Encryption for Security of Satellites

Thousands of satellites are orbiting the Earth. Naturally, they are wirelessly controlled with signals from a terrestrial station. Malicious control signals from an unauthorized entity might result in serious consequences ("Cybersecurity Principles for Space Systems" (2020)). Frequencies used in communication with satellites are not disclosed and messages are encrypted. But hackers might access such information, or might simply hack the ground station (車も衛星もハッキングされる時代！？注目が集まる衛星のサイバーセキュリティ (2021)). There are reported instances of actual hacking of satellites ("Hack a Satellite while it is in orbit" (2007), "AsiaSat accuses Falungong of hacking satellite signals" (2004) cited in Wikipedia).

CCSDS (Consultative Committee for Space Data System), an international standardization body since 1982, has a security work group, which has issued documents such as "Green Book on use of security in CCSDS" and "CCSDS Encryption Algorithms and authentication algorithms" among others (CCSDS Overview by NASA, p.14).
The encryption scheme specified for controlling satellites is, as expected, AES (Advanced Encryption Standard), a symmetric block cipher adopted for the US government in 2001 as a replacement for DES (Data Encryption Standard). The Green Book "CCSDS Cryptographic Algorithms" (2023) prescribes "AES is the sole symmetric encryption algorithm that is recommended for use by all CCSDS missions and ground systems." (The same expression is found at least as early as the 2014 version, but not in a 2012 Blue Book).
What was used before AES was recommended by CCSDS? One might think it was DES, but actually, "at first security was thought of as not required for civilian space missions by CCSDS", according to the 2008 Green Book "Encryption Algorithm Trade Survey". Indeed, one patent document JP 2000-341190 A1 says communication with satellites needs to be encrypted "for artificial satellites for specific purposes." Even today, researchers point out security measures for satellites are no more than "security by obscurity" ("Satellites Are Rife With Basic Security Flaws" (2023)).