Inflatable (expandable) modules

Bigelow-type expandables recur in the designs of 2014–2019. By 2022–2026 rigid Starship-sized modules had displaced them.

Key results

• Bigelow family used in designs:
• BA330 (330 m³, 6.7 m inner diameter, ~23 t), BA2100 (65–70 t), Olympus, BEAM.
• Purpose-built pre-inflated modules: "BA-880" (9 m inner diameter, 3 floors), BA990 (20 × 10 m) and BA1400 (18 × 12 m) Roy_H, 2014-03-16; Roy_H, 2015-05-13; Roy_H, 2018-06-24.
• A BA330 is about a third of the ISS's 916 m³ Coastal Ron, 2015-11-09.
• Structure.
• The walls are ≥6 in thick and hold ~10 t/m² internal pressure Paul451, 2015-10-23.
• The internal subdivisions are stretched fabric and not load-bearing, so floors must attach to the core after inflation mikelepage, 2015-03-04.
• Unknown loads on the end-cap/skin joints when a module hangs, so add load cables from the lower cap to the counterweight Paul451, 2015-03-04.
• Coastal Ron: expandables are designed for 0 g, not for structural spin loads Coastal Ron, 2018-07-14.
• Operations.
• Inflatables cannot be launched fully outfitted, so outfitting shifts to expensive crew time in orbit Jim, 2018-07-03; mikelepage, 2024-07-24.
• Unconstrained inflation of long tubes is dangerous; deploy them inside a truss or with restraints Asteroza, 2015-10-26; MattMason, 2015-10-26.
• The TransHab vertical layout was found superior to Bigelow's horizontal one RanulfC, 2014-03-20.
• Advantages.
• More volume and MMOD protection per launch mikelepage, 2018-07-15.
• BEAM GCR dose rates are similar to those in other ISS modules LMT, 2018-07-05.
• Genesis modules survived unmaintained in LEO; BEAM has been hit safely and is expected to last to 2028 Paul451, 2023-01-24.
• Flexibility damps vibration mikelepage, 2015-03-16.
• Longevity concerns. Use inflatables as formwork for a durable build-up Coastal Ron, 2022-12-12.
• Industry status. Bigelow is gone. Sierra Space's LIFE habitat continues the idea mijoh20, 2023-01-23; lamontagne, 2023-01-24.
• Inflatable elements in rotating designs:
• Spokes and tunnels, with internal tension cables mikelepage, 2014-03-23; Paul451, 2022-10-11.
• A 20 m inflatable toroid as a free-flying Nautilus-X demonstrator Paul451, 2015-03-12.
• Minovitch's aluminium-wrapped inflated Kevlar torus PMN1, 2015-10-08.
• Mylar hourglass Whipple balloon mikelepage, 2023-03-02.
• Stephen Seachord's game-designer concept, with inflatables throughout LMT, 2024-08-10.
• Sleeve tunnels between modules: a flexible pressurized sleeve with a ladder and fluid-balancing pipes sanman, 2019-01-07.

Open questions

• Can expandables be qualified for continuous hanging loads at 0.5–1 g?
• With Starship's 8–9 m fairing, do expandables still offer a volume advantage worth the outfitting penalty?

Related pages

• Module sizing and floors · Cables vs trusses · Roy_H designs

Sources

Forum posts

• Roy_H, 2014-03-16 (reply #157): BA-880 idea (9 m ID, 3 floors). Post.
• RanulfC, 2014-03-20 (reply #228): TransHab vertical layout superior. Post.
• mikelepage, 2014-03-23 (reply #253): Inflatable accordion spokes. Post.
• mikelepage, 2015-03-04 (reply #487): BA330 subdivisions not load bearing. Post.
• Paul451, 2015-03-04 (reply #491, 1 like): Add load cables from cap to counterweight. Post.
• Paul451, 2015-03-12 (reply #510): 20 m toroidal inflatable. Post.
• mikelepage, 2015-03-16 (reply #534, 1 like): Inflatables damp vibration. Post.
• Roy_H, 2015-05-13 (reply #564, 1 like): BA990 3-level module. Post.
• PMN1, 2015-10-08 (reply #682): Minovitch inflated Kevlar torus. Post.
• Paul451, 2015-10-23 (reply #728, 1 like): Bigelow walls strength. Post.
• Asteroza, 2015-10-26 (reply #732): Unconstrained inflation dangerous. Post.
• MattMason, 2015-10-26 (reply #733): BEAM with restraints for slow deployment. Post.
• Coastal Ron, 2015-11-09 (reply #741): BA-330 330 m³ vs ISS 916 m³. Post.
• Roy_H, 2018-06-24 (reply #843): BA1400 18 × 12 m. Post. Attachments: WholeStation.png, CentralHub.png, AssembledRimModules.png.
• Jim, 2018-07-03 (reply #857, 2 likes): Inflatables can't be launched outfitted. Post.
• LMT, 2018-07-05 (reply #882): BEAM dose similar to other modules. Post.
• Coastal Ron, 2018-07-14 (reply #929): Inflatables not for structural loads. Post.
• mikelepage, 2018-07-15 (reply #931): Expandables = more volume & MMOD. Post.
• sanman, 2019-01-07 (reply #1259): Flexible pressurized sleeve with ladder. Post.
• Paul451, 2022-10-11 (reply #1977, 2 likes): Inflatable tunnel with cables. Post.
• Coastal Ron, 2022-12-12 (reply #2637): Inflatables as formwork. Post.
• mijoh20, 2023-01-23 (reply #3041): BA330 dead. Post.
• Paul451, 2023-01-24 (reply #3047): Genesis & BEAM durability. Post.
• lamontagne, 2023-01-24 (reply #3049): Sierra Space LIFE habitat. Post.
• mikelepage, 2023-03-02 (reply #3454, 1 like): Multilayer mylar balloon inside torus. Post. Attachments: Torus with Dumbell air shield.gif.
• mikelepage, 2024-07-24 (reply #4662): Inflatables shift outfitting to orbit crew. Post.
• LMT, 2024-08-10 (reply #4737): Seachord concept with inflatables. Post. Attachments: Wire_Dis001.jpg.