  The revolution in the low Earth orbit (LEO) satellite networks will bring
changes on their communication models and a shift from the classical bent-pipe
architectures to more sophisticated networking platforms. Thanks to
technological advancements in microelectronics and micro-systems, the terahertz
(THz) band has emerged as a strong candidate for inter-satellite links (ISLs)
due to its promise of high data rates. Yet, the propagation conditions of the
THz band need to be properly modeled and controlled by utilizing reconfigurable
intelligent surfaces (RISs) to leverage their full potential. In this work, we
first provide an assessment of the use of the THz band for ISLs, and quantify
the impact of misalignment fading on error performance. Then, in order to
compensate for the high path loss associated with high carrier frequencies, and
to further improve the signal-to-noise ratio (SNR), we propose the use of RISs
mounted on neighboring satellites to enable signal propagation. Based on a
mathematical analysis of the problem, we present the error rate expressions for
RIS-assisted ISLs with misalignment fading. Also, numerical results show that
RIS can leverage the error rate performance and achievable capacity of THz
ISLs.
