The full paper proposes using this for literal greenhouses - growing plants only. What matters there is partial pressures of CO2 (actually higher than on Earth)

The full paper proposes using this for literal greenhouses - growing plants only. What matters there is partial pressures of CO2 (actually higher than on Earth), N2, and H2O. So the pressure differential would be relatively low, well within the structural limits of the aerogel as long as there's a sealant between sections. (They also ran tests on aerogel pebbles, but don't talk about sealing questions for that form.) https://www.nature.com/articles/s41550-019-0813-0 https://www.nature.com/articles/s41550-019-0813-0 "The higher carbon dioxide partial pressure on Mars versus Earth is favourable for plant growth, but the low total atmospheric pressure means that at temperatures of 273 K or higher, the undersides of silica aerogel greenhouse shields would need to remain slightly pressurized relative to the atmosphere to avoid loss of water vapour either vertically or laterally. This would place light demands on their structural properties, which could plausibly be met by interspersing the silica aerogel with thin layers of solid transparent material or via organic polymer reinforcement""