Habitat Bennu: Design Concepts for Spinning Habitats Constructed From Rubble Pile Near-Earth Asteroids

The authors explore the possibility that near-earth, rubble pile asteroids might be used as habitats for human settlement by increasing their rotation to produce spin gravity. Using previously published scaling by Maindl et al. and studies of asteroid populations, it is shown that there is no class of hollowed body that would survive the spin-up process on its own without additional reinforcement. Large solid-rock asteroids (diameter D > 10 km) would not have the tensile strength to withstand the required rotation rates and would fracture and break apart. Smaller asteroids, being ‘rubble piles’, have little tensile strength and would quickly disperse. The possibility of containing the asteroid mass using higher-strength materials like carbon nanofiber is instead considered. It is found that a moderate tensile strength container can maintain the integrity of a large spinning cylinder composed of dispersed asteroid regolith. The research extends the range of possible asteroid habitat candidates, since it may become feasible to construct habitats from the more numerous smaller bodies, including NEAs (Near Earth Asteroids). The required tensile strength of the container material scales with habitat radius and thickness and is ∼ 200 MPa for a starting asteroid body of radius 300 m that is spun up to provide 0.3 g⊕ while increasing its radius to 3 km and maintaining a rubble and regolith shield thickness of 2 m to protect against cosmic rays. Ambient solar power can be harvested to aid in spin-up and material processing.

On the possibility of through passage of asteroid bodies across the Earth’s atmosphere

ABSTRACT We have studied the conditions of through passage of asteroids with diameters 200, 100, and 50 m, consisting of three types of materials – iron, stone, and water ice, across the Earth’s atmosphere with a minimum trajectory altitude in the range 10–15 km. The conditions of this passage with a subsequent exit into outer space with the preservation of a substantial fraction of the initial mass have been found. The results obtained support our idea explaining one of the long-standing problems of astronomy – the Tunguska phenomenon, which has not received reasonable and comprehensive interpretations to date. We argue that the Tunguska event was caused by an iron asteroid body, which passed through the Earth’s atmosphere and continued to the near-solar orbit.

Asteroids

Using a number of different conventional observing methods of astronomy like spectrophotometry, polarimetry, IR-radiometry and UBV-photometry, physical properties of asteroids can be derived, such as diameters, spectral reflectivity and albedo. Based on observable parameters a classification in terms of taxonomic types can be made and the mineralogy of the surface can be determined and compared with meteoritic analogues. UBV-photometry at different phase angles can reveal something about surface properties and diameters, whereas from accurate photometry during different phases of the rotational cycles we are able to derive rotation periods, geometric irregularities of the asteroid-body and topographic features on the surface. If observations of lightcurves are obtained during several oppositions at different ecliptic positions, the orientation of the spin axis in space and sometimes the sense of rotation can be derived. Observations of asteroids are especially well suited to small and medium-sized telescopes, as most of the programmes need long telescope runs. In addition there is a definite need for a large number of observations of asteroids in the magnitude range 12–15 mag.