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SpaceX wiggles Starhopper’s Raptor engine, tests parts ahead of hover test debut
On the evening of July 12th, SpaceX technicians put Starhopper’s freshly-installed Raptor – serial number 06 (SN06) – through a simple but decidedly entertaining test, effectively wiggling the engine in circles.
Designed to verify that Raptor’s thrust vectoring capabilities are in order and ensure that Starhopper and the engine are properly communicating, the wiggle test is a small but critical part of pre-flight acceptance and a good indicator that the low-fidelity Starship prototype is nearing its first hover test(s). Roughly 48 hours after a successful series of wiggles, Starhopper and Raptor proceeded into the next stage of pre-flight acceptance, likely the final more step before a tethered static fire.
Routine for all Falcon rockets, SpaceX’s exceptionally rigorous practice of static firing all hardware at least once (and often several times) before launch has unsurprisingly held firm as the company proceeds towards integrated Starhopper and Starship flight tests. Despite the fact that Raptor SN06 completed a static fire as recently July 10th, SpaceX will very likely put Starhopper and its newly-installed Raptor through yet another pre-flight static fire, perhaps its fourth or fifth test this month.
Although it would undoubtedly be easier, cheaper, and faster to skip that post-delivery static fire, it will simultaneously lower the risk of Raptor failing mid-flight and verify that Starhopper itself is healthy and ready for untethered hovering. Although SpaceX could likely live without Starhopper in the event that it’s lost during flight-testing, any failure capable of destroying the vehicle itself is at least as capable of severely damaging or completely destroying the spartan but still expansive test and launch facilities the company built over the course of several months.
Would you like some testing with your testing?
Follow July 12th’s nighttime Raptor wiggle test, July 13th was mainly quiet and filled with inspections of Starhopper, Raptor, and other various work. The day after, however, SpaceX proceeded through several hours of propellant loading, ending with what looked like less energetic versions of the Raptor preburner ignition tests Starhopper previously performed with Raptor SN02.
In a staged-combustion engine like Raptor, getting from the supercool liquid oxygen and methane propellant to 200+ tons of thrust is quite literally staged, meaning that the ignition doesn’t happen all at once. Rather, the preburners – essentially their own, unique combustion chambers – ignite an oxygen- or methane-rich mixture, the burning of which produces the gas and pressure that powers the turbines that bring fuel into the main combustion chamber. That fuel then ignites, producing thrust as they exit the engine’s bell-shaped nozzle.
Although the fireworks are so subtle that they are easily missed, the conditions inside the preburner – hidden away from view – are actually far more intense than the iconic blue, purple, and pink flame that exists Raptor’s nozzle. This is because the preburners have to nurture the conditions necessary for the pumps they power to fuel the main combustion chamber. Much like hot water will cool while traveling through pipes, the superheated gaseous propellant that Raptor ignites to produce thrust will also cool (and thus lose pressure) as it travels from Raptor’s preburner to the main combustion chamber.
Thus, if the head pressure produced in the preburners is too low, Raptor’s thrust will be (roughly speaking) proportionally limited at best. At worst, low pressure in the preburners can completely prevent Raptor from starting and running stably and can even trigger a “hard start” or shutdown that could damage or destroy the engine. As such, to preburners fundamentally have to operate at higher chamber pressures (and thus higher temperatures) than the main combustion chamber (the big firey bit at the end). According to Elon Musk, Raptor’s oxygen preburner has the worst of it, operating at pressures as high or higher than 800 bar (11,600 psi, 80 megapascals).
Coincidentally, this is roughly equivalent to the pressure at the bottom of the Pacific Ocean.
In short, preburner testing is no less critical than full-on static fire testing with an engine like Raptor. July 14th’s test was also made doubly efficient due to the fact that preburner testing requires liquid propellant, which effectively makes the whole test a wet dress rehearsal (WDR) even before any engine ignition or partial ignition is involved. Per SpaceX moving from propellant loading to preburner/turbine testing, Starhopper is almost certainly healthy and operating as expected, an excellent sign that the ungainly vessel may be ready for a static fire of Raptor as early as 2pm CT, July 15th.
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SpaceX set to launch astronauts and a classified Falcon Heavy mission on the same day
SpaceX plans three launches Thursday, including Crew-13 astronauts and Falcon Heavy’s first classified NRO mission.
SpaceX is lining up one of the busiest single days in its history, and the company offered a preview on Wednesday morning with a simple post on X: “Sunrise at pad 40.” The video and photos show Falcon 9 standing at Space Launch Complex 40 at Cape Canaveral, roughly a day before it is scheduled to carry four astronauts to the International Space Station.
That launch is only the first of three SpaceX missions planned for Thursday, October 1, across both coasts.
Sunrise at pad 40 pic.twitter.com/J7Qme4VvIX
— SpaceX (@SpaceX) September 30, 2026
Crew-13 is targeting liftoff at 11:10 a.m. ET, with a backup opportunity Friday at 10:47 a.m. ET. NASA astronaut Jessica Watkins will command the mission, with NASA’s Luke Delaney as pilot and Canadian Space Agency astronaut Joshua Kutryk and Roscosmos cosmonaut Sergey Teteryatnikov serving as mission specialists. According to NASA, Dragon is set to dock with the forward port of the station’s Harmony module around 8 p.m. ET, less than nine hours after launch. Watkins is the only member of the crew who has flown before, and Kutryk will become the first Canadian to reach orbit through NASA’s Commercial Crew Program.
The Falcon 9 booster is flying for the third time after supporting Crew-12 and a Starlink mission, and it will attempt a landing at Landing Zone 40 beside the pad. That site made its debut in February when the Crew-12 booster touched down there, as Teslarati reported at the time. Crew-13 will relieve the Crew-12 astronauts, who have been aboard the station since the middle of February.
On the West Coast, another Falcon 9 is scheduled to lift off from Vandenberg Space Force Base in a window running from 2:18 to 3:16 p.m. ET, a flight NASASpaceflight lists as a Transporter rideshare mission.
The day is set to close at 11:53 p.m. ET, when Falcon Heavy launches from Launch Complex 39A with NROL-97, the first National Reconnaissance Office payload ever to fly on the rocket. SpaceX rolled the vehicle out to the pad Tuesday night. Its two side boosters, which previously flew GOES-U, ViaSat-3 F3 and NASA’s Roman Space Telescope, will return to Landing Zones 1 and 2, while a new center core will be expended in the Atlantic. The Roman launch took place on August 30, so NROL-97 will come barely a month later as Falcon Heavy’s third flight of 2026 and 14th overall.
NASA taps SpaceX to launch the telescope that could unlock new worlds
If all three Florida boosters land as planned, it would be the first time the Space Coast has seen landings at LZ-40, LZ-1 and LZ-2 on the same day, according to the Orlando Sentinel, which has warned residents in Brevard, Orange and Volusia counties that more than one sonic boom is possible.
The schedule arrives just three days after Starship reached orbit for the first time on Flight 14 from Starbase, Texas, deploying 26 Starlink V3 satellites. If Thursday’s missions stay on time, SpaceX will have flown Starship, Falcon 9 and Falcon Heavy from four different pads in about four days.
Crew-13 is also the start of a longer run for Dragon. NASA recently added Crew-15, Crew-16 and Crew-17 to SpaceX’s contract in a $946 million modification, keeping Dragon as the agency’s only operational ride to the station while Boeing’s Starliner remains grounded.
Although the two vehicles are built for completely different use cases, Tesla utilized engineering expertise while developing both the Cybercab and Semi to build a thermal architecture that would fit both vehicles. Of course, with some slight revisions.
The development was noted by Lars Moravy and Dan Priestley last week at Tesla’s Semi Handover event in Sparks, Nevada, where the company showed off its dedicated production facility for the Class 8 truck.
🚨 Tesla designed the integrated thermal systems for Cybercab and Semi at the same time as the vehicles were both in development
Tesla wanted to build one thermal system that worked with both vehicles, apart from small modifications.
Semi and Cybercab share parts 🤯 pic.twitter.com/KmzSsUbrcg
— TESLARATI (@Teslarati) September 25, 2026
Tesla’s decision to develop one thermal architecture for both the Cybercab and Semi is one of the more revealing engineering choices in the company’s 2026 lineup:
“We designed it at the same time we designed the Cybercab and we said okay we’re going to take our most efficient vehicle and our biggest vehicle and we’re going to take one thermal system and make it work for both.”
Core parts, meaning the compressor, pumps, and heat exchangers, are shared, with only modest changes to cooling-loop sizing and a larger radiator on the truck. The result, they said, is a compressor and thermal stack already proven across millions of miles, delivering “reliability from day one.”
Priestley also highlighted a practical payoff of the indirect design:
“There’s no AC lines, there’s no refrigerant lines…It comes from the factory fully charged, sealed with refrigerant, and it just exchanges coolant. It doesn’t actually run refrigerant up to the front of the vehicle.”
This eliminates potentially leak-prone plumbing that would otherwise require hands-on service, reducing overall uptime and potentially cutting into business margins. The megamanifold runs cabin HVAC and every powertrain heating and cooling loop at once, recapturing waste heat from motors and the battery instead of dumping it the way a diesel engine does.
The approach is just the latest chapter in a continuing story of stretching thermal solutions across wildly different vehicles. Model Y’s Octovalve evolved into the Super Manifold used on Cybertruck, and later Model S/X refreshes. Cybercab then introduced Supermanifold V3, which Tesla says is 80 percent automated to build and 38 percent more efficient than typical automotive thermal systems.
This thermal system is also shared with Cybercab – one thermal system for both our most efficient vehicle & our biggest vehicle
— Tesla Semi (@tesla_semi) September 25, 2026
Tesla has done the same with the 4680 cells, both being utilized in the Cybertruck and Semi, and with heat-pump compressors that Priestley noted were already common across the passenger-car fleet.
Concurrent development of crucial vehicle elements buys scale and reliability that a truck-only thermal system could not match. High-volume passenger car parts are cheaper and more accessible, which can give fleets a sealed, low-maintenance loop of operation from their first day of operation.
For owners and operators, that translates into less energy spent on cabin heat in the colder months, fewer refrigerant-related repairs, and a thermal architecture already stress-tested at passenger-car volumes before the first high-volume Semi left the lines in Nevada.
Tesla CEO Elon Musk certainly tipped off some details of the Tesla Roadster event with a broadening of information regarding the company’s decision to delay the unveiling for two weeks.
For years, people have speculated about what the Roadster will be capable of. While there have been plenty of things said about what it *could* do, we have not seen or been told by Tesla what it will actually be capable of.
However, over the past few days, Tesla’s weather updates have truly pushed the speculation into Plaid Mode, basically all but confirming the car will have some sort of aerial capability — whether that would be hovering or fully flying remains to be seen — but it definitely seems that it will be able to leave the ground intentionally.
“Because this event can only be held outdoors…”
Tesla posted on Monday that it would delay the Roadster event until October 15, and it indicated that it had to do this because the event “can only be held outdoors.”
With the potential SpaceX collaboration to develop cold-gas thrusters that will help the vehicle go airborne, doing this indoors is probably not a safe, or even plausible, possibility.
Roadster event update
We’ve been tracking the weather closely with local meteorologists, but given the severe conditions predicted & because this event can only be held outdoors, we’ve made the difficult decision to reschedule.
New date is October 15. Additional details to…
— Tesla (@Tesla) September 28, 2026
FAA Airspace Restriction
The FAA gave Tesla a Temporary Flight Restriction (TFR) for 10,000 feet above ground level, much higher than the typical 2,000-foot restrictions that are usually placed at SpaceX’s McGregor, Texas site.
Tesla Roadster event requires restricted airspace, and the FAA obliges
Some have said that this massive increase is due to Tesla’s need to restrict unauthorized drone use for spying on the event.
Elon Admits High Winds
“Due to high winds, the new Roadster demo is postponed by 2 weeks,” Musk said in a post on X yesterday.
Due to high winds, the new Roadster demo is postponed by 2 weeks https://t.co/dV3ojDh1iT
— Elon Musk (@elonmusk) September 30, 2026
A reply reading, “What’s strong wind got to do with a car demo with four grounded wheels?” was directly below Musk’s post, satirically and sarcastically probing for more details.
All signs are pointing toward an aerial demonstration for the Roadster.
SpaceX set to launch astronauts and a classified Falcon Heavy mission on the same day
Tesla Cybercab and Semi have more in common than you might think
