The short summary seems to be it's an attempt to verify every fix for every problem from Flight Test 12. The current schedule is still this Thursday, July 16th, NET 6:45 PM EDT 5:45PM local (CDT) or (2245 UTC) The launch will be from the new Pad 2 at Starbase Boca Chica.
The most notable change is the inclusion of real, functioning Starlink satellites inside Starship’s cargo bay. SpaceX previously tested the ship’s payload deployment mechanism using simulators mimicking the mass and dimensions of the company’s next-generation Starlink Version 3 broadband satellites.
Like FT-12, this will partly be a test of the "Pez dispenser" approach to carrying the V3 satellites into orbit. The majority of the satellites deployed will be Size and Weight mock-ups simply to provide weight and mass properties of the Starlink V3 satellites to test the Pez dispenser. The first couple of satellites will have more electronics than the mock-up V3 satellites will have, but the source article on Ars Technica doesn't give exact numbers for mock-ups or real V3 satellites. SpaceX's website for the mission says there are six satellites of the 20 modified for tests.
The satellites will not be part of SpaceX’s operational network, but engineers will attempt to briefly establish laser communication links between the Starlink V3s and other spacecraft flying in low-Earth orbit. If successful, these links will validate Starlink V3’s interoperability with SpaceX’s previous generation of Starlink satellites.
The overall mission plan is suborbital, just like FT-12 and all the previous Starship flights, and all of the satellites will reenter and burn up in the atmosphere, so there will be a few tests involving the functioning satellites but those are going to be lost.
Six of the satellites have been modified with a suite of cameras to scan Starship’s heat shield and transmit imagery down to operators to continue testing methods of analyzing Starship’s heat shield readiness for return to launch site on future missions. Several tiles on Starship have been painted white to simulate missing tiles and serve as imaging targets in the test.
FT-12 was intended to do a restart test of the Ship's Raptor 3 engines but was unable to attempt that. FT-13 intends to complete restart, which is considered the last major milestone that needs to be verified before going for an orbital insertion.
Without a doubt, though, the most important part of the mission is how well the heat shield functions.
“What’s the single biggest remaining problem for Starship? It’s having the heat shield be reusable,” Musk said in February on the Dwarkesh Podcast. “No one has ever made a reusable orbital heat shield. The heat shield’s got to make it through the ascent phase without shucking a bunch of tiles, and then it’s got to come back in and also not lose a bunch of tiles or overheat the main airframe.” [EDIT - change that first use of "No one has ever made a reusable orbital heat shield" to say "rapidly reusable heat shield ..." Musk says that in a different video I've seen - SiG]
“We have brought the ship back and had it do a soft landing in the ocean. We’ve done it a few times, but it lost a lot of tiles, and it … would not have been reusable without a lot of work,” Musk said. “If you want to be able to land it, refill propellant, and fly again, you can’t do this laborious inspection of 40,000 tiles type of thing.”
On this flight, SpaceX will test out modified tiles and attachment mechanisms to gather flight data on different heat shield options. The shield will also have “load sensing tiles” to take measurements as the vehicle experiences higher dynamic pressure during ascent than on previous flights. This higher dynamic pressure will put “added stress on the tile attachments in exchange for increased payload to orbit capability,” SpaceX said.
Artist's conception of the Starship Pez dispenser deploying a Starlink satellite. Image credi: SpaceX
There's a very good video from SpaceX that talks about all the things that went wrong on Flight 12 and what they've fixed and what they're going to do on Flight 13.
ReplyDeletehttps://www.youtube.com/watch?v=-a0ecQMq-rM
Excellent production. Makes me think SpaceX could go into documentary filming.
And, of course, I like that they openly talk about what went wrong.
There's a neat section where the head of the project talks about how they use very very sophisticated methods of determining how hot the exhaust is as it blasts through the flame trench while the water dampening is working. Very sophisticated system... Oh so very sophisticated....
I watched that over lunch today. Excellent video.
DeleteThe whole "We're hotter than Sharpie but not as hot as Copper melting" thingy was funny. And just common sense. It's like using melting cones in your ceramic kiln to turn off the heat (there are whole bunches of 'cones' set at various temperatures that melt. Held in a little holder thingy with the arm of the temperature shut-off switch on the top, cone melts, switch arm falls, switch turns off. You can also line up a series of cones where you can see them through a vision port and do it manually.)
DeleteSounds like they want to use laser cross-linking on their satellite constellation.
ReplyDeleteAbsolutely.
DeleteSpaceX has been using it for a while. They have provided communication, sometimes covert, in countries that either don't allow Starlink or that don't have much internet infrastructure.
Delete“If you want to be able to land it, refill propellant, and fly again, you can’t do this laborious inspection of 40,000 tiles type of thing.”.
ReplyDeleteI’m sure SpaceX’s tile design engineers have what they think are the optimum number of tiles to meet contiguous structural requirements, but given the obvious extreme atmospheric re-entry forces and the overriding need for rapid reusability, it seems a shame that larger tiles can’t be used on the more simpler parts of ship’s geometry such as the cylindrical body rather than the more demanding curves of the nose.
Perhaps it’s a compromise relating to risk of greater underlying structural damage following the loss of a larger tiles than the current smaller ones.
I’m sure SpaceX’s engineers are all over this and if anyone can solve this challenging design environment they’ll be the ones to do it.
I’m looking forward to watching Flight 13 on Thursday and hopefully it’ll be the validation they need for flight 14 to go orbital. A full load of Starlink V3 deployments should certainly start to help offset some of the R&D costs burning through SpaceX’s cash flow faster than re-entry plasma. Go SpaceX!
There have been a couple of videos I've watched lately that had interviews with Elon. He talks about the tiles being composed of fibers, like laid-up fiberglass but not plain old glass fibers, and they're experimenting with different materials for the other fibers. I have this problem of not bookmarking videos like that when I have them open in front of me so they become essentially impossible to find in a few hours.
DeleteSomething they've got going for them is the radius of the body is pretty large so they don't need to be strongly curved or really small to be form fitting. I'm guessing that almost all of the tiles are shaped like that part of the body, and things like the leading edges of the "flings" (flaps/wings) are done separately.
"you can’t do this laborious inspection of 40,000 tiles type of thing.”
DeleteSpaceX has the expertise to create a drone/AI system to inspect all of the tiles on a Starship in the matter of a short period of time; maybe even just 10s of minutes. I can visualize a swarm of drones around a just landed Starship doing that. This solution has probably already been presented at SpaceX.