

News
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 says it denied Musk CEO replacement report before it was published
Tesla says it responded to the WSJ’s request for comment, denying that it was in search of a new CEO to replace Elon Musk.

Tesla said that it denied seeking a replacement for CEO Elon Musk before a report was published claiming the company was considering a new frontman.
Last night, The Wall Street Journal reported that Tesla’s Board of Directors was looking for Musk’s replacement after he had devoted too much time to his role within the government. The publication revised its headline to the report no fewer than five times, initially stating the company was still seeking a replacement.
By the time the headline revisions were complete, it had outlined that Tesla had looked for a replacement a month ago, but had stopped its search following Musk’s commitment to Tesla during the company’s earnings call last month.
Shortly after the report surfaced, Board of Directors chairwoman Robyn Denholm officially issued a statement on behalf of Tesla:
“Earlier today, there was a media report erroneously claiming that the Tesla Board had contacted recruitment firms to initiate a CEO search at the company. This is absolutely false (and this was communicated to the media before the report was published). The CEO of Tesla is Elon Musk and the Board is highly confident in his ability to continue executing on the exciting growth plan ahead. – Robyn Denholm.”
Tesla Board Chair slams Wall Street Journal over alleged CEO search report
Interestingly, Denholm’s statement indicates it had responded to a request for comment from the Wall Street Journal before the report was published. This is especially interesting because Tesla does not typically respond to media outreach, as it dissolved its media department several years ago.
Tesla typically makes its statements publicly on X.
Musk also responded to the report, indicating that the WSJ had committed an “extremely bad breach of ethics” by publishing a “deliberately false article” that did not include Tesla’s “unequivocal denial beforehand.”
News
Robotaxis are already making roads safer, Waymo report reveals
Waymo Driver is already reducing severe crashes and enhancing the safety of vulnerable road users.

Industry leaders such as Elon Musk have always maintained that autonomous robotaxis will make roads safer. A recent blog post from Waymo about the safety of its self-driving cars suggests that Musk’s sentiments are on point.
Way More Safety
Waymo Driver is already reducing severe crashes and enhancing the safety of vulnerable road users. As per a new research paper set for publication in the Traffic Injury Prevention Journal, Waymo Driver had outperformed human drivers in safety, particularly for vulnerable road users (VRUs).
Over 56.7 million miles, compared to human drivers, Waymo Driver achieved a 92% reduction in pedestrian injury crashes. It also saw 82% fewer crashes with injuries with cyclists and 82% fewer crashes with injuries with motorcyclists. Waymo Driver also slashed injury-involving intersection crashes by 96%, which are a leading cause of severe road harm for human drivers. Waymo Driver saw 85% fewer crashes with suspected serious or worse injuries as well.
What They Are Saying
Mauricio Peña, Waymo’s Chief Safety Officer, was optimistic about Waymo Driver’s results so far. “It’s exciting to see the real positive impact that Waymo is making on the streets of America as we continue to expand. This research reinforces the growing evidence that the Waymo Driver is playing a crucial role in reducing serious crashes and protecting all road users,” the Chief Safety Officer noted.
Jonathan Adkins, Chief Executive Officer at Governors Highway Safety Association, also noted that Waymo’s results are very encouraging. “It’s encouraging to see real-world data showing Waymo outperforming human drivers when it comes to safety. Fewer crashes and fewer injuries — especially for people walking and biking — is exactly the kind of progress we want to see from autonomous vehicles,” Adkins stated.
Elon Musk
Tesla hints at June 1 launch of Robotaxi platform in Austin
Tesla has hinted at a potential launch date for the Robotaxi service in Austin, Texas.

Tesla just dropped its biggest hint yet about the potential launch date of its Robotaxi ride-hailing platform in Austin, Texas, shedding more light on when to expect it to take off.
In preparation for the ride-hailing service to launch, Tesla has been in talks with the City of Austin for months. It has also spent recent months bolstering its Full Self-Driving suite, aiming for it to handle initially supervised rides with the use of teleoperators to keep things safe and dependable, at least early on.
The company has also said that it expects the Robotaxi service, which will drive passengers in Tesla Model Y vehicles to start, to launch in Austin in June. However, Tesla has not given an exact date.
Now, Tesla is hinting that Robotaxi could launch on June 1, based on a very vague X post it published on May 1:
Of course, this is extremely speculative. However, it’s the first time Tesla has made any suggestions about a potential launch date, so it’s worth taking it seriously.
While the automaker has often missed timelines in the past, most notably the launch of a “feature-complete” Full Self-Driving platform, this is the first time we’ve seen Tesla be so adamant and truly reiterate a target date.
Tesla has not shied away from this June date for the Robotaxi launch yet, something that is worth noting as we move closer to June. All signs point toward Tesla being able to come through on this timeline, and it could be one of its biggest accomplishments yet on the grand scheme of things. The Robotaxi rollout will be controlled and small to start, the company noted on its most recent Earnings Call.
CEO Elon Musk said:
“The team and I are laser-focused on bringing robotaxi to Austin in June. Unsupervised autonomy will first be solved for the Model Y in Austin.”
At first, it also seems as if the first Robotaxi rides will be available to a select group, as Musk said the ability to order one will not be available to the general public until later in the month. He also said the initial fleet will be between 10 and 20 vehicles:
“Yeah. We’re still debating the exact number to start off on day one, but it’s, like, I don’t know, maybe 10 or 20 vehicles on day one. And watch it carefully. They scale it up rapidly after that. So, we want to make sure that you’re paying very close attention the first time this happens. But, yeah, you will be able to — end of end of June or July, just go to Austin and order a Tesla for autonomous drive.”
While the June 1st date of the Robotaxi launch is extremely speculative, Tesla seems convinced that its vehicles could already handle this task. It would be something to see them come through on this date, especially on the first day of the month.
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