hercules, eliminates the need to deliver a new descent and ascent stage with each cargo and crew delivery to Mars, reducing the mass delivered from Earth. As part of an evolvable transportation architecture, this investment is key to enabling continuous human presence on Mars. The extensive use of ISRU reduces the logistics supply chain from Earth in order to support population growth at Mars. Reliable and autonomous systems, in conjunction with robotics, are required to enable ISRU architectures as systems must operate and maintain themselves while the crew is not present. A comparison of Mars campaigns is presented to show the impact of adding these investments and their ability to contribute to sustaining a human presence on Mars.

Arney, Dale C.↗

The MSP 2001 Mars Environmental Compatibility Assessment (MECA)

The Mars Environmental Compatibility Assessment (MECA) will evaluate the Martian environment for soil and dust-related hazards to human exploration as part of the Mars Surveyor Program 2001 Lander. Sponsored by the Human Exploration and Development of Space (HEDS) enterprise, MECA's goal is to evaluate potential geochemical and environmental hazards that may confront future Martian explorers, and to guide HEDS scientists in the development of high fidelity Mars soil simulants. The integrated MECA payload contains a wet-chemistry laboratory, a microscopy station, an electrometer to characterize the electrostatics of the soil and its environment, and arrays of material patches to study the abrasive and adhesive properties of soil grains. The instrument will acquire soil samples with a robotic arm equipped with a camera. MECA will examine surface and subsurface soil and dust in order to characterize particle size, shape, hardness, and also physical characteristics that may provide clues to mineralogy. MECA will characterize soil/water mixtures with respect to pH, redox potential, total dissolved ions, and trace toxins. MECA will determine the nature of electrostatic charging associated with excavation of soil, and the influence of ionizing radiation on material properties. It will also observe natural dust accumulation on engineering materials. To accomplish these objectives, MECA is allocated a mass of 10 kg within an enclosure of 35 x 25 x 15 cm. The Wet Chemistry Laboratory (WCL) consists of four identical cells that will accept samples from surface and subsurface regions accessible to the Lander's robotic arm, mix them with water, and perform extensive analysis of the solution. Ion-selective electrodes and related sensors will evaluate total dissolved solids, redox potential, pH, and the concentration of many soluble ions and gases in wet Martian soil. These electrodes can detect potentially dangerous heavy-metal ions, emitted pathogenic gases, and the soil's corrosive potential. Experiments will include cyclic voltammetry and anodic stripping voltammetry. Complementary to the Viking experiments, the chemical laboratory will characterize the water-soil solution rather than emitted gases. Nonetheless, through analysis of dissolved gases it will be able to replicate many of the Viking observations related to oxidants. MECA's microscopy station combines optical and atomic-force microscopy (AFM) in an actively focused, controlled illumination environment to image particles from millimeters to nanometers in size. Careful selection of substrates allows controlled experiments in adhesion, abrasion, hardness, aggregation, magnetic and other properties. Special tools allow primitive manipulation (brushing and scraping) of samples. Soil particle properties including size, shape, color, hardness, adhesive potential (electrostatic and magnetic), will be determined using an array of sample receptacles and collection substrates. The simple, rugged atomic-force microscope will image in the submicron size range and has the capability of performing a particle-by-particle analysis of the dust and soil. On Earth, the earliest forms of life are preserved as microfossils. The atomic-force microscope will have the required resolution to image down to the scale of terrestrial microfossils and beyond. Mounted on the end of the robot arm, MECA's electrometer actually consists of four types of sensors: an electric field meter, several triboelectricity monitors, an ion gauge, and a thermometer. Tempered only by ultraviolet-light-induced ions and a low-voltage breakdown threshold, the dry, cold, dusty martian environment presents an imposing electrostatic hazard to both robots and humans. The field meter will measure the ambient field on nearby objects while the triboelectric sensors, using identical circuitry, will measure the charge accumulated on test substances as they are dragged through the soil by the arm. The ion chamber, open to the environment, will sense both charged dust and free ions in the air. Over and above the potential threat to electronics, the electrostatic environment holds one of the keys to transport of dust and, consequently, Martian meteorology. Viewed with the robot arm camera, the abrasion and adhesion plates are strategically placed to allow direct observation of the interaction between materials and soils on a macroscopic scale. Materials of graded hardness are placed directly under the robot arm scoop to sense wear and soil hardness. A second array, placed on the lander deck, is deployed after the dust plume of landing has settled. It can be manipulated in a primitive fashion by the arm, first having dirt deposited on it from the scoop and subsequently shaken clean. A third array will passively collect dust from the atmosphere. In addition to objectives related to human exploration, the MECA data set will be rich in information relevant to basic geology, paleoclimate, and exobiology issues. To understand both contemporaneous and ancient processes on Mars, the mineralogy, petrology, and reactivity of Martian surface materials should be constrained. The MECA experiment will shed light on these quantities through its combination of chemistry and microscopy. MECA will be capable of measuring the composition of ancient surface water environments, observing microscopic evidence of geological (and biological?) processes, inferring soil and dust transport, comminution and weathering mechanisms, and characterizing soil horizons that might be encountered during excavation.

Hecht, M. H.↗

The Mars Environmental Compatibility Assessment (MECA)

The Mars Environmental Compatibility Assessment (MECA) will evaluate the Martian environment for soil and dust-related hazards to human exploration as part of the Mars Surveyor Program 2001 Lander. Sponsored by the Human Exploration and Development of Space (HEDS) enterprise, MECA's goal is to evaluate potential geochemical and environmental hazards that may confront future martian explorers, and to guide HEDS scientists in the development of high fidelity Mars soil simulants. In addition to objectives related to human exploration, the MECA data set will be rich in information relevant to basic geology, paleoclimate, and exobiology issues. The integrated MECA payload contains a wet-chemistry laboratory, a microscopy station, an electrometer to characterize the electrostatics of the soil and its environment, and arrays of material patches to study the abrasive and adhesive properties of soil grains. MECA is allocated a mass of 10 kg and a peak power usage of 15 W within an enclosure of 35 x 25 x 15 cm (figures I and 2). The Wet Chemistry Laboratory (WCL) consists of four identical cells that will accept samples from surface and subsurface regions accessible to the Lander's robotic arm, mix them with water, and perform extensive analysis of the solution. Using an array of ion-specific electrodes (ISEs), cyclic voltammetry, and electrochemical techniques, the chemistry cells will wet soil samples for measurement of basic soil properties of pH, redox potential, and conductivity. Total dissolved material, as well as targeted ions will be detected to the ppm level, including important exobiological ions such as Na, K+, Ca++, Mg++, NH4+, Cl, S04-, HC03, as well as more toxic ions such as Cu++, Pb++, Cd++, Hg++, and C104-. MECA's microscopy station combines optical and atomic-force microscopy (AFM) to image dust and soil particles from millimeters to nanometers in size. Illumination by red, green, and blue LEDs is augmented by an ultraviolet LED intended to excite fluorescence in the sample. Substrates were chosen to allow experimental study of size distribution, adhesion, abrasion, hardness, color, shape, aggregation, magnetic and other properties. To aid in the detection of potentially dangerous quartz dust, an abrasion tool measures sample hardness relative to quartz and a hard glass (Zerodur).

Meloy, Thomas P.↗

Teleoperation from Mars Orbit: A proposal for Human Exploration

For a human expedition to Mars, a case can be made that the best strategy for initial exploration is not to actually land the humans on Mars, but to put the humans into Mars orbit and operate on the surface by the technology of teleoperation. This will provide the results of human exploration, but at greatly reduced risk and cost. Teleoperation of Mars surface robots from a Mars-orbital habitat will operation near real time operation with minimum time delay, giving a virtual presence on the surface. By use of teleoperation, it is possible to vastly simplify the surface exploration mission. We now have no need to develop a human-rated Mars Lander and Mars Ascent Vehicle, and we can send geologists & biologists on the mission; not VTOL pilots. It is a cheaper, simpler, and safer way to explore, and hence it will be a faster way to explore. It has the excitement of being there, at a fraction of the price. Tele-exploration from Mars orbit also allows human (virtual) presence at a wide variety of locations. With an orbital base controlling surface telerobotics, human explorers are not stuck with one base location, but can explore all over Mars. They can explore the polar caps and also near-equatorial canyon regions, from the same orbiting base. This frees the mission from landing site constraints. With no need to select a "grab bag" site that contains a large number of geologically diverse features at or near a single location; it is now possible go to all the best sites-- paleolake sites, river beds, volcanic calderas, lava tube sites, layered terrain, canyons, possible shoreline features, the North and South poles. A near-polar inclination 24-hr 39-minute period Mars orbit, for example, will put the orbital station in line-of-sight of a given region for about 8 hours per day-- one teleoperation shift. Since present day life could exist on Mars, planetary protection is also needed to preserve the (possible) fragile Mars biosphere from competition from ferocious Earth life. Isolated biospheres on Earth have been devastated when they have been exposed to alien life forms introduced-accidentally or deliberately-- from another continent. If there is life on Mars, we will wish to protect it from having to compete with introduced Earth biota. Reverse planetary protection-protecting the Earth biosphere from exposure to Mars microorganisms-is also an important consideration. Exploring from orbit will reduce biological risk by keeping humans from exposure to possible Mars microbes. A telerobotic mission will need no quarantine on return to Earth, and avoids the difficult human question of how to isolate Mars mission astronauts infected by Martian microorganisms.

Landis, Geoffrey A.↗

Altair Lunar Lander Development Status: Enabling Lunar Exploration

As a critical part of the NASA Constellation Program lunar transportation architecture, the Altair lunar lander will return humans to the moon and enable a sustained program of lunar exploration. The Altair is to deliver up to four crew to the surface of the moon and return them to low lunar orbit at the completion of their mission. Altair will also be used to deliver large cargo elements to the lunar surface, enabling the buildup of an outpost. The Altair Project initialized its design using a "minimum functionality" approach that identified critical functionality required to meet a minimum set of Altair requirements. The Altair team then performed several analysis cycles using risk-informed design to selectively add back components and functionality to increase the vehicle's safety and reliability. The analysis cycle results were captured in a reference Altair design. This design was reviewed at the Constellation Lunar Capabilities Concept Review, a Mission Concept Review, where key driving requirements were confirmed and the Altair Project was given authorization to began Phase A project formulation. A key objective of Phase A is to revisit the Altair vehicle configuration, to better optimize it to complete its broad range of crew and cargo delivery missions. Industry was invited to partner with NASA early in the design to provide their insights regarding Altair configuration and key engineering challenges. NASA intends to continue to seek industry involvement in project formulation activities. This paper will update the international coimmunity on the status of the Altair Project as it addresses the challenges of project formulation, including optinuzing a vehicle configuration based on the work of the NASA Altair Project team, industry inputs and the plans going forward in designing the Altair lunar lander.

Laurini, Kathleen C.↗

The Challenge of Mars EDL (Entry, Descent, and Landing)

This slide presentation reviews the some of the challenges of Martian atmospheric entry, descent and landing (EDL) on the surface of Mars. It reviews some of the technological difficulties, and some solutions that are being developed for future unmanned missions with larger payloads than previous landers, and ultimately human spacecraft landing.

Sostaric, Ronald↗

Rocket Exhaust Cratering: Lessons Learned from Viking and Apollo

During the Apollo and Viking programs NASA expended considerable effort to study the cratering of the regolith when a rocket launches or lands on it. That research ensured the success of those programs but also demonstrated that cratering will be a serious challenge for other mission scenarios. Unfortunately, because three decades have elapsed since NASA last performed a successful retro-rocket landing on a large planetary body - and ironically because Apollo and Viking were successful at minimizing the cratering effects - the space agency has a minimized sense of the seriousness of the issue. The most violent phase of a cratering event is when the static overpressure of the rocket exhaust exceeds the bearing capacity of the soil. This bearing capacity failure (BCF) punches a small and highly concave cup into the surface. The shape of the cup then redirects the supersonic jet - along with a large flux of high-velocity debris - directly toward the spacecraft. This has been observed in terrestrial experiments but never quantified analytically. The blast from such an event will be more than just quantitatively greater than the cratering that occurred in the Apollo and Viking programs. It will be qualitatively different, because BCF had been successfully avoided in all those missions. In fact, the Viking program undertook a significant research and development effort and redesigned the spacecraft specifically for the purpose of avoiding BCF [1]. (See Figure 1.) Because the Apollo and Viking spacecraft were successful at avoiding those cratering effects, it was unnecessary to understand them. As a result, the physics of a BCF-driven cratering event have never been well understood. This is a critical gap in our knowledge because BCF is unavoidable in the Martian environment with the large landers necessary for human exploration, and in Lunar landings it must also be addressed because it may occur depending upon the design specifics of the spacecraft and the weakening of the regolity by gas diffusion.

Metzger, Philip T.↗

Compact Telescoping Surface Array for Mars Solar Power

This paper describes a lightweight, large-area solar array concept for Mars surface power called the Compact Telescoping Surface Array (CTSA). The design is derived from the Compact Telescoping Array (CTA) proposed in 2015 for high-power spacecraft. The CTSA deploys horizontally from Mars landers, provides 1000 sq.m of solar cell area, and generates about 50-80 kW daytime and 10 kW nighttime power (from energy storage) near the equator with clear skies. The total mass is about 1500 kg, and the stowed volume is about 10 cu.m, equivalent to 200 W/kg and 30 kW/cu.m at 1 astronomical unit (AU) from the sun. These challenging mass and volume goals require compact, lightweight structures to deploy and tension thin solar cell blankets in the Mars 0.38 g gravity field. Other features include single-axis rotation for daily or seasonal sun tracking, dust shedding, and feathering in high winds and sufficient strength for sustained 40 m/s winds in dust storms and brief 100 m/s winds in dust devils (dynamic pressure of 120 Pa). Based on preliminary design and analysis reported in the paper, CTSA appears to be a feasible approach for 1000 sq.m-class Mars solar arrays that autonomously deploy from landers prior to human arrival.

Pappa, Richard↗

Hydrocarbon Cold-Flow Simulation of LOX/LH2 Rocket Aerodynamics

In FY19, this project developed a test method which employed heated ethane in the physical simulation of rocket plume aerodynamics. Based on this work, EUS partnered with significant leveraged funding. A portable, self-contained test bed was also fabricated to support validation of the new method. In FY20, this project focused on the formal validation of ethane’s performance as an aerodynamic simulant as well as the development of the analytical and hardware infrastructure required to carry out that task. The test bed was activated, a series of heated-ethane tests on one or more rocket/diffuser configurations were conducted, and characterizations of the performance of the ethane simulation compared to hot-fire were performed. A series of 127 tests were conducted on 13 aerodynamic configurations to evaluate ethane’s performance as a simulant. It was found that the new methodology can reproduce rocket plume flow fields with +/- 0.5% pressure error at ~3% physical scale. The result is a cost-per-test reduction of ~99% compared to the hot-fire subscale testing typically used to obtain equivalent data. Some initial efforts have taken place, and future efforts are being planned with LaRC supersonic retro propulsion and MSFC SLS aerodynamics teams, which are interested in using the ethane system to wind-tunnel test human-rated Mars lander retrorockets and SLS Booster. Details of the prototypical experiments were published as NASA TM 2020-5009122,and have been presented in JANNAF Virtual Conference paper, "New Developments in Retro propulsion Testing for Mars Entry, Descent and Landing".

Daniel Jones↗