Pre-Phase A Report - Lisa - Nasa

120 Chapter 5 Payload Design
• Finite Element Analysis has shown that additional load paths are required to achieve
the first structural design objective. These load paths take the form of launch-locks,
which are retracted after launch.
The following sections describe the structural components and launch-lock concept in
more detail.
5.2 Payload structural components
5.2.1 Optical assembly
One set of optical components (telescope, optical bench and support electronics), together
with a payload cylinder, make up one optical assembly, as shown in Figure 5.1 .
Figure 5.1 Optical assembly, section view.
Payload cylinder. The payload cylinder is a graphite-epoxy tube, 360 mm in diameter,
500 mm long and 2 mm thick. It is fabricated in at least two parts, so that sections can
be removed in turn to allow access to the internal components after integration.
The cylinder is reinforced at intervals along its length by stiffening rings, suitably positioned
to form mounting points for the optical components (see Figure 5.1). These rings
are tubes, made from graphite-epoxy, 10 mm in diameter and 2 mm in wall thickness.
They are either fabricated individually, then bonded onto the payload cylinder sections,
or formed in sections as integral parts of the payload cylinder panels during their manufacture.
Each ring is equipped with fittings into which the appropriate component support
struts are attached (see descriptions to follow).
Telescope assembly. The telescope assembly is mounted from the first stiffening ring.
It uses graphite-epoxy or stainless steel blade mounts to accommodate the radial thermal
expansion of the ULE primary mirror and the payload cylinder. No detailed design of this
assembly has been conducted to date.
3-3-1999 9:33 Corrected version 2.08