Virgin Orbit is ready for its first launch after successfully completing an end-to-end test proving that its carrier aircraft, Cosmic Girl, can ferry rockets to the skies for takeoff. The Virgin Group company, which aims to provide launch services for small satellites, sent Cosmic Girl over California with a LauncherOne rocket strapped under its wing. Virgin Orbit loaded the rocket’s tanks with water in previous tests, but this time, it filled those tanks with liquid nitrogen.

The water in previous tests was over 300 degrees Fahrenheit warmer than the liquid oxygen those tanks would carry for actual launches. Cryogenic liquids like liquid oxygen and nitrogen interact differently with hardware than water and are also handled differently.