LNG: TESLARATI

After operating in stealth mode for the past two years, Neuralink, the brain-machine interface startup co-founded by SpaceX and Tesla CEO Elon Musk, has revealed some of the innovations that it has been developing. The company also announced that it is aiming to start implanting devices in humans by 2020, starting with paralyzed individuals who could then control phones or computers through their brain-machine implants. 

Neuralink focused on two innovations on Tuesday’s presentation. The first involved flexible “threads” that are incredibly thin, measuring between 4 and 6 μm or about 1/3 the diameter of human hair. These threads are capable of transferring high volumes of data, with a white paper published by the company hinting at “as many as 3,072 electrodes per array distributed across 96 threads.” With the threads being incredibly thin, they would not damage the brain. 

Another key technology revealed by Neuralink on its recent presentation was a custom made robot designed to embed implants into the brain. Thanks to computer vision and lenses, the robot will be able to place implants on patients without hitting or damaging blood vessels, reducing damage to the brain and scar tissue. Neuralink researcher Philip Sabes noted that “because these things are so thin and flexible, the idea is that they move with the tissue instead of tearing the tissue.”  

Neuralink has performed at least 19 surgeries on animals with its robots, and so far, the machines have successfully placed the threads about 87% of the time. One of these subjects, a rather hefty rat that was shown off to the press, was fitted with a wired prototype of the company’s brain-machine interface. During the press demo, Sabes mentioned that the amount of data gathered from the rodent was about ten times greater than what is possible with today’s sensors. 

In his presentation, Elon Musk stated that the evolution of Neuralink’s tech would be gradual, though he did mention that the company’s goal is a form of “symbiosis” with technology. “It’s not going to be suddenly Nueuralink will have this neural lace and start taking over people’s brains. This is going to sound pretty weird, but ultimately, we will achieve symbiosis with artificial intelligence. This is not a mandatory thing. It is a thing you can choose to have if you want. This is something that I think will be really important on a civilization-level scale,” he remarked. 

While the technologies shared by Neuralink on Tuesday seemed borderline science fiction, Neuralink president Max Hodak noted that similar innovations have actually been introduced and implemented in the past. “Neuralink didn’t come out of nowhere; there’s a long history of academic research here. We’re, in the greatest sense, building on the shoulders of giants,” he said. Nevertheless, Neuralink’s goal of directly reading neural spikes in a minimally-intrusive way remains notably ambitious.

The potential for such technologies is enormous. Implants such as BrainGate, which was developed initially at Brown University, were used in cases such as those of Matthew Nagle, who suffered from a spinal cord injury. Back in 2006, Nagle was able to learn how to use a computer using brain implants, at one point even playing Pong with his mind. In its presentation, Neuralink noted that its brain implants could be used for several individuals afflicted by Parkinson’s Disease, Dystonia, Epilepsy, OCD, Depression, Chronic Pain, and Tinnitus, among many. 

Yet, despite its impressive innovations and its lofty goals, it should be noted that Neuralink is still a long way from achieving its targets. Dr. Matthew MacDougall, head surgeon at Neuralink, mentioned this while discussing how Neuralink implants could be as seamless as Lasik in the future. “There is a whole FDA process we have to go though. We haven’t done that yet,” he said. 

So why the presentation? As noted by Elon Musk, Tuesday’s event is, at its core, an invitation for interested individuals who would like to work on the innovations that Neuralink is pursuing. With this open invitation, it would not be surprising if the company attracts an impressive number of talent in the near future. But now it’s time for you to vote. Will you be open to getting a brain-machine interface implant from Neuralink in the future?

SpaceX’s Starhopper was engulfed in a fireball shortly after a static fire ignition of its Raptor engine, almost certainly delaying the low-fidelity Starship prototype and testbed’s first untethered flight.

With any luck, Raptor, Starhopper, and SpaceX’s spartan Boca Chica facilities have escaped relatively unharmed. Regardless, even if Raptor’s static fire was technically successful, some repairs will likely be necessary and the off-nominal behavior that occurred after the ignition test will have to be dealt with and understood to prevent such behavior during future Starhopper operations.

Aside from the anomalous behavior after the test, Starhopper’s Raptor static fire looked downright brutal from local livestreams hosted by LabPadre and several other onlookers.

Due to the inherently low quality of video captured through thousands of feet of thick, humid Texas air, it’s almost impossible to make specific details out. However, shortly after the static fire ignition and shutdown, some viewers believe that there was fire visible at one or several points on Starhopper, although what looks like fire could easily be a simple reflection of the active flare stack just a few hundred feet away.

By all appearances, the anomaly looks much worse than it was. More likely than not, some sort of leak began during or after Raptor’s static fire test, creating a cloud of gaseous oxygen and methane that was eventually ignited by either the latent heat of Raptor components or a fire somewhere on or around the vehicle. What’s important is that Starhopper appears to be fully intact after the incident, meaning that SpaceX should still be able to detank and safe the vehicle and analyze it to figure out what went wrong. Watch live as the rocket is safed and technicians (hopefully) begin to arrive on-site to begin inspections.

Check out Teslarati’s newsletters for prompt updates, on-the-ground perspectives, and unique glimpses of SpaceX’s rocket launch and recovery processes.

10:00 pm CDT

Per NASASpaceflight.com, Starhopper’s static fire ignition is approximately 30 minutes away (10:30 pm CDT).

9:15 pm CDT

Starhopper has begun venting, a sign that propellant loading is proceeding apace. Nominally, this is a strong indicator that the SpaceX prototype is roughly an hour out from a planned Raptor static fire ignition test. 

#Starhopper continues to vent like crazy as tanks fill up and systems chill down ahead of tonights static fire. @NASASpaceflight pic.twitter.com/QIS8h12dDv

— Jack Beyer (@thejackbeyer) July 17, 2019

Fire crews are on standby in Boca Chica, Texas, where SpaceX’s Starhopper is believed to be a few hours away from performing a full ignition and static fire test. If all goes well, July 15th’s Starhopper static fire will be a big step towards the low-fidelity Starship prototype’s first untethered flight, a hover test that could see the craft fly up to 20 meters (65 ft) off the ground, hold steady, and then return back to its pad for a (hopefully) soft landing.

Sounds like fueling has started.

— Mary (@BocaChicaGal) July 17, 2019

Bumpty bump for the streaming options. No absolute certainty of a Static Fire tonight, but let’s all have a fun evening of shouting webstream observations like «Flare Stack! Venting out the bottom. Venting out the top. Ooooh, massive flare stack!» 😂 https://t.co/IPDZFaYOSP

— Chris B – NSF (@NASASpaceflight) July 17, 2019

The data gathered from Starhopper – cobbled together out in the South Texas elements with thick stainless steel and parts snagged from SpaceX’s own Falcon 9 rockets – will be useful, given that it will technically be the first time SpaceX flies a rocket built out of steel, but the hover test will be even more significant as a milestone for Raptor itself.

SpaceX has announced via an official update and conference call the preliminary results of a failure investigation convened immediately after Crew Dragon capsule C201 exploded in the midst of an April 20th static fire test.

Hosted by SpaceX Vice President of Mission Assurance Hans Koenigsmann and NASA Commercial Crew Program manager Kathy Lueders, the call provided some minor additional insight beyond a fairly extensive press release issued just prior. According to the preliminary results from SpaceX’s failure investigation, Crew Dragon’s explosion was unrelated to the spacecraft’s propellant tanks, Draco maneuvering thrusters, or SuperDraco abort engines. Rather, the cause lies in a more exotic and unanticipated chemical/material interaction between a plumbing valve, liquid oxidizer, and a helium-based pressurization system.

When metal burns

According to Hans Koenigsmann, SpaceX is approximately 80% of the way through what is known as the fault tree, essentially meaning that the failure investigation is 80% complete. That additional 20% could certainly throw some curveballs but the SpaceX executive was fairly confident that the results presented on July 15th would be representative of the final conclusion.

The ultimate (likely) cause of Crew Dragon’s extremely energetic and destructive explosion centers around the spacecraft’s extensive SuperDraco/Draco plumbing and its associated pressurization system, which uses helium to keep the pressure-fed engines, propellant tanks, and feed lines around 2400 psi (16.5 megapascals). Necessarily, this method of pressurization means that there is direct contact between the pressurant (helium) and the oxidizer/fuel, thus requiring some sort of valve preventing the pressurized fluid from flowing into the pressurization system.

During flight-proven Crew Dragon capsule C201’s April 20th static fire testing, that is reportedly exactly what happened. Over the course of ground testing, a “check valve” separating the pressurization system and oxidizer leaked what SpaceX described as a “slug” of nitrogen tetroxide oxidizer (NTO) into the helium pressurization lines. Around T-100 milliseconds to a planned ignition of the vehicle’s 8 SuperDraco abort engines, the pressurization system rapidly “initialized” (i.e. quickly pressurized the oxidizer and fuel to operational pressures, ~2400 psi).

To do this, helium is rapidly pushed through a check valve – designed with low-molecular-mass helium in mind – to physically pressurize the propellant systems. Unintentionally, the NTO that leaked ‘upstream’ through that valve effectively was taken along for the ride with the high-pressure burst of helium. In essence, picture that you crash your car, only to discover that your nice, fluffy airbag has accidentally been replaced with a bag of sand, and you might be able to visualize the unintended forces Dragon’s check valve (the metaphorical airbag) was subjected to when a “slug” of dense oxidizer was rammed into it at high speed.

In itself, this sort of failure mode is not hugely surprising and SpaceX may have even been aware of some sort of check valve leak(s) and accepted what it believed to be a minor risk in order to continue the test and perhaps examine Dragon’s performance under suboptimal conditions. What SpaceX says it did not realize was just how energetic the reaction between the NTO and the check valve could be. SpaceX’s understanding is that the high-speed slug of dense NTO was traveling so fast and at such a high pressure that, by impacting the titanium check valve, it quite literally broke the valve and may have chemically ignited the metal, thus introducing a slug of burning NTO into the liberated NTO system itself – effectively a match tossed into a powder keg.

It’s unclear if the ignition came from a chemical reaction between titanium (a technically flammable metal similar to magnesium) and NTO, or if the source came from the titanium valve being smashed apart, perhaps quite literally creating a spark as metal debris violently interacted. Either way, the solution – as SpaceX perceives it – is the same: instead of a mechanical check valve (simple but still not 100% passive), the barrier between pressurant and oxidizer (as well as fuel, most likely) will be replaced with something known as a burst disk. According to Koenigsmann, only a handful (~4) of those valves exist and thus need to be replaced by burst disks, a relatively fast and easy fix.

Burst disks are single-use and inherently unreusable, but they are also completely passive and simply do not leak until subjected to a specific amount of pressure. Because they are single-use, they can’t be directly tested prior to flight, limiting some of the in-principle reliability for the sake of an extremely leak-proof barrier.

Ultimately, both Koenigsmann and Lueders went out of their way to avoid answering any questions about SpaceX’s Crew Dragon upcoming test and launch schedule and what sort of delays the explosion will ultimately incur. Both individuals were nevertheless upbeat and by the sound of it, delays to Crew Dragon will be far less severe relative to delays caused by a pressure vessel or engine failure. For the time being, NASA has published a tentative target of mid-November 2019 for Crew Dragon’s first crewed launch to the International Space Station, while Lueders and Koenigsmann expressed hope in a 2019 launch but refused to give a specific estimate of the odds of that occurring.

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On the evening of July 12th, SpaceX technicians put Starhopper’s freshly-installed Raptor – serial number 06 (SN06) – through a simple but decidedly entertaining test, effectively wiggling the engine in circles.

Designed to verify that Raptor’s thrust vectoring capabilities are in order and ensure that Starhopper and the engine are properly communicating, the wiggle test is a small but critical part of pre-flight acceptance and a good indicator that the low-fidelity Starship prototype is nearing its first hover test(s). Roughly 48 hours after a successful series of wiggles, Starhopper and Raptor proceeded into the next stage of pre-flight acceptance, likely the final more step before a tethered static fire.

Routine for all Falcon rockets, SpaceX’s exceptionally rigorous practice of static firing all hardware at least once (and often several times) before launch has unsurprisingly held firm as the company proceeds towards integrated Starhopper and Starship flight tests. Despite the fact that Raptor SN06 completed a static fire as recently July 10th, SpaceX will very likely put Starhopper and its newly-installed Raptor through yet another pre-flight static fire, perhaps its fourth or fifth test this month.

Although it would undoubtedly be easier, cheaper, and faster to skip that post-delivery static fire, it will simultaneously lower the risk of Raptor failing mid-flight and verify that Starhopper itself is healthy and ready for untethered hovering. Although SpaceX could likely live without Starhopper in the event that it’s lost during flight-testing, any failure capable of destroying the vehicle itself is at least as capable of severely damaging or completely destroying the spartan but still expansive test and launch facilities the company built over the course of several months.

Would you like some testing with your testing?

Follow July 12th’s nighttime Raptor wiggle test, July 13th was mainly quiet and filled with inspections of Starhopper, Raptor, and other various work. The day after, however, SpaceX proceeded through several hours of propellant loading, ending with what looked like less energetic versions of the Raptor preburner ignition tests Starhopper previously performed with Raptor SN02.

In a staged-combustion engine like Raptor, getting from the supercool liquid oxygen and methane propellant to 200+ tons of thrust is quite literally staged, meaning that the ignition doesn’t happen all at once. Rather, the preburners – essentially their own, unique combustion chambers – ignite an oxygen- or methane-rich mixture, the burning of which produces the gas and pressure that powers the turbines that bring fuel into the main combustion chamber. That fuel then ignites, producing thrust as they exit the engine’s bell-shaped nozzle.

Although the fireworks are so subtle that they are easily missed, the conditions inside the preburner – hidden away from view – are actually far more intense than the iconic blue, purple, and pink flame that exists Raptor’s nozzle. This is because the preburners have to nurture the conditions necessary for the pumps they power to fuel the main combustion chamber. Much like hot water will cool while traveling through pipes, the superheated gaseous propellant that Raptor ignites to produce thrust will also cool (and thus lose pressure) as it travels from Raptor’s preburner to the main combustion chamber.

Thus, if the head pressure produced in the preburners is too low, Raptor’s thrust will be (roughly speaking) proportionally limited at best. At worst, low pressure in the preburners can completely prevent Raptor from starting and running stably and can even trigger a “hard start” or shutdown that could damage or destroy the engine. As such, to preburners fundamentally have to operate at higher chamber pressures (and thus higher temperatures) than the main combustion chamber (the big firey bit at the end). According to Elon Musk, Raptor’s oxygen preburner has the worst of it, operating at pressures as high or higher than 800 bar (11,600 psi, 80 megapascals).

Coincidentally, this is roughly equivalent to the pressure at the bottom of the Pacific Ocean.

In short, preburner testing is no less critical than full-on static fire testing with an engine like Raptor. July 14th’s test was also made doubly efficient due to the fact that preburner testing requires liquid propellant, which effectively makes the whole test a wet dress rehearsal (WDR) even before any engine ignition or partial ignition is involved. Per SpaceX moving from propellant loading to preburner/turbine testing, Starhopper is almost certainly healthy and operating as expected, an excellent sign that the ungainly vessel may be ready for a static fire of Raptor as early as 2pm CT, July 15th.

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