Inflatable Antenna Experiment

Region

United States

Associated With

L’Garde, NASA Jet Propulsion Laboratory and NASA Langley Research Center - project participants

Defining Feature

A canister-packed reflector deployed in orbit using nitrogen-inflated supports

Status

Historical event - orbital deployment test flown in May 1996

Overview

The Inflatable Antenna Experiment was a vast, packable reflector flown aboard Space Shuttle Endeavour.

Released in orbit in May 1996, nitrogen inflated three long struts and a supporting ring around its thin reflector, turning a canister-sized payload into a structure spanning tens of metres.

The support structure formed and held its shape, but the reflector did not appear fully deployed and could not be characterised by the planned orbital measurements. The inflatable unit was later ejected; the shuttle retrieved its carrier.

Why It Mattered

The appeal of an inflatable reflector lay in a difficult spacecraft-design bargain: proposed large antennas faced constraints in mass, packed volume and development cost, while an inflatable structure offered another approach. Deployment also introduced complications. Preliminary analysis linked unexpected behaviour to residual air in the packed structure and strain energy released by its supporting ring, suggesting that conditions created during packing could affect how the structure unfolded in orbit.

Flight and Deployment Sequence

• Space Shuttle Endeavour launched with the experiment on 19 May 1996 and released it in Earth orbit on 20 May.
• A spring-loaded plate ejected the packed assembly from a canister mounted on the Spartan 207 carrier.
• Nitrogen inflated three 28-metre struts, a supporting torus and the 14-metre offset reflector-and-canopy assembly.
• Onboard imaging was intended to measure the reflector’s surface shape in orbit.

Measurement and Flight Result

• One-millimetre RMS surface precision was a project objective, not a result demonstrated in orbit.
• The measurement system could position the reflector rim, but the preliminary paper says the surface itself could not be characterised.
• The paper’s photogrammetric surface measurements were made on the ground, while its radiation patterns were calculated rather than measured in orbit.
• NASA’s June 1996 mission report left the final assessment of canopy inflation pending analysis of the recorded data.

Project Context and Later Assessment

• The project paper identifies participants at JPL in Pasadena, L’Garde in Tustin and NASA Langley Research Center in Hampton.
• The project authors presented inflatable reflectors as possible structures for mobile communications, Earth observation and space radar; IAE did not demonstrate those services.
• In 2000, JPL described the flight as a useful demonstration and a foundation for continuing inflatable-structure research, while presenting later concepts as future work.

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