David J. Barnhart

Very-Small-Satellite Design for Distributed Space Missions

A new class of remote sensing and scientific distributed space missions is emerging that requires hundreds to thousands of satellites for simultaneous multipoint sensing. These missions, stymied by the lack of a low-cost mass-producible sensor node, can become reality by merging the concepts of distributed satellite systems and terrestrial wireless sensor networks. A novel, subkilogram, very-small-satellite design can potentially enable these missions. Existing technologies are first investigated, such as standardized picosatellites and microengineered aerospace systems. Two new alternatives are then presented that focus on a low-cost approach by leveraging existing commercial mass-production capabilities: a satellite on a chip (SpaceChip) and a satellite on a printed circuit board. Preliminary results indicate that SpaceChip and a satellite on a printed circuit board offer an order of magnitude of cost savings over existing approaches.

Characterising Wireless Sensor Motes for Space Applications

This paper is concerned with application of standard wireless COTS protocols to space. Suitability of commercially available wireless sensor mote kits for communication inside and between satellites is investigated. Spacecraft applications of motes are being considered and a set of requirements are identified. Selected mote kits are tested under various scenarios complying with spacecraft testing procedures. The paper details the results of the carried out functional, EMC/I, vibration, thermal and radiation tests.

Enabling Technologies for Distributed Picosatellite Missions in LEO

Picosatellites are very small satellites with a mass of less than 1 kg. A number of picosatellite projects have been undertaken by University and government research teams. Constellations of picosatellites could prove to be a low-cost and efficient solution to remote sensing in LEO. Reconfiguration and adaptation are capabilities, which are of critical importance to such constellations. A conceptual model of a constellation consisting of heterogeneous picosatellite nodes with a payload function distributed among the nodes will be outlined. Enabling technologies for picosatellite constellations such as wireless intersatellite links, reconfigurable onboard computing and distributed processing will be discussed. A proposal for a test-bed to demonstrate a reconfigurable distributed computing platform will be outlined

Satellite Miniaturization Techniques for Space Sensor Networks

T HERE is a growing trend toward distributed missions for scientific and remote sensing applications in which large numbers of satellites are required. Analogous to proliferating terrestrial wireless sensor networks, space sensor networks could provide an unprecedented capability to investigate widespread phenomena. For example, several important space weather missions have yet to be realized, due to the present inability to take simultaneous measurements of a phenomenon over a large volume. Space economics and environmental concerns dictate a costeffective mass-producible low-mass satellite for such massively distributed missions in low Earth orbit (LEO). An investigation of very small (subkilogram) satellite miniaturization techniques has been undertaken, focusing on enabling technologies targeted at space sensor network applications. Existing and emerging very-small-satellite technologies have been assessed and compared, with power generation and payload volume being the key performance metrics. Two novel design methodologies have been developed, simulated, and verified through functional and environmental testing of hardware prototypes. SpaceChip, inspired by the satellite-on-a-chip vision, is a monolithic heterogeneous system-on-a-chip (SOC) integration approach [1,2]. PCBSat is a proposed miniaturization approach, which is based on printed circuit board (PCB) substrates [3]. PCBSat is focused on deriving the smallest practical satellite within the context of space sensor network and constrained to the use of commercial off-the-shelf (COTS) components, processes, and deployment systems. This Note is intended to summarize the existing research effort [1] and to update the interested reader with the most recent developments on very-small-satellite miniaturization techniques [2]. An example case study is considered in which a space sensor network could demystify ionospheric plasma depletions, which are thought to cause problematic navigation and communication signal scintillation (i.e., communication outages). The Note is organized as follows: Sec. II highlights an example space sensor network mission enabled by very small satellites; Secs. III and IV summarize results of the SpaceChip and PCBSat investigations, respectively; and Sec. V concludes the Note by presenting the mission suitability and cost effectiveness of all technologies considered in this research.

Satellite-on-a-Chip Development for Future Distributed Space Missions

A new dimension of space mission architectures is emerging where hundreds to thousands of very small satellites will collectively perform missions in a distributed fashion. To support this architecture, high volume production of femto-scale satellites at low cost is required. This paper reviews current and emerging distributed space systems. A conceptual design of SpaceChip, which is a monolithic “satellite-on-a-chip” based on commercial CMOS technology is detailed. Assessment of the SpaceChip design is given and its use in future distributed space missions is discussed.Copyright

Radiation Hardening by Design of Asynchronous Logic for Hostile Environments

A wide range of emerging applications is driving the development of wireless sensor node technology towards a monolithic system-on-a-chip implementation. Of particular interest are hostile environment scenarios where radiation and thermal extremes exist. Radiation hardening by design has been recognized for over a decade as an alternative open-source circuit design approach to mitigate a spectrum of radiation effects, but has significant power and area penalties. Similarly, asynchronous logic design offers potential power savings and performance improvements, with a tradeoff in design complexity and a lesser area penalty. These side effects have prevented wider acceptance of both design approaches. A case study supporting the development of monolithic system-on-a-chip wireless sensor nodes is presented. Synchronous, hardened, and asynchronous/hardened implementations of a textbook microprocessor in 0.35 mum austriamicrosystems SiGe BiCMOS technology are compared. The synergy of this novel asynchronous/hardened design approach is confirmed by simulation and hardware results.

Distributed space-based Ionospheric Multiple Plasma Sensor networks

Distributed small satellite mission concepts are emerging for commercial, scientific, and military applications requiring constellations of many hundreds of satellites. Massively distributed missions allow both simultaneous multipoint observations and significant redundancy. This paper presents an application case study based on the US Air Force Academys (USAFA) Ionospheric Multiple Plasma Sensors (IMPS) mission. IMPS is an integration of the satellite-on-a-Printed Circuit Board (PCBSat) miniaturization approach developed at the University of Surrey with the Miniaturized Electrostatic Analyzer (MESA) sensor developed at USAFA.

Design of self-powered wireless system-on-a-chip sensor nodes for hostile environments

A new dimension of wireless sensor network architecture design is emerging where hundreds to thousands of ultra-light low-cost sensor nodes are required to collectively perform a spectrum of distributed remote sensing missions in hostile conditions, predominantly those encountered in space. Research is underway to investigate the feasibility of fabricating survivable self-powered sensor nodes monolithically with commercially available SiGe BiCMOS technology. This paper presents simulation and test chip results of two novel and essential building blocks: a photovoltaic/solar cell power supply and an environmentally tolerant microprocessor, based on radiation hardening by design and asynchronous logic.