The Reaction Control System (RCS) of the Starship SN20, which is a series of thrusters meant to steer and control the vehicle in orbit, was first put to the test by SpaceX engineers. Photographers from Boca Chica captured footage of the vehicle's RCS thruster testing, which may be seen here. The back side of the Starship SN20 is clad in black heat tiles designed to endure extremely high temperatures and prevent burns during atmospheric reentry. SN20 lost a couple heat tiles during RCS testing. – Elon Musk, the founder of SpaceX, tweeted, "Headed tank vent knocked off a few tiles."

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“How are the titles going to stay on during ascent?” wondered Everyday Astronaut, a YouTuber who specialises in rocket science. “I'm still a little surprised nature didn't have the foresight to make the tiles look more like scales,” he wrote. “On ascent, there would be less room for aerodynamic forces to rip them off, and the steel would be able to expand and contract,” Everyday Astronaut proposed. “If tiles aren't very thin, hot plasma ‘waterfalls' off edges of tiles, creating hotspots,” Musk responded. “That said, I'm not entirely convinced that this couldn't be done with several overlapping scales of metal sheet with an insulator between scale armour & primary structure.”

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Later that night, SpaceX engineers put the Starship SN20 prototype through a cryogenic proof test. Engineers check the stainless-steel spacecraft's structural integrity during the test by pressurising SN20's tanks with sub-chilled liquid nitrogen and simulating the Raptor engines' forces. Six Raptors will be installed on the Starship. Although the company has only flown prototypes with three Raptors, Starship SN20 will be the first spacecraft to use vaccuum-optimized Raptors (R-Vac). For atmospheric flight, these R-Vac engines have a significantly bigger nozzle than Raptors at sea level.

We can expect to see Starship testing activity pick up at Starbase in the weeks ahead. SpaceX is still pending regulatory approval from U.S. Federal Aviation Administration (FAA) to launch Starship. The FAA is conducting an environmental review of the SpaceX site at Boca Chica to ensure the company can run safe operations at the village that is situated close to a public beach and a wildlife refuge. SpaceX also needs to conduct pre-flight testing on the gigantic Super Heavy Booster that will propel Starship SN20 to orbit. If all goes according to plan, we could see a fully-stacked launch vehicle soar to orbit before this year ends.