Why SpaceX Has to Catch Starship So Differently From the Booster...

Why SpaceX Has to Catch Starship So Differently From the Booster...
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#techfans #spacex #starship
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Why SpaceX Has to Catch Starship So Differently From the Booster...
“Unless we discover problems after mission data review, SpaceX will attempt to catch the ship with the tower on [the] next flight.”
Not long after Starship's upper stage touched down in the ocean, Elon Musk surprised everyone by announcing that SpaceX will attempt its first-ever Starship catch on Flight 14. But is the vehicle actually ready for that? What makes catching the upper stage so much more difficult than catching the booster that SpaceX needs 13 test flights before even considering it?
Well, let's answer all of those questions!

Catching a giant ship coming back from space is hard, but hitting that subscribe button is surprisingly easy, and it could also let you know when a cool thing in the spaceflight world happens, so don't be shy about hitting it. Now let’s get back to catching Starship.
Why SpaceX Has to Catch Starship So Differently From the Booster...

Ship catch vs Booster catch:
Okay, to begin, how hard would it be to catch the Starship upper stage?
I mean, SpaceX has already caught the Super Heavy booster multiple times. So catching a shorter upper stage should not be that difficult... right?
Well... not exactly.
In fact, even though Starship is shorter than the booster, most engineers would probably tell you it's actually the harder vehicle to catch.
And there are a few reasons why.
First, let's talk about the catch points themselves.
The booster was basically built around this idea. It has large, extremely robust hardpoints near the grid fin section that are specifically designed to take the enormous loads from the tower's chopsticks. On newer boosters, the grid fins themselves even double as part of the catch structure.
Starship is a completely different story.
Instead, it uses dedicated catch pins. Early versions carried test pins mainly to collect data, but an operational catch means those pins have to support the weight of the entire vehicle while it's being grabbed by the tower. And unlike the booster, those pins also have to survive one small inconvenience...
...coming back from orbit.
Why SpaceX Has to Catch Starship So Differently From the Booster...

That's because Starship doesn't just fall from a few hundred kilometers up. It slams into Earth's atmosphere at nearly 7.8 kilometers per second. The booster, by comparison, is only traveling around a couple of kilometers per second before it begins its return. It still moves incredibly fast, but it's nowhere near orbital velocity.
That difference is absolutely massive.
Even after atmospheric drag does most of the braking, Starship has to get rid of far more energy before it can even think about lining up with the tower. Depending on the exact masses, you're talking about roughly 10 to 20 times more kinetic energy than the booster has to deal with during recovery.
That's like comparing dropping your phone onto the couch... versus throwing it out of a moving car. They're both technically impacts, but one of them is going to ruin your day.
And that leads to another challenge.
The booster's catch happens after a relatively short trip. Starship's catch comes after an orbital mission, a deorbit burn, one of the hottest atmospheric reentries ever attempted by a reusable spacecraft, the belly-flop maneuver, the landing flip, and finally a powered descent toward the tower.
That's a lot of opportunities for something to go wrong.
If the heat shield loses too many tiles, the wrong parts of the vehicle could overheat. If the attitude control is even slightly off during reentry, the landing solution changes. If the timing is off by just a little, the tower isn't grabbing anything except empty air.