Inflated free fall habitat

Image from Lilly Harper
A freesphere is a large inflatable microgravity environment containing a breathable atmosphere.
Free fall habitat often used as a recreational area in an orbital band or as habitation for the space adapted.

Freespheres are large, transparent, double-walled open bubbles, ranging from several hundred meters to several thousand kilometers across, filled with air. Appropriately modified lifeforms create a free-fall ecology and a layer of water between the inner and outer walls, combined with magnetic screening, provides an effective radiation shield. Freespheres are especially popular when placed in planetary orbit due to both the spectacular views and the sense of truly flying 'above' something rather than merely floating in space.

For freesphere diameters greater than 100km, stronger materials and additional re-enforcing structures are required. This reinforcement attenuates the views, as does the longer sight lines through the internal atmosphere, but with a hull completely made of buckycables a Freesphere can be made much larger than a rotating habitat made of the same material; as large as 5,000 km across even with full, baseline comfortable, atmospheric pressure.

Freespheres may employ complex internal environmental systems, including airwalls, fusion or conversion reactor "suns", and various feedback-based systems to promote airflow, control temperature, and manage both general humidity and larger concentrations of moisture (ranging from small "pools" to "seas" several kilometers across).
Image from Steve Bowers
This Freesphere, in orbit around Hiederia, holds a number of freeform microgravity structures which serve as habitats and workshops for the low-gravity tweaks who live there
Related to freespheres are gravity balloons, which are typically covered in a layer of asteroid material which acts as a radiation shield and also counteracts the outward pressure of the atmosphere inside the balloon.

Both gravity balloons and freespheres may include habitable components which rotate to produce gravity, and these structures are generally tethered to an internal structure to ensure they remain in place and do not collide with other structures in the environment. Because the rotation of these habitats can cause wind eddies, the rotation rate and subsequent gravity is generally kept quite low.
Related Articles
Appears in Topics
Development Notes
Text by Todd Drashner
Additional material by Steve Bowers
Initially published on 02 February 2002.

Additional Information
Fiction relation to Freespheres

Traveler's Notes: Freesphere