This page looks at more advanced Orbital Warfare Manoeuvre Tactics that arise with manoeuvring satellites and, “potential future space warfare tactics” [Clark, C. 2021 US, China, Russia Test New Space War Tactics: Sats Buzzing, Spoofing, Spying. Breaking Defense (28 October)]. One such Orbital Manoeuvre Tactic, is manoeuvre between two spacecraft – one covering the other, “to spoof an enemy’s network for Space Situational Awareness” [Clark, 2021]. In this particular scenario, in 2018, the upper stage rocket – the apogee kick motor, for a Chinese military satellite Tongxin Jishu Shiyan-3 remained in Geosynchronous Orbit and moved parallel to the satellite it helped push into orbit initially:

“[manoeuvring] … to change their orbits, and … did that at the exact same time, and then the exact same way … those manoeuvres were basically done in tandem with each other. And … the apogee kick motor — which is basically a rocket body — is now flying where the Tongxin Jishu Shiyan-3 … used to be” [Clark, 2021; Chen, D.D. Singer, P.W. 2024 Fast Movers: Chinese Satellites Zoom Around for Inspections or Interference. Defense One (20 May)].

‘Orbital Manoeuvre Hide and Seek Tactic’: Is where one spacecraft is used for a decoy manoeuvre - a type of concealment, with one craft behind the other in relation to Earth-based observations. In this scenario, a satellite thrusts away from its original position, taking advantage of a period when ground-based telescopes are most likely to lose track of it. At the same time, its second stage motor is able to maneuverer next to the satellite so that any observer who reacquired it would see the booster sitting where the satellite was▼.

‘Moving a Satellite in Orbit’: At a basic level, “whenever a satellite makes the slightest change in speed or direction, it must change either its altitude or its orbit orientation.” [Dickey, R. Wilson, J. 2023 Why There Should Not Be A Norm For “Minimum Safe Distance” Between Satellites. War on the Rocks (11 December)] Further, in terms of Space Situation Mapping, “Altitude vs Inclination plots … illustrate the two most important factors concerning orbital manoeuvring, and provide an essentially fixed map illustrating which space objects are close to each other, and could be potential threats.” [Szymanski, P.S. 2019 How to Fight and Win the Coming Space War. Strategic Studies Quarterly (Fall)] For a spacecraft-satellite to manipulate the size, shape and angle of its orbit, it has to slow its orbit to go faster, and speed-up to go slower. Prograde and retrograde burn vectors are parallel with the direction of motion. The prograde burn is where the craft fires its engine into the direction that it comes from. A prograde burn will increase the craft’s velocity (kinetic energy at the specific point where the burn occurred), but not its altitude. The effect, if not arrested will be to make the craft’s orbit more elliptic, and the craft to climb in altitude (to fall away from Earth). The retrograde burn is where the craft fires its engine in the exact opposite direction to the prograde burn. This burn subtracts kinetic energy from the craft’s orbit at the point where the engine was fired. This affects altitude at the opposite side of the orbit, bringing it closer to the Earth. Normal and anti-normal burns are perpendicular to the craft’s direction of motion. Completing a normal burn the craft begins to rise-up, and away from the initial orbit, and the orbit will rotate in what is called an inclination change, which is costly in terms of fuel use. Burns are only used for corrections when matching the orbit of another craft▼.

STALKING-SATELLITE TACTICS (ORBITAL MANOEUVRE STALKING TACTICS)

A Russian satellite Kosmos 2542, is said to have onboard inspection technologies, and smaller subsatellite it was able to deploy, and both the satellite and subsatellite share the same orbits and remain within about 10 kilometres of each other [Krebs, G.D. 2024 Kosmos 2542, 2543. Gunter’s Space Page]. In 2020, Kosmos 2542 suddenly manoeuvred itself and it was able to closely shadow a United States reconnaissance satellite USA 245 [Patel, N.V. 2020 A Russian Satellite is Probably Stalking a US Spy Satellite in Orbit. MIT Technology Review (3 February)]. The satellites were less than 300 kilometres apart [Patel, 2020]; and, Kosmos 2542 synchronized its orbit with that of USA 245 and followed its manoeuvres [Krebs, 2024]. The scenario where Kosmos 2542 was able to closely shadow USA 245 requires, “[expending] … valuable propellant … to perfectly position … to view another satellite” [Patel, 2020]. In instances where one satellite purposely shadows another:

“inspector satellites can reveal exactly what kinds of targets on Earth are being surveilled by … [a reconnaissance] …  satellite … [such as] … it could determine the aperture and resolution of the cameras … [and] …if it has a radio-frequency probe, it could listen for faint signals … to deduce what kinds of computer processes are happening onboard, when it is operating, and when it is taking pictures.” [Patel, 2020]

‘Orbital Manoeuvre Chase-Down Tactic’: To counter, an inspecting satellite, another satellite (being chased) could move into a new orbital position, but even a small manoeuvre means expending precious fuel, and the inspecting satellite could simply follow the other to the new location [Patel, 2020]. Effectively, that could lead to a tactic where one satellite causes another to keep moving till it expends all its available fuel, and prematurely reaches its mission end of life; or alternatively, moving leads to mission failure, as it is a non-manoeuvrable satellite, and it is mission critical it stays in its correct orbital position.

▼ A manoeuvring satellite (RED), engages in Orbital Manoeuvre Stalking Tactics with a target satellite (BLUE). The RED satellite continues to raise its orbit, till it shares an orbital plane with BLUE. The RED satellite detaches a subsatellite, and the two travel in tandem chasing the BLUE satellite.

▼ A Satellite Safe Zone around a non-manoeuvrable satellite (BLUE), with a Guardian-Bodyguard Satellite positioned within the Zone, to protect it from other approaching satellites. A Spherical Space Safety Zone made-out around a critical but vulnerable satellite, has been suggested could be a minimum distance of some 50 kilometres at Geosynchronous Orbit. An opponent manoeuvrable satellite (RED), raises its orbit to catch up with the target satellite (BLUE), attempts to move into the Zone and approach. The BLUE Guardian-Bodyguard Satellite following the target satellite is positioned to block the opponent from making its approach.

▼ Orbital Chase Tactics between a satellite (BLUE) and opponent inspector mission satellite (RED). The RED satellite frequently comes close to the BLUE satellite. Both satellites orbit Earth in the same plane but at different speeds, and the RED satellite (as it is closer to Earth) is able to pass beneath the BLUE satellite. The RED satellite was launched after the BLUE satellite and was placed in almost the same orbit as it. The RED satellite can then perform an orbit-raising manoeuvre to a short distance in kilometres below the BLUE satellite to make a close pass and gather intelligence about the BLUE satellite. The BLUE satellite then makes its first jump to a higher orbit away from the RED satellite, and the orbit change increases the distance between the two.

THREE-SPACECRAFT PURSUIT-EVASION SCENARIO

An Orbital Manoeuvre Tactical problem of a Three-Spacecraft Pursuit-Evasion Scenario posed in a 2024 research paper looks at, “actively approaching non-cooperative targets … where … the pursuer aims to approach the evader and the evader tries to escape from the pursuer’s approach.” [Cao, X. Ning, X. Wang, Z. Liu, S. Cheng, F. Li, W. Lian, X. 2024 Intelligent Sequential Multi-Impulse Collision Avoidance Method For Non-Cooperative Spacecraft Based on An Improved Search Tree Algorithm. Chinese Journal of Aeronautics (28 August)].

▼ FIGURE 1: Looks at a Three-Spacecraft Pursuit-Evasion Scenario, involving a BLUE pursuer, and a RED ‘Follower-Leader Satellite System’, where the follower spacecraft accompanies behind the leader [Cao, 2024]. In the scenario, RED evader and BLUE pursuer are in the same orbital plane and orbital inclination. The RED follower (evader) satellite is non-cooperative in relation to the BLUE pursuer. A constraint on the RED evader’s manoeuvre safe area, is this has a limited radius for orbital manoeuvres (the minimum distance between the pursuer and the evader is 1.3 kilometres [Cao, 2024]), as the satellite has to keep within a certain distance to ensure the requirement of close-range communications between the leader-follower formation is met. In the 2024 research paper it suggests, “the follower is 15 kilometres behind the leader”, in what is called, “the follow-fly formation” [Cao, 2024].

Figure 1(a): BLUE pursuer satellite manoeuvres into potential collision, or capture with the RED follower satellite, and its leader travelling along the same orbit. Literature reference to ‘Follower-Leader Satellite System’ may relate to recent Chinese space operations involving a robotic arm on a manoeuvrable satellite, that carries/deploys a secondary support satellite ahead of the first. A 2006 research paper gives an early account of the basic configuration of a mobile satellite, carrying a micro target satellite, which can be released and captured again by the robot grappler-arm [Gao, X.H. et al. 2006 Development of the Chinese Intelligent Space Robotic System. IEEE/RSJ International (9 October)].

Figure 1(b): RED follower and evader satellite (evading from contacting BLUE) has a limited radius movement space to avoid a collision, or capture, which is also determined by its need to stay in communications with the RED leader satellite. Tactically, “the evader starts its first manoeuvre only when the pursuer approaches to a distance of 20, 30, 40 or 50 kilometres.” [Cao, 2024] However, a wider distance is potentially a trigger, “the evader starts to manoeuvre with a large distance between itself and the pursuer, about 100-450 kilometres.” [Cao, 2024] In a pursuit scenario where a third-party space object approaches, it appears to be a requirement the two satellites in a ‘Follower-Leader Satellite System’ remain in communications, which acts as a constraint on any avoidance-manoeuvre options. The other critical issue is also for the follower (evading) craft to avoid a potential collision with its leader:

“In addition to the need of collision avoidance, it is important to reduce the impact on the primary mission. This will limit the motion area of the evader to a finite space.” [Cao, 2024]

▲▲ In FIGURE 1: Three-Spacecraft Pursuit-Evasion Scenario, the in-plane problem (evader and pursuer are on the same orbital plane), is more challenging for the RED evader to escape because in a coplanar rendezvous process, the rendezvous window is longer [Cao, 2024]. This is because, if the RED evader performs a counter-rendezvous manoeuvre, the BLUE pursuer can achieve a re-rendezvous within the same plane with less fuel consumption, and the rendezvous time can be freely chosen, giving more opportunity to catch up with the RED evader [Cao, 2024]. In the case of a non-coplanar scenario, if the BLUE pursuer does not alter the orbital inclination, the rendezvous must occur at the orbital ascending or descending node, which increases the difficulty of the pursuit [Cao, 2024]. Besides, during in-plane manoeuvres, the RED evader’s range of motion is limited (only in the orbit plane), thereby increasing the difficulty of escape [Cao, 2024].

THREE-SPACECRAFT PURSUIT-EVASION SCENARIO WHERE EVADER ESCAPES PURSUER: Tactically, the pursuer and evader spacecraft, “take sequential turns to make decisions” [Cao, 2024]. Where there is a long initial relative distance and lengthy duration, “impulsive manoeuvre is more suitable than continuous thrust manoeuvre.” [Cao, 2024]

Impulsive Manoeuvres: Brief firings of on-board rocket motors change the magnitude and direction of the velocity vector instantaneously. During an impulsive manoeuvre, the position of the spacecraft is considered to be fixed; only the velocity changes.

Constant Thrust Manoeuvre: Engine thrust creates a constant acceleration of the spacecraft against the gravitational pull of celestial bodies. Compared to other manoeuvres which cause variable accelerations. Non-stop thrusts create elliptical final orbits, unless mass flow rate is dramatically reduced.

Tactically, the evader is able to successfully escape from the pursuer when the upper limit of the maximum impulsive velocity increment is the same for both the pursuer and the evader [Cao, 2024]. Noting that orbit manoeuvres are made through changes in velocity.

SATELLITE RENDEZVOUS TACTICS