Physical Interfaces

Envelopes

On-Orbit

The current baseline for the instrument envelope is as follows:

• 1.25m (height); including as applicable any support or mounting plate and the CPD as well as the instrument itself;
  
• 1.0m (width);
  
• 1.0m (length).
  

The SPDM standard envelope is what ultimately limits the allowable height (1.25m) of instruments on the EPA. Any greater height would put too many manoeuvering constraints on the robotic operations with the SPDM during the deinstailation of the European Early Utilisation EXPRESS Pallet Adapters after their three year in-orbit life. This height constraint may not apply during upioad and installation as the pre-integrated EP is transported in the NSTS Shuttle Orbiter cargo bay and installed by the SSRMS. This height constraint also may not apply where an entire EXPRESS Pallet is de-installed and returned to Earth in one piece. This height constraint always applies where single EPAs are transported to orbit and returned to ground and consequently need to be handled by the SPDM. In the other cases the limiting factor (on height) would be the height clearance envelope of the NSTS Shuttle Orbiter cargo bay.

Additionally the instrument design shall meet the requirements as specified in AD1.

Figure 4.1. shows the EPA overall dimensions and connector locations. The microconical fixture is grappled by the SPDM during the installation or de-installation of an individual EPA. Comer bolts (looking like, but not in fact being, microconical connectors, in the figure) are transportation mounting bolts and are torqued or untorqued by the SPDM during the installation or de-installation of an individual EPA. Figure 4.2. shows the EPA footprint for payload mounting and the corner and connector clearance envelopes associated with it. The stayout clearance envelops are needed for robotic access, blind mate power connection and pigtails for power and data cabling. These envelopes shall not be occupied by payload hardware except harness between the payloads and the EPA electrical connectors. Kinematic instrument elements may enter these areas during normal instrument operation.

Figure 4.1: EPA Dimensions and Locations of Connectors.
(Dimensions are in inches; see Section 3.4 for the metric equivalent).

Figure 4.2: EPA Footprint for Payload Mounting with Corner and Connector Clearance Envelopes.
(Dimensions are in inches; 1750 sq. in.= 1.129 m² ; 7 in.= 178mm; 17 in.= 432mm;
31 in.= 787mm; 41 in.= 1041mm; 35 in. = 889mm).

Transportation

The accommodation of the fully integrated EXPRESS Pallet in the NSTS Shuttle Orbiter cargo bay maximises the allowable payload envelope (in cases where the SPDM is not used for installation or de-installation), as shown in Figure 4.3.

Instrument Fields-of-View

tbd

Mass Requirements

The total mass of each instrument shall not exceed 225 kg (or 100 kg, if mounted on the CPD). Notwithstanding the 225 kg limit (which is the design limit for the single EXPRESS Pallet Adapter), it is in general the intention to accommodate several instruments in a suitable 'grouping' on each EPA. Similarly, a grouping of several instruments may be accommodated on the CPD.

Coordinate System

The instrument coordinate system shall conform to the coordinate system defined for EXPRESS Pallet as specified in AD1.
Local coordinate systems within the instrument shall be cross referenced to this global coordinate system on all relevant drawings throughout the instrument documentation.

Figure 4.3: EPA Envelope within NSTS Shuttle Orbiter Cargo Bay.