The AM, a tubular structure about 4.5 m long and 3 m in diameter, would thus provide a pressurized passageway for the crew from the spacecraft to the empty interior of the S-IVB hydrogen tank. Oxygen tanks in the module would pressurize the AM and interior of the S-IVB to create a "shirt-sleeve" environment for the crew. Objectives of the AM, Mueller explained, were to investigate the feasibility of using a spent rocket stage as a large habitable structure in space and to develop the capability for long-duration manned missions. If successful, he told Seamans, the AM would give NASA an early capability for manned experimentations and operations in space. Definition and design of the AM had already been completed, and the experiment already had approval of the Manned Space Flight Experiments Board. Moreover, procurement bids had been received from industrial firms and results of the competition presented to Administrator James E. Webb in mid-July. Thus, because the AM presented "a unique opportunity to investigate a major new manned space flight capability at a reasonable cost," Mueller urged Seamans to approve its early procurement. On 2 August, Seamans presented Mueller's arguments to Webb, recommending approval of the AM experiment. Seamans reasoned that the experiment, if feasible, would provide the United States with a major new capability for long-duration manned space operations without interfering with the basic Saturn IB launch vehicle program or the mainline Apollo lunar landing goal. Webb approved Seamans' arguments the following day, with an added comment: "particularly as it would open up additional areas of knowledge we might need if Russian programs accelerate to the degree that we wish to add to our manned operations with least lead time and maximum use of Apollo equipment."