SpaceX Starship Nails Risky Hot Staging Maneuver Before Exploding

• SpaceX’s Starship mega-rocket achieved a major milestone during Saturday’s launch. 
• The two stages of the rocket successfully separated, though the booster blew up seconds later.
• SpaceX’s main goal for Saturday’s launch was to achieve separation and prove “hot staging” works.

SpaceX launched its Starship mega-rocket toward space for the second time, ever, on Saturday.

Though Starship blew up just seconds before completing its launch sequence, the flight achieved a major milestone for SpaceX. The rocket proved a risky maneuver and solved the problem that sent Starship up in flames during its last launch in April.

SpaceX’s mega-rocket is a two-stage system, consisting of a first-stage Super Heavy booster and a second stage, Starship.

In order for Starship to reach space, it needs to ride atop Super Heavy to get the full power of the booster’s 33 Raptor engines, then Starship must separate from the booster and fire its own engines to complete the trip.

In other words, separation is absolutely critical to reaching space and realizing CEO Elon Musk’s dreams of colonizing Mars. SpaceX achieved this breakthrough engineering feat with Starship for the first time during Saturday’s launch by using a rare, creative strategy called “hot staging.”

You can watch the historic moment Starship separates from Super Heavy at 41:43 in SpaceX’s livestream below:

How the rare and risky ‘hot staging’ move works

On most traditional rocket flights, when it’s time for separation, the main engines on the booster stop, the stages separate, and then the second stage lights its engines to climb higher.

That didn’t go well for Starship-Super Heavy’s maiden flight in April, though. Instead of separating, the whole rocket tumbled out of control and exploded.

So SpaceX turned to hot staging — where the upper stage (Starship) fires its engines while still connected to the booster.

The benefit is that Starship gets an extra boost, increasing its payload capacity by 10%. The risk is that the engine fire from Starship could damage the booster and cause the rocket to blow itself up. That’s why SpaceX also added new vents and heavy-duty heat shields to the booster.

“In hot-staging, we throttle down and shut down most of the booster engines. Then we light the Starship engines. It’s one of the most efficient ways to do stage separation,” Musk said during a program update in October, per Aviation Week.

“I’d say that’s the riskiest part of the flight,” Musk added.

Successful hot staging and separation was the main goal for Saturday’s launch, and Starship succeeded.

At the crucial moment, the stages separately beautifully, with Super Heavy tumbling downward and Starship climbing away from it.

Within a few seconds, the booster exploded. That wasn’t a huge surprise for this flight, but it’s another wrinkle SpaceX will have to iron out since it wants to land its Super Heavy boosters in one piece for reuse.

Starship, however, kept trucking toward space — until something happened.

SpaceX cut its livestream shortly after SpaceX principal integration engineer John Insprucker said, “We have lost the data from the second stage,” adding that “what we do believe right now is that the automated flight termination system on the second stage appears to have triggered very late in the burn.”

It’s not yet clear what triggered Starship’s self-destruct.

“With a test like this, success comes from what we learn, and today’s test will help us improve Starship’s reliability as SpaceX seeks to make life multiplanetary,” SpaceX said in a statement released on its website Saturday.