lt01_assemble_apertures.jpg The "Leak Test" is a Colorado Space Grant tradition which tests the integrity of a rocket's skin, bulkheads and ports by floating it in a convenient pool, opening it, then looking for signs of water entry. After HOMER's flight, it will splash down 50 miles downrange into the Atlantic, so it is important that the payload be watertight and buoyant so that it will float until it can be recovered by the Coast Guard (the Wallops-supplied recovery section will include dye packets so that the payload may be easily spotted in the water). Recovery is not essential for our primary science objectives (all science data is downlinked by radio during the flight), but the Video Camcorder Experiment needs to be recovered so that we may view the videotape of the flight, and special effort has been taken with the structure design so that it can be easily reused for future missions (recycle!).
Click on any picture for a higher-resolution version
The apertures are the viewports in the rocket skin through which the scientific instruments collect their data. Each aperture consists of a hole in the rocket skin, a machined inner window mount, a quartz window, a window compression collar, and a set of 0-rings which make an air and watertight seal.
There are five apertures in all, three for the Photometer Suite, one for the CCD Spectrograph Experiment, and one for the Video Camcorder Experiment. Note that each aperture window must be transparent to the type of light which is recorded by that instrument (from ultraviolet for the CCD and Photometer 2, to visible for the Video Camcorder and Photometer 1, to infrared for the IR Photometer).
The skin consists of a single piece of aluminum which is installed over the entire structure, then bolted at the bottom. O-rings seal the skin to the top and bottom bulkheads.
An O-ring, made of a special type of rubber, is greased with silicone and installed on the top edge of the skin.
The top bulkhead is installed over the O-ring and bolted down.
The payload structure (minus the electronic components in case it DOES flood) is loaded onto a truck for a trip to the pool (thanks Linda).
Once at the pool, and under the curious stare of civilians, the nose cone is installed onto the payload.
The nose cone is tightened down. Each section has thirty-six bolts which need to be installed and tightened. There are three such sections on HOMER.
The rocket is placed in the water.
Without it's internal components, the rocket is fairly buoyant and is hard to force down into the water.
The men of HOMER show their balancing skills...
...or not.
Attempt 2 to force the payload into the water.
And the rocket wins again.
A quick conference.
The women of HOMER show off.
And splash down.
The nose cone is removed to look for signs of water entry.
There are no signs of water, the O-ring has done it's job.
HOMER would normally float with both the pressurized section and the nose cone section dry. But if the nose cone flooded, it needs to be determined if the payload would still float.
The pressurized section appears to float just fine without the extra buoyancy of the nose cone.
There doesn't appear to be any water in the pressurized section (as evidenced by the lack of condensation on the aperture ports). (When the payload is later officially unsealed, it is dry as a bone.)
The team enjoys a job well done.
And packs up the rocket for it's return trip to the shop.
These pictures were taken as part of an ongoing video documentary project of the CSGC HOMER mission. Video was taken using a Panasonic AG-455 SVHS camcorder, then framegrabbed using a DPS Personal Animation Recorder / TBCIV combo on an Amiga computer. Cleanup, sizing, and format conversion were done using OpalPaint and GFXcon.
michael.grusin@colorado.edu
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