Showing papers presented at "IEEE Aerospace Conference in 2016"

State of the art of virtual reality technology

Abstract: In the past three years, the so-called second wave of Virtual Reality (VR) has brought us a vast amount of new displays and input devices. Not only new hardware has entered the consumer market providing affordable pricing models but also completely new technologies are being designed and developed. Additionally new concepts for handling existing problems on the hardware and software side of the VR technology are constantly being introduced. This software and hardware development is mainly lead by enthusiasts interested in the domain of VR opposed to the established scientific community, which already partially makes use of the newly available technology. Besides Head-Mounted Displays (HMDs), either cable-based or mobile, other devices like haptics devices, controllers, vests, omnidirectional treadmills, tracking technologies, as well as optical scanners for gesture-based interaction are gaining importance in the field of commodity VR. Most of these technologies are already precise and robust enough to be used for professional operation and scientific experiments. The topics discussed are the common issues with the new technologies including the approaches to solve them as for example motion-to-photon latency, barrel distortion, and low-persistence displays. Additionally an in-depth analysis of the available solutions expected to hit the market is provided. A taxonomy categorising the current developments with the chosen implementation approaches will be given. The paper analyses the state of technological advancements in the field and provides an extensive overview on the current development considering the upcoming devices and the advancements from the software side.

Options for staging orbits in cislunar space

Abstract: NASA has been studying options to conduct missions beyond Low Earth Orbit, but within the Earth-Moon system, in preparation for deep space exploration including human missions to Mars. Referred to as the Proving Ground, this arena of exploration activities will enable the development of human spaceflight systems and operations to satisfy future exploration objectives beyond the cislunar environment. One option being considered includes the deployment of a habitable element or elements, which could be used as a central location for aggregation of supplies and resources for human missions in cislunar space and beyond. Characterizing candidate orbit locations for this asset and the impacts on system design and mission operations is important in the overall assessment of the options being considered. The orbits assessed in this paper were previously identified in work conducted by NASA and others. In this paper orbits are assessed for their relative attractiveness based on various factors. First, a set of constraints related to the capability of the combined Orion and Space Launch System (SLS) system to deliver humans and cargo to and from the orbit are evaluated. Second, the ability to support potential lunar surface activities is considered. Finally, deployed assets intended to spend multiple years in the Proving Ground would ideally require minimal station keeping costs to reduce the mass budget allocated to this function. Additional mission design drivers include potential for uninterrupted communication with deployed assets, thermal, communications, and other operational implications. The results of the characterization and evaluation of the selected orbits indicate a Near Rectilinear Orbit (NRO) is an attractive candidate as an aggregation point or staging location for operations. In this paper, the NRO is further described in terms which balance a number of key attributes that favor a variety of mission classes to meet multiple, sometimes competing, constraints.

Enceladus Life Finder: The search for life in a habitable Moon

Abstract: Enceladus is one of the most intriguing bodies in the solar system. In addition to having one of the brightest and youngest surfaces, this small Saturnian moon was recently discovered to have a plume erupting from its south polar terrain and a global subsurface ocean. The Cassini Mission discovered organics and nitrogen-bearing molecules in the plume, as well as salts and silicates that strongly suggest ocean water in contact with a rocky core. However, Cassini's instruments lack sufficient resolution and mass range to determine if these organics are of biotic origin. The Enceladus Life Finder (ELF) is a Discovery-class mission that would use two state-of-the-art mass spectrometers to target the gas and grains of the plume and search for evidence of life in this alien ocean.

Constellations, clusters, and communication technology: Expanding small satellite access to space

Abstract: The trend toward small-sized spacecraft continues in government applications and is even increasing in commercial space endeavors that are funded by venture capital. Small spacecraft, including nanosatellites, microsatellites, and small satellites (smallsats), are an attractive alternative to traditional, larger spacecraft due to reduced development costs, decreased launch costs, and increased launch opportunities. A significant disadvantage, however, of a small spacecraft is its reduced or limited capabilities. The physical size of the small spacecraft reduces the size of the payload and/or the number of payloads that it can host, its propulsion capabilities, and its power. Small spacecraft are most commonly used in low Earth orbit, limiting the number of observation opportunities for a particular area of the Earth or space and the number of ground station downlink opportunities for stored data. These constraints affect the complexity and types of applications that small spacecraft can serve. Using multiple spacecraft that work together can overcome many of these limitations and expand the utility of small spacecraft. Two concepts for cooperative groups of spacecraft are constellations and clusters. A key technical challenge for small spacecraft, constellations, and clusters is communication of data. Communication challenges exist for accommodating varying numbers of users, serving high user densities in a given geographical area, and providing a consistent quality of service for different types of applications (e.g., Internet access, voice communication, machine-to-machine). This paper explores concepts for emerging communication technologies for space-ground and inter-satellite communication, while citing examples of existing and new constellation and cluster concepts. Several aspects of the communication systems are examined in terms of frequency bands, data rates, multiple access methods, and accommodation on spacecraft.

Perpetual flight with a small solar-powered UAV: Flight results, performance analysis and model validation

Abstract: This paper presents the design of the small-scale hand-launchable solar-powered AtlantikSolar UAV, summarizes flight results of a continuous 28-hour solar-powered flight that demonstrated AtlantikSolar's capability for energetically perpetual flight, and offers a model-based verification of flight performance and an outlook on the energetic margins that can be provided towards perpetual flight given today's solar-powered UAV technology. AtlantikSolar is a 5.6m-wingspan and 6.9kg mass low-altitude long-endurance UAV that was designed to provide perpetual endurance at a geographic latitude of 45N in a 4-month window centered around June 21st. A specific design emphasis is robust perpetual endurance with respect to local meteorological disturbances (e.g. clouds, winds, downdrafts). Providing the necessary energetic safety margins is a significant challenge on small-scale solar-powered UAVs. This paper thus describes the design optimizations undertaken on the AtlantikSolar UAV for maximum energetic safety margins. In addition, this paper presents the flight test results, analysis and performance verification of AtlantikSolar's first perpetual endurance continuous 28-hour flight. The flight results show a minimum state-of-charge of 40% or excess time of 7 hours during the night. In addition, the charge margin of 5.9 hours indicates sufficiently-fast battery charging during the day. Both margins exceed the performance of previously demonstrated solar-powered LALE UAVs. Another centerpiece of the paper is the verification of these flight results with the theoretical structural-, aerodynamics- and power-models that were developed and used to conceptually design the UAV. The solar-power income model is extended to take into account solar-panel temperature effects, the exact aircraft geometry and the current orientation and is compared against flight results. Finally, the paper provides an analysis and overview into under what conditions and with which energetic margins perpetual flight is possible with today's battery- and solar-cell technology. A perpetual endurance window of up to 6 months around June 21st is predicted at northern latitudes for the AtlantikSolar UAV configuration without pay-load. A final outlook into first perpetual endurance applications shows that perpetual flight with miniaturized sensing payloads (small optical and infrared cameras) is possible with a perpetual flight window of 4–5 months.

Autonomous UAVs wildlife detection using thermal imaging, predictive navigation and computer vision

Abstract: There is an increased interest on the use of Unmanned Aerial Vehicles (UAVs) for wildlife and feral animal monitoring around the world. This paper describes a novel system which uses a predictive dynamic application that places the UAV ahead of a user, with a low cost thermal camera, a small onboard computer that identifies heat signatures of a target animal from a predetermined altitude and transmits that target's GPS coordinates. A map is generated and various data sets and graphs are displayed using a GUI designed for easy use. The paper describes the hardware and software architecture and the probabilistic model for downward facing camera for the detection of an animal. Behavioral dynamics of target movement for the design of a Kalman filter and Markov model based prediction algorithm are used to place the UAV ahead of the user. Geometrical concepts and Haversine formula are applied to the maximum likelihood case in order to make a prediction regarding a future state of the user, thus delivering a new waypoint for autonomous navigation. Results show that the system is capable of autonomously locating animals from a predetermined height and generate a map showing the location of the animals ahead of the user.

Open source computer-vision based guidance system for UAVs on-board decision making

Abstract: The use of UAVs for remote sensing tasks; e.g. agriculture, search and rescue is increasing. The ability for UAVs to autonomously find a target and perform on-board decision making, such as descending to a new altitude or landing next to a target is a desired capability. Computer-vision functionality allows the Unmanned Aerial Vehicle (UAV) to follow a designated flight plan, detect an object of interest, and change its planned path. In this paper we describe a low cost and an open source system where all image processing is achieved on-board the UAV using a Raspberry Pi 2 microprocessor interfaced with a camera. The Raspberry Pi and the autopilot are physically connected through serial and communicate via MAVProxy. The Raspberry Pi continuously monitors the flight path in real time through USB camera module. The algorithm checks whether the target is captured or not. If the target is detected, the position of the object in frame is represented in Cartesian coordinates and converted into estimate GPS coordinates. In parallel, the autopilot receives the target location approximate GPS and makes a decision to guide the UAV to a new location. This system also has potential uses in the field of Precision Agriculture, plant pest detection and disease outbreaks which cause detrimental financial damage to crop yields if not detected early on. Results show the algorithm is accurate to detect 99% of object of interest and the UAV is capable of navigation and doing on-board decision making.

The mass spectrometer for planetary exploration (MASPEX)

Abstract: The MASPEX instrument is a high-resolution, high-sensitivity time-of-flight mass spectrometer developed for planetary applications. Its high-resolution (25,000 mMm at 10% peak height) allows the unambiguous determination of volatile isotopes of methane, water, ammonia, carbon monoxide, molecular nitrogen, carbon dioxide, and low order (C2, C3, and C4) organic compounds in complex mixtures. The use of cryotrapping boosts MASPEX's sensitivity by up to 10,000 times the ambient performance enabling the measurement of trace compounds including organic compounds and the noble gases argon, krypton, xenon, and their isotopes. Such capabilities are ideal for the study of astrobiology and solar system formation in a diverse range of planetary objects including asteroids, comets, and icy satellites. A highly sensitive electron impact ionization source (>105 ions per extracted ion packet) operating at 2000 extractions per second in conjunction with the time-of-flight mass analyzer, which produces a complete mass spectrum from every ion extraction, enables the rapid acquisition of high precision measurements over a wide range of mass. This is particularly important for applications such as atmospheric probes that have a limited operating period and also for providing high temporal/spatial resolution for flyby or orbital missions. Over ten years of development funded by Southwest Research Institute and NASA have resulted in a Technology Readiness Level of 6 suitable for applications to Discovery, New Frontiers, and Flagship missions. Several promising applications will be discussed in this presentation including the recent selection of MASPEX for the Europa mission payload, and applications to three Discovery 2015 proposals including a mission to Enceladus (ELF), comet Hartley 2 (PRIME), and to the main belt comet Read (Proteus). Other new applications to be discussed include upcoming New Frontiers opportunities for probes, landers, and sample return missions.

Discovering the sky at the Longest Wavelengths (DSL)

Abstract: The radio sky at frequencies below ∼30 MHz is virtually unobservable from Earth due to ionospheric disturbances and the opaqueness of the ionosphere below ∼10MHz, and also due to strong terrestrial radio interference. Deploying a radio observatory in space would open up this largely unexplored frequency band for science in astronomy, cosmology, geophysics, and space science. A Chinese-European team is proposing an ultra long wavelength (ULW) radio interferometer mission DSL (Discovering the Sky at the Longest Wavelengths). The proposed radio interferometer will be deployed in low-altitude lunar orbit, exploiting the radio quietness of the lunar far side. DSL will consist of a mother-spacecraft for data transport and control, plus eight small micro-satellites each equipped with three orthogonal dipoles. These satellites form a virtual distributed observatory with adjustable baselines, allowing different scientific observation strategies. The satellites are configured in a flexible quasi-linear array in nearly identical orbits, guaranteeing low relative drift rates. Short orbital periods and orbit precession ensure quick filling of the interferometric spatial frequency (u, v, w) space, enabling high quality imaging. The science themes considered for the DSL mission include pioneering studies of the unknown and exploratory science such as the search for signatures of the cosmological Dark Ages, complementing current (e.g. LOFAR) and future SKA telescope searches; full-sky continuum survey of discrete sources, including ultra-steep spectrum extragalactic sources, pulsars, and transients (galactic and extragalactic); full-sky map of continuum diffuse emission; solar-terrestrial physics, planetary sciences, and cosmic ray physics. The main frequency band covered is 1–30 MHz extending down to 0.1 MHz, and up to about 50 MHz for cross-referencing with ground-based instruments. DSL will support a variety of observational modes, including broad-band spectral analysis for Dark Ages, radio interferometric cross-correlations for imaging, and flexible raw data downlink capability. Data processing will be performed at radio astronomy science data centres in Europe and China.

Commercialization of Deployable Space Systems' roll-out solar array (ROSA) technology for Space Systems Loral (SSL) solar arrays

Abstract: Deployable Space Systems (DSS) developed an advanced flexible blanket ROSA that provides ultra-low weight, compact stowage volume, high power capability, power modularity, scale-ability, and affordability. Recent NASA and AFRL programs have helped advance the ROSA solar array to Technology Readiness Level (TRL) 6. Space Systems Loral (SSL) has selected this technology for commercial qualification and infusion. SSL is currently developing and qualifying ROSA technology as part of a next generation power generating system for future geosynchronous (GEO) spacecraft, advanced NASA and DOD missions. The generic benefits (vs. standard rigid array technology) of adopting a flexible blanket solar array for the GEO application will be presented. An overview of the SSL ROSA qualification program will be presented in combination with relevant design modeling, key analysis, hardware build, validation testing tests performed to date, and next steps for implementation.

Inflatable antenna for CubeSats: Development of the X-band prototype

Abstract: CubeSats1 and small satellites have potential to provide means to explore space and to perform science in a more affordable way. As the goals for these spacecraft become more ambitious in space exploration, moving from Low Earth Orbit (LEO) to Geostationary Earth Orbit (GEO) or further, the communication systems currently implemented will need to be improved to support those missions. One of the bottlenecks is the antennas' size, due to the close relation between antenna gain and dimensions. Hence, a possible solution is to develop inflatable antennas which can be packaged efficiently, occupying a small amount of space, and they can provide, once deployed, large dish dimension and correspondent gain. A prototype of a 1 m inflatable antenna for X-Band has been developed in a joint effort between JPL and ASU. This paper will detail the principle challenges in developing the antenna technology focusing on: design, EM analysis, fabrication and tests.

Space Mobile Network: A near Earth communications and navigation architecture

Abstract: This paper shares key findings of NASA's Earth Regime Network Evolution Study (ERNESt) team resulting from its 18-month effort to define a wholly new architecture-level paradigm for the exploitation of space by civil space and commercial sector organizations. Since the launch of Sputnik in October 1957 spaceflight missions have remained highly scripted activities from launch through disposal. The utilization of computer technology has enabled dramatic increases in mission complexity; but, the underlying premise that the diverse actions necessary to meet mission goals requires minute-by-minute scripting, defined weeks in advance of execution, for the life of the mission has remained. This archetype was appropriate for a “new frontier” but now risks overtly constraining the potential market-based opportunities for the innovation considered necessary to efficiently address the complexities associated with meeting communications and navigation requirements projected to be characteristics of the next era of space exploration: a growing number of missions in simultaneous execution, increased variance of mission types and growth in location/orbital regime diversity. The resulting ERNESt architectural cornerstone — the Space Mobile Network (SMN) — was envisioned as critical to creating an environment essential to meeting these future challenges in political, programmatic, technological and budgetary terms. The SMN incorporates technologies such as: Disruption Tolerant Networking (DTN) and optical communications, as well as new operations concepts such as User Initiated Services (UIS) to provide user services analogous to today's terrestrial mobile network user. Results developed in collaboration with NASA's Space Communications and Navigation (SCaN) Division and field centers are reported on. Findings have been validated via briefings to external focus groups and initial ground-based demonstrations. The SMN opens new niches for exploitation by the marketplace of mission planners and service providers.

Data-driven surface traversability analysis for Mars 2020 landing site selection

Abstract: The objective of this paper is three-fold: 1) to describe the engineering challenges in the surface mobility of the Mars 2020 Rover mission that are considered in the landing site selection processs, 2) to introduce new automated traversability analysis capabilities, and 3) to present the preliminary analysis results for top candidate landing sites. The analysis capabilities presented in this paper include automated terrain classification, automated rock detection, digital elevation model (DEM) generation, and multi-ROI (region of interest) route planning. These analysis capabilities enable to fully utilize the vast volume of high-resolution orbiter imagery, quantitatively evaluate surface mobility requirements for each candidate site, and reject subjectivity in the comparison between sites in terms of engineering considerations. The analysis results supported the discussion in the Second Landing Site Workshop held in August 2015, which resulted in selecting eight candidate sites that will be considered in the third workshop.

Certification strategies using run-time safety assurance for part 23 autopilot systems

Abstract: Part 23 aircraft operation, and in particular general aviation, is relatively unsafe when compared to other common forms of vehicle travel. Currently, there exists technologies that could increase safety statistics for these aircraft; however, the high burden and cost of performing the requisite safety critical certification processes for these systems limits their proliferation. For this reason, many entities, including the Federal Aviation Administration, NASA, and the US Air Force, are considering new options for certification for technologies which will improve aircraft safety. Of particular interest, are low cost autopilot systems for general aviation aircraft, as these systems have the potential to positively and significantly affect safety statistics. This paper proposes new systems and techniques, leveraging run-time verification, for the assurance of general aviation autopilot systems, which would be used to supplement the current certification process and provide a viable path for near-term low-cost implementation. In addition, discussions on preliminary experimentation and building the assurance case for a system, based on these principles, is provided.

Fault detection and classification for flight control electromechanical actuators

Abstract: Future aircraft architectures will incorporate more energy-efficient electromechanical actuators (EMA) for flight controls actuation. Development of reliable health monitoring techniques for EMAs promises to maintain or even increase the overall availability and safety of these new aircraft designs. When it comes to EMAs and similar mechanisms, certain fault types clearly manifest themselves through loss of functionality. Other faults, referred to as latent, do not immediately result in a significantly compromised actuator performance, thus making them challenging to detect. This paper presents a new vibration-based hybrid technique for detecting latent EMA faults without needing an initial stage of fault feature learning. The two faults considered in the study are a high-criticality jam and a low-criticality spall (metal flaking) in the actuator ballscrew mechanism. The actuator position is used to resample variable-speed vibration measurements of a single accelerometer into constant-rate measurements. A set of health characterization signatures is derived theoretically based on the EMA ballscrew kinematics. These theoretical signatures are compared with the signatures extracted from vibration signals measured experimentally on the EMA test articles. The vibration signatures approach is also compared to the diagnostic approach based on EMA motor current measurements. The ability to detect and classify latent faults early as high-or low-critical can improve maintenance planning and increase aircraft dispatch reliability. The technique has been validated on fault-injected data sets collected on the NASA Ames Research Center Flyable Electro-Mechanical Actuator (FLEA) test stand.

Perspectives for using virtual reality to extend visual data mining in information visualization

Abstract: Although virtual reality (VR) has a huge success in increasing the quality of scientific visualization applications, there is a considerable lag in the development of VR applications in the case of information visualization (InfoVis). Some researchers in InfoVis claim that 2D representations are enough for data analysis; however, in the case of multi-dimensional datasets, other researchers indicate that studying multiple dimensions simultaneously is advantageous [1], [2], [3]. The first studies with low quality stereoscopic devices showed no advantages when performing simple tasks on simple datasets [4]. However, recent experiments using higher quality devices and more complex datasets show a huge improvement in performance [5]. Still, designing an effective 3D representation remains a complex endeavour. Brath [6] provides a list of things to take into account. This paper shows how a CAVE-like2 environment can allow the study of multi-dimensional datasets while keeping multiple 2D representations available, using genome comparisons as a usecase. Parallel coordinate plots and non-planar graph representation in 3D space are also described. Some potential applications in aerospace are also listed (this is by no means a complete listing of applications; readers are encouraged to suggest new ones).

Human Mars lander design for NASA's evolvable mars campaign

Abstract: Landing humans on Mars will require entry, descent, and landing capability beyond the current state of the art. Nearly twenty times more delivered payload and an order of magnitude improvement in precision landing capability will be necessary. To better assess entry, descent, and landing technology options and sensitivities to future human mission design variations, a series of design studies has been initiated. This paper describes the results of the first design study in the series of studies to be completed in 2016 and includes system and subsystem design details including mass and power estimates for a lander design using the Hypersonic Inflatable Aerodynamic Decelerator (HIAD) entry technology. Future design activities in this series will focus on other entry technology options.

System design of a miniaturized distributed occulter/telescope for direct imaging of star vicinity

Abstract: The Space Rendezvous Laboratory (SLAB) at Stanford is investigating the feasibility of a miniaturized distributed occulter/telescope system (mDOT) to directly image exozodiacal dust and Jovian exoplanets. The mDOT mission relies on formation flying in Earth orbit and promises a drastic decrease of the expected mission cost compared to large scale missions, such as NWO and Exo-S (NASA). The preliminary system design of mDOT, described in this paper, is complemented by concurrent novel studies of optimal formation dynamics and diffractive optics design. mDOT consists of a microsatellite carrying a 1 meter radius petal shaped occulter at a distance of 500 km from a 6U CubeSat carrying a 10 cm diameter aperture telescope designed to image at short visible and ultraviolet wavelengths. Following a systems analysis, based on the definition of mission requirements and a survey of CubeSat capabilities, the telescope spacecraft provides 80 days of operation with 50 W solar cells, 31 m/s of delta-v capability using cold gas thrusters. Together with ad-hoc relative metrology instruments, these are used for lateral alignment with the occulter spacecraft at 15 cm position control accuracy. The goal of the mDOT mission is to prove that a space telescope with an external star occulter can be miniaturized, greatly reducing the mission cost and complexity. As shown in this paper, the proposed mission has the capability to directly image the vicinity of nearby stars and, at the same time, prove that miniaturized space systems are capable of executing complex missions. mDOT can serve as a first-of-a-kind precursor, paving the way for larger missions with higher scientific return.

Photovoltaic electrolysis propulsion system for interplanetary CubeSats

Abstract: CubeSats are a new and emerging low-cost, rapid development platform for space exploration research. Currently, CubeSats have been flown only in Low Earth Orbit (LEO). Advancements in propulsion can enable these spacecraft to achieve capture orbits around the Moon, Mars and beyond. Such enabling technology can make science-focused planetary CubeSat missions possible for low cost. However, Cubesats, because of their low mass, volume and launch constraints, are severely limited by propulsion. Here we present an innovative concept that utilizes water as the propellant for a 6U, 12 kg, Interplanetary CubeSat. The water is electrolyzed into hydrogen and oxygen on demand using onboard photovoltaic panels, which would, in turn, be combusted to produce thrust. However, important challenges exist with this technology including how to design and operate high efficiency Polymer Electrolyte Membrane electrolyzers at cold temperatures, how to efficiently separate the water from the hydrogen and oxygen produced in a microgravity environment and how to utilize the thrust generated to produce efficient trajectories. Our proposed solution utilizes a centrifuge that separates water from the reactants. The system uses salts, such as lithium chloride, to reduce the freezing point of water. Our techniques identify a method to operate the propulsion system up to −80 °C. Analysis of the combustion and flow through the nozzle using both theoretical equations and finite-volume CFD modeling shows that the specific impulse of the system is in the 360 s to 420 s range. At this efficiency, and from preliminary results a 12 kg CubeSat with 7.8 kg of propellant provides a Δν of 4,400 m/s. In theory, this is sufficient for Lunar or Mars capture orbits once deployed from LEO. These feasibility studies point to a promising pathway to further test the proposed concept.

ORION: A simulation environment for spacecraft formation flight, capture, and orbital robotics

Abstract: The Florida Institute of Technology developed the Orbital Robotic Interaction, On-orbit servicing, and Navigation (ORION) laboratory for the testing of spacecraft guidance, navigation, and control systems for spacecraft proximity maneuvers, and autonomous or telerobotic capture. ORION combines the precise kinematics simulation and large load-bearing capacity of a Cartesian robotic system with the vehicle dynamics simulation capabilities of an air-bearing flat-floor setup, with all vehicles in the simulation being tracked by an optical tracking system. The vehicles can simulate the kinematics and dynamics aspects of three-dimensional formation flight, final approach of uncooperative target objects, and capture. In addition to spacecraft maneuvers, ORION will also serve experiments and tests in the domains of unmanned aerial vehicles and terrestrial robots. This paper describes the design and capabilities of the six degrees of freedom maneuver kinematics simulator of the ORION lab, and the six degrees of freedom air-bearing vehicles for the flat-floor. Furthermore, the paper provides examples of the ongoing research activities: the development and test of capture tools for space debris objects, the project Assessment, Diagnostics, Corrections and Ground Testing of RINGS (Resonant Inductive Near-field Generation Systems), and the development and validation of a distributed virtual sensor for deflection, rate of rotation and acceleration of flexible structures based on fiber Bragg sensor arrays.

Secondary spacecraft in 2016: Why some succeed (And too many do not)

Abstract: This paper updates previous reviews of secondary spacecraft. With the number of new secondary spacecraft exceeding 100 per year, it is necessary to revisit the data, to better understand the trends and make new predictions. While CubeSats are the dominant type of secondary payloads, they are not the sole focus of this work. For 2016, we will re-examine our data and previous claims using a new set of classifications. We now believe that secondary-spacecraft developers are best divided into three groups: novices, traditionalists and experimentalists. Each of these groups approaches the development and operation of rideshares in very different ways, and the mission success rates between the three groups diverge. In this paper, we will review the census data (mass, lifetime, mission category, contributing organizations). examining trends and identifying deviations from (or confirmations of) previous predictions. Our focus will be on mission success and failure. We have accumulated sufficient information to define failure rates based on the type of organization, and to identify most-likely-causes based on the mission and organization type.

Model-based off-nominal state isolation and detection system for autonomous fault management

Abstract: This paper presents a model-based fault management (FM) system designed to provide off-nominal state detection and isolation capabilities that are key components to assessing spacecraft state awareness. The ability to autonomously isolate spacecraft failures to component levels will enable faster and more targeted responses and recovery thereby reducing down time. The use of model-based systems and practices is being explored by the FM community as a viable approach to developing more capable, autonomous systems in order to meet mission objectives. Model-based systems can provide better fault identification than traditional methods of fault detection such as limit-checking. They also lend themselves to more straight-forward approaches to verification and validation. We have chosen a particular model-based technique called Constraint Suspension for autonomous fault detection and isolation that does not require explicit fault modeling. The system is composed of a diagnostic engine and nominal system models of the target application, for example sensors and actuators. Sensed data are propagated through models of nominal system behavior. Faults are diagnosed when inconsistencies arise between sensed and modeled data. Several benefits result from this choice. First, because knowledge of faulty behavior is not required, it is possible to detect unanticipated and unforeseen faults. In fact, anomalous, degraded, and failed states all can be detected. Second, the same models used for nominal analyses and operations can be re-used for fault management, saving development resources and time. Third, the core diagnostic engine algorithm is complete and requires no additions to accommodate a potentially growing number of faults over time resulting in a relatively compact software footprint. Related to the second and third points is that the core algorithm and, potentially, models can be reused from mission to mission. Finally, the system can be used early in the design phase as a tool for sensor placement analyses and model verification. Health information produced by the FM system can be used to make resource allocation and planning and scheduling decisions by ground operations or by other on-board autonomy agents. Autonomous fault detection, isolation, and recovery (FDIR) on board space vehicles will provide protection and increased mission availability and reliability. On the ground such systems enable lights-out monitoring as well as training and support for operators. This paper presents the development of fault detection and isolation algorithms and models. Application of the system to a spacecraft attitude control system is discussed. Finally we apply Model-Based Systems Engineering (MBSE) modeling patterns to the fault management system models as a way to facilitate the development of the models through the use of SysML.

NEEMO 18–20: Analog testing for mitigation of communication latency during human space exploration

Abstract: NASA Extreme Environment Mission Operations (NEEMO) is an underwater spaceflight analog that allows a true mission-like operational environment and uses buoyancy effects and added weight to simulate different gravity levels. Three missions were undertaken from 2014–2015, NEEMO 18–20. All missions were performed at the Florida International University's Aquarius Reef Base, an undersea research habitat. During each mission, the effects of communication latencies on operations concepts, timelines, and tasks were studied METHODS: Twelve subjects (4 per mission) were weighed out to simulate near-zero or partial gravity extravehicular activity (EVA) and evaluated different operations concepts for intergration and management of a simulated Earth-based science team (ST) to provide input and direction during exploration activities. Exploration traverses were preplanned based on precursor data. Subjects completed science-related tasks including presampling surveys, geologic-based sampling, and marine-based sampling as a portion of their tasks on saturation dives up to 4 hours in duration that were designed to simulate EVA on Mars or the moons of Mars. One-way communication latencies, 5 and 10 minutes between space and mission control, were simulated throughout the missions. Objective data included task completion times, total EVA times, crew idle time, translation time, ST assimilation time (defined as time available for ST to discuss data/imagery after data acquisition). Subjective data included acceptability, simulation quality, capability assessment ratings, and comments. RESULTS: Precursor data can be used effectively to plan and execute exploration traverse EVAs (plans included detailed location of science sites, high-fidelity imagery of the sites, and directions to landmarks of interest within a site). Operations concepts that allow for presampling surveys enable efficient traverse execution and meaningful Mission Control Center (MCC) interaction across communication latencies and can be done with minimal crew idle time. Imagery and contextual information from the EVA crew that is transmitted real-time to the intravehicular activity (IVA) crewmember(s) can be used to verify that exploration traverse plans are being executed correctly. That same data can be effectively used by MCC (across comm latency) to provide meaningful feedback and instruction to the crew regarding sampling priorities, additional tasks, and changes to the EVA timeline. Text / data capabilities are preferred over voice capabilities between MCC and IVA when executing exploration traverse plans over communication latency.

SEXTANT X-ray Pulsar Navigation demonstration: Flight system and test results

Abstract: The Station Explorer for X-ray Timing and Navigation Technology (SEXTANT) is a technology demonstration enhancement to the Neutron-star Interior Composition Explorer (NICER) mission. NICER is a NASA Explorer Mission of Opportunity that will be hosted on the International Space Station (iSS). SEXTANT will, for the first time, demonstrate real-time, on-board X-ray Pulsar Navigation (XNAV), a significant milestone in the quest to establish a GPS-like navigation capability available throughout our Solar System and beyond. This paper gives an overview of the SEXTANT system architecture and describes progress prior to environmental testing of the NICER flight instrument. It provides descriptions and development status of the SEXTANT flight software and ground system, as well as detailed description and results from the flight software functional and performance testing within the high-fidelity Goddard Space Flight Center (GSFC) X-ray Navigation Laboratory Testbed (GXLT) software and hardware simulation environment. Hardware-in-the-loop simulation results are presented, using the engineering model of the NICER timing electronics and the GXLT pulsar simulator — the GXLT precisely controls NASA GSFC's unique Modulated X-ray Source to produce X-rays that make the NICER detector electronics appear as if they were aboard the ISS viewing a sequence of millisecond pulsars. SEXTANT is funded by the NASA Space Technology Mission Directorate, and NICER is funded by the NASA Science Mission Directorate.

Uncertainty based online planning for UAV target finding in cluttered and GPS-denied environments

Abstract: There are some scenarios in which Unmmaned Aerial Vehicle (UAV) navigation becomes a challenge due to the occlusion of GPS systems signal, the presence of obstacles and constraints in the space in which a UAV operates. An additional challenge is presented when a target whose location is unknown must be found within a confined space. In this paper we present a UAV navigation and target finding mission, modelled as a Partially Observable Markov Decision Process (POMDP) using a state-of-the-art online solver in a real scenario using a low cost commercial multi rotor UAV and a modular system architecture running under the Robotic Operative System (ROS). Using POMDP has several advantages to conventional approaches as they take into account uncertainties in sensor information. We present a framework for testing the mission with simulation tests and real flight tests in which we model the system dynamics and motion and perception uncertainties. The system uses a quad-copter aircraft with an board downwards looking camera without the need of GPS systems while avoiding obstacles within a confined area. Results indicate that the system has 100% success rate in simulation and 80% rate during flight test for finding targets located at different locations.

Advancing the search for extra-terrestrial genomes

Abstract: Widespread synthesis of complex organics, including nucleobases and ribose precursors, occurred early in the history of the solar system in the solar nebula. These organics, delivered to multiple potentially habitable zones, may have biased the evolution of life towards utilization of similar informational polymers. Meteoritic exchange might also have produced shared ancestry, most plausible for Earth and Mars. To test this hypothesis, we are developing the Search for Extra-Terrestrial Genomes (SETG), a life detection instrument for in-situ isolation and sequencing of nucleic acids. Our mission focus area is astrobiology and the search for life beyond Earth. Our science goal for Mars is to search for related or unrelated nucleic acid-based life, particularly life that has the potential to interact with life on Earth; this may also inform sample selection for Mars Sample Return (MSR) and reduce the risks of false positives through the first in-situ measurement of forward contamination. Our science goal for Enceladus is to search for a second genesis based on nucleic acids in the plumes emanating from the South Polar Region. Life detection may also be possible in Europa orbit but the availability of a suitable plume is tenuous and it is a challenge for biological reagents to survive intense radiation there. Here we describe advancements in SETG geared towards in-situ sequencing during a future Mars mission, including extraction of nucleic acids coupled with proof of principle for in-situ single-molecule nanopore-based sequencing. We briefly describe plans to advance SETG from Technology Readiness Level 3 to 6 in preparation for future flight definition and show that under realistic assumptions, a sensitivity of parts per billion or better is feasible.

RC64: High performance rad-hard manycore

Abstract: RC64 is a rad-hard manycore DSP combining 64 VLIW/SIMD DSP cores, lock-free shared memory, a hardware scheduler and a task-based programming model. The hardware scheduler enables fast scheduling and allocation of fine grain tasks to all cores.

Human Mars landing site and impacts on Mars surface operations

Abstract: This paper describes NASA's initial steps for identifying and evaluating candidate Exploration Zones (EZs) and Regions of Interests (ROIs) for the first human crews that will explore the surface of Mars. NASA's current effort to define the exploration of this planet by human crews, known as the Evolvable Mars Campaign (EMC), provides the context in which these EZs and ROIs are being considered. The EMC spans all aspects of a human Mars mission including launch from Earth, transit to and from Mars, and operations on the surface of Mars. An EZ is a collection of ROIs located within approximately 100 kilometers of a centralized landing site. ROIs are areas relevant for scientific investigation and/or development/maturation of capabilities and resources necessary for a sustainable human presence. The EZ also contains one or more landing sites and a habitation site that will be used by multiple human crews during missions to explore and utilize the ROIs within the EZ. With the EMC as a conceptual basis, the EZ model has been refined to a point where specific site selection criteria for scientific exploration and in situ resource utilization can be defined. In 2015 these criteria were distributed to the planetary sciences community and the in situ resource utilization and civil engineering communities as part of a call for EZ proposals. The resulting “First Landing Site/Exploration Zone Workshop for Human Missions to the Surface of Mars” was held in October 2015 during which 47 proposals for EZs and ROIs were presented and discussed. Proposed locations spanned all longitudes and all allowable latitudes (+/−50 degrees). Proposed justification for selecting one of these EZs also spanned a significant portion of the scientific and resource criteria provided to the community. Several important findings resulted from this Workshop including: (a) a strong consensus that, at a scale of 100 km (radius), multiple places on Mars exist that have both sufficient scientific interest to sustain multiple crews of exploring astronauts, AND potential resource deposits for ISRU indicating the current EZ definition is viable and should be retained for now, (b) new data types (needed for more definitive analysis of EZs) argued strongly for a new orbiter mission, and possibly one or more surface missions, to obtain these data, (c) a general consensus that this Workshop was an excellent start to identifying a place where future human missions to Mars can productively explore this planet and learn to live and work there for the long term. Building on these findings, HEOMD and SMD are: (a) refining the EZ selection criteria and overall selection process to improve on lessons learned from the first EZ workshop, (b) using these proposed locations to develop “reference EZs” for assessment purposes (primarily engineering assessments), (c) gathering data and conducting analyses to better understanding the different potential sources for water, including the ease of extraction and purification, and (d) assessing trends in additional data that are needed to better characterize EZs proposed at the workshop and how these data needs impact the design and operation of future robotic Mars missions.

Performance evaluation of SATCOM link in the presence of radio frequency interference

Abstract: Digital Video Broadcasting — Satellite — Second Generation (DVB-S2) and Digital Video Broadcasting — Return Channel via Satellite (DVB-RCS) are two important commercial satellite communications (SATCOM) standards, for forward link and return link information transmission via satellites, correspondingly. Advanced channel coding schemes have been designed in DVB-S2 and DVB-RCS to mitigate the information transmission uncertainties and unintentional interferences effects. However, the intentional interferences have been shown to increase dramatically in SATCOM application scenarios. Therefore, performance evaluation of a SATCOM link in the presence of both unintentional radio frequency interference (RFI) and intentional RFI are critical. The evaluation could provide guidance for next-generation SATCOM upgrades. In this paper, we leverage the Intelligent Fusion Technology, Inc. (IFT) communication data link simulator (ICDLS) to evaluate the performances of SATCOM links in the presence of various RFI conditions. The comprehensive RFIs are categorized into three types, which are wideband RFI, narrowband RFI, and radar RFI. Specifically, the carrier and phase synchronization errors caused by RFI are evaluated. Various waveforms including modulation and coding (MODCOD) schemes set in DVB-S2 and DVB-RCS standards are then evaluated considering the synchronization errors due to the existence of various RFI. Valuable observations are obtained based on ICDLS, which can be provided for next-generation SATCOM standards development.

IRASSI: InfraRed astronomy satellite swarm interferometry — Mission concept and description

Abstract: A current focus of modern astronomy is the characterization of the physical properties and of the chemical processes which can lead to prebiotic conditions in Earth-like planets. In order to identify such conditions, the first step is to observe regions in space which could originate Earth-like planets, such as stellar disks. The involved chemical processes are visible in the far-infrared radiation spectrum — more specifically in the spectral range of 1 to 6 THz. In order to perform observations in the far-infrared frequencies with high resolution, sophisticated instrumentation needs to be used. This spectrum is attenuated by the atmosphere and therefore can only be observed directly from space. Due to the high requirements placed on the spatial resolution, interferometry has gained popularity in recent years. Interferometric systems employ arrays of telescopes to extract information about a source with high resolution, by super-imposing electromagnetic wavefronts which are phase-shifted and measuring their interference. Such a system relies on the determination of the baseline of the telescopes with an accuracy proportional to the observed wavelength. In the far-infrared, this corresponds to accuracies in the micrometer level. This paper presents the IRASSI mission, whose aim is the observation of stellar disks and protoplanetary regions so as to understand the genesis of planets, star formation and evolution processes. IRASSI is a multidisciplinary interferometric telescope mission to the second Lagrange point, L2, of the Sun-Earth/Moon system. The constellation is composed of 5 spacecraft. The operating principle of IRASSI is that by dynamically changing the baseline distances between the spacecraft during scientific observations, one can measure the interference of the wavefronts at different locations. This technique allows the observation of the far-infrared phenomena at better resolution than that obtained with a single spacecraft. The outline of the IRASSI mission was built on precursor mission studies and concepts, such as ESPRIT and DARWIN. Unlike DARWIN, for instance, IRASSI does not require active control of the formation because it uses heterodyne detection in combination with a ranging system, which can provide inter-satellite distances with a very high accuracy. The present paper introduces therefore the mission concept of IRASSI, followed by a detailed description of the in-orbit operational concept at L2, while addressing how such mission fills in the gap of information regarding the observations in the far-infrared. The main mission analysis results obtained thus far are subsequently presented, and a hypothesized mechanical configuration is described. The key technical challenges posed by such endeavor are identified, complemented by an overview of the future work. The concluding remarks of the IRASSI study are then provided.