Optical high bitrate communication links are maturing and will likely be a part of the future strategy for transferring ever growing amounts of data from satellites to the ground, including for the small satellite segment. This paper discusses both recent developments on the OPTEL-µ ® optical terminal developed by TAS-CH as well as the optical ground networks being studied by SSC, both as a part of the TESLA-C project under ESA ARTES 3-4 5 . The OPTEL-µ ® terminal is designed for LEO to ground communications with a bit rate of 2 Gbps. The system is aimed for small satellites with a terminal mass of 8 kg, 8 litres volume and a power consumption of 45 W. The OPTEL-µ ® EQM model is currently under assembly and integration, consisting of three main units: (1) the optical head, (2) the electronics unit and (3) the laser unit. An overview of the system design and discussion on latest EQM status is included in the paper. The characteristics of the optical space-to-ground link differs significantly from the traditional S/X-band RF link, due to the need of a clear optical path and high dependency on atmospheric conditions. This has large consequences not only on single link performance but also on the operational concept between spacecraft owner, ground network provider and spacecraft. The traditional notation of a pass as the core quantifier of ground communications goes away. A more data-centric view is needed, focusing on customer Service Level Agreement (SLA) and timeliness of data. New approaches are needed on several layers, from service management and delivery, to the protocols used for the interaction with ground and space elements. To achieve an efficient overall system, changes in the operational concept are needed on both spacecraft and ground systems. In order to evaluate and characterize the optical ground networks, different metrics are being used, where two key metrics are discussed in the paper -the daily volume of a network and the latency distribution of data transferred to ground. These two metrics illustrates and allows comparison of the characteristics of pure optical networks as well as hybrid networks consisting of both RF and optical ground stations. A few examples are being presented in the paper, including both ground station network design variations as well as satellite orbit selection effects.

CubeSats in LEO has become a popular tool for entering the space domain, initially for universities but now also used by commercial startups, commercial traditional companies and agencies. The purpose is often technical development but also commercial services are starting up being based on CubeSat technology. To a large degree these activities has been limited to LEO orbits, due to several reasons, mostly that CubeSats traditionally do not have dedicated launchers nor on-board propulsion systems. What if this changes, if we have an expansion of interplanetary CubeSatwhat would the limits of communications and operations be for such small systems? SSC is today operating a global ground network of antennas in the 13-m class, primary used by earth-bound satellites in S/X-band as well as the occasional near deep space mission. This paper discusses the possibilities of using an existing commercial ground network like the SSC network for direct-from-earth operations of Cubesats or very small spacecrafts in near deep space such as the Moon, Lagrange points or Near-Earth Asteroids. In some cases, agency based networks with very large deep space antennas could be used for such missions depending on the mission characteristics, either as separate networks or as a complement to 13-m antenna sized networks. In the analysis of this scenario, the RF link power between the Cubesat and ground is one key critical resource, where limitations on the spacecraft applies both for the on-board power generation through the solar panels, and the size of on-board antennas that can be mounted on a CubeSat or small spacecraft. The paper discusses assumptions and technical developments related to these on-board parameters, and the requirements that a deep space operation would imply on the on-board radio system in terms of bit rate, modulation and support for ranging and coherent lock, especially when being used in conjunction with "small" apertures in deep space terminology. Based on these assumptions, the operational range and potential performance for usage of commercial 13-m antenna networks and associated equipment are presented. The downlink bitrates from these spacecrafts will be significantly less than what is expected today from traditional large deep space spacecraftswhich can affect both science, technical and public outreach approach. A discussion is held on how this could partly be mitigated with changed operational concepts, both on ground and on spacecraft by including concepts like advanced on-board autonomy in operations and navigation. Upcoming technologies that may introduce alternatives to this ground network concept is discussed, including the possibilities of optical links on small satellites.

A large portion of CubeSat projects have either been demonstrations or educational missions, where the science or operational concept has not been in focus. For efficient use of CubeSat platforms and realization of efficient services, either for scientific or commercial purposes, a full end-to-end design is needed, where the operational concept as well as a focused scientific or commercial rationale is taken into consideration. The SEAM project (funded within European Union's Seventh Framework Programme) addresses parts of this challenge and develops operational concepts as well as on-board systems for scientific missions. The SEAM platform is using S-Band for downlink and uplink and is fully compliant to the CCSDS standards for satellite link services thus allowing compatibility with a global commercial ground station network. The project is led by the Royal Institute of Technology KTH and SSC is an industrial partner in the consortium. The 3U SEAM CubeSat is designed with an operational concept that includes on-board selection of data to download with earth in the loop, and flexible ground network scheduling. The spacecraft SBand transceiver is full duplex with a downlink data-rate capability of 3 Mbps and uplink capability up to 100 Kbps. The communication link is CCSDS compatible in both directions, and operates with COTS multi-mission ground station equipment. A newly developed onboard module, that integrates mass memory and CCSDS functionality with a direct transceiver interface, is being demonstrated in the project. The data link layer of the CCSDS standards is implemented in hardware while the network layer and the data storage coordination in the mass memory are handled by software. This functionality partitioning ensures high data throughput and performance while providing flexibility in data collection and handling. It is noted that although the satellite is small, the complexity of such spacecraft is fully comparable to scientific microsatellites and its communication systems and operational concept use technology, equipment and procedures often found in much bigger satellites. The SEAM CubeSat is planned to be launched in early 2017 and the presentation will include the latest news from the mission operations 2 Nomenclature Mbps= mega bit per second MB = mega byte LTAN = local time of ascending node SEAM = Small explorer for advanced missions

Interest in small satellites, ranging from a few hundred kilos down to cubesats of a few kilos, has grown over the decades and lately seen an increase beyond the simplest applications. This is based on a number of factors working in tandem: The miniaturization of once-bulky satellite components, standardization of many satellite parts, and other factors have trimmed costs substantially. That has made the building, launching, and operation of "smallsat" constellations increasingly doable. This lower entry cost to the space domain makes it more feasible for new companies to invest in Space to develop new commercial products. The operations of newcomer's small satellites as single mission or in large constellations has shifted the operational concepts and opened for new ways of performing operations, focusing on low cost and scalability for large constellations. With the introduction of these new space actors and new operational concepts, the interfaces and services provided from a commercial ground network service provider need to change as well in order to support the objectives of the new space missions. The paper will analyze the Space Link Extensions (SLE) Standard defined by the Consultative Committee for Space Data Systems (CCSDS) for transferring data between the spacecraft and the control center and the advantages and disadvantages that the use of this standard would have in the context of the small satellite operations.

Small satellites, including Cubesats, are today mainly launched as piggyback payloads with very limited opportunities for choosing orbit. As the satellites and their applications get more sophisticated, the need to launch them into carefully designed orbits arise. There is already a queue of Cubesats looking for launch opportunities and a further increase is expected. Thus, there is a need for dedicated launchers which regularly launch into standardized orbits. To meet these needs, SSC has initiated SmallSat Express, a launch capability for small satellites from SSC's launching facility Esrange Space Center. Esrange is located in the very north of Sweden, above the Arctic Circle (68°N, 21°E) and has access to a vast, unpopulated recovery area. The facility has been operated since 1966 and is presently used for sounding rocket and balloon launches. It also hosts one of the world's largest civilian satellite ground stations.