|
|
AUSTRALIAN
NATIONAL UNIVERSITY System Design Note 6.14 Created: 4 May 2002 Last modified: 4 May 2002 |
STRUCTURAL SYSTEM MODIFICATIONS
Peter Conroy
Research School of Astronomy
and Astrophysics
Institute of Advanced
Studies
Australian National
University
Revision History
|
Revision No. |
Author & Date |
Approval & Date |
Description |
|
Revision 1 |
Peter Conroy 14 May 2001 |
Peter J. McGregor 03 May 2002 |
Original document. |
|
|
|
|
|
Contents
1 Purpose
This document shows proposed changes to the Gemini Near-infrared Integral Field Spectrograph (NIFS) integration frame to 1) allow the instrument to fit into the large elevator in the Gemini telescope building and to 2) allow the instrument to be mounted on the up-looking port of the ISS.
2 Applicable Documents
|
Document ID |
Source |
Title |
|
|
|
|
3 Introduction
The Gemini Near-infrared Integral Field Spectrograph (NIFS) duplicates many of the Near-Infra-Red Imager (NIRI) designs. The NIRI integration frame was modified during commissioning to allow NIRI to be mounted on the up-looking port of the Instrument Support Structure (ISS). This has necessitated modifications to the NIFS integration frame. The proposed modifications will also allow NIFS to fit within the large elevator in the telescope building. These modifications are described below.
4 Proposed Modifications
Figure 1 shows the completed NIFS integration frame and thermal enclosures as presently constructed at Mt Stromlo. A large steel frame passes through the integration frame and supports the thermal enclosures at the outboard ends of the frame.
Figure 1: NIFS integration frame as built in Jan 2001.
In Figure 2, the rear-most square frame has been separated from the three horizontal struts, the struts have been shortened by 100 mm, and the rear-most frame has been re-welded to the ends of the shortened struts. This reduces the overall length of the frame to 2281mm as measured from the mounting face of the ISS interface plate to the very rear-most face of the instrument handling pads. The frame can be shortened more than 100 mm if necessary, but it may prove harder to meet the Gemini specified 20 kNm moment about the ISS interface plate. Note that the NIFS window and environmental cover protrude forward of the ISS interface plate and the overall length of the instrument is about 2353 mm.
Figure 2: Simplest possible modifications to the NIFS structure.
Figure 2 also shows the simplest possible modifications that will reduce the overall width of the integrated instrument. In this figure, the thermal enclosure support structure has been cut into two separate pieces and the pieces rotated and shortened such that they span from the center to the rear-most of the square frames. The two separate pieces of the frame can be bolted, or more cheaply welded to the integration frame. Both of the thermal enclosures are now rotated by 90° such that the patch panel near the bottom of the enclosures faces towards the ISS interface plate. The overall width of the instrument is 2710 mm. As a bonus, this configuration allows for shorter cable runs to the NIFS instrument and for shorter runs to the patch panels on the instrument rotator. A more elegant and better looking support for the enclosures could be built from 25 mm thick strips that span the two rear frames. This would further reduce the width of the instrument by about 150 mm.
Figure 3 shows a plan-view of the instrument superimposed over the Gemini elevator floor plan and includes the dimensions of the elevator. The instrument fits within the boundaries of the elevator and will be able to be loaded into the elevator if the instrument is carried on the wheeled handling trolley that will be supplied to Gemini with the NIFS instrument. This wheeled trolley does not protrude beyond the boundaries of the integration frame. The instrument has about 85 mm clearance between the elevator doors and the extremes of the instrument. We do not presently have enough information to determine whether the instrument can be loaded into the elevator if it is carried on one of the Gemini air pallets. This may be possible if the pallet handle and its attached air bearing control are relocated. Figure 4 shows the instrument passing through the elevator door and includes the dimensions of the as-built instrument presently at Mt Stromlo, but shortened by 100 mm.
Figure 3: Plan-view showing NIFS in the Gemini elevator.
Figure 4: Plan-view showing NIFS passing through an elevator door.