By Rob Coppinger in Paris
As it prepared Space Shuttle Discovery for its scheduled 1 July launch, NASA was planning further external tank (ET) testing. In late September the agency will windtunnel test another ET ice frost ramp redesign. The ramps cover pressurisation lines and cabling along much of the length of the tank. The redesign will see less foam on top of the ramps and along their leading edges and will undergo cryogenic testing in an environmental chamber to emulate different seasons.
The ET’s 34 ramps and aft tank aerodynamic fairings have been determined to be potential sources of foam debris of 0.09kg (0.2lb) mass, although NASA thinks they do not present a threat to an orbiter’s wing, only to other tile areas.
Meanwhile, STS121/Discovery’s tank, ET119, has had its protruberance air load ramp, which covers a cable tray, removed as it was an area of foam loss seen during the ascent of the first return-to-flight mission, STS114. Space Shuttle Atlantis, for its scheduled STS115 mission in August, will use the ET118 tank that has the same modification.
The STS121 tank has been instrumented for in-flight analysis. “Development flight instrumentation in the cable trays has 12 accelerometers whose data will be recorded on devices in the solid-rocket booster skirts and downloaded after the boosters are retrieved,” says NASA, which spent much of the year after the 2005 STS114 mission windtunnel testing the design change.
Source: Flight International
