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Guidance, Navigation and Control of Asteroid Mobile Imager and Geologic Observer (AMIGO)
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Abstract
The science and origins of asteroids is deemed high priority in the Planetary Science Decadal Survey. Major scientific goals for the study of planetesimals are to decipher geological processes in SSSBs not determinable from investigation via in-situ experimentation, and to understand how planetesimals contribute to the formation of planets. Ground based observations are not sufficient to examine SSSBs, as they are only able to measure what is on the surface of the body; however, in-situ analysis allows for further, close up investigation as to the surface characteristics and the inner composure of the body. To this end, the Asteroid Mobile Imager and Geologic Observer (AMIGO) an autonomous semi-inflatable robot will operate in a swarm to efficiently characterize the surface of an asteroid. The stowed package is 10x10x10 cm (equivalent to a 1U CubeSat) that deploys an inflatable sphere of ~1m in diameter. Three mobility modes are identified and designed: ballistic hopping, rotation during hops, and up-righting maneuvers. Ballistic hops provide the AMIGO robot the ability to explore a larger portion of the asteroid's surface to sample a larger area than a stationary lander. Rotation during the hop entails attitude control of the robot, utilizing propulsion and reaction wheel actuation. In the event of the robot tipping or not landing up-right, a combination of thrusters and reaction wheels will correct the robot's attitude. The AMIGO propulsion system utilizes sublimate-based micro-electromechanical systems (MEMS) technology as a means of lightweight, low-thrust ballistic hopping and coarse attitude control. Each deployed AMIGO will hop across the surface of the asteroid multiple times.
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There are thousands of asteroids in near-Earth space and millions in the Main Belt. They are diverse in physical properties and composition and are time capsules of the early solar system. This makes them strategic locations for planetary science, resource mining, planetary defense/security and as interplanetary depots and communication relays. However, asteroids are a challenging target for surface exploration due it its low but highly nonlinear gravity field. In such conditions, mobility through ballistic hopping possess multiple advantages over conventional mobility solutions and as such hopping robots have emerged as a promising platform for future exploration of asteroids and comets. They can traverse large distances over rough terrain with the expenditure of minimum energy. In this paper we present ballistic hopping dynamics and its motion planning on an asteroid surface with highly nonlinear gravity fields. We do it by solving Lambert's orbital boundary value problem in irregular gravity fields by a shooting method to find the initial velocity required to intercept a target. We then present methods to localize the hopping robot using pose estimation by successive scan matching with a 3D laser scanner. Using the above results, we provide methods for motion planning on the asteroid surface over long distances. The robot will require to perform multiple hops to reach a desired goal from its initial position while avoiding obstacles. The study is then be extended to find optimal trajectories to reach a desired goal by visiting multiple waypoints. INTRODUCTION The millions of asteroids in the solar system are known to be diverse in size, shape and composition. Exploration of asteroids can give further insight into the origin questions, namely the origin of the solar system, origin of Earth and origin of life. Certain C-type asteroids are known to contain water-rich carbon based organic-molecules and rare-minerals. Some of these asteroids are hypothesized to have seeded Earth with the needed organic building-block to start life. Some asteroids contain remains of existing planets and serve as time-capsules that can provide pristine records of the early geology and geohistory of the planets. Some of these asteroids are known to be composed of material billions of years old. These small bodies are remnants of planet formation, progenitors of meteorites, and are therefore high-value targets in the Planetary Science Decadal Survey. The exploration of these small-bodies can give us insight into the formation of the solar-system, planetary defense and future prospect for in-situ resource utilization. Exploration of these asteroid can also provide useful insight into the primordial solar system. The exact composition of these asteroids is hard to discern, as they have undergone layering and surface weathering processes that modify chemical composition of the surface. Flyby and long-range observation of asteroids is insufficient to determine what is beneath the top layer of the asteroid. Only surface and subsurface exploration of asteroids can answer these questions. The recent exploration of asteroids such as Bennu and Ryugu all show evidence for the 'brazil nut' effect, where large objects end up on the surface compared to small objects. This makes surface extremely rugged and extremely challenging for surface exploration. This also further confirms that the material underneath will be substantially different. All of these factors reinforce the need for surface exploration and use of in-situ instruments to analyze composition of the surface and subsurface material. We have identified the need to perform excavation to perform chemical analysis, pene-trometery and seismic analysis as high-priority science. 1 However, the surface environment of asteroids presents many unique challenges and opportunities. Unlike Earth, Mars or Moon, asteroid gravity is low (10-1,000 µg) and their irregular shape results in highly irregular gravity fields. This eliminates the practical use of conventional multi-wheeled rovers that rely on surface traction. Instead, hopping rovers are more naturally suited for such environments, as they can traverse large distances over arbitrarily rough terrain with the expenditure of little energy and little need for traction. Although the cost of hopping over an asteroid surface is significantly low, too high a thrust can result in a rover attaining escape velocity and tumbling into space. Thus, the surface operation will be limited by the local gravitational field. As communication suffers from large delays over very long distances, the hopping rover operating on an asteroid surface will require a high degree of autonomy in addition to controllability. The rovers deployed on asteroid surfaces to date relies on a mothership relay, however they are infrequent. Wheeled rovers operate through continuous interaction with the environment, and as such path planning is performed through visual perception and terrain classification. However, hopping rovers can only apply forces from rest on the surface and have no control of their trajectory mid-flight. Thus, a sequential architecture for hopping rover autonomy is required that can plan ahead before executing any hop. Mothership-independent localization feedback is also required for the hoping rovers to be autonomous as interaction with the mothership is infrequent. In this paper we present a dynamics model for a rover deployed on the surface of an asteroid followed by ballistic hopping simulations and a self-localization method by using a 3D LiDAR sensor onboard the rover. Ballistic hopping and self-localization methods are then used to develop an algorithm that provides optimal trajectories for a rover to reach a target position from its initial position. The algorithm can also be used to guide the rover through multiple waypoints in between the initial and target position. These very same tactics to perform asteroid surface and subsurface science is needed for resource prospecting and mining. Asteroids are rich in resources required for a space economy, including sources of propellent, structural materials and rare minerals. The low gravity of asteroids makes it especially appealing for supplying resources in cis-lunar and inter-planetary space. There are also many asteroids in strategic locations to be future communication relays, 2 propellant sources and space construction material. In the following section, we present background followed by the dynamic model of the rover and asteroid environment. Next, we present the dynamics of ballistic hopping, localization and motion planning to enable a hopping rover to traverse an asteroid followed by conclusions and future work. BACKGROUND
There are thousands of asteroids in near-Earth space and millions expected in the Main Belt. They are diverse in their physical properties and compositions, and are time capsules of the early Solar System. They are valuable for planetary science, and are strategic for resource mining, planetary defense/security and as interplanetary depots. But we lack direct knowledge of the geophysical behavior of an asteroid surface under milligravity conditions, and therefore landing on an asteroid and manipulating its surface material remains a daunting challenge. Towards this goal we are putting forth plans for a 12U CubeSat that will be in Low Earth Orbit and that will operate as a spinning centrifuge on-orbit. In this paper, we will present an overview of the systems engineering and instrumentation design on the spacecraft. Parts of this 12U CubeSat will contain a laboratory that will recreate asteroid surface conditions by containing crushed meteorite. The laboratory will spin at 1 to 2 RPM during the primary mission to simulate surface conditions of asteroids 2 km and smaller, followed by an extended mission where the spacecraft will spin at even higher RPM. The result is a bed of realistic regolith, the environment that landers and diggers and maybe astronauts will interact with. The CubeSat is configured with cameras, lasers, actuators and small mechanical instruments to both observe and manipulate the regolith at low simulated gravity conditions. A series of experiments will measure the general behavior, internal friction, adhesion, dilatancy, coefficients of restitution and other parameters that can feed into asteroid surface dynamics simulations. Effective gravity can be varied, and external mechanical forces can be applied. These centrifuge facilities in space will require significantly less resources and budget to maintain, operating in LEO, compared to the voyages to deep space. This means we can maintain a persistent presence in the relevant deep space environment without having to go there. Having asteroid-like centrifuges in LEO would serve the important tactical goal of preparing and maintaining readiness, even when missions are delayed or individual programs get cancelled.
The increasingly successful use of nanosatellites has made CubeSat an attractive form factor for a number of missions that require both an attitude control system (ACS) and primary propulsion. The CubeSat High Impulse Propulsion System (CHIPS), under development by CU Aerospace with partner VACCO Industries, is designed to enable CubeSat mission operations beyond simple orbit maintenance, including significant altitude changes, formation flying, and proximity operations such as rendezvous and docking. CHIPS integrates primary propulsion, ACS and propellant storage into a single bolt-on module that is compatible with a variety of non-toxic, self-pressurizing liquid propellants. The primary propulsion system uses micro-resistojet technology developed by CU Aerospace to superheat the selected propellant before subsequent supersonic expansion through a micro-nozzle optimized for frozen-flow efficiency. The 1U+ baseline design is capable of providing an estimated 563 N-s total impulse at 30 mN thrust using R134a propellant, giving an impulse density of 552 N-s/liter. The ACS is a cold gas, 4-thruster array to provide roll, pitch, yaw, and reverse thrust with a minimum impulse bit of 0.4 mN-s. An engineering prototype, with integrated pressure control, power control, and data logging, was extensively tested in cold and warm gas modes on the University of Illinois thrust stand under a range of conditions. This paper presents thrust and specific impulse data for the resistojet thruster using two different propellants. Resistojet data include cold and warm gas performance as a function of mass flow rate, plenum pressure, geometry, and input power.
Wheeled ground robots are limited from exploring extreme environments such as caves, lava tubes and skylights. Small robots that can utilize unconventional mobility through hopping, flying or rolling can overcome these limitations. Multiple robots operating as a team offer significant benefits over a single large robot , as they are not prone to single-point failure, enable distributed command and control and enable execution of tasks in parallel. These robots can complement large rovers and landers, helping to explore inaccessible sites, obtaining samples and for planning future exploration missions. Our robots, the SphereX, are 3-kg in mass, spherical and contain computers equivalent to current smartphones. They contain an array of guidance, navigation and control sensors and electronics. SphereX contains room for a 1-kg science payload, including for sample return. Our work in this field has recognized the need for miniatur-ized chemical mobility systems that provide power and propulsion. Our research explored the use of miniature rockets, including solid rockets, bi-propellants including RP1/hydrogen-peroxide and polyurethane/ammonium-perchlorate. These propulsion options provide maximum flight times of 10 minutes on Mars. In addition, we have been developing mechanical hopping mechanisms. Flying, especially hovering consumes significant fuel; hence, we have been developing our robots to perform ballistic hops that enable the robots to travel efficiently over long distances. Techniques are being developed to enable mid-course correction during a ballistic hop. Using multiple cameras, it is possible to reconstitute an image scene from motion blur. Hence our approach is to enable photo mapping as the robots travel on a ballistic hop. The same images would also be used for navigation and path planning. Using our proposed design approach, we are developing low-cost methods for surface exploration of planetary bodies using a network of small robots.
The application of GNC devices on small robots is a game-changer that enables these robots to be mobile on low-gravity planetary surfaces and small bodies. Use of reaction wheels enables these robots to roll, hop, summersault and rest on precarious/sloped surfaces that would otherwise not be possible with conventional wheeled robots. We are extending this technology to enable robots to climb off-world canyons, cliffs and caves. A single robot may slip and fall, however, a multirobot system can work cooperatively by being interlinked using spring-tethers and work much like a team of mountaineers to systematically climb a slope. A multirobot system as we will show in this paper can climb surfaces not possible with a single robot alone. We consider a team of four robots that are interlinked with tethers in an " x " configuration. Each robot secures itself to a slope using spiny gripping actuators, and one by one each robot moves upwards by crawling, rolling or hopping up the slope. If any one of the robots loses grip, slips or falls, the remaining robots will be holding it up as they are anchored. This distributed controls approach to cliff climbing enables the system to reconfigure itself where possible and avoid getting stuck at one hard to reach location. Instead, the risk is distributed and through close cooperation, the robots can identify multiple trajectories to climb a cliff or rugged surface. The benefits can also be realized on milligravity surfaces such as asteroids. Too fast a jump can result in the robot flying off the surface into space. Having multiple robots anchored to the surface keeps the entire system secure. Our work combines dynamics and control simulation to evaluate the feasibility of our approach. The simulation results show a promising pathway towards advanced development of this technology on a team of real robots.
Wheeled planetary rovers such as the Mars Exploration Rovers (MERs) and Mars Science Laboratory (MSL) have provided unprecedented, detailed images of the Mars surface. However, these rovers are large and are of high-cost as they need to carry sophisticated instruments and science laboratories. We propose the development of low-cost planetary rovers that are the size and shape of cantaloupes and that can be deployed from a larger rover. The rover named SphereX is 2 kg in mass, is spherical, holonomic and contains a hopping mechanism to jump over rugged terrain. A small low-cost rover complements a larger rover, particularly to traverse rugged terrain or roll down a canyon, cliff or crater to obtain images and science data. While it may be a one-way journey for these small robots, they could be used tactically to obtain high-reward science data. The robot is equipped with a pair of stereo cameras to perform visual navigation and has room for a science payload. In this paper, we analyze the design and development of a laboratory prototype. The results show a promising pathway towards development of a field system.
Directed in-situ science and exploration on the surface of small Solar System bodies requires controlled mobility. In the microgravity environment of small bodies such as asteroids, comets or small moons, the low gravi-tational and frictional forces at the surface make typical wheeled rovers ine↵ective. Through a joint collaboration , the Jet Propulsion Laboratory together with Stanford University have been studying microgravity mobility approaches using hopping/tumbling platforms. They have developed an internally-actuated spacecraft/rover hybrid platform, known as " Hedgehog, " that uses flywheels and brakes to impart mobility. This paper presents a model of the platform's mobility, analyzing its three main states of motion (pivoting, slipping and hopping) and the contact dynamics between the platform's spikes and various regolith simulants. To experimentally validate the model, an Atwood machine (pulley and counterbalance) was used to emulate microgravity. Experiments were performed with a range of torques on both rigid and granular surfaces while a high-speed camera tracked the platform's motion. Using parameters measured during the experiments, the platform was simulated numerically and its motion compared. Within the limits of the experimental setup, the model is consistent with observations; it indicates the ability to perform controlled forward motions in microgravity on a range of rigid and granular regolith simulants.
Methods to constrain the surface mineralogy of asteroids have seen
considerable development during the last decade with advancement in laboratory
spectral calibrations and validation of our interpretive methodologies by
spacecraft rendezvous missions. This has enabled the accurate identification of
several meteorite parent bodies in the main asteroid belt and helped constrain
the mineral chemistries and abundances in ordinary chondrites and basaltic
achondrites. With better quantification of spectral effects due to temperature,
phase angle, and grain size, systematic discrepancies due to non-compositional
factors can now be virtually eliminated for mafic silicate-bearing asteroids.
Interpretation of spectrally featureless asteroids remains a challenge. This
paper presents a review of all mineralogical interpretive tools currently in
use and outlines procedures for their application.
Space missions to small solar system bodies must deal with multiple perturbations acting on the spacecraft. These include strong perturbations from the gravity field and solar tide, but for small bodies the most important perturbations may arise from solar radiation pressure (SRP) acting on the spacecraft. Previous research has generally investigated the effect of the gravity field, solar tide, and SRP acting on a spacecraft trajectory about an asteroid in isolation and has not considered their joint effect. In this paper a more general theoretical discussion of the joint effects of these forces is given.
The future exploration of small Solar System bodies will, in part, depend on the availability of mobility platforms capable of performing both large surface coverage and short traverses to specific locations. Weak gravitational fields, however, make the adoption of traditional mobility systems difficult. In this paper we present a planetary mobility platform (called “spacecraft/rover hybrid”) that relies on internal actuation. A hybrid is a small (~ 5 kg), multi-faceted robot enclosing three mutually orthogonal flywheels and surrounded by external spikes or contact surfaces. By accelerating/decelerating the flywheels and by exploiting the low-gravity environment, such a platform can perform both long excursions (by hopping) and short, precise traverses (through controlled “tumbles”). This concept has the potential to lead to small, quasi-expendable, yet maneuverable rovers that are robust as they have no external moving parts. In the first part of the paper we characterize the dynamics of such platforms (including fundamental limitations of performance) and we discuss control and planning algorithms. In the second part, we discuss the development of a prototype and present experimental results both in simulations and on physical test stands emulating low-gravity environments. Collectively, our results lay the foundations for the design of internally-actuated rovers with controlled mobility (as opposed to random hopping motion).
It is now feasible to construct highly capable ‘nanosatellites’ (i.e. sub–10 kg satellites) to provide cost–effective an rapid–response orbiting test vehicles for advanced space missions and technologies. The UK's first nanosatellite, SNAP–1—designe and built by Surrey Space Centre (SSC) and Surrey Satellite Technology Ltd (SSTL) staff — is an example of such a test vehicle in this case, built with the primary objective of demonstrating that a sophisticated, fully agile nanosatellite can be constructe rapidly, and at very low cost, using an extension of the modular–COTS–based design philosophy pioneered by SSC for its microsatellites.
SNAP–1 was successfully launched into orbit on 28 June 2000 from the Plesetsk Cosmodrome on board a Russian Cosmos rocket.
It flew alongside a Russian Cospas–Sarsat satellite called Nadezhda, and an SSTL–built Chinese microsatellite, called Tsinghua–1.
The first year of operations has been highly successful, with SNAP–1 becoming the first nanosatellite to have demonstrate full attitude and orbit control, via its miniature momentum–wheel–based attitude control system and its butane–propellant–base propulsion system. This paper reviews the initial results of the SNAP–1 mission.
This paper presents a new mission concept for planetary exploration, based on the deployment of a large number of small spherical mobile robots (“microbots”) over vast areas of a planet’s surface and subsurface, including structures such as caves and near‐surface crevasses (see Figure 1). This would allow extremely large‐scale in situ analysis of terrain composition and history. This approach represents an alternative to rover and lander‐based planetary exploration, which is limited to studying small areas of a planet’s surface at a small number of sites. The proposed approach is also distinct from balloon or aerial vehicle‐based missions, in that it would allow direct in situ measurement. In the proposed mission, a large number (i.e. hundreds or thousands) of cm‐scale, sub‐kilogram microbots would be distributed over a planet’s surface by an orbital craft and would employ hopping, bouncing and rolling as a locomotion mode to reach scientifically interesting artifacts in very rugged terrain. They would be powered by high energy‐density polymer “muscle” actuators, and equipped with a suite of miniaturized imagers, spectrometers, sampling devices, and chemical detection sensors to conduct in situ measurements of terrain and rock composition, structure, etc. Multiple microbots would coordinate to share information, cooperatively analyze large portions of a planet’s surface or subsurface, and provide context for scientific measurements. © 2005 American Institute of Physics
Exploration of asteroids, comets and small moons ('small bodies') can answer fundamental questions relating to the formation of the solar system, the availability of resources, and the nature of impact hazards. Near-earth asteroids and the small moons of Mars are potential targets of human exploration. But as illustrated by recent missions, small body surface exploration remains challenging, expensive, and fraught with risk. Despite their small size, they are among the most extreme planetary environments, with low and irregular gravity, loosely-bound regolith, extreme temperature variation, and the presence of electrically charged dust. Here we describe the Asteroid Origins Satellite (AOSAT-I), an on-orbit, 3U CubeSat centrifuge using a sandwich-sized bed of crushed meteorite fragments to replicate asteroid surface conditions. Demonstration of this CubeSat will provide a low-cost pathway to physical asteroid model validation, shed light on the origin and geophysics of asteroids, and constrain the design of future landers, rovers, resource ex-tractors, and human missions. AOSAT-I will conduct scientific experiments within its payload chamber while operating in two distinct modes: 1) as a nonrotating microgravity laboratory to investigate primary accretion, and 2) as a rotating centrifuge producing artificial milligravity to simulate surface conditions on asteroids, comets and small moons. AOSAT-I takes advantage of low-cost, off-the-shelf components, modular design, and the rapid assembly and instrumentation of the CubeSat standard, to answer fundamental questions in planetary science and reduce cost and risk of future exploration.
An analysis of the surface and interior state of Asteroid (101955) Bennu, the target asteroid of the OSIRIS-REx sample return mission, is given using models based on Earth-based observations of this body. These observations have enabled models of its shape, spin state, mass and surface properties to be developed. Based on these data the range of surface and interior states possible for this body are evaluated, assuming a uniform mass distribution. These products include the geopotential, surface slopes, near-surface dynamical environment, interior stress states and other quantities of interest. In addition, competing theories for its current shape are reviewed along with the relevant planned OSIRIS-REx measurements.
This paper provides an update of the Delfi nanosatellite programme of the Delft University of Technology (TU Delft), with a focus on the recent in-orbit results of the second TU Delft satellite Delfi-n3Xt. In addition to the educational objective that has been reached with more than 80 students involved in the project, most of the technological objectives of Delfi-n3Xt have also been fulfilled with successful in-orbit demonstrations of payloads and platform. Among these demonstrations, four are highlighted in this paper, including a solid cool gas micropropulsion system, a new type of solar cell, a more robust Command and Data Handling Subsystem (CDHS), and a highly integrated Attitude Determination and Control Subsystem (ADCS) that performs three-axis active control using reaction wheels. Through the development of Delfi-n3Xt, significant experiences and lessons have been learned, which motivated a further step towards DelFFi, the third Delfi CubeSat mission, to demonstrate autonomous formation flying using two CubeSats named Delta and Phi. A brief update of the DelFFi mission is also provided.
Using a numerically modeled nonmonotonic potential profile plasma
sheath, we identify the equilibrium height and charge of levitating dust
particles for nanometer to 10 µm sized particles over a five order
of magnitude variation in the gravity of an airless central body. The
stability and time scales of the dust particle motion about the
equilibria are computed. The range of initial velocities that results in
levitation of a dust particle is dominated by the particle size and is
relatively insensitive to the mass of the central body and the
particle's charge. By studying the dynamics of levitating dust
particles, we are able to move beyond the point solutions that have been
previously considered. This work enables more complete evaluations of
the importance of dust levitation in the evolution of airless bodies and
the hazard that levitating dust particles pose to exploration vehicles.
The problem of attitude stabilization for a spacecraft system which is nonlinear in dynamics with inertia uncertainty and external disturbance is investigated in this paper. An adaptive law is applied to estimate the disturbances, where a sliding mode controller is designed to force the state variables of the closed-loop system to converge to the origin. Then, the spacecraft system subjected to control constraints is further considered, and another adaptive sliding mode control law is designed to achieve the attitude stabilization. No prior knowledge of inertia moment is required for both of the proposed adaptive control laws, which implies that the designed control schemes can be applied in spacecraft systems with a large parametric uncertainty existing in inertial matrix or even in unknown inertial matrix. Also, simulation results are presented to illustrate the effectiveness of the control strategies.
This paper presents a new approach for the design of variable structure control (VSC) of nonlinear systems. The approach is based on a new method called the reaching law method, and is complemented by a sliding mode equivalence technique. They facilitate the design of the system dynamics in all three modes of a VSC system including the sliding, reaching, and steady-state modes. Invariance and robustness properties are discussed. The approach is applied to a robot manipulator to demonstrate its effectiveness.
Vision and Voyages for Planetary Science in the Decade
"Vision and Voyages for Planetary Science in the Decade 2013-2022." NASA, NASA, 18 Jan. 2018,
solarsystem.nasa.gov/science-goals/about/.
The MUSES-CN rover and asteroid exploration mission
- R M Jones
R.M. Jones. The MUSES-CN rover and asteroid exploration mission. In 22nd International Symposium on Space Technology and Science, pages 2403-2410, 2000.
Design, Control, and Experimentation of Internally-Actuated Rovers for the Exploration of Low-Gravity Planetary Bodies
- B Hockman
- A Frick
- I A D Nesnas
- M Pavone
B. Hockman, A. Frick, I. A. D. Nesnas, M. Pavone, "Design, Control, and Experimentation of Internally-Actuated Rovers for the Exploration of Low-Gravity Planetary Bodies," Conference on
Field and Service Robotics, 2015.
Hopping robot for planetary exploration" 8th iSAIRAS
- E Dupius
- S Montminy
- P Allard
E. Dupius, S. Montminy, P. Allard, "Hopping robot for planetary exploration" 8th iSAIRAS, September 2005.
Flying, hopping Pit-Bots for cave and lava tube exploration on the Moon and Mars" 2nd International Workshop on Instrumentation for Planetary Missions
- J Thangavelautham
- M S Robinson
- A Taits
- T J Mckinney
- S Amidan
- A Polak
J. Thangavelautham, M. S. Robinson, A. Taits, T. J. McKinney, S. Amidan, A. Polak, "Flying,
hopping Pit-Bots for cave and lava tube exploration on the Moon and Mars" 2nd International Workshop on Instrumentation for Planetary Missions, NASA Goddard, Greenbelt, Maryland, 2014.
What Is NASA's Asteroid Redirect Mission?" NASA, NASA
- Jim Wilson
Wilson, Jim. "What Is NASA's Asteroid Redirect Mission?" NASA, NASA, 16 Apr. 2015.
TW-1: A CubeSat Constellation for Space Networking Experiments
- S Wu
- Z Mu
- W Chen
- P Rodrigues
- R Mendes
- L Alminde
Wu, S.; Mu, Z.; Chen, W.; Rodrigues, P.; Mendes, R.; Alminde, L. TW-1: A CubeSat Constellation
for Space Networking Experiments. In Proceedings of the 6th European CubeSat Symposium, Estavayer-le-Lac, Switzerland, 16 October 2014.
CanX-4 and CanX-5 Precision Formation Flight: Mission Accomplished! In Proceedings of the 29th Annual AIAA/USA Conference on Small Satellites
- G Bonin
Bonin, G et al. CanX-4 and CanX-5 Precision Formation Flight: Mission Accomplished! In Proceedings of the 29th Annual AIAA/USA Conference on Small Satellites, Logan, UT, USA, 8-13
August 2015.
Asteroid Regolith Mechanics and Primary Accretion Experiments in a Cubesat
- E Asphaug
- J Thangavelautham
Asphaug, E., Thangavelautham, J., "Asteroid Regolith Mechanics and Primary Accretion Experiments in a Cubesat," 45th Lunar and Planetary Science Conference, 2014.
Analysis of Actuation and Dynamic Balancing for a Single Wheel Robot
- Y Xu
- K W Au
- G C Nandy
- H B Brown
Y. Xu, K. W. Au, G. C. Nandy, H. B. Brown, "Analysis of Actuation and Dynamic Balancing for a
Single Wheel Robot" IEEE/RSJ International Conference on Intelligent Robots and Systems, October 1998.