ExPRESS Payload Simulator is a Flight Demonstration of the Boeing developed Software Toolkit for Ethernet Lab-Like Architecture (STELLA) integrated with LabVIEW Payload Software developed by the University of Tennessee at Chattanooga (UTC). STELLA is a toolkit product provided to ISS ExPRESS Rack Payload Developers to significantly aid in the development of the payload software interface to the International Space Station (ISS) Command and Data Handling subsystem.Principal Investigator(s)
Boeing, Huntsville, AL, United States
National Aeronautics and Space Administration (NASA)Sponsoring Organization
National Laboratory (NL)ISS Expedition Duration
March 2010 - September 2010
23/24Previous ISS Missions
The ExPRESS Payload Simulator shows how the Software Toolkit for Ethernet Lab-Like Architecture (STELLA) integrates with standard Ethernet protocols. STELLA provides transparent Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) network communications and other services from a ground computer to and from an on-orbit payload computer. Other services include remote interactive console terminal, File Transfer Protocol (FTP)-like file transfer uplink/downlink, and a simple predefined interface for capturing, generating, and receiving Health and Status data. STELLA also can bypass the ExPRESS Rack Interface Controller (RIC) to downlink payload telemetry via the Payload Ethernet Hub Gateway (PEHG) for a faster downlink data rate. All of these capabilities hide the complex and unique NASA/ISS command, science telemetry, and health and status protocols from the payload software and the payload developer.
In a ground laboratory, Ethernet data are transmitted via standard protocols between two computers: a computer to manage the research and view results (Manager Computer), and a computer to control equipment or gather research data (Controller Computer). For flight operations, Ethernet data transmitted via the same standard protocols are transparently redirected by STELLA through the NASA systems so the on-orbit “Controller Computer” and ground-based “Manager Computer” operate unchanged as if they were still located in the ground laboratory. STELLA consists of ground and flight software. STELLA flight software is compatible with Linux and Windows operating systems, and STELLA ground software is compatible with Windows.
The ExPRESS Payload Simulator demonstrates the functionality of the Software Toolkit for Ethernet Lab-Like Architecture (STELLA). STELLA is available to ExPRESS rack payload developers and allows them to focus on software development.Earth Applications
The STELLA software simplifies payload development for the ISS.
STELLA software operates with NASA developed Telescience Resource Kit (TReK) to interface to commands and telemetry. Command and telemetry downlink resource accommodations are required. STELLA interfaces to the on-orbit payload via the Lean ExPRESS Command and Data Handling (C&DH) data set.Operational Protocols
The ExPRESS Payload Simulator requires the crew to install a DVD in a T61p laptop. The flight software is developed to automatically load to the T61p hard drive, reboot, and automatically start-up initial ExPRESS Payload Simulator software processes (STELLA and payload software developed by the University of Tennessee at Chattanooga (UTC)). No further crew activities are required. Functionality is demonstrated from the ground. Ground operations are conducted from a Boeing Facility in Houston, Texas. The ground computer interfaces to the ISS using the NASA developed Telescience Resources Kit (TReK) and the STELLA ground software services. Five days of on-orbit operations are required to exercise all of the software functionality.