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SpaceX Starship booster’s ‘hot gas’ thrusters make first public appearance
‘Hot gas’ thrusters meant to boost the efficiency of SpaceX’s Starship spacecraft and Super Heavy boosters have been spotted in public for the first time.
On the evening of June 21st, spaceflight photographer Brady Kenniston – on assignment for NASASpaceflight – caught the first glimpses ever of what amounts to the newest rocket engine designed and built by SpaceX. As yet unnamed, SpaceX CEO Elon Musk has consistently referred to the new engine as a “hot gas thruster” for several years, though virtually no concrete details have ever been shared.
The reason behind the lack of major visible progress is simple enough: until Starship is ready for serious orbital testing, hot-gas thrusters just aren’t necessary. Instead, SpaceX has relied on tried and true cold gas thrusters derived – or quite literally taken, in the case of Starhopper – from those used on Falcon 9 and Falcon Heavy boosters to maintain attitude control in space and safely land back on Earth.
For Starhopper and Starships SN5 and SN6, all three of which focused on simple hop tests, those cold-gas thrusters primarily augmented Raptor’s thrust vectoring capabilities by fine-tuning vehicle rotation and attitude. On Starships SN8, SN9, SN10, SN11, and SN15, cold-gas thrusters played a more substantial role in their more complex medium-altitude test flights, flipping each ship horizontal at apogee, helping to maintain stability during skydiver-style freefalls back to Earth, and augmenting three Raptor engines during the final landing flip and landing burn.
By all appearances, the thrusters did their jobs perfectly on all nine test flights. However, those eight suborbital prototypes could all afford to expend large portions of their mass budgets on a plethora of pressure vessels filled with tons of nitrogen gas. More importantly, empty Starships and their Super Heavy boosters are expected to weigh anywhere from 10-50 times more than Falcon 9’s booster and upper stage, and SpaceX’s suborbital prototypes have also required much less performance (delta V) than operational ships and boosters will need.
Cold gas (nitrogen) thrusters are too inefficient and the exponential aspects of rocket engineering too cruel for what works on Falcon to efficiently meet the needs of Starship and Super Heavy. SpaceX’s long-planned solution has been the development of a bipropellant thruster that would borrow from Raptor expertise and use the same methane and oxygen propellant – albeit in their high-pressure gaseous forms. If properly realized, such a thruster could offer around five times the efficiency and thrust of a similarly-sized cold-gas system – a boon for maneuvering and manipulating massive 100-250 ton (~250,000-550,000 lb) ships and boosters in space.
In theory, moving from nitrogen to methalox thrusters also means that Starship could refuel its thrusters using a tiny fraction of the vast supply of liquid methane and oxygen propellant it will already be carrying to the Moon or Mars. Ultimately, though, Musk says that those hot gas attitude control thrusters will debut on the Super Heavy booster assigned to Starship’s first orbital test flight. While SpaceX’s initial July target now appears to be out of the question, all flight and pad hardware could still be ready to launch as early as August or September.
Update: One month after Elon Musk stated that SpaceX was “aiming” to have hot gas thrusters on the first flightworthy Super Heavy booster, the CEO says those thrusters would be “an unnecessary complication for now” and “are being removed to speed up time to” Starship’s first orbital launch.
Elon Musk
SpaceX issues statement on Starship V3 Booster 18 anomaly
The incident unfolded during gas-system pressure testing at the company’s Massey facility in Starbase, Texas.
SpaceX has issued an initial statement about Starship Booster 18’s anomaly early Friday. The incident unfolded during gas-system pressure testing at the company’s Massey facility in Starbase, Texas.
SpaceX’s initial comment
As per SpaceX in a post on its official account on social media platform X, Booster 18 was undergoing gas system pressure tests when the anomaly happened. Despite the nature of the incident, the company emphasized that no propellant was loaded, no engines were installed, and personnel were kept at a safe distance from the booster, resulting in zero injuries.
“Booster 18 suffered an anomaly during gas system pressure testing that we were conducting in advance of structural proof testing. No propellant was on the vehicle, and engines were not yet installed. The teams need time to investigate before we are confident of the cause. No one was injured as we maintain a safe distance for personnel during this type of testing. The site remains clear and we are working plans to safely reenter the site,” SpaceX wrote in its post on X.
Incident and aftermath
Livestream footage from LabPadre showed Booster 18’s lower half crumpling around the liquid oxygen tank area at approximately 4:04 a.m. CT. Subsequent images posted by on-site observers revealed extensive deformation across the booster’s lower structure. Needless to say, spaceflight observers have noted that Booster 18 would likely be a complete loss due to its anomaly.
Booster 18 had rolled out only a day earlier and was one of the first vehicles in the Starship V3 program. The V3 series incorporates structural reinforcements and reliability upgrades intended to prepare Starship for rapid-reuse testing and eventual tower-catch operations. Elon Musk has been optimistic about Starship V3, previously noting on X that the spacecraft might be able to complete initial missions to Mars.
Investor's Corner
Tesla analyst maintains $500 PT, says FSD drives better than humans now
The team also met with Tesla leaders for more than an hour to discuss autonomy, chip development, and upcoming deployment plans.
Tesla (NASDAQ:TSLA) received fresh support from Piper Sandler this week after analysts toured the Fremont Factory and tested the company’s latest Full Self-Driving software. The firm reaffirmed its $500 price target, stating that FSD V14 delivered a notably smooth robotaxi demonstration and may already perform at levels comparable to, if not better than, average human drivers.
The team also met with Tesla leaders for more than an hour to discuss autonomy, chip development, and upcoming deployment plans.
Analysts highlight autonomy progress
During more than 75 minutes of focused discussions, analysts reportedly focused on FSD v14’s updates. Piper Sandler’s team pointed to meaningful strides in perception, object handling, and overall ride smoothness during the robotaxi demo.
The visit also included discussions on updates to Tesla’s in-house chip initiatives, its Optimus program, and the growth of the company’s battery storage business. Analysts noted that Tesla continues refining cost structures and capital expenditure expectations, which are key elements in future margin recovery, as noted in a Yahoo Finance report.
Analyst Alexander Potter noted that “we think FSD is a truly impressive product that is (probably) already better at driving than the average American.” This conclusion was strengthened by what he described as a “flawless robotaxi ride to the hotel.”
Street targets diverge on TSLA
While Piper Sandler stands by its $500 target, it is not the highest estimate on the Street. Wedbush, for one, has a $600 per share price target for TSLA stock.
Other institutions have also weighed in on TSLA stock as of late. HSBC reiterated a Reduce rating with a $131 target, citing a gap between earnings fundamentals and the company’s market value. By contrast, TD Cowen maintained a Buy rating and a $509 target, pointing to strong autonomous driving demonstrations in Austin and the pace of software-driven improvements.
Stifel analysts also lifted their price target for Tesla to $508 per share over the company’s ongoing robotaxi and FSD programs.
Elon Musk
SpaceX Starship Version 3 booster crumples in early testing
Photos of the incident’s aftermath suggest that Booster 18 will likely be retired.
SpaceX’s new Starship first-stage booster, Booster 18, suffered major damage early Friday during its first round of testing in Starbase, Texas, just one day after rolling out of the factory.
Based on videos of the incident, the lower section of the rocket booster appeared to crumple during a pressurization test. Photos of the incident’s aftermath suggest that Booster 18 will likely be retired.
Booster test failure
SpaceX began structural and propellant-system verification tests on Booster 18 Thursday night at the Massey’s Test Site, only a few miles from Starbase’s production facilities, as noted in an Ars Technica report. At 4:04 a.m. CT on Friday, a livestream from LabPadre Space captured the booster’s lower half experiencing a sudden destructive event around its liquid oxygen tank section. Post-incident images, shared on X by @StarshipGazer, showed notable deformation in the booster’s lower structure.
Neither SpaceX nor Elon Musk had commented as of Friday morning, but the vehicle’s condition suggests it is likely a complete loss. This is quite unfortunate, as Booster 18 is already part of the Starship V3 program, which includes design fixes and upgrades intended to improve reliability. While SpaceX maintains a rather rapid Starship production line in Starbase, Booster 18 was generally expected to validate the improvements implemented in the V3 program.
Tight deadlines
SpaceX needs Starship boosters and upper stages to begin demonstrating rapid reuse, tower catches, and early operational Starlink missions over the next two years. More critically, NASA’s Artemis program depends on an on-orbit refueling test in the second half of 2026, a requirement for the vehicle’s expected crewed lunar landing around 2028.
While SpaceX is known for diagnosing failures quickly and returning to testing at unmatched speed, losing the newest-generation booster at the very start of its campaign highlights the immense challenge involved in scaling Starship into a reliable, high-cadence launch system. SpaceX, however, is known for getting things done quickly, so it would not be a surprise if the company manages to figure out what happened to Booster 18 in the near future.
SpaceX issues statement on Starship V3 Booster 18 anomaly
Tesla analyst maintains $500 PT, says FSD drives better than humans now
