Rama Forerunner energy output calc 1

For the purposes of this discussion we'll ignore the myriad of layers that form the concentric structure that contain the inner mechanisms of Requiem and instead focus on the three most pertinent and observable examples of Requiem's internal and external geometry: the outermost shell, the inhabitable sphere and her present atmosphere. For the sake of the solid structures, based on volumetric scalings of the Forerunner ships using their masses as depicted in Warfleet we can at least deduce the following average material density for Forerunner constructs as a lower limit using 3D models of their craft.

For a Keyship:
Volume: 8.026 x 109 m^3
Mass: 19 billion metric tons
Average material density: 2367.2 kg/m^3

The outermost layer of Requiem (ignoring the armored sections) has an approximate thickness of 50 km, placing her overall volume at 3.588 x 1019 m^3 due to Requiem having a diameter of 10,787 km. The second inhabitable sphere, existing approximately 200 km before the outermost shell would have a diameter of roughly 10,587 km. Assuming a similar composition to the first her overall volume would be on the order of 1.988 x 1019 m^3. The mass of the atmosphere, assuming a consistent average density equal to air at sea level (due to Requiem having an approximately sufficiently breathable atmosphere throughout multiple layers), would total to 7.06 x 10^20 kg.

Thus, the total lower limit of her sum volume would mass 1.263 x 10^23 kg as this assumption ignores not only the additional mass of machinery between the habitable outermost layer and the core (containing ship cradles, weapons, manufacturing facilities etc.), but the sheer volume of armored bands (some of which were hundreds of kilometers thick) encircling the hull of the Dyson shell.

Assuming Requiem is approximately 150 million km away from Epoloch and is moving at an orbital velocity of 30 km/s (similar to Earth), in order to de-orbit Requiem so that it falls into her parent star you would have to remove her total kinetic energy accumulated from her orbital velocity to allow her to fall into Epoloch's own Roche limit. The star's gravity well would then pull the planet in a steadily straightening line toward her surface along a flattening orbital curve until the two eventually collided. Thus, you need to remove 5.63 x 10^31 J of kinetic energy from Requiem in order for her elliptical orbit to sufficiently flatten as to pass through the parent body. The issue with this hypothesis however is one of time; due to the Sun's gravity being considerably weaker than 1g at a distance of 1 AU from her surface, it's estimated that the gradual action of her gravitational potential (assuming the elimination of a planet's velocity) would require months to pull a planet into a collision course. Whilst in stellar terms this is incredibly quick, it's evident that greater urgency was required throughout the events of Spartan Ops, with the actions of Majestic and Crimson culminating over mere hours rather than the time frame required for the UNSC to rally their fleet elements and evacuate the vessel and conduct a full inspection of Requiem virtually unopposed.

By contrast, instead of steadily decreasing her kinetic energy, Requiem's descent is in fact a far more violent reduction of her perigee, being subsumed within the convective layers of Epoloch within two seconds would require impact velocities of 5,393.5 km/s to utterly envelop the structure - thus not only did her propulsion systems exceed the potential kinetic energy of her orbital velocity, they applied sufficient transverse acceleration as to increase her descent velocity into the photosphere to 1.6% light speed; thereby increasing her total potential kinetic energy to 1.83 x 10^36 J (a quarter of the total energy output of the entire Milky Way galaxy) or 2.1 x 10^31 W (5 zettatons per second) assuming a 24 hour time span by which to alter the perigee of Requiem.