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).
Check out Teslarati’s Marketplace! We offer Tesla accessories, including for the Tesla Cybertruck and Tesla Model 3.
Investor's Corner
xAI targets $5 billion debt offering to fuel company goals
Elon Musk’s xAI is targeting a $5B debt raise, led by Morgan Stanley, to scale its artificial intelligence efforts.
xAI’s $5 billion debt offering, marketed by Morgan Stanley, underscores Elon Musk’s ambitious plans to expand the artificial intelligence venture. The xAI package comprises bonds and two loans, highlighting the company’s strategic push to fuel its artificial intelligence development.
Last week, Morgan Stanley began pitching a floating-rate term loan B at 97 cents on the dollar with a variable interest rate of 700 basis points over the SOFR benchmark, one source said. A second option offers a fixed-rate loan and bonds at 12%, with terms contingent on investor appetite. This “best efforts” transaction, where the debt size hinges on demand, reflects cautious lending in an uncertain economic climate.
According to Reuters sources, Morgan Stanley will not guarantee the issue volume or commit its own capital in the xAI deal, marking a shift from past commitments. The change in approach stems from lessons learned during Musk’s 2022 X acquisition when Morgan Stanley and six other banks held $13 billion in debt for over two years.
Morgan Stanley and the six other banks backing Musk’s X acquisition could only dispose of that debt earlier this year. They capitalized on X’s improved operating performance over the previous two quarters as traffic on the platform increased engagement around the U.S. presidential elections. This time, Morgan Stanley’s prudent strategy mitigates similar risks.
Beyond debt, xAI is in talks to raise $20 billion in equity, potentially valuing the company between $120 billion and $200 billion, sources said. In April, Musk hinted at a significant valuation adjustment for xAI, stating he was looking to put a “proper value” on xAI during an investor call.
As xAI pursues this $5 billion debt offering, its financial strategy positions it to lead the AI revolution, blending innovation with market opportunity.
News
SpaceX to debut new Dragon capsule in Axiom Space launch
Ax-4’s launch marks the debut of SpaceX’s latest Crew Dragon and pushes Axiom closer to building its own space station.
Axiom Space’s Ax-4 mission targets the International Space Station (ISS) with a new SpaceX Crew Dragon capsule.
The Axiom team will launch a new SpaceX Dragon capsule atop a Falcon 9 rocket from NASA’s Kennedy Space Center in Florida on Wednesday at 8:00 a.m. EDT (1200 GMT). The Ax-4 mission launch was initially set for Tuesday, June 10, but was delayed by one day due to expected high winds.
As Axiom Space’s fourth crewed mission to the ISS, Ax-4 marks the debut of an updated SpaceX Crew Dragon capsule. “This is the first flight for this Dragon capsule, and it’s carrying an international crew—a perfect debut. We’ve upgraded storage, propulsion components, and the seat lash design for improved reliability and reuse,” said William Gerstenmaier, SpaceX’s vice president of build and flight reliability.
Axiom Space is a Houston-based private space infrastructure company. It has been launching private astronauts to the ISS for research and training since 2022, building expertise for its future station. With NASA planning to decommission the ISS by 2030, Axiom has laid the groundwork for the Axiom Station, the world’s first commercial space station. The company has already begun construction on its ISS replacement.
The Ax-4 mission’s research, spanning biological, life, and material sciences and Earth observation, will support this ambitious goal. Contributions from 31 countries underscore the mission’s global scope. The four-person crew will launch from Launch Complex 39A, embarking on a 14-day mission to conduct approximately 60 scientific studies.
“The AX-4 crew represents the very best of international collaboration, dedication, and human potential. Over the past 10 months, these astronauts have trained with focus and determination, each of them exceeding the required thresholds to ensure mission safety, scientific rigor, and operational excellence,” said Allen Flynt, Axiom Space’s chief of mission services.
The Ax-4 mission highlights Axiom’s commitment to advancing commercial space exploration. By leveraging SpaceX’s Dragon capsule and conducting diverse scientific experiments, Axiom is paving the way for its Axiom Station. This mission not only strengthens international collaborations but also positions Axiom as a leader in the evolving landscape of private space infrastructure.
News
Tesla named official AV operator in Austin ahead of robotaxi launch
Tesla robotaxis could begin operating around Austin any day now, as echoed by an update to the city’s website.
Just as Tesla prepares to launch its own commercial robotaxi services in Austin, Texas this month, the company has now appeared on the state’s website as an official operator of autonomous vehicles (AVs).
As of Monday, Tesla has been listed as an AV operator on Austin’s official Department of Motor Vehicles (DMV) site, ahead of the company’s expected launch of the long-awaited service sometime this month. The news, which X user Tesla Yoda first spotted, precedes some reports suggesting the robotaxi service could launch in the coming days, and it comes as the city becomes an increasingly competitive stomping ground for the emerging technology.
Although Tesla has been included on the list, the website says that Tesla is still in the testing phase, alongside most of the other AV operators in the city. At this time, Alphabet-owned robotaxi company Waymo is the only operator listed as being in the deployment phase, while Hyundai-owned company Motional is listed as being in the mapping phase.
Tesla is set to initially deploy the service as a limited pilot program using the company’s existing Model Y vehicles, and it will start by testing them in the safest areas of the city within geo-mapped boundaries as extra safety precautions upon launch.
🚨 Elon says by end of June, the public should be ready to take a Robotaxi in Austin without an invitation
Initial launch will be small and riders will be picked by Tesla https://t.co/zEQOkXnE6s
— TESLARATI (@Teslarati) May 29, 2025
Below you can see the full list of AV operators on the Austin DMV website at the time of writing, including both the Alphabet-owned Waymo and the Amazon-run Zoox.
Current list of AV operators in Austin
- ADMT
- Phase: testing
- Parent company: VW
- AVRide
- Phase: testing
- Parent company: AVRide Inc
- Motional
- Phase: mapping
- Parent company: Hyundai
- Waymo
- Phase: deployment
- Parent company: Alphabet (Google)
- Tesla
- Phase: testing
- Parent company: Tesla
- Zoox
- Phase: testing
- Parent company: Amazon
READ MORE ON AUTONOMOUS VEHICLES: Elon Musk just revealed more about Tesla’s June Robotaxi launch
Tesla’s Austin robotaxi launch, Full Self-Driving, and other AV companies
The news follows a report from Bloomberg a few weeks ago saying that Tesla was considering a launch date of June 12 for the service, though the validity of that report is still unclear. Additionally, Tesla could still change its plans on a launch date, though the company’s inclusion on the Austin DMV AV operators list appears to be a good sign either way.
The company has also been running internal pilot programs for the robotaxi service in Austin and around the Bay Area, California, with around 300 test operators operating the vehicles in the Texas city since at least April. Last fall, CEO Elon Musk also said that employees had already been piloting a ride-hailing program around the Bay.
Tesla has long touted its Full Self-Driving (FSD) program as the solution to autonomy, with the system utilizing cameras and real-time driver footage to train its AI neural network on how to drive. By comparison, most other companies utilize cameras and radar systems together, while relying on geo-mapped systems to determine where the robotaxi can operate.
Waymo launched driverless ride-hailing services in Austin through a partnership with Uber, though the company has also been running paid robotaxi rides in various parts of California since last year through its Waymo One app. Other companies such as the Amazon-owned firm Zoox and the Hyundai-led company Motional are also preparing to deploy services in Austin and other U.S. cities.
Tesla’s ‘Project Alicorn’ and what it means for the Robotaxi platform
xAI targets $5 billion debt offering to fuel company goals
SpaceX to debut new Dragon capsule in Axiom Space launch
Tesla named official AV operator in Austin ahead of robotaxi launch
-
News1 week agoTesla to lose 64 Superchargers on New Jersey Turnpike in controversial decision
-
News2 weeks agoTesla gets major upgrade that Apple users will absolutely love
-
News2 weeks agoTesla teases new color while testing refreshed Model S, X
-
Elon Musk2 weeks agoTesla investors demand 40-hour workweek from Elon Musk
-
Elon Musk7 days agoElon Musk explains Tesla’s domestic battery strategy
-
News2 weeks agoTesla Cybertrucks join Jalisco’s police fleet ahead of FIFA World Cup
-
News2 weeks agoTesla rolls out new crucial safety feature aimed at saving children
-
News2 weeks agoTesla’s apparent affordable model zips around Fremont test track