Our goal was to determine whether Rama can provide an environment as close as possible to the one on Earth. We looked at the gravity, the temperature and lighting, and the wind and natural convection patterns. The result is that we found nothing that would prevent Rama from providing the same "gravity", lighting and temperature as on Earth, with "normal" wind speeds, although things like clouds, for instance, would not be possible. In more details:
- we found that Rama can withstand the stress forces caused by its rotation (used to simulate gravity via the centrifugal force). Even if there was no hole in the shell structure, ordinary steel would suffice to withstand these forces. Due to the centrifugal force, the shell radius would increase only by 0.07% at the poles and by 0.4% at the cylindrical sea. Its total mass would be ~17000 GT. We found, however, that much bigger spining cylinders providing the same artificial gravity are not possible.
- we found that Rama can provide at the same time similar lighting conditions and similar temperatures as on Earth (35.000 lux and 15°C on average). As on Earth, this requires a greenhouse effect, which can be achieved by using two or more concentric shells separated by empty space. However, in the most energy efficient scenario, where light sources would emit only in the visible range, this would require a power source of ~600 GW, i.e. about 170% of the total power of all the nuclear reactors on Earth in 2011.
- we found that the temperature variations at the ground level and in the atmosphere would be very small, on the order of +/- 0.5°C around the average temperature (except in small regions near the linear light sources). As on Earth, the pressure would decrease with altitude, but less quickly because the centrifugal force decreases with altitude (while gravity in the Earth atmosphere is nearly constant). On the axis, 8000 m above the ground, the pressure would be the same as on Earth at 4000 m. Also, because of the nearly constant temperature, clouds would not form in the atmosphere.
- finally, we found that the winds would be very light, on the order of 4 km/h and, in one scenario, up to ~20 km/h. A few hours after the linear lights are turned on they would form 6 convections cells rotating in alternating directions, and almost parallel to the surface. We were not able, however, to determine the long term evolution of the convection patterns and wind speeds.
