Design Solutions For Modular Satellite Architectures

The cost-effective access to space envisaged by ESA would open a wide range of new opportunities and markets, but is still many years ahead. There is still a lack of devices, circuits, systems which make possible to develop satellites, ground stations and related services at costs compatible with the budget of academic institutions and small and medium enterprises (SMEs). As soon as the development time and cost of small satellites will fall below a certain threshold (e.g. 100,000 to 500,000 €), appropriate business models will likely develop to ensure a cost-effective and pervasive access to space, and related infrastructures and services. These considerations spurred the activity described in this paper, which is aimed at: - proving the feasibility of low-cost satellites using COTS (Commercial Off The Shelf) devices. This is a new trend in the space industry, which is not yet fully exploited due to the belief that COTS devices are not reliable enough for this kind of applications; - developing a flight model of a flexible and reliable nano-satellite with less than 25,000€; - training students in the field of avionics space systems: the design here described is developed by a team including undergraduate students working towards their graduation work. The educational aspects include the development of specific new university courses; - developing expertise in the field of low-cost avionic systems, both internally (university staff) and externally (graduated students will bring their expertise in their future work activity); - gather and cluster expertise and resources available inside the university around a common high-tech project; - creating a working group composed of both University and SMEs devoted to the application of commercially available technology to space environment. The first step in this direction was the development of a small low cost nano-satellite, started in the year 2004: the name of this project was PiCPoT (Piccolo Cubo del Politecnico di Torino, Small Cube of Politecnico di Torino). The project was carried out by some departments of the Politecnico, in particular Electronics and Aerospace. The main goal of the project was to evaluate the feasibility of using COTS components in a space project in order to greatly reduce costs; the design exploited internal subsystems modularity to allow reuse and further cost reduction for future missions. Starting from the PiCPoT experience, in 2006 we began a new project called ARaMiS (Speretta et al., 2007) which is the Italian acronym for Modular Architecture for Satellites. This work describes how the architecture of the ARaMiS satellite has been obtained from the lesson learned from our former experience. Moreover we describe satellite operations, giving some details of the major subsystems. This work is composed of two parts. The first one describes the design methodology, solutions and techniques that we used to develop the PiCPoT satellite; it gives an overview of its operations, with some details of the major subsystems. Details on the specifications can also be found in (Del Corso et al., 2007; Passerone et al, 2008). The second part, indeed exploits the experience achieved during the PiCPoT development and describes a proposal for a low-cost modular architecture for satellite

Cellular Based Aggregated Satellite System: The Design and Architecture of a Three Degree of Freedom Near-Frictionless Testbed for Ground Validation of CubeSat Operations

As small and nano-satellite operations become more complex and increase in functionality, the need to validate new concepts prior to deployment in a low-cost and time efficient manner has further increased. While computer simulations have traditionally provided acceptable results for guidance navigation and control (GNC) algorithms, more complex actions such as rendezvous and proximity operations and docking (RPOD) require alternative methods, which often require ground-based platforms. The concept of on-orbit autonomous docking of small satellites has grown in popularity due to its broad range of applications. However, most existing ground testing platforms (GTP) are expensive due to the technologies used and large physical space required. Due to the importance of RPOD to nano-satellites specifically, the development of a low-profile GTP is a crucial component in the testing and validation of small satellite concepts. The Space Engineering Research Center (SERC) at the University of Southern California (USC) has designed and manufactured a GTP capable of validating various unique nano-satellite operations in a cost-effective and space-efficient manner. This paper will focus on the design and architecture of a three degree of freedom (3DoF) near-frictionless testbed for ground validation of RPOD in a microgravity environment and its use with various small satellite applications

A Modular Small Satellite Bus for Low Earth Orbit Missions

The University of Surrey has demonstrated its capability in the field of small, low-cost spacecraft with the UoSAT-1 and 2 missions launched into low earth orbit in 1981 and 1984. Surrey Satellite Technology Ltd., a company formed by the University of Surrey, is now developing a flexible spacecraft bus based on the experience gained from these missions. The paper describes how the design philosophy used on the UoSAT spacecraft has been advanced to produce a bus providing basic power conditioning, telecommand, telemetry and attitude control functions. This basic bus is sufficient to support a variety of payloads, but the architecture is such that bus may be expanded (for example in number of telecommands) to support more demanding payloads. The use of this approach allows a standard proven product to support a wide variety of missions. The careful selection and screening of ensures a realistic cost, and the adoption tolerant \u27layered\u27 architecture give a high reliability in comparison to the low cost

Distributed Aperture Radar using Small Satellites

Recent work on key technological problems of self-cohering and high speed processing has led to a concept for distributed space based radar. Experimentally demonstrated self-cohering techniques allows a duster of small satellites to form a coherent aperture even though the position of each satellite in the cluster is not precisely known. The signal processing of the receive beams has been sized and the architecture of spaceborne VLSI processor outlined and shown to the practical in size, weight and power consumption. Clutter is reduced by the extremely narrow receive beams so that small targets can he detected and tracked. The goal is to achieve a low life cycle cost of this sensor system using light satellite technology

Closing the Deep Space Communications Link with Commercial Assets

Growing commercial and governmental interest in lunar and asteroid resource extraction, as well as continuing interest in deep space scientific missions, means an increase in demand for deep space communications systems. Jet Propulsion Laboratory’s MarCo demonstrated the viability and usefulness of cubesats as relay stations for deep space communications. Given their relatively low cost of construction and launch, cubesats can decrease the cost of building deep space communication systems. This has the potential to make it feasible for a group without a large budget, such as a university cubesat team, to build such a system. However, while minimizing the cost of the satellite is important, it is only one part of the communications link. The ground station is the other. The cost of accessing the Deep Space Network puts it out of reach for most operations that are not NASA programs, including our student-designed and built University of Colorado Earth Escape Explorer (CU-E3) 6U cubesat. This means that a project such as ours has to look at options provided by commercial ground station services. As a competitor in the NASA Cubequest Challenge Deep Space Derby, the CU-E3 team’s goal is to demonstrate it is possible to build a deep space communications system that is small, powerful, and (relatively) low cost. This means not just the hardware on the satellite but also the ground station. On the satellite side, we have developed custom hardware to interface with an AstroDev Li-2 radio for C-band uplink. For downlink, we will be using an X-band radio developed for low earth applications at the University of Colorado Boulder under the NASA Small Satellite Technology Development program. For ground station services, we will be partnering with a commercial provider, ATLAS. This paper describes the architecture of the CU-E3 communications system, the challenges of developing a communications system small enough to fit in a 6U cubesat yet powerful enough for deep space, and the process we used to research and partner with a commercial ground station service to help us fulfill our mission

Summary of Space Environment Magnetometer and Particle Replacement Experiment (SEMPRE) Study

As part of the GOES-R series follow on architecture study following the NOAA Satellite Observing System Architecture (NSOSA) study, a study team evaluated the feasibility of accommodating the GOES in-situ instruments (Magnetometer and Particle Detectors) on a dedicated spacecraft with no impact to the overall baseline mission cost assuming two large observatories. The accommodations cost on a primary operational type observatory are non-negligible requiring: a large non-magnetic boom to reduce the impact of the spacecraft interference on the magnetometer; and strict contamination control and magnetic cleanliness to prevent magnetic contamination near the magnetometers. These, along with the additional interface complexities greatly increase the cost of larger spacecraft by extending integration time with a large marching army. By contrast, a dedicated mission provides flexibility in location and refresh rate not afforded when these sensors are launched as secondary payloads. This study performed an informal industry survey of small form-factor instruments currently flying or in process of being developed. The study identified three potential particle detector suites and multiple magnetometers that will satisfy the requirements while having low enough volume and mass to allow accommodation on a rideshare class spacecraft. Using the largest of the identified particle detector suites, the Goddard Space Flight Center Mission Design Lab developed a design for a rideshare spacecraft that will accommodate the particle detector suite and magnetometer. The cost of the spacecraft, based on multiple cost models, is comparable to the cost of accommodating the magnetometer and particle detector suite on two (East and West) larger main observatories

Description and Simulation of a Fast Packet Switch Architecture for Communication Satellites

The NASA Lewis Research Center has been developing the architecture for a multichannel communications signal processing satellite (MCSPS) as part of a flexible, low-cost meshed-VSAT (very small aperture terminal) network. The MCSPS architecture is based on a multifrequency, time-division-multiple-access (MF-TDMA) uplink and a time-division multiplex (TDM) downlink. There are eight uplink MF-TDMA beams, and eight downlink TDM beams, with eight downlink dwells per beam. The information-switching processor, which decodes, stores, and transmits each packet of user data to the appropriate downlink dwell onboard the satellite, has been fully described by using VHSIC (Very High Speed Integrated-Circuit) Hardware Description Language (VHDL). This VHDL code, which was developed in-house to simulate the information switching processor, showed that the architecture is both feasible and viable. This paper describes a shared-memory-per-beam architecture, its VHDL implementation, and the simulation efforts

Analysis and Implementation of Communications Systems for Small Satellite Missions

Nano satellites are becoming more and more popular space platforms due to their relatively low cost. Constellations of many of these small satellites are being launched for scientific and research purposes. This thesis has examined implementing a communications system for small satellites that can be used to maintain constant contact with satellites as they orbit the Earth. It analyzes the various components of a small satellite and how they integrate. It then discusses the different abstraction layers that will be required in order to support the same software architecture across various types of hardware. An orbital analysis was performed to define the requirements for acquisition and loss of signal. Due to the ever increasing threat from space debris, a simulation using a high performance computing system to determine satellite threats was conducted. The thesis concludes with a communications analysis followed by a case study

A Distributed Computing Architecture for Small Satellite and Multi-Spacecraft Missions

Distributed computing architectures offer numerous advantages in the development of complex devices and systems. This paper describes the design, implementation and testing of a distributed computing architecture for low-cost small satellite and multi-spacecraft missions. This system is composed of a network of PICmicro® microcontrollers linked together by an I2C serial data communication bus. The system also supports sensor and component integration via Dallas 1-wire and RS232 standards. A configuration control processor serves as the external gateway for communication to the ground and other satellites in the network; this processor runs a multitasking real-time operating system and an advanced production rule system for on-board autonomy. The data handling system allows for direct command and data routing between distinct hardware components and software tasks. This capability naturally extends to distributed control between spacecraft subsystems, between constellation satellites, and between the space and ground segments. This paper describes the technical design of the aforementioned features. It also reviews the use of this system as part of the two-satellite Emerald and QUEST university small satellite missions

A Low, Cost Portable Ground Station to Track and Communicate with Satellites in VHF Band

In this thesis, we present the architecture and implementation of a low-cost, small, mobile and easily deployable ground station to track and receive signals from satellites that operate on the VHF-band (144 MHz to 147 MHz). The ground station uses a handheld 5-dB gain Yagi-Uda antenna, a low noise amplifier with 23 dB gain and a software defined radio (FUNcube Dongle) to receive the signals. The analog front end’s software-defined nature gives it the flexibility to target satellites with diverse power, modulation and error-correcting schemes. Software for satellite tracking, signal decoding and processing is freely-available. The low cost of the ground station makes its affordable for classroom and laboratory activities in a research or educational institution that involve satellite signal processing in wireless communication courses. The small size and portability of the proposed ground station means it can be adopted in locations with limited access to fixed outdoor antennas, whether because of financial, regulatory or other restrictions. Examples of ground station-tracked and received signals include satellites such as FUNcube (AO-73), International Space Station (ISS) and NOAA satellites. Specifically, the National Oceanographic and Atmospheric Administration (NOAA) series of satellites (NOAA 15, 18, 19) were tracked. The signals received were processed to recover images of the earth using various software. This thesis also presents the details of decoding the image using MATLAB