Oh Snap!

Normally, the FAA does not ground a rocket after a failure, but normally, the launch pad is not chosen in a location where debris rains downs on homes, businesses, beach goers, and protected wetlands. 

Elon Musk, being Elon Musk, thought that worrying about debris raining down on the surrounding neighborhoods was beneath him.

I don't care, I don't have to ……… I'm Elon.

He's Ernestine the telephone operator without Lily Tomlin's comic genius.  (Or much genius at all for that matter)

It turns out that Elon was wrong. and the FAA has grounded his latest booster because he is putting people's lives at risk.

Musk was not that far from an Intelsat 708 disaster, where a Chinese Long March rocket malfunctioned and killed at least 6 people in the surrounding countryside.  (Some estimates put it in the hundreds)

America's Federal Aviation Administration has grounded SpaceX's Starship to conduct a safety investigation after the heavy-lift rocket destroyed a chunk of the launch pad, malfunctioned, and had to be blown up mid-test.

SpaceX was unable to get Starship, said to be the world's most powerful rocket, into orbit during that experiment last week. The rocket started rotating mid-air when it failed to break free of its booster shortly after takeoff on April 20. It fell uncontrollably back to Earth, and was deliberately detonated over Boca Chica, Texas, for safety reasons within minutes of launch.

Before it even got to that point, Starship had damaged the pad and nearby space center infrastructure during its blastoff, and scattered ash and dust over wildlife areas and a nearby town.

A video recording of the flight showed chunks of concrete being kicked up by the launch and smashing the windows of a car, and created a cloud of ash and dirt. The stuff descended onto Port Isabel, where residents reported hearing the roar of Starship's engines and feeling the ground shake.

The FAA is concerned about two things, neither of which have much to do with the primary systems of the rocket.

First, there is the fact that the launch threw debris for miles, because some of the pad preparation was not done, and might have been inadequate in any case, the acoustic engineers are reported to have recommended a water deluge system.  (This happened because Elon wanted to launch on April 20 because, you know 420)

Elon, the 420 joke was not funny the first 20 times that you made it.  It's immature and stupid.

The second issue is that the flight termination (self-destruct) system did not work as intended.  It was more than 50 seconds between when the destruct command was issued and when the rocket broke up.  (See a quick take from Scott Manley here.)

50 seconds is a VERY long time in this sort of scenario, and I imagine that the FAA will be looking at a more robust termination system. 

This would have the effect of complicating recovery of the first stage, and given Musk's commitment to reusable boosters, this could create a relatively complex technical issue.