Structural interfaces

General Interface Concept

This section describes the interface between the payload instruments and the carrier. The interfaces are with the NASA EXPRESS Pallet (in particular the EXPRESS Pallet Adapter) and with additional Payload Support Equipment (PSE) provided by ESA and mounted on the EXPRESS Pallet Adapter.

It must be stressed that the EXPRESS pallet is still in a very preliminary phase of design and development and significant changes in the information presented below could occur later on. The EXPRESS Pallet Data reported here relates to the design following the Project Requirements Review (PRR) in December 1996. Similarly, the details of the ESA provided PSE reflect design concepts which are not fixed and which can be expected to evolve and develop in parallel with the scientific instrument selection and development.

The interfaces will be described in an Interface Requirement Document (IRD), the first issue of which will have to be established in parallel to, or slightly after, the selection of instruments. This document will be reviewed and approved by ESA and the Principal Investigator (Pl) before being made applicable to instruments. Then the interface will be controlled by Interface Control Documents (ICD) based on information provided by the instruments developers.

Instruments will be grouped on EPAs according to their requirements. Additionally, PSE will be accommodated to ensure efficient and coordinated use of interfaces and resources. Details will depend upon the combination of instruments selected.

Mechanical Interfaces

Instruments Bolted Directly to an EPA

Payloads bolted to the EPA shall respect the EPA mounting hole pattem (which is tbd).

Instruments Bolted to a Support/Mounting Plate

This option is intended for smaller payloads. A support/mounting plate is introduced as a specific mechanical interface between the instrument and the EPA. This mechanical interface must be compatible with the EPA mounting hole pattern (which is tbd). The design of the plate will respect the mechanical fittings required by the instruments and hence will be dependent on instrument groupings, once these have been defined.

The support/mounting plate will be specified by the mission integrator.

Instruments mounted on a Coarse Pointing Device (CPD)

The two axis Coarse Pointing Device (CPD) will be provided by ESA for:

• solar pointing instruments;
  
• space biology experiments requiring exposure to the sun.