2019.P.1.3. Generic Tool for planning ‘Sequence Of Events’ for small satellite missions


Roshini Muralidhar (1)
Vishal Rao (1)
Viraj Bukitagar (1)
M Mahendra Nayak (1)
Maanya Rajan (1)





Sequence of Events, Telemetry, TeleCommand, Generic Tool, Visibility Plan


RSAT is a 3-axis stabilized nanosatellite being designed and developed at PES University, Bangalore with Automatic Identification System (AIS) as a payload, to be placed in sun-synchronous orbit. RSAT is conceived to support the national cause of coastal surveillance and harbor traffic management.

There are three modes of operation – Sun Acquisition, Sun Pointing, and Station
Steering, which are achieved by using the Onboard control system with four reaction wheels and three magnetic torquers using sun sensors and IMU. The satellite payload receives AIS signals transmitted by ships in VHF band, stores onboard and transmits to the ground station in X-band through a high gain phased array antenna during ground station visibility period. The S-band Ground Station is in the visible region four times a day, for approximately 10 mins during each visibility pass. Therefore, it is critical for the Mission Team to have a tool that can be used to plan the sequence of events during each visibility period.

This Paper gives an insight into the design aspects of a generic tool developed using Python to help the Mission Team to plan for the sequence of events for every visible pass, which gives flexibility in creating new plans or editing existing ones. The tool has been built over the command interface, which helps in sending TeleCommand and receiving Telemetry data from the Satellite.

The tool provides two modes -Automated Mode, where each event of the plan is executed sequentially at the scheduled time. It also equips the user with Manual Mode, where the user is allowed to skip to any event, he/she wishes to execute. In times of contingency, the tool loads the appropriate contingency recovery procedure to bring satellite into normal sun pointing mode or safe mode. This action is taken automatically by the interface during the visibility period.

The tool has been made generic so that it can be used across multiple satellite missions. The tool can be easily configured to control the satellite in autonomous mode after initial acquisition and stabilization.


  • Download slides in PDF format here later


  • Download paper in PDF format here (<1 MB)

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