Alternative History

A Castra Astra (English: Sky Fortress) is an orbital installation designed for long-term human habitation for the purposes of military intelligence or deployment. The first one was completed under orders of the CCR on December 21st, 1947, it was the consequence of plans from the original Artemis Program since 1932 during WWII. The greatest hurdle in its construction was perfecting a process for fusing separate pressurized modules without future risk of breaches. The details were worked out in theory by 1943 but construction and assembly were slowed by Rome's focus on the lunar mission.

Serving the empire for twenty years, the Castra Astra was decommissioned in 1970 and replaced by the Castra Astra II, an enormous advancement over the first model. Like its predecessor, the CA II was assembled in orbit with the assistance of custodes angeles satellites.

Today, space beyond the atmosphere is teeming with 98 sky fortresses devoted to expanding Rome's military presence off-planet and ensure an unparalleled dominance for the Legions.


Castra Astra I[]

  • Code name: Hadrianus
  • Maximum crew: 11 (nine officers, one doctor, one CO)
  • Launch period: 1944-1947
  • Average speed: 27,206 km/h
  • Perigee: 462 km
  • Apogee: 483 km
  • Orbital decay: 0.7 km/month
  • Mass: 330,402 kg
  • Consumables: 4 months
  • Water supply: 6 months (with filtration)
  • Air supply: Indefinite (filters changed every 2 years)
  • Maximum Power Output: 520.4 kW (assuming maximum direct sunlight)
  • Reactor life: 16 years

Castra Astra II[]

  • Code name: Trajanus
  • Maximum crew: 17 (16 officers, one CO)
  • Launch period: 1968-1970
  • Average speed: 23,604 km/h
  • Perigee: 493 km
  • Apogee: 535 km
  • Orbital decay: N/A (negated by propulsion systems)
  • Mass: 1,072,400 kg
  • Consumables: 15 months
  • Water supply: six to seven years (with filtration)
  • Air supply: Indefinite (with filtration)
  • Maximum Power Output: 100 MW
  • Reactor life: 42 years
  • Weapons: Six missile launchers (100 missiles); four 300 kW lasers


In mid-1944 the Habitation module was placed in a stable low-Earth orbit by aid of a Custos Angelus satellite, which continued to control the orbit of the structure until construction was completed. This module included 6 of the 11 sleeping units, food storage systems lasting four months and one of the five exercise machines. In December 1944 the Power Module was sent up containing a single radioisotope piston generator and one pair of photovoltaic arrays. By late-1945 the Filtration Module and Command Center had been sent up, whilst plans for the remaining three pieces set the completion date for early-1948. Following the success of the Moon Landing, the Star Fortress took top priority in the empire and by late-1946 the AI Module, containing the single-most advanced computer of the day, attached itself to the growing structure. Early 1947 saw the attachment of the Communication Module which, in addition to radio equipment, had an extensive ground radar system to monitor movement on Earth.

Finally, on 21 December 1947, the Observation Module was installed on the Fort, and all connections between modules were fully secured. This final unit had optical and further radio scanners directed both towards the planet, and at the area around the satellite. The first time humans actually entered the structure was following the connection of the AI Module, as this unit was also the location of the docking station. Actual operations began late-1946, at which point the Fort was habitable for long periods of time, though these projects mostly consisted of maintenance of the structure and the various electronic systems onboard. During the New Year of 1948 the Castra Astra entered full service and regular action onboard the station officially began.

Abridged Timeline[]

  • 1932 - Start of the Artemis Program, beginning of state funding for potential space travel
  • 1936 - Conceptual designs for an inhabited-military satellite are completed
  • 1942 - The Castra Astra becomes public knowledge within the Roman Empire
  • 1943 - Detailed plans of the station are fully drawn-out. Construction on several of the modules begins
  • Mid-1944 - Completion of the Habitation Module
  • Late-1944 - Completion of the Power Module
  • Mid-1945 - Completion of the Filtration Module
  • Late-1945 - Completion of the Command Center
  • Mid-1946 - Monthly funding for the Castra Astra more than triples
  • Late-1946 - Completion of the AI Module
  • Early-1947 - Completion of the Communication Module
  • Late-1947 - Completion of the Observation Module
  • 1 January 1948 - Normal operations for the Catra Astra begin

  • Late-1967 - Start of the project to replace the first Castra Astra
  • 1968 - Construction of the Castra Astra II is started
  • Late-1968 - Completion of Power Module and Habitation Module
  • Early-1969 - Completion of Life Support Module and the Docking Station section
  • Late-1969 - Completion of Center of Operations and Space Observer sections
  • Mid-1970 - Completion of Missile Module and Locomotion Module
  • Late-1970 - Completion of Defense Module and the Ground Observer section
  • Early-1970 - Completion of AI Module and Communication Module
  • 25 December 1970 - Castra Astra II begins normal operations
  • 1 January 1971 - Castra Astra performs a controlled crash into the Mediterranean Sea


The Castra Astra's purpose was to spearhead an extension of Roman military power into space, the newest limes of the empire. This goal was not entirely set out of vanity, that factor nevertheless playing a part, but was justified by arguments for the strategic importance of Earth's orbit, laid out over numerous debates in the Senate during the 1930's. The majority opinion was ultimately that as the metaphorical highest ground a country could occupy, outer space provided a great deal of logistic flexibility and mobility to its controller.

While orbit could technically be controlled from the ground with ICBM's and ground-to-space missiles, a presence there, a real physical presence, had its advantages. For the most part, the advantage of direct management of one's orbital territory was the ability to approach problems from an angle that wasn't possible by from the ground. Then, as Rome expanded its presence in space, the Castra Astra had to expand as well.


The only military threat against the Fort is the existence of ICBM's and even this is a miniscule threat as, not only are all the nations with ICBM's Rome's ally, but the station has an outer coating designed to reduce its radio signature to a minimum, making targeting it a significant challenge. In addition to this, most natural threats to the Catra Astra have been contained or avoided in one way or another. A layer of lead around the Command Center and Habitation Module protects all crew members inside from most radiation and protects 73% of the crew while they are sleeping. Scans performed over the course of 1946 showed that a single year in the station incurs a four times increase in radiation dosage when compared to the same time at sea level.

Aside from the threats of Rome's enemies and radiation, there is the additional risk of space debris. Although a small amount of particulate matter exists in space, originating from Earth, the greatest risk in orbit is that of micrometeoroids. A thick outer shell covered the CA, weathering decades of extraterrestrial abuse. Lastly, the Castra Astra has no windows and any fragile equipment either has additional armor or is positioned within the station to be beyond the reach of most external collisions.

The station is capable of receiving and transmitting an incredible amount of information at any one time and, thanks to its onboard computer, processing this information at an even more impressive rate. This gives the Roman Military the most extensive Information Network of any civilizations at the time. As the station had near realtime connection with command on the ground the Romans could easily outmaneuver any enemy and surprise attacks against the Legion were virtually impossible at the time.

Despite the original Castra's military role, it was not outfitted with any kind of weapon. This seemingly obvious design flaw was not corrected until the newer model was launched in the late-60's.


April of 1948 was the first time the Castra Astra was put to work. It oversaw the maiden voyage of the spacecraft Archimedes, performing constant scans on the vessel the entire time. It was this station that was the overseer of nearly all space launches, both foreign and domestic, until 1956 when an automated space station dedicated to the surveillance of space travel was completed. In any case, this was only a secondary function of the Castra, and one of its minor ones at that.

The first time that the station actually performed its primary function was in October of the same year it went into operations. With the beginning of the Swahilium Civil War, the Roman's military assets were mobilized to deal with the problem in as frugally a way as possible. To do this, the massive logistics and technological capabilities of the empire would have to be fully exploited, this included the Castra Astra.

Late into the war, the station was used to perfectly synchronize Cherubim spatial attacks with the actions of the Sifocaeli in the air. This incredible correlation between the different sections of the Roman military, thanks to the station, is what made it the most successful force in the world.

In 1964, a second permanently-manned satellite station was completed. This one was however meant as a research station, and so it never functioned in coalition with the Castra at any point.

Castra Astra II[]

By 1967, the station's technology had become outdated while it reached subpar standards for safety. Radiation levels were measured above recommended amounts and filtration was less efficient than more modern engineers needed it to be. The Curia Imperia elected to replace the Castra Astra with a newer installation, correcting the flaws of the previous model. Greelit by the emperor, the project was underway before the year's end.

Due to the enormous storage capacity of the Prometheus, in comparison to the rockets of the 40's, each of the new modules could be substantially larger than the old fortress. Nevertheless, specialized modules were built to have an advantage in efficiency over the alternative of all-purpose components.

Technical Data[]

Power generation depends on a 100 MW fusion reactor on a lateral module away from the habitation pods. Solar panels built into some walls, almost as decoration, can keep essential life support running in the event the reactor gets jettisoned. Heavy water is transported by ship for conversion into deuterium fuel within the Power module. This fuel is far more efficient than hydrogen and favored aboard specialized vessels.

The second sky fortress' dedicated life support pod performs the various functions necessary to sustain humans in a hostile environment such as outer space. 99.5% of water is regularly extracted from human waste while air dryers, showers and sinks take similar portions of used liquid. Dehumidifiers maintain a constant, low humidity throughout the station, condensing water vapor for extraction to the filters - which work fast enough for normal and consistent use of the 24,000 litres stored onboard.

Docking with the sky fortress has sophisticated protocols. A Prometheus-class space shuttle can attach to the main port for unloading personnel, cargo up to 3.48 m across and water for the reactor or life support, which is pumped directly into the station. Patroni and custodes angeles drones recharge at three ports which draw power from the main reactor. This became the primary energy source of mobile satellites in the 1970's.

Defending the vital operations of the Castra Astra II are two separate modules - the missile module and defense pod - with their respective weapons. The former stores a hundred high-explosive missiles designed for space-to-space combat. These can be fired from any of six launchers around the module. The latter is outfitted with four omnidirectional laser ports with a maximum continuous output of 400 kW. The laser pod has impressive coverage of the space station, missing about two-tenths of its surface, but orbital maneuverability allows rapid reorientation towards targets when defending the fortress is a top priority.

For reorientation, the station has thrusters on its tail-end, opposite the laser pod. These can set it into rotations around its center of gravity that alter position without changing trajectory. Expelling a stream of ions in nine possible directions, the thrusters offer range of possible options when repositioning.

The raison d'être of the second Castra Astra is surveillance of activity on the ground and organization of spy satellite data for dispatch to the national military command. It is the duty of soldiers and officers onboard to identify crucial information gathered by Roman intelligence networks on a constant basis. Onboard cameras in the infrared and visible spectrums monitor objects entering and exiting the atmosphere, with an eye on lunar travel in particular. Motion detection with active radar runs 24 hours a day, noting objects of interest for the more sophisticated cameras to analyze.

Inhabitants of the Castra Astra live within a habitation module under less radiation than people will experience at sea level. This area is the heart of the space station, in a thick tube directly in line with the laser pod and thruster module forming the main body. The entire satellites constantly spins to produce ~1g when standing in the main body and slightly less than 1g in the docking bay and missile module which are attached by arms to the body.

Separate rooms are allocated for each of the seventeen occupants, providing a bed, bookcase and lighting for one person. A shower, toilet, sink, kitchen and dining table are shared by everyone. Frozen food separately stored in a refrigerated pod can last the crew 15 months.

The Castra Astra II is still in use by the Roman military, although it has since been joined by several other orbital installations. Its continued operation will be decided after discussions planned about it in 2012.