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NASA’s SLS Moon rocket almost aces vital prelaunch test on 7th try

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3 years ago

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Following several incomplete attempts in April, June, August, and September, NASA’s first Space Launch System (SLS) Moon rocket has almost aced a vital prelaunch test on the seventh try.

NASA says that “all objectives were met” during the ten-hour test, which wrapped up around 4:30 pm EDT (20:30 UTC) on Wednesday, September 21st. Despite the rocket running into multiple additional issues, some old and others new, the agency was confident enough in the preliminary results of the wet dress rehearsal (WDR) – deemed a “cryogenic demonstration test” – to reaffirm that it’s still working towards a third launch attempt as early as September 27th.

That launch date is not set in stone, but NASA also hasn’t ruled out the window after the latest round of SLS testing. The agency will host a press conference on Friday, September 23rd, to provide its final decision and offer more details about the seventh wet dress rehearsal.

Despite NASA’s apparent confidence after the test, which was admittedly smoother than most previous SLS tests at the launch pad, it was far from smooth. The immediate story of the “cryogenic demonstration test” dates back to the SLS Artemis I rocket’s second so-called “launch attempt” on September 3rd. During that attempt, the launch was aborted well before SLS was ready when NASA detected a major hydrogen fuel leak around one of the quick-disconnect umbilical panels that fuels and drains the rocket. Remote troubleshooting was unable to solve the problem, forcing NASA to stand down.

Over the last few weeks, teams inspected, tested, and repaired the faulty Tail Service Mast Umbilical (TSMU), preparing for a cryogenic proof test meant to verify that the issue was fixed. During that September 21st test, the TSMU still leaked significantly for the whole duration, but it did so more predictably and – unlike prior leaks – never violated the limits that would trigger a launch abort.

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But near the end, a different umbilical panel developed a significant hydrogen leak that did violate those launch constraints, meaning that NASA would have likely had to stand down yet again if it had attempted to launch before completing additional testing. The test was completed successfully, but its goals and constraints were not the same as those facing a launch.

A NASA-developed rocket leaking hydrogen is unfortunately a tale as old as time. That the agency that struggled with hydrogen leaks throughout the 30-year career of the Space Shuttle appears to be just as flabbergasted by nearly identical problems on a new rocket – SLS – that has Shuttle ‘heritage’ on almost every square inch is not surprising, even if it is somewhat embarassing.

Liquid hydrogen fuel always has been and likely always will be a massive pain to manage in any rocket, but especially in a large rocket. As the smallest element in the universe, it is fundamentally leak-prone. Combined with the fact that it only remains liquid below the extraordinarily low temperature of -253°C (-423°F), generates ultra-flammable hydrogen gas as it continually attempts to warm to a more stable temperature, and naturally embrittles most metals, it’s an engineering nightmare by almost every measure.

For all that pain, hydrogen does provide rocket engineers exceptional efficiency when properly exploited, but even that positive aspect is often diminished by hydrogen’s ultra-low density. For rocket stages that have already reached orbit, hydrogen-oxygen propellant offers unbeatable efficiency. But for a rocket stage that will never be used in orbit, like the SLS core stage, hydrogen fuel is rarely worth the tradeoffs – a reality that SLS is unfortunately providing a strong reminder of.

Demonstrating the Groundhog Day-esque nature of NASA rockets and hydrogen leaks, the same leaky TSMU panel that aborted SLS’ September 3rd launch attempt (sixth WDR) and had to be fixed and retested on September 21st also caused a hydrogen leak that partially aborted the rocket’s third wet dress rehearsal attempt in April 2022. NASA then rolled the rocket back to the Vehicle Assembly Building (VAB), where workers spent almost two months inspecting and reworking the fuel TSMU and fixing other issues. During its first test (WDR #4) after rolling back to the pad in June, the same fuel TSMU leaked and NASA had to return the rocket to the VAB again to fix the problem.

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The fuel TSMU then leaked on the SLS rocket’s first launch attempt (really WDR #5), but the problem was resolved and was not what caused NASA to stand down. It was, however, a primary reason behind NASA’s second aborted launch attempt (WDR #6). With any luck, the eighth time will be the charm.

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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 analyst compares Robotaxi to Waymo: ‘The contrast was clear’

“In short, robotaxi felt like a more luxurious service for half the cost and the driving felt more human-like.”

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2 hours ago

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August 20, 2025

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Credit: Tesla

Tesla analyst Jed Dorsheimer of Wall Street firm William Blair compared the company’s Robotaxi platform to Waymo’s driverless ride-sharing program, and had a clear-cut consensus over which option was better in terms of rider experience.

Dorsheimer visited Austin recently to ride in both Tesla’s Robotaxi ride-sharing program and Waymo, which has operated slightly longer than Tesla has in the city. Tesla started rides on June 22, while Waymo opened its vehicles to the public in March.

A Tesla Model Y L Robotaxi is a legitimate $47k Waymo killer

The analyst gave both platforms the opportunity to present themselves, and by the end of it, one was better than the other in terms of rider experience. However, he noted that both platforms gave safe and smooth rides.

Overall, there was a tremendous difference in the feel and environment of each option.

Tesla Robotaxi vs. Waymo

Dorsheimer said that Tesla’s first big advantage was vehicle appearance. Robotaxi uses no external equipment or hardware to operate; just its exterior cameras. Meanwhile, Zoox and Waymo vehicles utilize LiDAR rigs on their vehicles, which made them “stick out like a sore thumb.”

“In contrast, the robotaxis blended in with other Teslas on the road; we felt inconspicuous flowing with the traffic,” he added.

The next big victory went in the way of Robotaxi once again, and it concerned perhaps the most important metric in the ridesharing experience: price.

He continued in the note:

“Confirming our thesis, robotaxi was half the price of Uber, showing its ability to win market share by weaponizing price.”

In terms of overall performance, Dorsheimer noted that both platforms provided safe and “top-notch” experiences. However, there was one distinction between the two and it provided a clear consensus on which was better.

He said:

“In Austin, we took multiple robotaxi and Waymo rides; the contrast was clear. Aside from the visual difference between each pulling up to the curb, the robotaxi was comfortable and familiar, and it felt as though a friendly ghost chauffeur was driving our personal car. Driving was smooth and human-like, recognizing and patiently waiting for pedestrians, switching into less crowded lanes, patiently waiting to execute a safe unprotected turn, and yet, discerning and confident enough to drive through a light that just turned yellow, so as not to slam on the brakes.

Waymo also provided a top-notch service, and we did not encounter any safety concerns, but if we were to be overly critical, it felt more … robotic. In the cabin, you have to listen to an airline-esque preamble on Waymo and safety protocols, and during the ride, you can hear all the various spinning lidar sensors spooling up and down with electronic whizzing sounds.”

Tesla Robotaxi provides an experience that seems to be more catered toward a realistic ride experience. You can control the music, the cabin temperature, and transitioning your travel from one vehicle to the next during a trip will continue your entertainment experience.

If your first trip ends in the middle of a song, your next trip will pick up the music where it left off.

Meanwhile, Waymo’s experience sounds as if it is more focused on rider expectations, and not necessarily providing a ride that felt catered to the occupants. Still, what’s important is that both platforms provided safe rides.

Dorsheimer ended the note with one last tidbit:

“In short, robotaxi felt like a more luxurious service for half the cost and the driving felt more human-like.”

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Tesla offers new deal on used inventory that you won’t want to pass up

Tesla opened up lease deals on used Model 3 and Model Y inventory in California and Texas on Tuesday, marking the first time it has launched the option on pre-owned cars.

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3 hours ago

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August 20, 2025

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Credit: Tesla

Tesla is offering a new deal on its used vehicle inventory that consumers looking for a great deal won’t want to pass up.

Traditionally, Tesla has not allowed potential car buyers to lease its used inventory. The only two options were to buy with cash or finance it through Tesla or a bank.

However, with the elimination of the $7,500 new and $4,000 used EV tax credits, Tesla is breaking its own rules and is now offering lease deals on its used vehicle inventory, but only in a couple of states, as of right now.

Tesla is ready with a perfect counter to the end of US EV tax credits

Tesla opened up lease deals on used Model 3 and Model Y inventory in California and Texas on Tuesday, marking the first time it has launched the option on pre-owned cars.

The deals are tremendous and can cost as little as $0 down and under $225 per month for some vehicles.

Tesla also allows customers to buy the vehicle at the end of their lease deal, which enables some really great ways to end up an owner of the car you plan to drive for the next two or three years.

The lease deal also helps Tesla rid itself of older vehicles that might not be of future use to the company. It formerly planned to use leased vehicles in its eventual Robotaxi fleet, but many of the cars in its used inventory have Hardware 3, which is less capable than Hardware 4, which is installed in the new Model 3 and Model Y.

More importantly, Tesla is giving people yet another way to be in the market for a Tesla before the tax credit ends on September 30.

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Tesla Model Y L might not come to the U.S., and it’s a missed opportunity

The Model Y L has a variety of big changes that would be advantageous for the U.S. market, including a longer wheelbase, more comfortable seats, a third row that appears to be more spacious than Tesla’s six-seat Model Y that it previously offered, B-Pillar vents for rear passengers, and more.

Published

5 hours ago

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August 20, 2025

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Credit: Tesla China

Tesla’s new Model Y L might not come to the U.S., CEO Elon Musk said this morning.

It’s a missed opportunity, and I’m not the only one who feels this way.

In the past, I have personally written a handful of articles about what Tesla owners have been wanting in the United States: a full-sized SUV, or at least a vehicle that is larger than the Model Y but less of a crossover than the Model X.

Tesla is missing one type of vehicle in its lineup and fans want it fast

The only thing that Tesla has announced that even slightly matches this sort of idea is the Robovan, which is, optimistically, several years off because it lacks a steering wheel and pedals and will require Full Self-Driving to be fully autonomous.

Even if Tesla launches FSD next year, it will take a year or two to figure out manufacturing, go through regulatory hurdles with the EPA, and eventually enter mass production for customers.

The Model Y L has a variety of big changes that would be advantageous for the U.S. market, including a longer wheelbase, more comfortable seats, a third row that appears to be more spacious than Tesla’s six-seat Model Y that it previously offered, B-Pillar vents for rear passengers, and more.

However, Musk said it won’t come to the U.S. until next year, and that it “might not ever, given the advent of self-driving in America.”

To be blunt, I’m not sure if I truly believe that Musk thinks the Model Y L won’t come to the U.S. Some believe he said this to not Osborne Effect Model Y sales here, which seems more likely than anything.

Tesla Model Y L gets disappointingly far production date in the United States

People have been buying the Model Y for two years more than any other car in the world. To act as if many families would not appreciate the extra space seems very strange; a big complaint with the Model Y is that it simply does not fit larger families.

If you have four kids, you’re forced into the Model X, which might be too expensive for some families, as it starts at $79,990.

While Tesla’s focus is undoubtedly on autonomy, it is important to remember that some people still really enjoy the act of driving their cars. Tesla has worked very hard to create a fun and sporty driving experience, especially in the new Model Y. Many consumers, including myself, like to take advantage of that.

Autonomy might eventually take over human driving completely, but in the near term, it does not seem as if that is the case. Even if someone were interested in never driving again, this longer and more spacious Model Y L would be an ideal option for American families that need the room for at least six passengers.

Quite a few big names in the Tesla community share this sentiment:

More than likely, Musk does not want to announce a more attractive option than the current Model Y, as many consumers would likely wait a year or two for the L in an effort to have more space.

In all honesty, I see the Model Y L coming to the United States, as it truly fits the bill as an ideal car for the modern American family.

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