SpaceX has set the stage for a record-breaking Starship booster static fire after the rocket completed a complex fueling test and launch rehearsal earlier this week.

On January 25th, a tower the size of a skyscraper activated a pair of giant mechanical arms to disassemble the largest rocket ever built. The arms carefully grabbed Starship using hard points under its flaps and lifted the 50-meter-tall second stage and spacecraft off of Super Heavy Booster 7. Nicknamed Mechazilla, the robot lowered the hundred-ton (~220,000+ lbs) vehicle hundreds of feet onto a waiting stand and eventually let go. On January 26th, SpaceX transported Ship 24 back to its Starbase, Texas factory for finishing touches.

Booster 7 remained installed on Starbase’s donut-shaped orbital launch mount, which uses clamps and umbilicals to hold Starship in place and power, fuel, and pressurize Super Heavy. In theory, the next time Booster 7 leaves that launch mount, it will do so under its own power. But first, SpaceX must ensure that that unprecedented power can be controlled (and survived).

The update that's rolling out to the fleet makes full use of the front and rear steering travel to minimize turning circle. In this case a reduction of 1.6 feet just over the air— Wes (@wmorrill3) April 16, 2024

This, unfortunately, is far from the first iteration of this story. SpaceX has been seemingly close to the milestone at many points over the last year and a half. In September 2021, for example, CEO Elon Musk reported that Super Heavy Booster 4 would attempt the first static fire on Starbase’s orbital launch mount later that month. Eleven months later, Super Heavy Booster 7 gave the OLM its inaugural static fire test – albeit with just one of its 33 engines.

In the months following that static fire, Booster 7 completed another single-engine test, a two-engine test, a seven-engine test, a fourteen-engine test, and a long-duration eleven-engine test. All of that slow and steady testing has been fairly successful and caused no major damage to the rocket or pad. But five months after it began, SpaceX has never ignited more than 14 – 42% – of Super Heavy’s 33 Raptor engines at once. That must change before SpaceX can gain enough confidence in Starship for (and convince the FAA to license) an orbital launch attempt.

During Super Heavy B7’s 14-engine static fire, the booster could have produced up to 3220 tons (7.1 million pounds) of thrust. When it ignites all 33 available engines for the first time, its maximum thrust could leap to 7590 tons (16.7 million pounds), beating the next most powerful rocket in history – the Soviet N1 – by nearly 60%. In other words, SpaceX will be attempting something unprecedented in rocketry. Success is far from guaranteed and the worst possible failure mode could almost entirely destroy Starship’s only finished orbital launch site, explaining SpaceX’s unusual caution.

On January 23rd, Ship 24 and Booster 7 completed Starship’s first full wet dress rehearsal (a fueling and launch rehearsal test) on the first try – an extremely impressive achievement for any rocket, let alone the largest in history. With that combined test out of the way, the only unprecedented test standing between Starship and its first orbital launch attempt is a 33-engine Super Heavy static fire.

To reduce risk, Ship 24 was removed from Booster 7. Back at the factory, SpaceX needs to close a few gaps left in its heat shield, and will likely also conduct careful inspections to ensure that the Starship is ready for flight. Unburdened of Ship 24, Booster 7 may finally be on the cusp of the most challenging ground test in Starship and SpaceX history. SpaceX has scheduled 12-hour road closures that could be used for that purpose as early as January 30th, 31st, and February 1st.

Those road closures could be used for Ship 25 static fire testing instead of or in addition to Booster 7. The Super Heavy is also missing an important hydraulic power unit (HPU) that was removed before the wet dress rehearsal. It’s unclear if static fire testing can be conducted without that HPU (one of two), why it was removed, or how long replacing it will take, adding more uncertainty. Nonetheless, it still appears that SpaceX is no more than a few weeks away from Starship’s first 33-engine static fire attempt.