There are a variety of materials that could have been sticking to the “lens,” but metal is a good guess.

As time went on, we could see some cracks that we could see through the fogging “lens.” This was likely not the lens itself but a protective covering over the lens, perhaps made of glass, crystal, or plastic. The fogging of this cover would be something like smoke, some sort of material coming off the disintegrating fin and condensing onto the cover. As the cover cracked, we could see through some of the holes made by the cracks, and eventually the cover seems to have fallen away enough for us to make out a much clearer picture right around the time of landing.
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Jeff Wright wrote: “Not everything has to be re-used…in addition to the hot staging ring, perhaps a length of RCC could cover the hinge area–with the tips of the fins themselves having tiny RCC winglets used in conjunction with thrusters.”

For fast turnaround time, Starship will need as little refurbishment as possible. During development, though, it is acceptable to do things differently in order to learn enough to make it to the next step. Throwing away the heavy hot staging ring for now helps them to make this kind of progress. They may even learn more about how to lighten up this ring for operational flights.

Because this booster, and a few others, were designed and built before they added a lot of weight to the staging ring, losing the ring allows them to have enough propellants in their already-sized-and-built header tank to succeed with the landing. Otherwise, they may run out of propellants before demonstrating a successful landing. Later boosters may come with a slightly larger header tank to account for the increased mass of the staging ring section.
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Steve Richter asked: “Is the US Navy, the federal government even trying to help SpaceX as it conducts these tests? Put some ships, helicopters in the landing area to take photos of Starship as it lands. That would help access damage to all parts of the heatshield, no? Does the US have any remote federal land that can be used as a landing zone?”

Part of the timing of the very first orbital test flight, two years ago, was waiting for the availability of a NASA airplane that is equipped to observe a reentering body so that NASA and SpaceX can assess the craft as it reenters. SpaceX undoubtedly hired this airplane for each of its orbital test flights. This airplane could be flying a hundred miles away from the targeted landing point, giving it a great deal of safety from the chance of collision with the spacecraft, if it should stray from the path, or with any debris, should the spacecraft break apart during reentry. As Richard M noted: “ship landing was several km off due to flap damage”

Being several kilometers off from its landing point is a good reason to not have a landing point on land. There is too much danger that the craft may come down in a populated place or on remote buildings or hardware. If it had once again broken up during reentry, the likelihood increases of some large part of the vehicle landing on something or someone we don’t want struck. It is better to first prove the concept that something as large as Starship can not only survive reentry but can be controlled during and after reentry. And while on orbit, for that matter.

As Starship gets better at reaching its target point, it will become safer to put manned vessels closer to that target, similar to a Dragon splashdown. SpaceX already believes that Super Heavy may be safe enough to bring it back to the launch site, similar to Falcon launches.
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Robert Zimmerman wrote: “Such a landing will immediately raise hackles at the FAA, because the booster will be returning to Boca Chica and will thus pose a safety risk.”

The experience with the Falcons may demonstrate that safety is not such a great risk, although Richard M could be right that “maybe, this could be the opportunity for more FAA kibitzing.”

The problem that I see is the disposal of the hot staging ring, for the next few flights. That must be done at a time that assures it will not reach the ground in an unsafe location.

Another challenge for catching Super Heavy is moving and stopping (controlling) those immensely massive “chopsticks.” SpaceX wants them to close quickly, but they also have to stop with a timing and precision that could be difficult. Not only do they have to be pointed correctly so that they catch the vehicle without striking it, they have to stop their swing in a way that does not induce a vibration that may cause the arm(s) to strike it or to miss either of the nubs that they use as mount points to support the vehicle. When it comes to vibration, everything is a spring.

If you are impressed with Starship surviving despite some burn through, catching a falling rocket should take your breath away and rock your world!

During the early stages of reentry, there was view from a camera on one of the trailing flaps looking forward. That view went away about halfway into reentry. It might have also picked up burnthrough of whatever forward flap it was looking at.

Looks like they are using landing burn timing similar to that of Falcon 9, starting somewhere about 2 km altitude. The inner ring of engines and the core 3 all relight. One didn’t. The outer ring goes out after the initial pulse and the rest of landing is flown on the inner 3 engines. Gimballing of that set was obvious as they maneuvered for landing. Didn’t know the video was from a buoy. Thought they had a boat out there. Cheers –

Adrian Dittmann @AdrianDittmann·
The landing burn and soft splashdown of Super Heavy in the Gulf of Mexico demonstrated that a mechazilla catch is not only possible but may occur as early as IFT5.

Elon Musk @elonmusk
Next flight is the goal

https://x.com/elonmusk/status/1799630698137170387

Stay tuned.

Either way, this is the kind of risk that SpaceX still embraces in its development programs. They move fast and they are willing to break things. NASA could never get away with this in a million years.

Richard M: If they try a chopstick landing, then I think my prediction for a late July launch might be a bit optimistic. Such a landing will immediately raise hackles at the FAA, because the booster will be returning to Boca Chica and will thus pose a safety risk.

Well, Elon is now saying that they are planning to attempt a “chopstick” catch landing on IFT-5! Apparently they must have really liked what they saw in their footage and data.

(In this regard, Elon says, in response to a Scott Manley tweet this evening: “Booster landing was on target, ship landing was several km off due to flap damage, but both were soft landings.” Which, as Manley says, is impressive, in that the software clearly was able to adapt to failures of the hardware (i.e., that engine that failed on descent) and still nail the landing. https://x.com/elonmusk/status/1799510160592834764 )

Elon hinted at this on Twitter yesterday; then confirmed it in his interview with Eliana Sheriff (aka “Ellie in Space”) yesterday, and today, he underlined it in a post on Twitter: “Starship booster makes soft landing in water, next landing will be caught by the tower arms.”

So apparently they are going for it! I assume that they will use a not dissimilar protocol as they do for Falcon 9 landings on their land-based LZ’s: Initially target the landing target for a point just offshore, and only have the onboard computer switch it to the Starbase pad if all necessary conditions they assign are met, in order to minimize their risks.

Richard M: That footage is awesome and very informative. First the bad news: That SpaceX cuts off the drone footage just before landing is very revealing. Just before landing that footage shows that Superheavy is struggling to get vertical. I suspect it wasn’t at touchdown.

Now the good news: The booster touched down exactly where it was supposed to. Like the early Falcon 9 failed landings, SpaceX has solved landing precision right off the bat. It needs only figure out how to get the booster to land. And in this case, even if my bad news is correct that bad news is not very bad. I bet the next landing will be perfect, setting the stage for a tower landing using chopsticks.

Half an hour ago, for what it is worth, SpaceX released footage of SuperHeavy’s landing via a camera they had on a nearby buoy:

https://x.com/SpaceX/status/1799458854067118450

Jaw dropping!

For the most part, the thermal protection tiles seem to have worked well enough. They had glued some tiles to the body in areas where the tiles had been coming off regularly. The desired method for fastening the tiles is not glue but a fastener that allows for quick removal and replacement for any cases where repair is necessary. Glue does not fit that condition and was a reason why the Space Shuttle was so costly and time consuming to turn around for its next launch. SpaceX is looking for ways to attach to these problem areas without glue for ease of maintenance.

After SpaceX can show that they have the ability to restart Raptor engines on orbit and to change the craft’s attitude, demonstrating that they can reenter the atmosphere whenever — and therefore wherever — they want, they will be able to launch into orbits that are more useful for Starlink, and their test flights can become operational Starlink flights. Until then, they are stuck with orbits that are not good for Starlink satellites but are good for safety concerns.

I agree with several commenters. Once I saw that the fin was being destroyed from the inside to the outside, I was convinced that the rest of the hinge was being destroyed. I think the important question for SpaceX to ask and answer is: why did the burn-through and damage occur at this part of the hinge and seam but not at other parts?

We were shown this one camera, but there could have been others, or there could have been thermistors or thermocouples in other locations that could give SpaceX engineers important information as to whether similar problems occurred at similar locations on the other fins.

The decision to not perform other tests, such as an engine relight, is curious. In previous flight tests, SpaceX has tried to maximize the information it can gain from the flight. In this case, they chose to postpone a test that is important to advancing the project.

He noted that upcoming versions of the Ship portion of Starship, would have the fins placed further leeward to help alleviate the intrusion of plasma into the joins.

The robust nature of the design, materials, hardware and software was impressive on this flight. Even seriously damaged the Ship managed the intended ocean landing. Amazing!!!

The melt seemed to propagate from the bottom of the fins upward. Usually melt in metal wings flying nose forward starts at the WLE and shoulder.

Perhaps ablative end caps could be slid on from either side. Portree’s Beyond Apollo articles for WIRED once had a stop-gap plan for shuttle orbiter ablatives.

The shuttle orbiter itself had a flap of sorts under the SSME’s, right?

Anything of use there?

After re-entry, the fins actuate and shatter the RCC hinge cover, leaving a pristine joint.

Despite the advances in CGI and special effects that have been achieved since, the best looking ships in the “Star Trek” universe came from the Original Series. Federation, Romulan, Klingon, and even the Tholians!

Regarding the Enterprise specifically, however, the best looking was the Refitted/Enterprise A.

Thank you!

Andi: Fixed. Thanks.

M Puckett: It does. I have included both the March and this launch, because both reached their planned orbit.

It should, IMO.

geoffc: I have corrected the flight number error. Thanks.

Watching that flap melt lose tiles and then continue to actuate till the end was astonishing! Reusable, ok, maybe some work to do. Survivable? Heck Ya!

The hot stage was great to watch, ejecting the ring was liek something out of Star Wars (Coloured like a Star Destroyer it seemed to me). The boostback and landing was amazing. Seemed like they waited to long for landing burn but it nailed it. The hover, then the tip over. Wild.

Then watching that flap melt, every time thinking, this is the end, but we got further this time, and then the video would come back to finally that flip! Amazing.

Cannot wait for flight 5. Wow.

PS: Starship marshmellow torches was a great and silly touch.

I hope they publish some good feedback.