Space Communication

In early 2018 the Irvine Cubesat STEM Program (ICSP) from California-USA, requested that the Ecuadorian Space Agency (EXA) supply a miniaturized LASER emitter for the IRVINE02 cubesat to be launched on board the NASA ELaNa 24 slot in November 2018. The device was requested to meet certain conditions like a minimum output power of 0.7 Watts, operate at a maximum temperature of 50 degrees Celsius, use a maximum electrical power of 3 Watts and be NMOS operated through a UART modulation circuit at a minimum speed of 100 Kilobits per second. The resulting device was shipped one month later to ICSP exceeding all initial requirements. This device is currently in orbit and its denomination is PLM01. To date, it is the most compact laser ever own on board a cubesat as small as 1U form factor; this work was funded by the Irvine Public Schools Foundation. This paper will describe the methodology for stabilizing the LASER in its various electrical and thermal dimensions, tests performed, mechanical, electrical and thermal design and tools used. It also will describe the new generation of laser transceivers PLM02 and PLM03 to be installed in the IRVINE03 and IRVINE04 1U cubesat satellites which will combine radio communications in VHF and UHF frequencies, from 200 MHz to 900 MHz range for uplink and optional downlink and a LASER emitter in the 405nm to 450nm wavelength, operating at a minimum of 10 Mbps and a maximum of 50 Mbps in OOK modulation. Different challenges to achieve this performance are discussed, such as the power budget, thermal dissipation techniques, processor speed, data bus speeds, bus technology selection, data processing approaches and techniques. That allows this hybrid transceiver to be used by a wide range of cubesat architectures, even those based on relatively slow speed data transfer buses like I2C and CAN bus, and those based on faster data transfer buses like SPI, USB and USART. It also details optical link budgets, detector technology and how geometry selection matrices have to be applied to achieve the objectives of having cost-effective high data rate transfers from orbit to ground, using a very compact and efficient device that can be installed in wide range of satellites, from 1U cubesats to full-size satellites.

This paper aims at providing a feedback on the ISL performances of several missions with CNES implication, among which the Rosetta and Philae mission, (ESA/DLR/CNES project) from the separation to the final lander transmission on the 67P/Churyumov-Gerasimenko comet nucleus. CNES specified and procured the equipment and was responsible of the ISL operations during the cruise and after separation. This paper presents an analysis of the Rosetta/Philae mission events on the basis of the available ISL telemetry and compares the results to the reconstructed trajectory. Information like the Philae rotation speed during bouncing or multipath interferences due to the local environment can thus be deduced. This Rosetta-Philae ISL equipment was already used by NASA for the Impactor-Solar Orbiter link of the Deep Impact mission which explored the comet 9P/Tempel in 2005. In the same way, CNES is involved in the Mascot ISL procurement, part of the Hayabusa-2 mission (JAXA/DLR/CNES). Equipment characteristics and first in-orbit performances measurement will be also developed in this paper. Finally, this paper will describe the CNES/ESA S-band TT&C equipment development for nanosatellite, used as input to start the development of next generation miniaturized ISL transponder. This equipment will be provided with meter-class ranging accuracy and multiple access techniques for a network of at least four nodes, like one orbiter and three landers. This development will be described in the paper, including the architecture at system and equipment levels, the specific used algorithms and typical link budgets for the case of an asteroid exploration mission.

At this point in time there is a growing global tendency from many nations to join efforts to develop an interdisciplinary space development program regarding the establishment of a lunar settlement in the near future. The European Space Agency has been proposing this concept under the name of " Moon Village" and among one of the most important interdisciplinary aspects are communications, specifically how to bring internet connectivity to such a lunar settlement and connecting it to Earth's internet as well as other spacecrafts in Earth orbit and/or cislunar space. In this paper we propose and analyze possible communication architectures based on the existing TCP/IP protocol; from satellites-only networks to mixed or hybrid architectures based on lunar and/or terrestrial ground segment networks. We will also analyze protocol issues and physical transport medium, key technologies such as communications, thermal, power, shielding and space technologies, minimal requirements needed and the lunar ground last-mile implementation. The analysis of the proposed architectures is done in terms of technology availability and maturity, approximate financial and maintenance costs and estimated target performance. As a result, we demonstrate that there are efficient and viable ways to communicate a Moon settlement with the Earth using the current technologies.