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SpaceX delays Starhopper’s first flight a few days despite Raptor preburner test success

According to NASASpaceflight.com, SpaceX's Starhopper successfully completed a Raptor preburner taste on July 15th. A static fire ignition test should follow on July 16th.(NASASpaceflight - bocachicagal)

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SpaceX has (partially) ignited Starhopper’s freshly-installed Raptor engine, successfully verifying that the engine is ready for its next major test: a full ignition and static firing. Although successful, SpaceX still has some work to do before the vehicle is ready for its first untethered flight(s).

July 15th’s progress is just the latest in a several day-series of preflight tests designed to reduce the likelihood that Starhopper is destroyed over the coming days and (hopefully) weeks. If all goes planned during the awkward Starship prototype’s first foray into hover tests, SpaceX CEO Elon Musk has stated that he will provide an official presentation updating the public on the status of the company’s ever-changing next-generation rocket.

The past week or so of Starhopper preflight testing began with Raptor serial number 6 (SN06) completing the last of a series of acceptance test fires in McGregor, Texas on June 10th. Even on its own, this was a major milestone for the new SpaceX engine: Raptor SN06 was the first of the new, full-scale engines to pass the acceptance test program with flying colors. According to Musk, for the engine to complete those tests so successfully, SpaceX had to solve a challenging bug in which some sort of mechanical resonance (i.e. vibration) damaged or destroyed Raptors SN01-05.

Hours later, the engine began a short ~450 mi (720 km) journey south to Starhopper, located in Boca Chica, Texas. The engine arrived on July 11th and was fully installed on Starhopper by the following evening (July 12th), at which point SpaceX put Starhopper and Raptor through some mild but valuable thrust vector controller (TVC) tests, wiggling the car-sized engine to ensure it can accurately steer the prototype rocket.

Around two days after the above ‘wiggle’ test was successfully completed, SpaceX moved into the next stage, partially fueling Starhopper with liquid methane and oxygen propellant and helium pressurant in what is known in rocketry as a wet dress rehearsal (WDR). The (implicitly) successful WDR was capped off with a duo of what can now safely be concluded were some sort of Raptor test preceding even pre-ignition operations. Whatever the tests were, they appear to have been completed successfully.

That appears to be the case because less than 24 hours after their completion, on July 15th, SpaceX once again began loading Starhopper with propellant and pressurant for a second round of wet testing. This time around, SpaceX got right into more critical Raptor tests once enough propellant was loaded, igniting the engine’s interwoven oxygen and methane preburners.

Starhopper (technically) came alive for the third time ever on July 15th, albeit only partially. SpaceX ignited the engine’s preburners as a precursor to a full static fire, now NET July 16th. (LabPadre – YouTube livestream)

Previously discussed 24 hours ago in a Teslarati article focused on Raptor wiggles and other miscellaneous tests, Raptor is an extremely advanced rocket engine based on a cycle (i.e. how propellant is turned into thrust) known as full-flow staged combustion.

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.

Unintuitively, conditions inside the preburner – hidden away from view – are actually far more intense than the iconic blue, purple, and pink flame that visibly exists Raptor’s nozzle. 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 its main combustion chamber. If the 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 trigger a “hard start” or shutdown that could destroy the engine. According to Elon Musk, Raptor’s oxygen preburner thus has the worst of it, operating at pressures as high or higher than 800 bar (11,600 psi, 80 megapascals).”

In full-flow staged combustion (FFSC), even more complexity is added as all propellant that touches the engine must necessarily end up traveling through the main combustion chamber to eke every last ounce of thrust out of the finite propellant a rocket lifts off with. As such, FFSC engines can be about as efficient as the laws of physics allow any given chemical rocket engine to be, at the cost of exceptional complexity and brutally difficult development.

Additionally, FFSC physically requires two separate preburners and then makes things even harder by making each separate preburner (methane and oxygen) depend on each other’s operation for the engine to fully ignite. This means that no individual preburner can be used to kickstart Raptor – instead, SpaceX must somehow spin the turbopumps that feed propellant into each preburner with some separate system. This is all just to emphasize the fact that Raptor’s ignition sequence is a spectacularly complex orchestra of valves, spark plugs, sensors, and magic. This is why it’s valuable for Raptor to test its preburner system independently of an actual ignition test, at least as long as the engine is still in the development stages.

A Raptor engine is pictured here during a static fire test in McGregor, Texas. (SpaceX)

According to NASASpaceflight.com managing editor Chris Bergin, what this practically translates to is a minor Starhopper hover test delay of 1-2 days, while the static fire has also been pushed roughly 24 hours from July 15th to July 16th. If that full static fire produces lots of happy data, Starhopper could be cleared for a hover test debut attempt as early as Wednesday or Thursday (July 17/18).

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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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Elon Musk

Elon Musk sheds two new bits of detail on Starship after 13th test launch

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Credit: SpaceX

Elon Musk shed two new bits of detail on Starship following its 13th test launch, which was an overwhelming success.

SpaceX launched Starship for the 13th time last Friday after two delays: one on Monday when several Raptor engines did not ignite, and another on Thursday due to unfavorable weather conditions in Starbase, Texas.

The launch was overwhelmingly successful. SpaceX was able to complete a necessary test of the heat shield tiles by increasing the acceleration of Starship from launch throughout the flight; 20 Starlink v3 satellites were released with no issue; the Super Heavy Booster landed safely in the Gulf of America, Ship successfully reignited engines while in space; and it also splashed down without incident in the Indian Ocean.

SpaceX Starship just nailed something it’s never done before

Nevertheless, more details are coming out about Starship, and Musk is doing the talking.

Starship Will Be Retrieved in the Ocean

Musk revealed on Tuesday night that Starship would be recovered by a ship in the Indian Ocean. SpaceX routinely tries to recover Starship after splashdown in an effort to find out more about the flight by examining the spacecraft afterward.

This helps engineers find out more about why things might have happened, allows them to examine any potential damage or anomalies that might have occurred, and increases the chances of an even more successful flight next time thanks to the additional information recovered.

Ship Could Have Been Caught by Tower Arms, Musk claims

Musk has already indicated that SpaceX will plan to attempt a catch of Starship with the 14th test flight. While this would be a major accomplishment, it would be an expected next step, considering the fact that the Super Heavy Booster has already been caught by the chopsticks on numerous occasions.

A ship catch would be a great indication of where SpaceX stands in terms of reusability and launch cadence. A successful catch with relatively no incidents would be a good sign that SpaceX is nearing a more frequent launch of Starship, but also that the reusability of the massive rocket would be something many would expect in the near future.

It is a necessity to make life multiplanetary.

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Elon Musk

Elon Musk updates the SpaceX timeline for Mars

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Rendering of a colonized Mars by way of SpaceX
Rendering of a colonized Mars by way of SpaceX

Elon Musk has updated his timeline for when humans will walk on Mars and for when ships will simply get there.

The objective of getting to Mars has been one of Musk’s biggest goals since becoming a serial entrepreneur and realizing that time on Earth is limited. Musk has said several times he hopes to die on Mars, and not by impact.

Musk now believes that people will be on Mars in “roughly 5 to 7 years.” He said that a Mars lander will get there “a few years sooner.”

The response from Musk comes after NASA Administrator Jared Isaacman said that SpaceX’s biggest priority is the Moon and not Mars. Because of this, Isaacman conceded that he believes nuclear power and propulsion investments will provide “potentially the pathway with the fewest miracles required to put four people on Mars in the next 10 to 15 years.”

Of course, this is what NASA can do through taxpayer funding and nuclear investments, he added.

Musk’s grand ambitions are much more optimistic than most, and it is certainly a double-edged sword. This is not the first time timelines for Mars have been somewhat lofty, especially to those normal thinkers like you and me, not super geniuses like Musk.

SpaceX Board has set a Mars bonus for Elon Musk

In fact, the SpaceX and Tesla frontman has said on at least a dozen occasions that we could be on Mars in the coming years. Musk said 2020 would be the big year as early as 2009. In 2020, he was “highly confident” of a landing in 2026, and had even said 2024 in a best-case scenario.

The point is, the range has varied, and it’s anyone’s guess when we’ll get there. This latest adjustment to the timeline is typical of Musk, and while the Moon has seemingly taken priority over Mars, it is still worth mentioning that the ultimate goal is to make life multiplanetary, and it starts potentially with the Red Planet.

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Investor's Corner

SpaceX gets an absolutely crazy price target after rough IPO

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Credit: SpaceX

SpaceX (NASDAQ: SPCX) got an absolutely crazy price target rating from Raymond James after the company experienced a tough first few weeks following its Initial Public Offering (IPO).

Despite the tumultuous start, SpaceX has plenty of believers, and the company’s massively successful Starship launch last Friday, its 13th test flight of the massive rocket, went so smoothly that Raymond James analysts pushed its price target on the company to roughly 7 times its current trading level.

SpaceX Starship just nailed something it’s never done before

The firm officially put a “Strong Buy” rating and an $800 price target on the stock. It currently trades at around $113. Its all-time high is $225.64, reaching this trading level shortly after shares first went public.

Raymond James’ price target is tied to the firm’s confidence after Starship’s 13th test flight. Analysts at the firm said it was an incremental step that reduces engineering risks, citing the widely successful heat shield test that CEO Elon Musk recently detailed, the smooth deployment of Starlink V3 satellites, and a successful in-space engine relight.

SpaceX also managed to see Starship splash down safely in the Indian Ocean, while the Super Heavy Booster fell down to the Gulf of America with no incidents.

It is interesting to see these launches have such a tremendous impact on the stock and what investors think of it. After SpaceX initially delayed the Starship launch last week, shares fell tremendously. Most probably did not realize that the stand-down is a standard practice, especially if everything is not perfect.

The mission was initially aborted due to an issue with Raptor engines. This was resolved, and Starship launched last Friday after another delay on Thursday, which was caused by weather.

Now that analysts have seen what SpaceX launches are capable of and how impressive the feat is, firms are adjusting their price targets accordingly, making it known that they have high expectations for the space exploration company.

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