TDP1 Ground System Design

This paper illustrates the historical development of the TDP-1 ground segment, the system as implemented and operational experience, as well as an outlook to future programs. Aim of the project TDP-1 – Technology Demonstration Payload No.1 - is the demonstration of a data relay service, using an optical High Data Rate Inter-Satellite Link (ISL) between a Laser Communication Terminal (LCT) flown on a low earth orbiting satellite (LEO-LCT) and a second LCT (GEO-LCT) placed on the geostationary communication satellite AlphaSat (of INMARSAT) . The LCT planning system consists of one geostationary satellite (GEO) and up to five low orbiting satellites (LEO) which are also referred to as customers. The main task of GEO within this system is to serve as service provider for the LEOs and one optional optical ground station (OGS). The service consists of an optical data link between the Laser Communication Terminals (LCT) of the satellites (inter-satellite-link,ISL) and a link from a satellite to a ground station (space-to-ground-link, SGL). DLR’s Operations Center (GSOC) role in the TDP-1 program includes design, development and integration of ground infrastructure and operations of the satellites and ground stations. GSOC already gained experience operating Laser Terminals in test scenarios on the TerraSAR spacecraft. This knowledge was be used to develop the TDP-1 operations concept. One major task is the planning of the laser connections and the required coordination between all parties. This paper will illustrate the development from the first activities at GSOC in connection with laser data transfer through the design of the TDP-1 system to an outlook at the EDRS operations concept

THE EUROPEAN DATA RELAY SYSTEM (EDRS): OPERATIONAL CHALLENGES

This paper will illustrate the challenges and preliminary solutions in operating the EDRS constellation. EDRS will include two communication payloads hosted on a dedicated spacecraft and as piggy-back on a commercial satellite. The two satellites will be positioned in geosynchronous orbit to provide nearglobal coverage for satellites in low earth orbit (LEO). EDRS is designed to reduce time delays in the transmission of large amounts of data and to allow faster access for end users. This is achieved by using an optical Laser Communication Terminal (LCT) for the link between the LEO and the EDRS payload and a Ka-band link between the EDRS payload and the ground. The latter will be established via three dedicated feeder link ground stations in Europe from where the data is distributed to the users. The users may also use their own ground stations directly receiving the data. By using EDRS extended capabilities for TM/TC operations will be possible with LEO satellites. This will enable short-time changes to the payload timeline and better reactions to anomalies while optimizing the number of necessary ground stations. DLR with its German Space Operations Center (GSOC) plays a major role in EDRS operations. This role includes design, development and integration of ground infrastructure and operations of the satellites and ground stations. The EDRS concept of operations di�ers from the conventional communication satellites. Two challenging new technologies will be integrated in order to provide faster data turnaround times and downlink capabilities of up to 600 Mbit/s. 1. Laser-Optical Inter-satellite link: The large distance between a satellite in GEO and one in LEO makes the pointing of both LCT very difficult. Good attitude information and control of both satellites is required. A good quality orbit determination is vital for good laser acquisition times and both payloads need to keep accurately track of their fast moving counterparts. Thus, development of the operations concept requires consideration of the interfaces and coordination of operations with the LEO satellites, which are operated by di�erent control centres. 2. Ka-band up- and downlink: The small wavelength of the Ka-band signal leads to signi�cant atmospheric and rain attenuation. Besides that, due to the sensibility of Ka-band technology the requirements for ground stations (pointing accuracy, higher doppler shifts and high data rates) are very challenging compared to standard S/X/Ku-band ground stations. Careful consideration has to be taken designing the ground stations, during link establishment and station operations

EDRS Operations at GSOC- relevant heritage and new developments

Das Paper beschreibt frühere Missionen des GSOC, die für das Projekt EDRS von Bedeutung sind und vorläufugt Entwürfe für den EDRS Betrieb

Flight Experience

This chapter covers examples of lessons learned at DLR/GSOC, particularly in the course of multiple LEOP phases of communication satellites. It describes the process of dealing with system contingencies, mostly on spacecraft side and wraps up with several spacecraft anomalies and the attempts to deal with them

How Galileo Planning became automated

Galileo is one of the four worldwide Global Navigation Satellite Systems (GNSS). Being a programme of the European Commission (EC), the Galileo Service provision is under the responsibility of the GNSS Service Agency (GSA), who in turn contracted the Galileo Service Operations (GSOp) to Spaceopal GmbH. The Spaceopal Planning Team is in charge of coordinating all Galileo operations and infrastructure activities. In July 2018 the team took on the task to automate all GSOp internal planning processes. Galileo planning involves three timelines: a Short-Term plan (STP), two Mid-Term plans (MTP), one for the Operational (OPE) and one for the Validation (VAL) Chain, and a Long-Term plan (LTP). The activities in these timeframes cover all entities working on Galileo. The three planning levels are interlinked and dependent on each other. But the original set up had these four plans handled not only by different tools, but also by different teams, complicating or even preventing resolution of interdependencies between the planning processes and plans itself. This paper describes how the different plans and timelines were taken over by the Spaceopal Planning Team and moved into the Galileo Planning Tool (GPT). An interface to the GPT was developed to allow all MTP actors to provide inputs via a standard planning input sheet directly into the activities of the current timeline, which are then sent to the SPO Planning Team. These inputs are automatically imported into the GPT eliminating any human error or additional intervention. For this process, a transitioning period was necessary and new processes had to be set up and documented. The result is that now the plans are interlinked: not only via communication channels, but also via automatic linking of the activities within the tool. Also the processes and output from the weekly planning meetings are now identical every week. But these were only the first steps to fully complete the automation and this paper will also give an outlook of what else is to come

Mission Operations

The success of a space mission depends not only on a properly designed and built space segment and the successful launch via a launch segment. It also depends on the ground segment and successful mission operations, carried out by a team of experts using the infrastructure and processes of the mission’s ground segment. Its organization and design as well as the assembly, integration, test, and verification (AITV) are therefore equally important as the respective activities of the space and launch segment. A ground segment thereby comprises a ground system, i.e., infrastructure, hardware, software, and processes, and a team that conducts the necessary operations on the space segment

Long-term outcome of speech and language in children after corrective surgery for cyanotic or acyanotic cardiac defects in infancy.

The purpose of this prospective study was to assess whether outcome of speech and language in children 5-10 years after corrective surgery for tetralogy of Fallot (TOF) or ventricular septal defect (VSD) in infancy was influenced by the preoperative condition of hypoxemia or cardiac insufficiency and whether it was associated with perioperative risk factors and neurodevelopmental outcome. A total of 35 unselected children, 19 with TOF and hypoxemia and 16 with VSD and cardiac insufficiency, operated with combined deep hypothermic circulatory arrest and low-flow cardiopulmonary bypass at mean age 0.7+/-0.3 (mean+/-standard deviation) years, underwent, at mean age 7.4+/-1.6 years, standardized evaluation of speech and language functions. Results were compared between subgroups and related to perioperative factors, sociodemographic and neurodevelopmental status. Age at testing, socioeconomic status and history of speech and language development were not different between the subgroups. In contrast, total scores on oral and speech motor control functions (TFS) as well as on oral and speech apraxia (Mayo Test) were significantly reduced (p<0.02 to <0.05), and scores on anatomical oral structures tended to be lower (p<0.09) in the TOF group as compared to the VSD group. No differences were found for auditory word recognition and phonological awareness as assessed by the Auditory Closure subtest of the Illinois Test of Psycholinguistic Abilities and the test of auditory analysis skills, respectively. In all children, higher age at testing and better socioeconomic status were associated with better results in all domains of assessment (p<0.001 to <0.04). Consistent impairments of all oral and speech motor control functions (TFS and Mayo Test) were present in 29% of all children with a mean age of 6.5 years in contrast to 43% with normal performance and a mean age of 8.3 years. On the receptive speech tasks, only 6% scored below the normal range of their age group. TFS subscores were significantly correlated with age, bypass duration and motor function, but not correlated with socioeconomic status, duration of cardiac arrest, intelligence and academic achievement. Children with preoperative hypoxemia due to cyanotic cardiac defects in infancy are at higher risk for dysfunction in speech and language than those with cardiac insufficiency due to acyanotic heart defects. Age at testing, socioeconomic status, and duration of cardiopulmonary bypass influenced test results. Long-term outcome in speech and language functions can be considered as a sensitive indicator of overall child development after cardiac surgery