Updated: June 8, 2021

This document describes different configurations of artifacts within Major Tom and of Gateway software components interfaced to it.  The intent is to illustrate a variety of the different architectural options that are available, and to highlight which ones are most appropriate for different satellite and ground station alternatives.

Definition of Terms

The following terms are used in this document and have very specific meanings within Major Tom’s architecture.

• Team -- a group of people working together. Individual people are identified by unique email addresses, and a person can be a member of only one Team. People who are members of a Team are assigned to a role within that team which determines what operations they’re authorized to perform and what data they’re authorized to see.
• Mission -- a group of related satellites, ground stations, and software components. Missions are owned by Teams, and people’s role within the Team may be as members of only a given Mission, in which case all of their authorizations are confined to that Mission. There can be any number of Missions for a Team.
• System -- a generic concept in Major Tom: anything that can generate telemetry and/or receive commands is considered a “System.”
• Satellite (Sat) (System) -- the primary type of System with which Major Tom is concerned. All Satellites are within exactly one mission, and there can be any number of Satellites in a Mission.
• Ground Station (GS) (System) -- an individual antenna/radio system with a specific physical location. When a Mission contains at least one Satellite with known orbital elements and at least one Ground Station with known coordinates, Major Tom predicts and notifies of passes of the Satellite(s) over the Ground Station(s).
• Ground Station Network (GSN) (System) -- A coordinated set of Ground Stations maintained by a third party, some of which are authorized for use in communicating with the Mission’s Satellite(s).
• dedicated Ground Station -- a Ground Station that is not part of a Ground Station Network.
• Gateway -- a software component, typically supplied by Major Tom’s users, that stands between Major Tom and an external system, and is responsible for mapping between the external system’s encodings or API and Major Tom’s device-independent command and telemetry.

This document is organized into the following Sections:

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Section 1: Single Satellite Configurations

1 Sat, 1 GS Configuration (2 Gateways)

The most straight-forward case is a simple Mission that contains only one Satellite.  There remain a number of architectural and configuration options even in this case.  The set that most directly matches Major Tom’s conceptual model employs a single dedicated Ground Station, and two different pieces of Gateway software, one that is responsible for the Ground Station and one for the Satellite.

In this configuration, the lower Gateway is responsible for reporting telemetry from, and sending commands to, only the dedicated Ground Station.  The data to and from the Satellite passes through the Ground Station, but is the responsibility of the upper Gateway in the illustration.