Survey of Inter-satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View

Small satellite systems enable whole new class of missions for navigation, communications, remote sensing and scientific research for both civilian and military purposes. As individual spacecraft are limited by the size, mass and power constraints, mass-produced small satellites in large constellations or clusters could be useful in many science missions such as gravity mapping, tracking of forest fires, finding water resources, etc. Constellation of satellites provide improved spatial and temporal resolution of the target. Small satellite constellations contribute innovative applications by replacing a single asset with several very capable spacecraft which opens the door to new applications. With increasing levels of autonomy, there will be a need for remote communication networks to enable communication between spacecraft. These space based networks will need to configure and maintain dynamic routes, manage intermediate nodes, and reconfigure themselves to achieve mission objectives. Hence, inter-satellite communication is a key aspect when satellites fly in formation. In this paper, we present the various researches being conducted in the small satellite community for implementing inter-satellite communications based on the Open System Interconnection (OSI) model. This paper also reviews the various design parameters applicable to the first three layers of the OSI model, i.e., physical, data link and network layer. Based on the survey, we also present a comprehensive list of design parameters useful for achieving inter-satellite communications for multiple small satellite missions. Specific topics include proposed solutions for some of the challenges faced by small satellite systems, enabling operations using a network of small satellites, and some examples of small satellite missions involving formation flying aspects.Comment: 51 pages, 21 Figures, 11 Tables, accepted in IEEE Communications Surveys and Tutorial

DISCUS - The Deep Interior Scanning CubeSat mission to a rubble pile near-Earth asteroid

We have performed an initial stage conceptual design study for the Deep Interior Scanning CubeSat (DISCUS), a tandem 6U CubeSat carrying a bistatic radar as main payload. DISCUS will be operated either as an independent mission or accompanying a larger one. It is designed to determine the internal macroporosity of a 260-600 m diameter Near Earth Asteroid (NEA) from a few kilometers distance. The main goal will be to achieve a global penetration with a low-frequency signal as well as to analyze the scattering strength for various different penetration depths and measurement positions. Moreover, the measurements will be inverted through a computed radar tomography (CRT) approach. The scientific data provided by DISCUS would bring more knowledge of the internal configuration of rubble pile asteroids and their collisional evolution in the Solar System. It would also advance the design of future asteroid deflection concepts. We aim at a single-unit (1U) radar design equipped with a half-wavelength dipole antenna. The radar will utilize a stepped-frequency modulation technique the baseline of which was developed for ESA's technology projects GINGER and PIRA. The radar measurements will be used for CRT and shape reconstruction. The CubeSat will also be equipped with an optical camera system and laser altimeter to sup- port navigation and shape reconstruction. We provide the details of the measurement methods to be applied along with the requirements derived of the known characteristics of rubble pile asteroids.Comment: Submitted to Advances in Space Researc

JUMPSAT: Qualifying three equipments in the CubeSat mission

JUMPSAT is a 3-Unit CubeSat mission expected for launch in 2017. It is a collaborative project involving the French research institutes CNES and ONERA as well as two universities, the Institut Supérieur de l'Aéronautique et de l'Espace and TELECOM Bretagne. The main mission objectives are the technological verification of both the three-axis attitude control system as well as the verification of two embedded payloads: A low cost Star Tracker developed by ISAE-Supaero for future small satellite missions and a directional radiation sensor for precise mapping of the Earth radiation belt. This article focuses on the mission concept and the status of the mission design in fall 2013. Main mission parameters are introduced, with emphases on the characteristic properties of the Jumpsat mission, as for example the choice of a sun-synchronous elliptical low-Earth Orbit, which is necessary to be in compliance with the payload requirements and at the same time to ensure space debris prevention. Furthermore, due to the limited observation time of a polar satellite, it was decided to utilize a distributed ground station network on S-band frequency for ensuring the necessary communication bandwidth for up- and downlink. The space segment will be equipped with deployable solar panels for improving the thermal and power budget of the overall system. Finally, a brief overview of the specifications and design of the attitude control system and both payloads are also given in the article

Quantum Communication Uplink to a 3U CubeSat: Feasibility & Design

Satellites are the efficient way to achieve global scale quantum communication (Q.Com) because unavoidable losses restrict fiber based Q.Com to a few hundred kilometers. We demonstrate the feasibility of establishing a Q.Com uplink with a tiny 3U CubeSat (measuring just 10X10X32 cm^3 ) using commercial off-the-shelf components, the majority of which have space heritage. We demonstrate how to leverage the latest advancements in nano-satellite body-pointing to show that our 4kg CubeSat can provide performance comparable to much larger 600kg satellite missions. A comprehensive link budget and simulation was performed to calculate the secure key rates. We discuss design choices and trade-offs to maximize the key rate while minimizing the cost and development needed. Our detailed design and feasibility study can be readily used as a template for global scale Q.Com.Comment: 24 pages, 9 figures, 2 tables. Fixed tables and figure

Space activities in Glasgow; advanced microspacecraft from Scotland

The City of Glasgow is renowned for its engineering and technological innovation; famous Glaswegian inventors and academics include James Watt (Steam Engine) and John Logie Baird (television), amongst many others. Contemporary Glasgow continues to pioneer and invent in a multitude of areas of science and technology and has become a centre of excellence in many fields of engineering; including spacecraft engineering. This paper will discuss how Clyde Space Ltd and the space groups at both Glasgow and Strathclyde Universities are combining their knowledge and expertise to develop an advanced microspacecraft platform that will enable a step change in the utility value of miniature spacecraft. The paper will also explore how the relationship between the academic and industrial partners works in practice and the steps that have been taken to harness resulting innovation to create space industry jobs within a city that was, until recently, void of any commercial space activity

PRETTY: Grazing altimetry measurements based on the interferometric method

The exploitation of signals stemming from global navigation systems for passive bistatic radar applications has beenproposed and implemented within numerous studies. The fact that such missions do not rely on high power amplifiersand that the need of high gain antennas with large geometrical dimensions can be avoided, makes them suitable forsmall satellite missions. Applications where a continuous high coverage is needed, as for example disaster warning,have the demand for a large number of satellites in orbit, which in turn requires small and relatively low cost satellites.The proposed PRETTY (Passive Reflectometry and Dosimetry) mission includes a demonstrator payload for passivereflectometry and scatterometry focusing on very low incidence angles whereby the direct and reflected signal will bereceived via the same antenna. The correlation of both signals will be done by a specific FPGA based hardwareimplementation. The demonstration of a passive reflectometer without the use of local code replica implicitly showsthat also signals of unknown data modulation can be exploited for such a purpose.The PRETTY mission is proposed by an Austrian consortium with RUAG GmbH as prime contractor, relying on theresults from a previous CubeSat mission (OPS-SAT) conducted by TU Graz under ESA contract [18]. Within thepresent paper we will describe the architecture of the passive reflectometer payload within this 3U CubeSat mission anddiscuss operational routines and constraints to be elaborated in the frame of the proposed activity