The Space Force’s X-37B OTV-7 mission demonstrates advanced orbital capabilities and the strategic military use of highly elliptical orbits.
The X-37B, the U.S. Space Force, has completed its seventh mission (OTV-7) after 434 days in orbit. This mission marks a major technical evolution: first use of a Falcon Heavy launcher, insertion into a highly elliptical orbit (HEO), unprecedented aerocapture maneuvers, and technological tests on knowledge of the space domain. The X-37B remains an experimental vehicle, but its proven capabilities raise strategic issues in the face of the emergence of similar technologies developed, in particular, by China. Despite these advances, the Space Force does not plan to purchase additional units, focusing instead on data collection and the future development of a fleet more suited to real military needs.
Highly elliptical orbit: a strategic and tactical choice
The insertion of the X-37B into a highly elliptical orbit (HEO) is one of the main innovations of the OTV-7 mission. Unlike previous missions, which mainly used low (LEO) or medium (MEO) orbits, this mission enabled the shuttle to reach altitudes of over 35,786 km, i.e. beyond the geostationary belt (GEO).
The elliptical orbit allows a perigee closer to the Earth (a few hundred kilometers) and a very distant apogee (sometimes beyond 50,000 km). This asymmetrical trajectory makes positioning predictions difficult for foreign surveillance systems. This gives the X-37B a major tactical advantage: it can reappear unexpectedly, changing its trajectory to avoid detection or to surprise a targeted orbital object.
HEO orbits are particularly used in polar observation missions, but their use in military maneuvers makes it possible to optimize the surveillance field and to intervene in several orbital zones without spending too much fuel. At present, very few military vehicles have such capabilities.
From a technical point of view, these orbits require extremely precise attitude control and propulsion systems, as the change in speed is critical during the perigee passage. This type of trajectory also requires optimization of thermal protection, as the stresses on passage through the dense layers of the atmosphere are increased.
This mastery illustrates the growing orientation of the United States towards a discreet militarization of outer space, particularly in response to the development of the Chinese Shenlong program, an equivalent of the X-37B.
Aerobraking: a tactical innovation with low energy cost
Aerocapture, used for the first time by the X-37B during the OTV-7 mission, represents a significant advance. This technique makes it possible to modify the orbit of a spacecraft without resorting to significant chemical propulsion, by using atmospheric drag as orbital leverage.
Technically, this maneuver consists of deliberately diving into the upper layers of the atmosphere over several orbits, taking advantage of friction to gradually slow down the craft. This mechanism, if properly controlled, makes it possible to reduce altitude in a precise manner, while conserving fuel for possible subsequent maneuvers.
In the case of the X-37B, airbraking was used to:
- Gradually enter a low Earth orbit (LEO).
- Detach the service module at a controlled altitude.
- Test the performance of the Space Surveillance Network (SSN) in tracking objects with variable trajectories.
This tactical capability offers advantages in terms of orbital stealth. A craft capable of changing its trajectory without visible propulsion complicates the task of adversary radar tracking systems. This also has consequences for the strategic planning of ISR (Intelligence, Surveillance, Reconnaissance) missions, since the craft can adapt dynamically to its target or area of interest.
It should be noted that such a system may inspire the construction of future multi-regime orbital vehicles capable of adapting their orbit at will according to military requirements.
Space surveillance: a growing military challenge
The OTV-7 mission was also an opportunity to test space domain awareness (SDA) technologies. These systems aim to better understand, map and monitor active or inactive objects in orbit, in order to guarantee strategic freedom of action in an increasingly dense orbital environment.
The United States already operates a complex space surveillance network, consisting of ground-based sensors (radar, optical) and geostationary orbiting observers (GSSAP program). The X-37B is used here as an experimental vector for these technologies. It is able to:
- Identify the electromagnetic signatures of foreign objects.
- Stealthily approach foreign satellites to analyze their capabilities.
- To serve as a test platform for passive and active sensors.
The ability to control the space domain is a major issue. In 2023, more than 10,000 active objects were identified by the SSN. The proliferation of satellites, particularly commercial ones (Starlink, OneWeb), is creating a congested orbital environment, making surveillance more complex.
In this context, the ability to detect a change in orbit, a separation of payloads, or suspicious activity becomes essential to anticipate potentially hostile acts. The role of the X-37B, even experimental, is therefore strategic in the training and calibration of future orbital engagement doctrines.
A strategic tool limited by its experimental status
Despite its performance, the X-37B remains a military prototype. It is not intended to become a permanent operational platform, according to official statements from the Space Force. The fleet is limited to two units, and no additional orders are planned at the moment.
There are several technical and economic reasons for this decision:
- The estimated cost of development and missions exceeds 1 billion euros.
- The dimensions of the cargo bay (2.1 m long, 1.2 m wide) limit payloads.
- The system remains difficult to reuse on a large scale, with long maintenance phases after each mission.
In the medium term, the lessons learned from the X-37B will undoubtedly be incorporated into more modular and efficient vehicles, designed from the outset for offensive or defensive uses. Furthermore, technological competition with China and Russia is prompting a reconsideration of the role of space in military superiority.
Maintaining an experimental fleet also makes it possible to anticipate the use of these technologies by competing powers. In this sense, the X-37B is used as much to test capabilities as to study the necessary countermeasures against similar enemy vehicles.
War Wings Daily is an independant magazine.