The low-Earth orbiting (LEO) satellite constellations in the 90s (such as Iridium and Globalstar), although representing a major technical breakthrough, were not able to achieve the initial goal of complementing the second-generation mobile terrestrial networks due to the rapid worldwide adoption of GSM and other standards. However, the decline of conventional linear television and the persisting need to mitigate the digital divide still affecting billions of people recently generated a renewed interest by private investors for Low-Earth Orbiting (LEO) satellite mega-constellations. The mega-constellations under deployment can provide lower delays versus geostationary (GEO) satellites, broadband access anywhere, anytime leveraging the low-cost series production of small satellites, and more affordable launch solutions. At the end of the last decade, key industrial players realized the potential complementary role satellites can play to extend the 5G terrestrial network coverage over low-density populated areas, oceans, or similar. This has led to great technological developments and a sharp reduction in LEO satellite volume, weight, and, ultimately, manufacturing and launching costs. Also, it has triggered the inclusion of a non terrestrial network (NTN) component in the latest 5G 3GPP standard releases. Yet, there are many technological challenges remaining to ensure that both the quality and cost of the NTN services are comparable to the terrestrial counterpart. This is mainly due to the constraints in satellite payload power, mass, and antenna size. This comes in addition to the stringent power flux density limitations on the ground, in particular in the below 6 GHz satellite bands. The required order of magnitude increase of the effective delivered throughput and service cost reduction can only be achieved by a mix of system architectures and innovative technologies for both the space and ground segments. Space communication systems and technologies will also play a key role in human return to the Moon planned for mid-2020, to prepare for human exploration of Mars in the more distant future and further cosmic exploration. As missions voyage further from Earth, it is important to consider how we can continue to reliably communicate with them and how they will accurately navigate through space when they are so far from home.

中文翻译：

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客座社论太空通信新领域：从近地到深空

20世纪90年代的低地球轨道（LEO）卫星星座（如铱星和全球星）虽然代表了重大技术突破，但由于全球范围内的快速发展，未能实现补充第二代移动地面网络的最初目标。采用GSM和其他标准。然而，传统线性电视的衰落以及缩小仍然影响数十亿人的数字鸿沟的持续需求最近引起了私人投资者对低地球轨道（LEO）卫星巨型星座的新兴趣。正在部署的巨型星座可以提供比对地静止 (GEO) 卫星更低的延迟、利用低成本系列生产的小型卫星提供随时随地的宽带接入以及更实惠的发射解决方案。上个十年末，主要工业参与者意识到卫星可以发挥潜在的补充作用，将 5G 地面网络覆盖范围扩展到低密度人口稠密地区、海洋或类似地区。这带来了巨大的技术发展，并大幅降低了低地球轨道卫星的体积、重量，并最终降低了制造和发射成本。此外，它还促使在最新的 5G 3GPP 标准版本中纳入非地面网络 (NTN) 组件。然而，要确保 NTN 服务的质量和成本与地面服务相当，仍然存在许多技术挑战。这主要是由于卫星有效载荷功率、质量和天线尺寸的限制。除此之外，地面上的功率通量密度也有严格的限制，特别是在 6 GHz 以下的卫星频段。有效交付吞吐量和服务成本降低所需数量级的增加只能通过空间和地面部分的系统架构和创新技术的组合来实现。空间通信系统和技术也将在人类计划于2020年中期重返月球的过程中发挥关键作用，为人类在更遥远的未来探索火星和进一步的宇宙探索做好准备。随着任务远离地球，重要的是要考虑我们如何继续与他们进行可靠的通信，以及当他们远离家乡时如何准确地在太空中导航。