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SpaceX begins testing first flightworthy Super Heavy booster
More than three months after the building-sized Starship booster’s latest return to Starbase’s orbital launch site, SpaceX has finally begun the process of testing what CEO Elon Musk says is still the first flightworthy Super Heavy.
After completing a number of pad tests in the days prior, SpaceX began filling Super Heavy Booster 4 (B4) with liquid nitrogen – supplied by the first orbital-class Starship launch – for the first time on December 17th. It’s unclear exactly what was done during the test but regardless of what transpired, the test and B4’s survival were a major, long-awaited milestone for both the Starship booster and the orbital launch site (OLS).
At this point in time, the general consensus among close followers of SpaceX’s Starship program is that the unprecedented amount of time it’s taken the company to complete Booster 4’s first test was not because of the rocket itself but rather because the orbital launch site needed to fully test it had yet to be completed. While it was SpaceX’s choice to not perform some kind of initial testing with B4 at one of the site’s two suborbital test and launch mounts, it’s clear that the company ultimately concluded that Super Heavy Booster 3’s successful July 2021 tests – including a cryogenic proof virtually identical to Booster 4’s first test – made such partial testing redundant.
Put a different way, SpaceX must already be confident enough in the quality of the first few Super Heavies rolling out of its Starbase factory to deem it unnecessary to verify the structural integrity of the first truly completed Super Heavy booster before putting the one and only orbital Starship launch site directly in the line of fire. Nonetheless, depending on how far Super Heavy Booster 4’s first cryogenic proof test went, it appears that SpaceX’s presumptions were correct.
On December 17th, SpaceX subjected Super Heavy B4 to a cryogenic proof test about twice as ambitious as B3’s, filling the booster maybe a sixth of the way with a few hundred tons of liquid nitrogen (LN2). What isn’t clear is if that test also raised the booster’s propellant tanks to flight pressures (6-8 bar or 90-115 psi). If Booster 4 did reach those pressures, the test is even more significant – partially proving that the rocket is ready for flight. On December 21st, SpaceX performed a similar series of cryogenic tests, again partially filling Booster 4 with about the same amount of liquid nitrogen but doing so two or three times in a row. Again, the Super Heavy survived the several-hour ordeal without any obvious issues. Still, a number of additional tests – some even more important – are still in front of SpaceX and Super Heavy B4.
The most obvious is simple enough: SpaceX needs to fully fill a Super Heavy booster for the first time. Depending on the storage situation, that process will likely begin by filling Booster 4 with about 2500 tons (5.5M lb) of liquid nitrogen (LN2) – about two-thirds full. If SpaceX also temporarily fills one of the orbital tank farm’s liquid oxygen (LOx) or methane (LCH4) tanks with nitrogen, it could fully load Booster 4 with around 3500 tons (7.7M lb) of nitrogen. At least according to SpaceX’s own website, that’s about the same weight as the propellant (3400t/7.5M lb) Super Heavy is designed to lift off with. If that full cryoproof goes well, SpaceX will then likely perform one or several wet dress rehearsals, ultimately filling Booster 4 with approximately 2900 tons (6.4M lb) of cryogenic oxygen and 500 tons (1.1M lb) of cryogenic methane.
Finally, SpaceX will probably kick off static fire testing, likely beginning by igniting just one or a few of Super Heavy’s many engines. Eventually, that process could culminate in the ignition of all 29 of Booster 4’s Raptors, briefly producing a bit less than 5400 tons (~11.9M lbf) of thrust – 50% more powerful than NASA’s retired Saturn V Moon rocket.
According to Elon Musk, despite a number of recent signs and reports to the contrary, SpaceX still intends to fly Booster 4 and Ship 20 on Starship’s first orbital-velocity launch attempt, so the scope and scale of testing are only likely to grow over the next several weeks.
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Tesla hosts Rome Mayor for first Italian FSD Supervised road demo
The event marked the first time an Italian mayor tested the advanced driver-assistance system in person in Rome’s urban streets.
Tesla definitely seems to be actively engaging European officials on FSD’s capabilities, with the company hosting Rome Mayor Roberto Gualtieri and Mobility Assessor Eugenio Patanè for a hands-on road demonstration.
The event marked the first time an Italian mayor tested the advanced driver-assistance system in person in Rome’s urban streets. This comes amid Tesla’s push for FSD’s EU regulatory approvals in the coming year.
Rome officials experience FSD Supervised
Tesla conducted the demo using a Model 3 equipped with Full Self-Driving (Supervised), tackling typical Roman traffic including complex intersections, roundabouts, pedestrian crossings and mixed users like cars, bikes and scooters.
The system showcased AI-based assisted driving, prioritizing safety while maintaining flow. FSD also handled overtakes and lane decisions, though with constant driver supervision.
Investor Andrea Stroppa detailed the event on X, noting the system’s potential to reduce severe collision risks by up to seven times compared to traditional driving, based on Tesla’s data from billions of global fleet miles. The session highlighted FSD’s role as an assistance tool in its Supervised form, not a replacement, with the driver fully responsible at all times.
Path to European rollout
Tesla has logged over 1 million kilometers of testing across 17 European countries, including Italy, to refine FSD for local conditions. The fact that Rome officials personally tested FSD Supervised bodes well for the program’s approval, as it suggests that key individuals are closely watching Tesla’s efforts and innovations.
Assessor Patanè also highlighted the administration’s interest in technologies that boost road safety and urban travel quality, viewing them as aids for both private and public transport while respecting rules.
Replies on X urged involving Italy’s Transport Ministry to speed approvals, with one user noting, “Great idea to involve the mayor! It would be necessary to involve components of the Ministry of Transport and the government as soon as possible: it’s they who can accelerate the approval of FSD in Italy.”
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Tesla FSD (Supervised) blows away French journalist after test ride
Cadot described FSD as “mind-blowing,” both for the safety of the vehicle’s driving and the “humanity” of its driving behaviors.
Tesla’s Full Self-Driving (Supervised) seems to be making waves in Europe, with French tech journalist Julien Cadot recently sharing a positive first-hand experience from a supervised test drive in France.
Cadot, who tested the system for Numerama after eight years of anticipation since early Autopilot trials, described FSD as “mind-blowing,” both for the safety of the vehicle’s driving and the “humanity” of its driving behaviors.
Julien Cadot’s FSD test in France
Cadot announced his upcoming test on X, writing in French: “I’m going to test Tesla’s FSD for Numerama in France. 8 years I’ve been waiting to relive the sensations of our very first contact with the unbridled Autopilot of the 2016s.” He followed up shortly after with an initial reaction, writing: “I don’t want to spoil too much because as media we were allowed to film everything and I have a huge video coming… But: it’s mind-blowing! Both for safety and for the ‘humanity’ of the choices.”
His later posts detailed FSD’s specific maneuvers that he found particularly compelling. These include the vehicle safely overtaking a delivery truck by inches, something Cadot said he personally would avoid to protect his rims, but FSD handled flawlessly. He also praised FSD’s cyclist overtakes, as the system always maintained the required 1.5-meter distance by encroaching on the opposite lane when clear. Ultimately, Cadot noted FSD’s decision-making prioritized safety and advancement, which is pretty remarkable.
FSD’s ‘human’ edge over Autopilot
When asked if FSD felt light-years ahead of standard Autopilot, Cadot replied: “It’s incomparable, it’s not the same language.” He elaborated on scenarios like bypassing a parked delivery truck across a solid white line, where FSD assessed safety and proceeded just as a human driver might, rather than halting indefinitely. This “humanity” impressed Cadot the most, as it allowed FSD to fluidly navigate real-world chaos like urban Paris traffic.
Tesla is currently hard at work pushing for the rollout of FSD to several European countries. Recent reports have revealed that Tesla has received approval to operate 19 FSD test vehicles on Spain’s roads, though this number could increase as the program develops. As per the Dirección General de Tráfico (DGT), Tesla would be able to operate its FSD fleet on any national route across Spain. Recent job openings also hint at Tesla starting FSD tests in Austria. Apart from this, the company is also holding FSD demonstrations in Germany, France, and Italy.
Tesla Optimus showed off its newest capability as progress on the project continues to accelerate toward an ultimate goal of mass production in the coming years.
Tesla is still developing Optimus and preparing for the first stages of mass production, where units would be sold and shipped to customers. CEO Elon Musk has always marketed the humanoid robot as the biggest product in history, even outside of Tesla, but of all time.
He believes it will eliminate the need to manually perform monotonous tasks, like cleaning, mowing the lawn, and folding laundry.
However, lately, Musk has revealed even bigger plans for Optimus, including the ability to relieve humans of work entirely within the next 20 years.
JUST IN: Elon Musk says working will be ‘optional’ in less than 20 years because of AI and robotics. pic.twitter.com/l3S5kl5HBB
— Watcher.Guru (@WatcherGuru) November 30, 2025
Development at Tesla’s Artificial Intelligence and Robotics teams has progressed, and a new video was shown of the robot taking a light jog with what appeared to be some pretty natural form:
Just set a new PR in the lab pic.twitter.com/8kJ2om7uV7
— Tesla Optimus (@Tesla_Optimus) December 2, 2025
Optimus has also made several public appearances lately, including one at the Neural Information Processing Systems, or NeurIPS Conference. Some spectators shared videos of Optimus’s charging rig, as well as its movements and capabilities, most interestingly, the hand:
You have to hand it to Elon 🤟 pic.twitter.com/fZKDlmGAbe
— Ric Burton · NeurIPS 2025 (@_ricburton) December 2, 2025
The hand, forearm, and fingers have been one of the most evident challenges for Tesla in recent times, especially as it continues to work on its 3rd Generation iteration of Optimus.
Musk said during the Q3 Earnings Call:
“I don’t want to downplay the difficulty, but it’s an incredibly difficult thing, especially to create a hand that is as dexterous and capable as the human hand, which is incredible. The human hand is an incredible thing. The more you study the human hand, the more incredible you realize it is, and why you need four fingers and a thumb, why the fingers have certain degrees of freedom, why the various muscles are of different strengths, and fingers are of different lengths. It turns out that those are all there for a reason.”
The interesting part of the Optimus program so far is the fact that Tesla has made a lot of progress with other portions of the project, like movement, for example, which appears to have come a long way.
However, without a functional hand and fingers, Optimus could be rendered relatively useless, so it is evident that it has to figure this crucial part out first.
Tesla hosts Rome Mayor for first Italian FSD Supervised road demo
Tesla FSD (Supervised) blows away French journalist after test ride
