Towards Multifunctional Characteristics of Embedded Structures With Carbon Nanotube Yarns

This paper presents recent results on research of achieving multifunctional structures utilizing Carbon Nanotube (CNT) yarns. The investigation centers on creating composite structures with CNT yarns to simultaneously achieve increases in mechanical strength and the ability to sense strain. The CNT yarns used in our experiments are of the single-ply and two-ply variety with the single-ply yarns having diameters on the order of 10–20 μm. The yarns are embedded in silicon rubber and polyurethane test specimens. Mechanical tests show an increase in modulus of elasticity, with an additional weight increase of far less than one-percent. Sensing characteristics of the yarns are investigated on stainless steel test beams in an electrical bridge configuration, and are observed to have a strain sensitivity of 0.7mV/V/1000 micro-strain. Also reported are measurements of the average strain distribution along the direction of the CNT yarns on square silicon rubber membranes.

Contemporary Technology and Application of MEMS Rocket

MEMS rocket array is one of the most promising propulsion systems for micro satellite. Its recent development researches have reached close to practical devices. This paper reviews the performances and maturities of recently-build MEMS rockets. Four MEMS rocket projects are treated; LAAS-CNRS, France, Tohoku University, Japan, National University of Singapore, and Kyushu University, Japan. Their design, size, propellant, etc. are explained. The smallest MEMS rocket of Kyushu University using DDNP propellant and PDMS micro tank is also introduced.

Micro (Cost) Technologies for Spacecraft Control and Command: An Example, Balloon-Borne Stabilised Gondolas

Balloons are long-time known space vehicles for science missions and technology in-flight experiments, with instruments that need out-of-atmosphere or in-situ measurements, thus being complementary to the satellite. They carry micro (few hundred grams) to mega (few tons) payloads, but all of them require micro cost, short development, multiple flights. Among the big ones, CNES stabilised gondolas are versatile space platforms used to fly science instruments mainly coming for aeronomy and astrophysics communities, and requiring stabilisation and pointing capabilities, analogous to satellite attitude control subsystems. For them, cost and development constraints cannot be met without highly flexible architectures and off-the-shelf components. In order to increase gondola flexibility to new missions (or adaptability to mission evolutions), new hardware and software solution have been studied for control & command, including stabilisation and pointing functions. Promoted technologies are those of industrial computers, ground networks, free software and, over all, Ada language, for they are open, standard, powerful, low-cost and long-lasting solutions. After a brief description of domain-oriented characteristics of the stabilised gondola control & command, this paper introduces the various technologies and main design principles proposed to meet system-level goals. Then focus is put on on-board architectures: full Ada95 real-time distributed applications on an Ethernet-IP LAN of industrial PCs running Linux, and describes the prototyping work and preliminary development done to ensure feasibility. The paper then discusses the applicability of such solutions to global, ground-to-board, distributed control & command applications, through an IP-based telemetry & telecommand link, such as the one under development in CNES for balloon systems. As a conclusion, this paper shows how adoption of these technologies for other space programs such as satellite platforms and payloads may change design, development costs, duration and organisation, as well as it may open new ways in ground-to-board communication and spacecraft operation.

Integration of New Sensors Into Space Vehicles

For the successful integration of new sensors into space vehicles, it is necessary to establish early in the project a close and interactive between the technology developer and the end user. The problem to be solved and prospective solutions required from the technology developer should be clearly identified and well defined to demonstrate that the proposed technology works satisfactorily in the relevant environment and that it presents no danger or interference to existing systems. The technology provider has to remain involved with the user through installation, acceptance testing, and acclimation of the new technology. The product developer and end user must jointly perform the following functions: • Develop a detailed set of requirements: performance, physical, environmental, safety, reliability, and maintainability. • Establish the qualification process to certify the product. • Define the documentation requirements for the qualification process. • Establish a quality control process to monitor the design, fabrication, testing, and integration of the product into the vehicle or the ground support system. It is important that the performance requirements established by the user be well defined before any potential solution to a problem is considered viable. The successful integration of micro- and nanotechnology into space vehicles requires a coordinated effort throughout the design, development, installation, and integration processes. The selection of materials for sensors and associated instrumentation is critical because certain materials can cause hazards in the space environment that are not apparent in the ground environment. Materials should be selected early, and their use approved by the user. The safety community should be involved early in the design process, even during the conceptual design phase. Certification and safety problems that are often found late in the design cycle can be avoided easily and less expensively if they are addressed early in the process. Flight and ground operations personnel should also contribute to the design process since they are the people who will be installing sensors and instrumentation, as well as operating the systems. They understand the vehicle and support systems that will be required to support the installation and operation of new systems.

MEMS Reliability: Accurate Measurements of Beam Stiffness Using Nanoindentation Techniques

Bending tests on suspended parts of MicroElectroMechanical System (MEMS) can be achieved thanks to nanoindentation techniques. The paper presents the main difficulties met when performing such a test, and shows how they can be reduced by experimental ways. An application is realized on gold bridges, with a validation of some theoretical assumptions.

Environmental Chamber for Temperature and Pressure Investigations on MEMS Devices

In this paper, we present a new tool developed for environmental testing of MEMS: the EMA (Environmental MEMS Analyzer) 3D. Based on white light profilometry coupled with an environmental chamber, it permits large temperature scale and different pressure testing. This system has been used to characterize the environmental behavior of two types of RF MEMS, from −20 to 200°C.

Industrial Verification of Piezo Motors on a CubeSat Based Verification Platform

Due to the classification of technologies in NASA’s and ESA’s technology readiness levels, newly developed components have to be space proven before they can be utilized in space missions. This space prove can be adduced by sending these technologies to orbit either as experiment on a piggyback flight or a dedicated mission. Over the last years the size of technologies and satellites has shifted to much smaller sizes. In this paper, the possibility of industrial verification of MEMS (Micro Electro Mechanical System) applications using dedicated pico-satellite missions is examined. Based on the CubeSat concept, a technology verification platform can be realized for verification of not only pico-satellite components, but also of components of complex systems and missions. Therefore a platform fulfilling the requirements for such industrial verification of components named MOVE (Munich Orbital Verification Experiment) is developed at the Institute of Astronautics (LRT). This platform enables professional verification of MEMS technology and techniques at overall mission costs of less than 100k€. As a first application of this approach, a mission called π-MOVE (π for piezo) will verify piezo motors on the developed platform. These piezo motors are representative for components of complex systems, as this motor concept is considered to be key technology for future segmented mirror telescope missions. In the mission design process for this platform, strong emphasis is put on the robustness of the design, low complexity and realizability within the institute’s environment. The advantages through access to both university and industry resources will be taken. The feasibility of professional technology verification is highly dependent on the test plans, which are developed in cooperation with the experienced industrial partners.

Monolithic Silicon-Based Microthruster for Orbital and Attitude Control Fabricated by Using MEMS Technologies

In the last decades there has been an increasing development of small satellites allowing remarkable reduction of both cost and fabrication time. In parallel, there has been a general increase of LEO missions for Earth observation based on small satellites. The miniaturization technologies developed in the 80’s have allowed the development of microsensors and microactuators compatible with applications on microsatelites. This trend has stimulated the need of microthrusters to maintain orbital and attitude control requiring thrust ranging from some micro-Newton to some milli-Newton. In this work is described the design and development of a Micro Thruster, monolithically fabricated in Silicon with photolithographic technologies usually applied for MEMS fabrication. The thrust is obtained by using, as propellant, high concentration H2O2 that is induced to the liquid-to-vapour phase exothermal transition by means of a suitable catalyst. Design parameters, fabrication details as well as preliminary tests will be presented and discussed.

MEMS Based One Shot Electro-Thermal Micro-Switches for System Reconfiguration

A new concept of one shot micro-switches is proposed. Different switches have been developed to achieve either ON-OFF switching or OFF-ON switching. They are based on electrothermal mechanisms. ON-OFF switching consists in breaking an electrical connection using energetic material or low melting point metal like aluminum. OFF-ON switching consists in micro-soldering locally two electrical connections. Switches commute with a few hundred of mW and do not need energy to stay in the stable OFF or ON state. These switches are particularly adapted to spatial redundancy applications that need high quality contact and reliable commutation even after long time storage. The fabrication process of these switches is based on classic MEMS technology steps (LPCVD, PECVD, copper electrodeposition, lift-off and plasma etching) and is IC compatible. Fabrication yield reaches 99%.

Variable Emissivity Surfaces for Micro and Nanosatellites

The contemporary satellites usually utilize louvers as variable emissivity surfaces (VES) for the thermal control subsystem. This means is only particularly scalable down and the next generation of small satellites definitely requires new techniques for thermal control. Further, the low mass, volume and cost of the micro and nanosatellite require additional features from the future VES. Besides high reliability, which is an unconditional requirement for a space application, the other criteria are as follows: low mass, deep modulation of emissivity, low heat leak in off-state, fast reaction time, passive action, as well as other lower level criteria. These requirements are complex and sometimes contradictory. The current approaches to find alternatives to the traditional mechanical louvers branch in several directions: electrophoretic, electrochromic, electrostatics actuated VES, MEMS shutters, etc. None of the current solutions is successful in meeting all of the posed criteria. We present a novel VES subsystem, particularly developed for use in micro and nanosatellites. The concept is simple, reliable and very efficient. The bionic structure, a flower-like design, is made from a thin and elastic foil. The artificial flower consists from a peduncle, fixed to the satellite radiator panel and 4–6 petals. The upper surface of the petal is made as the second-surface mirror and the lower surface is the gold plated or the first-surface mirror. The kinematic mechanism which opens and closes the artificial flower is the shape memory actuator located in the petal root. The SMA actuators are trained as the “two way actuators”. The “two way” memory effect has been recognized as difficult to control and suffering from amnesia. However, the new learning process of the shape memory actuators enables more than 350.000 cycles without SMA parameter degradation. The artificial flower works as follow: when the sun irradiates the flower and/or the radiator temperature exceeds the preset value, the SMA actuators bend and open the flower. In such a manner the flower exposes the highly reflective surface to the sun and shadows the satellite radiator until the sun sets again. The flower structure is without any friction-connected kinematic movements, thus the reliability of device should be high. The mass of the flower is less than 450 g/m2, the heat leak trough the open flower is >2% and the efficiency of the closed flower is <80%. The SMA actuator is passive and quite resistant to the radiation, oxygen and EDS.