A SpaceX Super Heavy booster prototype has survived its first major test seemingly without issue, potentially opening the door for a static fire test with several Raptor engines as early as this week.
Not long after the latest line of propellant storage implements was transported from SpaceX’s Boca Chica, Texas factory to Starship’s first orbital launch pad, the company officially closed the one highway to the pad and nearby beach. By ~4:30pm CDT (UTC-5), the first major test of an integrated Starship booster was under way and clouds of cryogenic vapors were pouring off of Super Heavy B3’s thrust (aft) dome as the humid air came in contact with steel cooled to around –330°F (–200°C).
While technically known as a cryogenic proof test, Booster 3’s first major challenge looked more like a basic pressure test. Curiously, only small amount of frost – the telltale sign of a ‘cryo proof’ – formed on the outside of Super Heavy’s ~65m (~215 ft) tall propellant tanks in two hours of activity, indicating that SpaceX likely chose a more cautious approach to Booster 3’s first cryo proof.
In short, Booster 3 was likely filled with a few hundred tons of liquid nitrogen relative to the more than 3000 tons its tanks could easily hold and the fraction of that total capacity SpaceX’s suborbital launch site can actually supply. Teams have been working around the clock for months to outfit Starship’s first orbital launch site with enough propellant storage for at least one or two back to back orbital launches – on the order of 10,000 tons (~22M lb) – but the nascent tank farm is far from even partially operational. That’s left SpaceX with its ground testing and suborbital Starship launch facilities, which appear to be able to store around 1200 tons of propellant.
Assuming the suborbital pad’s main liquid oxygen and methane tanks can also both store and distribute liquid nitrogen, which isn’t guaranteed, SpaceX thus has the ability to fill approximately 30-40% of Super Heavy B3’s usable volume. Frost lines aren’t always a guaranteed sign of fill level but if they’re close, SpaceX likely filled Booster 3’s tanks just 5-10% of the way during the rocket’s first cryoproof.
Based on loud, visible venting that occurred throughout the process, it’s likely that Super Heavy’s first cryo proof was more focused on pressure testing with just a small taste of the true thermal shock, loads, and general mechanical stress Starship boosters will have to withstand when loaded with thousands of tons of propellant and generating thousands of tons of thrust with dozens of Raptor engines.
Following July 12th’s test, Super Heavy B3’s next steps could either be one or several additional cryo proofs or a static fire test with an unknown number of Raptor engines installed. The booster completed Monday’s testing with one Raptor installed, while the most engines ever tested simultaneously is three. SpaceX has yet to update backup test windows scheduled from noon to 10pm CDT on July 13th, 14th, and 15th, any of which could be used for additional cryo proof or static fire testing.