News
Ex-SpaceX engineer leads Stratolaunch to major rocket engine test milestone
Led by rocket propulsion expert Jeff Thornburg, Stratolaunch – famous for owning the largest fixed-wing aircraft ever built – has completed the first hot-fire test of a full-scale rocket engine component known as the preburner, a major milestone in the development of any launch vehicle or propulsion system.
Despite the significant size and power of the component, destined to support an engine that will generate 200,000 pounds (~900 kN) of thrust, Thornburg and his team of engineers and technicians have managed to go from designing the preburner to successfully hot-firing a full-scale test article, an extraordinary achievement by any measure.
The team made amazing progress this week! Check out the #PGAEngine preburner’s first hot-fire test at @NASAStennis. #NewUSEngine pic.twitter.com/kKTnf0bj1S
— Stratolaunch (@Stratolaunch) November 6, 2018
Aside from SpaceX, Blue Origin, and Aerojet-Rocketdyne, Stratolaunch is the only private entity developing – let alone testing full-scale parts for – a liquid-fueled rocket engine as large as PGA. Shorthand for the Stratolaunch’s late founder and bankroller Paul G. Allen, PGA is a fuel-rich staged combustion cycle engine that uses liquid hydrogen and oxygen (hydrolox) fuel and oxidizer, typically resulting in high efficiency. In terms of scale and thrust, PGA is very closely comparable to SpaceX’s Merlin 1D engine, which uses kerosene instead of hydrogen but produces roughly 190,000 lbf (850 kN) of thrust and stands 4 feet (1.2m) wide and ~10 feet (~3m) tall.
Another major difference between PGA and Merlin 1D is the fact Merlin 1D’s nozzle is largely optimized for sea level while PGA is being built for a rocket that will be “launched” from a massive plane flying around 35,000 feet (~10.5 km), ultimately resulting in a nozzle that is much wider and longer, featuring nearly the same proportions as fully vacuum-optimized engines like SpaceX’s MVac. By widening the nozzle relative to the rest of the engine, rocket engines are able to operate far more efficiently at higher altitudes, where Earth’s atmosphere thins and exerts less pressure on the escaping exhaust gases. This is visualized well by the visible expansion of rocket exhausts during launches, morphing from a straight cylinder to a massive teardrop-shaped plume. At lower altitudes (and thus higher atmospheric pressures), wider nozzles can produce extreme turbulence and will ultimately shake themselves to destruction, preventing their usage on ground-launched rocket boosters.
Judging from official renders of the engine, PGA’s in-atmosphere variant appears to utilize a form of regenerative nozzle cooling very similar to that used on M1D, where liquid propellant flows through thin capillaries sandwiched between two or more layers of metal to cool the nozzle much like cold water chills the skin of an uninsulated water bottle.
- A to-scale comparison of Falcon 1, Pegasus XL, MLV, and Falcon 9. (Teslarati/Stratolaunch/Wikipedia)
- A render of Stratolaunch’s impressive PGA engine. Note the giant nozzle relative to the throat. (Stratolaunch)
Testing rocket engine preburners
In the case of staged combustion cycle hydrolox rocket engines, a small portion of liquid oxygen and all of the liquid hydrogen (hence “fuel-rich”) are mixed and combusted to generate hot gas that then spools up the engine’s primary turbopump(s), ultimately drawing fuel and oxidizer into the combustion quickly enough to ignite the engine and generate sustained thrust. The components that get those main turbopumps started are known collectively as the preburner, which is what Stratolaunch successfully tested – at full-scale – for the first time ever last week. For any liquid rocket engine that cannot solely rely on propellant tank pressure to deliver fuel to the combustion chamber, full-scale tests of preburners or gas-generators effectively mark the moment that engines truly become real.
“This is the first step in proving the performance and highly efficient design of the PGA engine. The hot-fire test is an incredible milestone for both the propulsion team and Stratolaunch.” – Jeff Thornburg, VP of Propulsion, Stratolaunch
Stratolaunch’s propulsion team will continue to test the preburner for longer durations and at higher power levels over the next several months, likely optimizing operations and tweaking or upgrading the preburner’s hardware as real tests produce valuable lessons-learned. Built entirely with additive manufacturing (3D printing), the team should be able to rapidly iterate on the physical design of the engine, a rarity in a field where traditional fabrication methods can take weeks or months to produce complex turbomachinery components with mercilessly strict tolerances.
According to Thornburg, the ultimate goal is to continue that additive-manufacturing-only strategy throughout the development of this rocket engine, theoretically enabling unprecedented design flexibility while also slashing production time throughout. PGA will ultimately power the creatively-named Medium Launch Vehicle (MLV), a small-ish air-launched rocket designed to place a respectable 3400 kg into low Earth orbit (LEO) as early as 2022, as well as a Heavy version of MLV and, potentially, a reusable spaceplane somewhere down the line.
- PGA’s first full-scale preburner seen during assembly. (Stratolaunch)
- PGA’s first full-scale preburner seen during assembly. (Stratolaunch)
- Jeff Thornburg stands in front of Stratolaunch’s NASA Stennis Space Center test stand. (Stratolaunch)
- The PGA preburner seen after installation at Stennis. (Stratolaunch)
- The control center. (Stratolaunch)
- MLV is released from Stratolauncher. (Stratolaunch)
- A concept video produced by Stratolaunch shows the Roc launching a Kraken rocket. (Stratolaunch, via Wired)
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News
Tesla ships ‘spooky’ Halloween Mode with creepy and fun features
Tesla is now starting to ship a “Halloween Mode” that is filled with some creepy and fun features; the company says, “This spooky update turns your Tesla into a haunted house on wheels.”
The update is just the latest in a series of updates that Tesla typically ships out in a seasonal fashion. The Spring and Summer Updates provided some fun novelty items while also packing some cool features that are actually useful for the ownership experience.
This one seems to be more fun-forward, and there are not any updates to the Full Self-Driving suite or overall operation of the vehicle. Instead, these novelty features are geared toward getting you in the mood for the Fall and Halloween.
Halloween Mode now rolling out 🎃
This spooky update turns your Tesla into a haunted house on wheels
– Ghost costume on your car’s avatar
– Enable Trick or Treat to play spooky sounds & flicker the lights when visitors approach
– New haunting light show, wraps & lock sound
– A rather chilling Photobooth
– Frighten people remotely by speaking through the app…your car will say it in a voice of its own
Side effects may include neighborhood notoriety
— Tesla (@Tesla) October 6, 2026
New Ghost Costume on Car Avatar
Driver Visualization will now show your vehicle as a ghost, as an all-white sheet is draped over the vehicle. Pedestrians are turned into mummies or skeletons, and other vehicles are all a spooky green:

Credit: Tesla
Additionally, the Park Scene with your Tesla now displays that ghost costume draped over your vehicle in the foreground of a scary backdrop with Jack-o-Lanterns and a haunted house:

Credit: Tesla
Trick or Treat Mode
Trick or Treat Mode will enable the vehicle to play spooky sounds and flicker the lights as visitors approach. This might be a nice touch for when you’re handing out candy to kids on Halloween Night.
Other Features
Tesla is also adding a new Light Show, new Wrap Options, and a new Lock Sound with this update.

Credit: Tesla
Additionally, Photobooth has a new Halloween option:

Credit: Tesla
You will also be able to speak remotely through the app and transmit your voice to people outside, which is not a new feature, but the car will say it in a voice of its own, which is a new feature with that bullhorn-like feature.
Investor's Corner
SpaceX reveals how its 1 Million AI satellite network will work and prevent space collisions
SpaceX reveals plans for one million Starmind AI satellites and calls out operators hiding maneuvers.
SpaceX has put the largest satellite count it has ever published into writing, and it says that plan only works if every other operator in orbit starts sharing what it knows.
In a new Space Safety page highlighted Tuesday morning by Sawyer Merritt on X, SpaceX said it “plans to operate up to 100,000 Starlink satellites and up to 1 million Starmind AI satellites to meet the growing demand for broadband and supercompute.” Starlink has a little over 11,000 satellites in orbit today, so the target alone implies roughly a ninefold expansion of the broadband network.
Starmind is SpaceX’s orbital AI compute constellation. Elon Musk confirmed the Starmind name in June after an xAI trademark filing surfaced, and in August SpaceX said it was working with Nvidia on the compute payload. The FCC accepted the filing for up to one million satellites back in February.
FCC accepts SpaceX filing for 1 million orbital data center plan
SpaceX also released a new render of what a full Starmind constellation could look like. Alongside it, SpaceX VP Michael Nicolls explained why the satellites will not operate on their own. “We need to operate clusters of satellites in tight formation to get enough coherent compute to run AI models efficiently,” Nicolls said. “A cluster will be 10-ish satellites connected with 10 terabits or so of bandwidth between them, and interconnected to the broader constellation.”
That is the most specific detail SpaceX has given on how Starmind will be built. Instead of a million independent servers, the network would work as tightly packed groups of about 10 satellites acting as one compute unit, with Starlink’s laser links carrying results back to Earth.
There is a bright and exciting future for humanity ahead – and space is fundamental to that future.
To achieve this, space safety must be done right. We encourage every operator to not only share ephemeris data proactively the same way Starlink already does, but to also adopt the high standards of space safety that SpaceX and Starlink use every day → https://t.co/QizAkQZvEm
— Starlink (@Starlink) October 6, 2026
Packing satellites that close together, at that scale, makes collision avoidance the central problem, and most of the Space Safety page is aimed at other operators. SpaceX said Starlink encountered collision risks with about 650 unique maneuvering third party satellites in 2026, and only about half of them shared data. Over six months, Starlink recorded roughly 164,000 more collision risks where the closest approach came within four hours of an unannounced maneuver.
Some operators keep maneuver plans private over proprietary concerns, while others cannot get government permission to share them. SpaceX called those policies “counterproductive,” saying they “largely only serve to create preventable collision risk between satellites.” Starlink is also offering a free ephemeris sharing and screening platform that returns risk results within a minute, backed by its Stargaze network of 30,000 optical sensors.
The push comes as the Starmind application draws opposition from astronomers and environmental groups. In a September filing with the FCC, SpaceX said each Starmind satellite could weigh up to 4,000 kg, nearly seven times the mass of a Starlink V2 Mini. Musk has brushed off crowding concerns before, telling viewers in June that “space is enormous” and that SpaceX already knows how to run very large constellations safely.
SpaceX’s Starmind page says its Gigasat factory in Bastrop, Texas, is designed to produce AI satellites at scale, with deployment of thousands of units starting as soon as late 2027.
News
Five things that are keeping Tesla Full Self-Driving supervised
Tesla Full Self-Driving is really good. I have used it for over 76 percent of my driving since FSD v14 launched around this time last year, equating to about 76 percent of my miles using the suite. It’s truly the only way I prefer to travel, but admittedly I save some of the more fun drives for myself.
Even with all of the great things it has done for me, including saving me from being involved in an accident, there are still a handful of things that it needs to improve on. These issues recur from update to update, and while there have been some improvements, they still give me reasons to either soft or hard intervene.
A soft intervention means an adjustment that is needed without disengaging the suite, like manually using a turn signal to change lanes while the car still operates on FSD. What I’d consider to be a “hard intervention” is anything that requires me to disengage the suite altogether, like missing a turn or performing a maneuver I’m uncomfortable with. Of course, some hard interventions will be subjective.
Here are the five things I’d like to see Tesla really focus on through the final versions of v14 and hope to see completely improved with v15.
Speed Limit Recognition and Adjustment
There are entirely too many instances of FSD traveling at a speed that is just totally outrageous. While some of these events can occur on Hurry Mode, I’ve even had issues with it on Standard from time to time, and despite wanting more aggressive maneuvers or a slight bit of urgency, I don’t want to worry about getting a ticket while doing it.
The two areas I notice it the most are in school zones and on local roads. When a Speed Limit changes from 45 to 35, FSD does not always slow down in a way that would appease local law enforcement. On Hurry, 52-55 is pretty standard for a rate of travel in a 45 MPH zone. When it changes to 35, FSD shows zero urgency to slow down to an appropriate speed.
School Zones have been a true pain point, and as recently as last week, I had an issue with it:
Threw FSD into Sloth to see how it handled this school zone. You can see well before I enter it, the car is traveling 34 MPH, one MPH under the limit.
Still not slowing down nearly enough.
@Tesla_AI, not 25, not 30…15 MPH in School Zones https://t.co/YQuQ8ydhKh
— TESLARATI (@Teslarati) September 29, 2026
Realistically, most Speed Limit issues are a soft intervention, as I simply scroll into a slower Speed Profile to get the car to slow down. School Zones are a hard intervention, as they require me to completely take over and travel at the posted 15 MPH limit. Even on Sloth, it simply does not get down to a low enough speed.
Parking
Parking is one thing that has really improved over time, but there are still some pretty considerable hoops Tesla needs to jump through to get it to a point where it can be unsupervised.
Parking preferences seem to be where a lot of these issues will be resolved, as most of my complaints come from the fact that the place FSD chooses to park are usually not where I would personally choose to park. This morning, for example, when I arrived at the gym, FSD chose to park next to a vehicle that was parked with its two tires in the spot that FSD picked.
This is a big reason Parking Preferences with Supervised FSD will be so valuable.
If possible, parking a little further away and being distant from people like this is worth it. https://t.co/3Ac71KQiQ3
— TESLARATI (@Teslarati) June 7, 2026
There were three spots in between that car and the nearest car, so FSD could have chosen the spot that would have given a one-spot buffer between the two vehicles. In a parking lot full of empty spots, don’t be that guy who parks next to a car.
Generally, parking performance is vastly improved from where it was a year ago; I rarely am adjusting how it pulls or backs into a spot on v14.3.10, but in earlier versions, I definitely had my problems. It’s gotten really good since, and this version has been the best in terms of parking performance. It’s more about the places FSD choose to park, and not necessarily the parking itself.
There are also no options or map data to allow you to choose a charger at a place like a grocery store if it offers charging. These are things that are a bit more complex, but they will be needed for unsupervised FSD operation.
Navigation
Navigation was always going to be on this list, simply because it is one of the most inconsistent and mind-boggling things about FSD. Even after a year of intervening, sending voice notes, and overriding decisions, FSD still tries to take me out of my neighborhood the wrong way. You cannot turn left out of my neighborhood’s main entrance and exit, only right. Navigation still prompts a left turn out of my neighborhood’s main entrance and exit, instead of going around the neighborhood and exiting where a left turn is legal.
Tesla rolled out Preferred Routes with the Summer Update, and this has resolved some of the issues. I also found my own personal workaround:
🚨See if this cool Tesla Navigation Hack works for you!
I have used it to get out of my neighborhood legally with FSD, thus enabling completely hands-free drives! https://t.co/DlDsCQjxRI
— TESLARATI (@Teslarati) July 16, 2026
Some of the more mind-boggling things that FSD used to do with Navigation have been remedied, but it is still a frequent complaint for me and many other owners. I’d just like to see it adopt those preferred routes more frequently and maybe learn them a little faster.
Certain Highway Behaviors
Highway travel is the most consistent and perhaps FSD’s best use case. There is nothing better than having FSD handle busy highway traffic or just long, monotonous, and boring drives. I love to use it for my trips to the Flight 93 Memorial where I volunteer. When I drove manually, I chose to get a hotel and stay overnight because it’s about a 2.5 hour drive. FSD lets me make the drive, put in a volunteering shift, and drive home, without much fatigue. I have found that this is where FSD is most valuable for me, personally.
However, there are a few things FSD does on the highway that are just weird.
One thing I’ve had issues with as of late is that there will be times when I’m about a mile from my exit, the car is in the left lane and is traveling faster than the traffic in the cruising late. Instead of completing a pass and then getting over with no traffic ahead, the car will sometimes drastically and suddenly slow down, switch to the slow lane, and get behind a vehicle — all with a mile until the exit. On average, I’ll have around one minute from the time I get to my exit if it’s a mile away, because in most cases, I’m traveling somewhere around 60 MPH on the highway.
There is no reason to not complete that last pass, then get into the right lane, and have an unobstructed path to the exit. This is one of the more strange behaviors I’ve seen it do, and it really does feel like a bug. Here’s an example of it from FSD v14.3.7:
🚨 Tesla FSD v14.3.7 did nearly the exact opposite — nearly 2.5 miles before the exit it got over into the slow lane and got behind much slower traffic.
Now, v14.3.8, anecdotally, waited til the last minute to get off the highway https://t.co/Lc9vAKDyQC
— TESLARATI (@Teslarati) August 29, 2026
I ended up overriding the turn signal and using the accelerator to nudge the car to do what I wanted it to do. There was no reason to get in the left lane and add to the congestion in that lane.
Another thing that FSD does frequently is camps in the left lane, especially on Hurry. Cruising in the passing lane is illegal in Pennsylvania, and I know it is not a crime to do that everywhere. However, it is here, and I really wish the car was a little quicker to get over in the left lane when it’s cruising.
Here’s a pretty drastic example I had just a couple weeks back:
Recognizing Drastic Changes in Road Condition
I think anyone who has ever used FSD knows that potholes are a huge issue, but so are large bumps or sudden changes in road condition. At the intersection of Kreutz Creek Rd. and Rt. 462 in Hellam, PA the roads are nearly set up as a ramp, and going over it at a speed of over 35 MPH can send your head into the glass roof, your butt off your seat, and a brace for the sudden thud that is inevitably coming when you finally touch back down again.
You can see here I tried to change Speed Profiles quickly, but I did it a tad too late:
This is that big bounce that I mentioned in the quoted post.
It’s just a tad too drastic to take at the speed FSD wants to go over it. You can see me quickly swipe down into Sloth, but I intervened. https://t.co/81Oc82ZJcZ
— TESLARATI (@Teslarati) August 2, 2026
There are other roads in my area that should not be taken at even the posted Speed Limit because of the damage it could do to your car. Here’s another, where I disengaged FSD altogether:
🚨 I’ve talked in the past about my struggles with FSD when large bumps or sudden changes in sloping are approaching.
Today I tried switching down into Sloth from Standard but I did it a tad too late and I had to take over. You can see this isn’t a bump you take at 35 MPH https://t.co/f4tK13hsz1
— TESLARATI (@Teslarati) September 6, 2026
The recognition of these bumps is so crucial for two main reasons: they can cause injury, and they can cause damage to the car. These are reasons why the suite is supervised and drivers should remain attentive. I could not imagine going over that bump at an excessive speed if I had back issues, or if I were older.
Potholes are rarely recognized and usually require a lead car to avoid them. I had FSD use a lead car to avoid a pretty sizeable manhole cover a few weeks back:
🚨 Interesting observation on FSD v14.3.8 – Make note of the van in front of me as it swerves out of the way of a sewer cover
FSD followed this behavior, but interestingly did not swerve for the next sewer cover
What do we make of this? https://t.co/RO19941AIP
— TESLARATI (@Teslarati) September 2, 2026
Tesla says that there are improvements coming for potholes, so hopefully that means these bumps will also be recognized consistently.








