Software has been a common thread across all of NASA's major achievements from the Moon landing to the deepest images of our Universe. Today, NASA relies on, releases, and contributes to Open Source Software to advance its scientific missions. From powering our databases monitoring our planet and Sun to running in our missions on other planets, Open Source Software is critical to addressing NASA's biggest challenges on climate change, exploring the solar system, and discovering life beyond Earth. The Ingenuity helicopter, exploring the surface of Mars, is guided by Open Source Software. The amazing images of the earliest galaxies from the James Webb Space Telescope were made possible by open source software developed openly and contributed back to the community. Now, NASA is taking the next steps to further broaden the impact of open source by applying it to the scientific process with its Open Source Science Initiative. NASA is directly supporting open source scientific software through grants and contributions. To further advance scientific reproducibility and reuse, the scientific software underlying future scientific results will be made openly available and unrestricted mission software will be developed openly to allow for community contributions.