LISALISA - iucaa

Chapter 9 Spacecraft Design
Table 9.1 Payload and platform unit definitions
Unit No. Total Mass [kg]
Laser head (incl. phase mod) 4 8
Laser head electronics 2 4
USO 2 0.8
Inertial sensor 2 13
IRS Electronics 2 4
UV box 2 1
Interfer. analogue elec. 2 3
Interfer. digital elec. 2 7
Instrument control elec. 1 4.5
Optical bench 2 11.2
Fibre Positioner 2 0.6
Telescope 2 13
Optical assy. structure 2 10
Optical assy. mechanisms 2 4
Optical assy. thermal 2 2
Str/Therm. shield 1 13
Total 99.1
The change to a triangle formed around three strong columns is also a consequence of reviewing
the instrument fork structure and its mounting. It is necessary to retain the outer fork of two
tubes and the “root” as a stand-alone structure containing the instrument telescope elements
and front end electronics.
To avoid any undesired distortion and thermal effects from the main structure feeding into the
fork, and thus its internal elements, the attachments for the fork must be so designed to carry
the expected loads but be so arranged to minimise carry-over of distortions. This means the
walls themselves should not be the main load carriers throughout the entire satellite stack as
were the cylindrical walls. The introduction of the columns is then necessary for the transfer of
loads between stacked satellites.
The ends of these columns are used as the load transfer points between modules and are fitted
with hold-down and release mechanisms. These mechanisms form two groups. The first group
connects each science module to its partner propulsion module forming a combination, and the
second group connects each module combination to each other, and the lowest to the launcher
13-9-2000 11:47 146 Corrected version 1.04