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SpaceX Starship stacked with ballast for hop test debut

Starship SN4 has been outfitted with a ballast weight to enable its inaugural flight test. (NASASpaceflight - bocachicagal)

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SpaceX has installed a custom-built ballast atop its fourth full-scale Starship prototype, a sign that the company is rapidly approaching the ship’s first Starhopper-style hop test.

Although CEO Elon Musk officially “redirected” SpaceX’s resources away from Starship’s first flight and towards Crew Dragon’s NASA astronaut launch debut, the company continues to work around the clock to ready Starship SN4 for the program’s biggest test yet. Designed with the goal of creating a fully-reusable, ultra-capable launch vehicle that is unprecedentedly affordable, SpaceX’s Starship spacecraft and Super Heavy booster have made impressive progress over the last 12 or so months.

In July and August 2019, Starhopper – a low-fidelity testbed and proof of concept – successfully performed two untethered hop tests, ultimately flying more than 150m (~500 ft) above ground before safely touching down. Three months later, the first full-scale Starship prototype was destroyed almost immediately after its first pressure test began, a failure that lead SpaceX to expedite factory upgrades. Just six months later, SpaceX has completed multiple successful tests, including pressure tests that pushed beyond the pressures needed for safe human spaceflight, several full wet dress rehearsals (WDRs) with live propellant, and three Raptor engine static fires. In fewer words, Starship is ready for its next big test: flight.

SpaceX technicians prepare to complete a jerryrigged ballast weight for Starship SN4. (NASASpaceflight – bocachicagal)

However, Starship SN4 currently has just one Raptor engine installed and will remain in that configuration for its inaugural hop, expected to reach a maximum altitude identical to Starhopper (150m/500ft). The odd configuration means that the rocket will be propelled by asymmetric thrust, as Starship’s ‘thrust puck’ engine section is designed to hold three Raptor engines in a triangular formation. Raptor is capable of producing up to 200 metric tons (~440,000 lbf) of thrust with an unclear level of throttle control (likely mediocre according to comments made by Elon Musk).

Impressively, although it might seem reasonable to assume that Starship SN4 is about as heavy as the ~120 ton Starhopper, the clear and present need to install substantial ballast suggests otherwise. Combined with comments made during SN4’s April 2020 transport from factory to launch site, it appears that even SpaceX’s early Starship engine sections weigh just 50-60 metric tons (110,000-125,000 lb) empty. That weight doesn’t account for the flaps, heat shield, nose section, or many other heavy components that orbital Starships will eventually need but is still impressive.

Starship SN4 was transported to the launch pad on April 23rd. (NASASpaceflight – bocachicagal)
On May 27th, SpaceX installed a massive ballast weight on top of the Starship prototype. (NASASpaceflight – bocachicagal)

That impressive weight reduction, Raptor’s inability to safely throttle low, and the FAA’s lack of interest in dozens (up to hundreds) of tons of explosive propellant flying above or around populated areas poses its own challenges for the first full-scale Starship flight. The addition of ballast helpfully solves (or at least alleviates) several of those issues. Notably, ballast can prevent SpaceX from having to fuel Starship SN4 with dozens of extra tons of explosive propellant to counteract the high thrust of its single engine and permit a safe launch and landing.

At the same time, if Starship SN4’s wet weight is reduced by carrying less propellant during its first flight, that actually exacerbates the problem of Raptor’s small throttle range, as a lighter ship would be much harder to manage as the engine rapidly burns propellant and thus loses mass. With ballast, Raptor won’t have to throttle as low as it would otherwise have to to ensure a gentle rate of deceleration. Built out of sheet steel and two spare rolls of the same steel used to form Starship rings, Starship SN4’s new ballast likely increases its dry mass by some 50% or more (25+ metric tons).

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(NASASpaceflight – bocachicagal)
Starship SN4’s solid steel ballast. (NASASpaceflight – bocachicagal)

Pending Crew Dragon’s inaugural astronaut launch, now scheduled no earlier than 3:22 pm EDT (19:22 UTC), May 30th after weather delayed the first May 27th launch attempt, Starship SN4 has no testing periods on the calendar at the moment. Speaking around May 23rd, Musk stated that the ship was likely at least a “few weeks” away from its flight debut, suggesting that the ship will perform another static fire test to prepare for its first hop as early as next week. Stay tuned for updates as SpaceX’s works towards two very exciting Crew Dragon and Starship milestones.

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Eric Ralph is Teslarati's senior spaceflight reporter and has been covering the industry in some capacity for almost half a decade, largely spurred in 2016 by a trip to Mexico to watch Elon Musk reveal SpaceX's plans for Mars in person. Aside from spreading interest and excitement about spaceflight far and wide, his primary goal is to cover humanity's ongoing efforts to expand beyond Earth to the Moon, Mars, and elsewhere.

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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.

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(Credit: Tesla)

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.”

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Robotaxis are already making roads safer, Waymo report reveals

Waymo Driver is already reducing severe crashes and enhancing the safety of vulnerable road users.

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Waymo hires former Tesla Executive 
(Credit: Waymo)

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.

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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.

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tesla robotaxi app on phone
Credit: Tesla

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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