NASA's Orion crew exploration vehicle landing work has produced a 180kg (400lb) airbag system for emergency onshore touchdowns, replacing a 680kg design originally for nominal land landings that forced a decision to have the CEV land in water.

While NASA changed the Orion crew module's nominal landing from land to water because of the airbag system's mass penalty, it concluded there was still a need for an emergency land landing capability.

The 180kg system's airbags only deploy on the side of the CEV that first hits the ground. To do this Orion would have to be designed to land "toe first", with the vehicle's parachute attachment and centre of gravity ensuring the module is angled down to ensure one side makes contact first.

Despite the airbags' land design, NASA's project Orion manager Mark Geyer expects them to be deployed regardless of the landing surface: "We want to make sure that these airbags will also work in a water landing."

Like the Apollo command module, Orion will require flotation devices. According to a study by NASA Langley Research Center's Edwin Fasanella, Apollo-era testing indicated that retro rockets are also effective for water impacts, but airbags are better for reusability.

Fasanella's study also cites simulations that found a 7,200kg capsule, landing on packed sand with six airbags at a horizontal velocity of 24kt (44km/h) and a sink speed of 7.62m/s (25ft/s), will tumble and come to rest on its side. This issue was to be addressed in further studies.

Source: Flight International