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NASA Landing Systems Research Aircraft (LSRA) is Convair 990 airplane modified to incorporate tire-and-landing-gear test facility containing test fixture. Airplane instrumented to measure loads, velocities, and slip angles between tires and runways.
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As planetary spacecraft landing system complexity increases, pre-flight performance assessments include correspondingly more detailed and complex models that represent the various environmental elements and vehicle subsystems. Specifically, the relevance and criticality of planetary terrain modeling in the context of precision landing and hazard avoidance (PL&HA) has become evident as both commercial and national agencies return to the Lunar surface and beyond.
Analysis of inflatable landing systems - Mars soft lander capsule study
Payload soft landing system using stowable gas bag
An MLS (microwave landing system) certification system based on the Global Positioning System (GPS) is described. To determine the position history of the flight inspection aircraft during runway approach, signals from the GPS satellites, together with on-board radar altimetry, are used. It is shown that the aircraft position relative to a fixed point on the runway at threshold can be determined to about 30 cm vertically and 1 m horizontally. A requirement of the system is that the GPS receivers be placed on each flight inspection aircraft and at selected ground sites. The effects of different error sources on the determination of aircraft instantaneous position and its dynamics are analyzed.
Results for the Microwave Landing System (MLS) guidance algorithm development conducted under the Advance Transport Operating System (ATOPS) Technology Studies (NAS1-16202) are documented. The study consisted of evaluating guidance law for vertical and lateral path control, as well as speed control, for approaches not possible with the present Instrument Landing System (ILS) equipment. Several specific approaches were simulated using the MD-80 aircraft simulation program, including curved, descending (segmented glide slope), and decelerating paths. Emphasis was placed on development of guidance algorithms specifically for approaches at Burbank, where proposed flight demonstrations are planned. Results of this simulation phase are suitable for use in future fixed base simulator evaluations employing actual hardware (autopilot and a performance management system).
Landing systems including events sequencing devices, deceleration, stabilization and main descent subsystems
Test flights were conducted to evaluate the capability of Differential Global Positioning System (DGPS) to provide the accuracy and integrity required for International Civil Aviation Organization (ICAO) Category (CAT) III precision approach and landings. These test flights were part of a Federal Aviation Administration (FAA) program to evaluate the technical feasibility of using DGPS based technology for CAT III precision approach and landing applications. An IAI Westwind 1124 aircraft (N24RH) was equipped with DGPS receiving equipment and additional computing capability provided by E-Systems. The test flights were conducted at NASA Ames Research Center's Crows Landing Flight Facility, Crows Landing, California. The flight test evaluation was based on completing 100 approaches and landings. The navigation sensor error accuracy requirements were based on ICAO requirements for the Microwave Landing System (MLS). All of the approaches and landings were evaluated against ground truth reference data provided by a laser tracker. Analysis of these approaches and landings shows that the E-Systems DGPS system met the navigation sensor error requirements for a successful approach and landing 98 out of 100 approaches and landings, based on the requirements specified in the FAA CAT III Level 2 Flight Test Plan. In addition, the E-Systems DGPS system met the integrity requirements for a successful approach and landing or stationary trial for all 100 approaches and landings and all ten stationary trials, based on the requirements specified in the FAA CAT III Level 2 Flight Test Plan.
The objective was to investigate the ability of present day aircraft equipped with automatic flight control systems to fly advanced Microwave Landing Systems (MLS) approaches. The tactical approach used to achieve this objective included reviewing the design and autoland operation of the MD-80 aircraft, simulating the MLS approaches using a batch computer program, and assessing the performance of the autoland system from computer generated data. The results showed changes were required to present Instrument Landing System (ILS) procedures to accommodate the new MLS curved paths. It was also shown that in some cases, changes to the digital flight guidance systems would be required so that an autoland could be performed.
Prototype beacon landing system (BLS) allows helicopters to make precise landings in all weather. BLS easily added to existing helicopter avionic equipment and readily deployed at remote sites. Small and light, system employs X-band radar and digital processing. Variety of beams pulsed sequentially by ground station after initial interrogation by weather radar of approaching helicopter. Airborne microprocessor processes pulses to determine glide slope, course deviation, and range.
An automatic landing system was developed for the Augmentor Wing Jet STOL Research Airplane to establish the feasibility and examine the operating characteristics of a powered-lift STOL transport flying a steep, microwave landing system (MLS) glide slope to automatically land on a STOL port. The flight test results address the longitudinal aspects of automatic powered lift STOL airplane operation including glide slope tracking on the backside of the power curve, flare, and touchdown. Three different autoland control laws were evaluated to demonstrate the tradeoff between control complexity and the resulting performance. The flight test and simulation methodology used in developing conventional jet transport systems was applied to the powered-lift STOL airplane. The results obtained suggest that an automatic landing system for a powered-lift STOL airplane operating into an MLS-equipped STOL port is feasible. However, the airplane must be provided with a means of rapidly regulation lift to satisfactorily provide the glide slope tracking and control of touchdown sink rate needed for automatic landings.
Compared to the current instrument landing system, the microwave landing system (MLS), which is in the advanced stage of implementation, can potentially provide significant fuel and time savings as well as more flexibility in approach and landing functions. However, the expanded coverage and increased accuracy requirements of the MLS make it more susceptible to the features of the site in which it is located. An analytical approach is presented for evaluating the multipath effects of scatterers that are commonly found in airport environments. The approach combines a multiplane model with a ray-tracing technique and a formulation for estimating the electromagnetic fields caused by the antenna array in the presence of scatterers. The model is applied to several airport scenarios. The reduced computational burden enables the scattering effects on MLS position information to be evaluated in near real time. Evaluation in near real time would permit the incorporation of the modeling scheme into air traffic control automation; it would adaptively delineate zones of reduced accuracy within the MLS coverage volume, and help establish safe approach and takeoff trajectories in the presence of uneven terrain and other scatterers.
A representative Human System Interface for a precision lunar landing system, ALHAT, has been developed as a platform for prototype visualization and interaction concepts. This facilitates analysis of crew interaction with advanced sensors and AGNC systems. Human-in-the-loop evaluations with representatives from the Crew Office (i.e. astronauts) and Mission Operations Directorate (MOD) were performed to refine the crew role and information requirements during the final phases of landing. The results include a number of lessons learned from Shuttle that are applicable to the design of a human supervisory landing system and cockpit. Overall, the results provide a first order analysis of the tasks the crew will perform during lunar landing, an architecture for the Human System Interface based on these tasks, as well as details on the information needs to land safely.
On March 26, 2019, in keeping with Space Policy Directive-1, NASA was charged 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 transportation in deep space to 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. On April 30, 2020, NASA announced the awardees for NASA’s Human Landing System contracts under Appendix H of the NextSTEP-2 Broad Agency Announcement: A Blue Origin-led team including Lockheed Martin, Northrup Grumman, and Draper; Dynetics (a Leidos company); and SpaceX. The companies began work in a multi-month base period during which NASA teams will work with the companies to streamline requirements, to establish standards and methods, to review required products and to share the NASA’s expertise in human spaceflight systems development. Following the base period, which ends in the spring of 2021, NASA will determine which company or companies will develop Artemis human landing systems for the initial demonstration missions, including the goal of landing on the Moon in 2024.This paper examines how the Human Landing System program is at the center of NASA’s Artemis lunar exploration program, designed to yield groundbreaking science, develop and utilize lunar surface resources and leverage the Moon as a proving ground for future Mars 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.
Compared to the current instrument landing system, the microwave landing system (MLS), which is in the advanced stage of implementation, can potentially provide significant fuel and time savings as well as more flexibility in approach and landing functions. However, the expanded coverage and increased accuracy requirements of the MLS make it more susceptible to the features of the site in which it is located. An analytical approach is presented for evaluating the multipath effects of scatterers that are commonly found in airport environments. The approach combines a multiplane model with a ray-tracing technique and a formulation for estimating the electromagnetic fields caused by the antenna array in the presence of scatterers. The model is applied to several airport scenarios. The reduced computational burden enables the scattering effects on MLS position information to be evaluated in near real time. Evaluation in near real time would permit the incorporation of the modeling scheme into air traffic control automation; it would adaptively delineate zones of reduced accuracy within the MLS coverage volume, and help establish safe approach and takeoff trajectories in the presence of uneven terrain and other scatterers.
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.
The effects of steady wind, turbulence, data sample rate, and control-actuator natural frequency on the response of a possible automatic landing system were investigated in a nonstatistical study. The results indicate that the system, which interfaces with the microwave landing system, functions well in winds and turbulence as long as the guidance law contains proper compensation for wind. The system response was satisfactory down to five data samples per second, which makes the system compatible with the microwave landing system. No adverse effects were observed when actuator natural frequency was lowered. For limiting cases, those cases where the roll angle goes to zero just as the airplane touches down, the basic method for computing the turn-algorithm gains proved unsatisfactory and unacceptable landings resulted. Revised computation methods gave turn-algorithm gains that resulted in acceptable landings. The gains provided by the new method also improved the touchdown conditions for acceptable landings over those obtained when the gains were determined by the old method.