satellite/docs/problem_statement.md

Problem Statement

You are a member of the flight software team at Umbra and are responsible for writing code that manages the satellite’s propulsion system.

Firing the propulsion system involves waiting for a certain period of time before ignition.

The following is an example usage of this system:

• At absolute time t = 0, send a command to the computer to fire the propulsion in 15 seconds
• At absolute time t = 2, send a command to the computer to fire the propulsion in 30 seconds
• At absolute time t = 32, the computer begins firing the propulsion

The flight computer should accept a command with a relative time of when to fire the propulsion - once that time has elapsed, the program should print out “firing now!”. If another command is received before the propulsion is fired then the most recently received relative time should overwrite any existing commands.

More formally, if a command A is waiting to fire and another command B is received before A has fired, then B should replace A as the pending command and A should never fire.

If a time of -1 is given, any outstanding commands to fire the propulsion are cancelled.

Note that the flight computer should be able to fire the thruster multiple times in a single execution of the program.

You may use exactly one of the following interfaces for getting data into and out of your program:

• Standard input/standard output
• TCP

You can use whichever is more convenient - we note that some languages make asynchronous IO with standard input/standard output cumbersome and have thus included TCP.

If you do choose to use TCP, please have your server listen on port 8124.

A sample TCP client, propulsion_tcp_client.py, is provided that plumbs standard input to TCP writes and likewise plumbs TCP reads to standard output.

Commands should be delineated by newlines.

A sample complete execution of your program using standard input and output is shown below

./your_program
15
30
firing now!

Submitting your code

You may complete this assignment in any programming language that you wish. We're most familiar with Rust and Python at Umbra, but we always enjoy learning new languages and seeing solutions with different tools!

Your final submission for this exercise should be a zip file including:

• The source code of your program.
• A brief README with a description of your approach and instructions on how to build and run the program.
• Any libraries or frameworks needed to run your program, or instructions for installing them.

Please ensure that your code is clear and legible before submitting.

While we don't expect you to write production-quality code for this exercise, readability goes a long way in helping us review your submission.