As the commercial space economy expands, existing ground-based infrastructure faces severe bottlenecks in supporting the data-intensive continuous connectivity needs of next-generation "space users," including CubeSats, space data centers, and more. Even when utilizing existing Ku-band ground relay networks, the contact time with a CubeSat at low-Earth orbit (LEO) is often still limited to minutes per day only. This paper analyzes an alternative system design that leverages emerging high-rate millimeter-wave (mmWave) and sub-terahertz (sub-THz) inter-satellite links to build a high-throughput and high-availability satellite-based relay backbone for space vehicles. To evaluate this concept, we develop a comprehensive mathematical framework that jointly incorporates complex time-variant orbital dynamics and mmWave/sub-THz link characteristics. We then derive the key performance indicators, including contact probability, channel capacity, and energy efficiency. The numerical results, cross-verified by computer simulations, demonstrate that such systems can provide improvements of up to several orders of magnitude compared to existing networks of ground stations. Notably, we identify a fundamental bound on download capacity and show that continuous 24/7 connectivity becomes achievable with only ten LEO relay satellites. These findings establish mmWave and sub-THz satellite relay networks as a promising, scalable, and energy-efficient solution, thus unlocking improved connectivity with various space vehicles of tomorrow.

翻译：随着商业太空经济的扩张，现有地面基础设施在支撑下一代"太空用户"（包括立方星、太空数据中心等）对数据密集型连续连接需求时面临严重瓶颈。即便利用现有Ku波段地面中继网络，近地轨道立方星的每日接触时间仍通常仅限数分钟。本文分析了一种替代系统设计方案，该方案利用新兴的高速毫米波与亚太赫兹星间链路，为太空飞行器构建高吞吐量、高可用性的星基中继骨干网。为评估这一概念，我们发展了一个联合纳入复杂时变轨道动力学与毫米波/亚太赫兹链路特性的综合数学框架，进而推导出关键性能指标（包括接触概率、信道容量及能量效率）。经计算机仿真交叉验证的数值结果表明，相较现有地面站网络，此类系统可实现高达数个数量级的性能提升。值得注意的是，我们发现了下载容量的基本界限，并证明仅需十颗低轨中继卫星即可实现全天候连续连接。这些发现确立了毫米波与亚太赫兹卫星中继网络作为可扩展、高能效的解决方案，从而为未来各类太空飞行器解锁更优连接性能。