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SpaceX delays Starhopper’s first flight a few days despite Raptor preburner test success
SpaceX has (partially) ignited Starhopper’s freshly-installed Raptor engine, successfully verifying that the engine is ready for its next major test: a full ignition and static firing. Although successful, SpaceX still has some work to do before the vehicle is ready for its first untethered flight(s).
July 15th’s progress is just the latest in a several day-series of preflight tests designed to reduce the likelihood that Starhopper is destroyed over the coming days and (hopefully) weeks. If all goes planned during the awkward Starship prototype’s first foray into hover tests, SpaceX CEO Elon Musk has stated that he will provide an official presentation updating the public on the status of the company’s ever-changing next-generation rocket.
The past week or so of Starhopper preflight testing began with Raptor serial number 6 (SN06) completing the last of a series of acceptance test fires in McGregor, Texas on June 10th. Even on its own, this was a major milestone for the new SpaceX engine: Raptor SN06 was the first of the new, full-scale engines to pass the acceptance test program with flying colors. According to Musk, for the engine to complete those tests so successfully, SpaceX had to solve a challenging bug in which some sort of mechanical resonance (i.e. vibration) damaged or destroyed Raptors SN01-05.
Hours later, the engine began a short ~450 mi (720 km) journey south to Starhopper, located in Boca Chica, Texas. The engine arrived on July 11th and was fully installed on Starhopper by the following evening (July 12th), at which point SpaceX put Starhopper and Raptor through some mild but valuable thrust vector controller (TVC) tests, wiggling the car-sized engine to ensure it can accurately steer the prototype rocket.
Around two days after the above ‘wiggle’ test was successfully completed, SpaceX moved into the next stage, partially fueling Starhopper with liquid methane and oxygen propellant and helium pressurant in what is known in rocketry as a wet dress rehearsal (WDR). The (implicitly) successful WDR was capped off with a duo of what can now safely be concluded were some sort of Raptor test preceding even pre-ignition operations. Whatever the tests were, they appear to have been completed successfully.
That appears to be the case because less than 24 hours after their completion, on July 15th, SpaceX once again began loading Starhopper with propellant and pressurant for a second round of wet testing. This time around, SpaceX got right into more critical Raptor tests once enough propellant was loaded, igniting the engine’s interwoven oxygen and methane preburners.
Previously discussed 24 hours ago in a Teslarati article focused on Raptor wiggles and other miscellaneous tests, Raptor is an extremely advanced rocket engine based on a cycle (i.e. how propellant is turned into thrust) known as full-flow staged combustion.
“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.
Unintuitively, conditions inside the preburner – hidden away from view – are actually far more intense than the iconic blue, purple, and pink flame that visibly exists Raptor’s nozzle. 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 its main combustion chamber. If the 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 trigger a “hard start” or shutdown that could destroy the engine. According to Elon Musk, Raptor’s oxygen preburner thus has the worst of it, operating at pressures as high or higher than 800 bar (11,600 psi, 80 megapascals).”
In full-flow staged combustion (FFSC), even more complexity is added as all propellant that touches the engine must necessarily end up traveling through the main combustion chamber to eke every last ounce of thrust out of the finite propellant a rocket lifts off with. As such, FFSC engines can be about as efficient as the laws of physics allow any given chemical rocket engine to be, at the cost of exceptional complexity and brutally difficult development.
Additionally, FFSC physically requires two separate preburners and then makes things even harder by making each separate preburner (methane and oxygen) depend on each other’s operation for the engine to fully ignite. This means that no individual preburner can be used to kickstart Raptor – instead, SpaceX must somehow spin the turbopumps that feed propellant into each preburner with some separate system. This is all just to emphasize the fact that Raptor’s ignition sequence is a spectacularly complex orchestra of valves, spark plugs, sensors, and magic. This is why it’s valuable for Raptor to test its preburner system independently of an actual ignition test, at least as long as the engine is still in the development stages.
According to NASASpaceflight.com managing editor Chris Bergin, what this practically translates to is a minor Starhopper hover test delay of 1-2 days, while the static fire has also been pushed roughly 24 hours from July 15th to July 16th. If that full static fire produces lots of happy data, Starhopper could be cleared for a hover test debut attempt as early as Wednesday or Thursday (July 17/18).
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Elon Musk
Tesla CEO Elon Musk confirms Robotaxi safety monitor removal in Austin: here’s when
Musk has made the claim about removing Safety Monitors from Tesla Robotaxi vehicles in Austin three times this year, once in September, once in October, and once in November.
Tesla CEO Elon Musk confirmed on Tuesday at the xAI Hackathon that the company would be removing Safety Monitors from Robotaxis in Austin in just three weeks.
This would meet Musk’s timeline from earlier this year, as he has said on several occasions that Tesla Robotaxis would have no supervision in Austin by the end of 2025.
On Tuesday, Musk said:
“Unsupervised is pretty much solved at this point. So there will be Tesla Robotaxis operating in Austin with no one in them. Not even anyone in the passenger seat in about three weeks.”
Musk has made the claim about removing Safety Monitors from Tesla Robotaxi vehicles in Austin three times this year, once in September, once in October, and once in November.
In September, he said:
“Should be no safety driver by end of year.”
The safety driver is just there for the first few months to be extra safe.
Should be no safety driver by end of year.
— Elon Musk (@elonmusk) September 4, 2025
On the Q3 Earnings Call in October, he said:
“We are expecting ot have no safety drivers in at least large parts of Austin by the end of this year.”
Finally, in November, he reiterated the timeline in a public statement at the Shareholder Meeting:
“I expect Robotaxis to operate without safety drivers in large parts of Austin this year.”
Currently, Tesla uses Safety Monitors in Austin in the passenger’s seat on local roads. They will sit in the driver’s seat for highway routes. In the Bay Area ride-hailing operation, there is always a Safety Monitor in the driver’s seat.
Three weeks would deliver on the end-of-year promise, cutting it close, beating it by just two days. However, it would be a tremendous leap forward in the Robotaxi program, and would shut the mouths of many skeptics who state the current iteration is no different than having an Uber.
Tesla has also expanded its Robotaxi fleet this year, but the company has not given exact figures. Once it expands its fleet, even more progress will be made in Tesla’s self-driving efforts.
News
SpaceX reportedly mulling IPO, eyeing largest of all time: report
“I do want to try to figure out some way for Tesla shareholders to participate in SpaceX. I’ve been giving a lot of thought to how to give people access to SpaceX stock,” Musk said.
SpaceX is reportedly mulling an initial public offering, eyeing what would be the largest valuation at the time of availability of all time, a new report from Bloomberg said on Tuesday.
It is one of many reports involving one of Elon Musk’s companies and a massive market move, as this is not the first time we have seen reports of an IPO by SpaceX. Musk himself has also dispelled other reports in the past of a similar nature, including an xAI funding round.
SpaceX and Musk have yet to comment on the report. In the past, untrue reports were promptly replied to by the CEO; this has not yet gained any response, which is a good sign in terms of credibility.
However, he said just a few days ago that stories of this nature are inaccurate:
“There has been a lot of press claiming SpaceX is raising money at $800B, which is not accurate. SpaceX has been cash flow positive for many years and does periodic stock buybacks twice a year to provide liquidity for employees and investors. Valuation increments are a function of progress with Starship and Starlink and securing global direct-to-cell spectrum that greatly increases our addressable market. And one other thing that is arguably most significant by far.”
There has been a lot of press claiming @SpaceX is raising money at $800B, which is not accurate.
SpaceX has been cash flow positive for many years and does periodic stock buybacks twice a year to provide liquidity for employees and investors.
Valuation increments are a…
— Elon Musk (@elonmusk) December 6, 2025
Musk has discussed a potential IPO for SpaceX in recent months, as the November 6 shareholder meeting, as he commented on the “downsides” of having a public company, like litigation exposure, quarterly reporting pressures, and other inconveniences.
Nevertheless, Musk has also said he wants there to be a way for Tesla shareholders to get in on the action. At the meeting in early November, he said:
“I do want to try to figure out some way for Tesla shareholders to participate in SpaceX. I’ve been giving a lot of thought to how to give people access to SpaceX stock.”
Additionally, he added:
“Maybe at some point., SpaceX should become a public company despite all the downsides of being public.”
Musk has been historically reluctant to take SpaceX public, at times stating it could become a barrier to colonizing Mars. That does not mean it will not happen.
Bloomberg’s report cites multiple unidentified sources who are familiar with the matter. They indicate to the publication that SpaceX wants to go public in mid-to-late 2026, and it wants to raise $30 billion at a valuation of around $1.5 trillion.
This is not the first time SpaceX has discussed an IPO; we reported on it nine years ago. We hope it is true, as the community has spoken for a long time about having access to SpaceX stock. Legendary investor Ron Baron is one of the lucky few to be a SpaceX investor, and said it, along with Tesla, is a “lifetime investment.”
Tesla bull Ron Baron reveals $100M SpaceX investment, sees 3-5x return on TSLA
The primary driver of SpaceX’s value is Starlink, the company’s satellite internet service. Starlink contributes 60-70 percent of SpaceX’s revenue, meaning it is the primary value engine. Launch services, like Falcon 9 contracts, and the development of Starship, also play supporting roles.
SpaceX reached an incredible milestone with its Starlink program with a launch last night, as the 3,000th satellite of the year was launched into low Earth orbit.
On Monday, SpaceX also achieved its 32nd flight with a single Falcon 9 rocket from NASA’s Kennedy Space Center.
The mission was Starlink 6-92, and it utilized the Falcon 9 B1067 for the 32nd time this year, the most-used Falcon booster. The flight delivered SpaceX’s 3000th Starlink satellite of the year, a massive achievement.
There were 29 Starlink satellites launched and deployed into LEO during this particular mission:
Falcon 9 launches 29 @Starlink satellites from Florida pic.twitter.com/utKrXjHzPN
— SpaceX (@SpaceX) December 9, 2025
SpaceX has a current goal of certifying its Falcon boosters for 40 missions apiece, according to Spaceflight Now.
The flight was the 350th orbital launch from the nearby SLC-40, and the 3,000 satellites that have been successfully launched this year continue to contribute to the company’s goal of having 12,000 satellites contributing to global internet coverage.
There are over five million users of Starlink, the latest data shows.
Following the launch and stage separation, the Falcon 9 booster completed its mission with a perfect landing on the ‘Just Read the Instructions’ droneship.
The mission was the 575th overall Falcon 9 launch, highlighting SpaceX’s operational tempo, which continues to be accelerated. The company averages two missions per week, and underscores CEO Elon Musk’s vision of a multi-planetary future, where reliable connectivity is crucial for remote work, education, and emergency response.
As Starlink expands and works toward that elusive and crucial 12,000 satellite goal, missions like 6-92 pave the way for innovations in telecommunications and enable more internet access to people across the globe.
With regulatory approvals in over 100 countries and millions of current subscribers, SpaceX continues to democratize space, proving that reusability is not just feasible, but it’s also revolutionary.
Tesla CEO Elon Musk confirms Robotaxi safety monitor removal in Austin: here’s when
SpaceX reportedly mulling IPO, eyeing largest of all time: report
