2 Space systems are reliant on information systems and networks from design conceptualization through launch and flight operations. Further, the transmission of command and control and mission information between space vehicles and ground networks relies on the use of radio-frequency-dependent wireless communication channels. These systems, networks, and channels can be vulnerable to malicious activities that can deny, degrade, or disrupt space operations, or even destroy satellites. Examples of malicious cyber activities harmful to space operations include spoofing sensor data; corrupting sensor systems; jamming or sending unauthorized commands for guidance and control; injecting malicious code; and conducting denial-ofservice attacks. Consequences of such activities could include loss of mission data; decreased lifespan or capability of space systems or constellations; or the loss of positive control of space vehicles, potentially resulting in collisions that can impair systems or generate harmful orbital debris. The National Security Strategy of December 2017 states that "[t]he United States must maintain our leadership and freedom of action in space." As the space domain is contested, it is necessary for developers, manufacturers, owners, and operators of space systems to design, build, operate, and manage them so that they are resilient to cyber incidents and radio-frequency spectrum interference. Space Policy Directive-3 (SPD-3) of June 18, 2018 (National Space Traffic Management Policy), states that "[s]atellite and constellation owners should participate in a pre-launch certification process" that should consider a number of factors, including encryption of satellite command and control links and data protection measures for ground site operations. The National Cyber Strategy of September 2018 states that my Administration will enhance efforts to protect our space assets and supporting infrastructure from evolving cyber threats, and will work with industry and international partners to strengthen the cyber resilience of existing and future space systems. Sec. 2. Definitions. For the purposes of this memorandum, the following definitions shall apply: