from the Oooooh!-Shiny!! dept.
SpaceX's Starship and Super Heavy (formerly Big Falcon Spaceship and Big Falcon Booster, or Big Falcon Rocket) have undergone further changes following a "final" iteration of the design in September. Elon Musk also said that a downscaled Starship hopper (for vertical takeoffs and landings) will "hopefully" be tested starting in March or April 2019, which is months sooner than a "late 2019" estimate made by SpaceX CEO Gwynne Shotwell in September.
Recent photos taken of SpaceX's operation in Boca Chica, Texas have shown a stainless steel nose cone being built. The new stainless steel design was confirmed by Elon Musk, along with numerous other details. Musk said that stainless steel can beat carbon fiber composites due to its superior strength-to-mass ratio and "mirror-like" thermal reflectivity. SpaceX is using an on-site foundry to create its own steel "superalloy", although some steel parts will be made by a supplier. Finally, the test hopper will feature three "radically redesigned" Raptor engines while being slightly shorter than the full-scale Starship, although it will share the same 9-meter diameter:
While the suggestion that Raptor's turbopumps (basically fuel pumps) would need at least 100,000 HP per engine seems to indicate that the flight design's thrust has been appreciably uprated, a past figure of ~2000 kN (450,000 lbf) per engine suggests that Starship V0.1 could weigh as much as an entire Falcon 9 Block 5 rocket (~1.2 million pounds, 550,000 kg) and still having a solid 80-100% of Falcon 9's liftoff thrust. Put simply, the rocket that appears to be coming together in the boonies of South Texas could rival almost any other liquid fuel rocket booster in service, while still being the testbed for BFR's upper stage alone.
While it's ambiguous if several additional comments applied to the Starship prototype, the final product, or both, Musk also indicated that some of the biggest benefits of a shift away from carbon composites to stainless steel would be relative ease with which the material handles extreme heating. Thanks to the fact that stainless steel can ultimately be polished to mirror-like levels of reflectivity and that mirrors are some of the most efficient reflectors of thermal energy (heat), shiny and unpainted steel would ultimately perform far better than carbon composites and could end up requiring "much less" heat shielding for the same performance.
Perhaps most unintuitive is the fact that steel can apparently beat carbon composites when it comes to usable strength-to-weight ratios at supercool temperatures. According to Musk, steel also performs "vastly better" at high temperatures and appreciably better at room temperatures. A comment made on Saturday may lend additional credence to what seems at face value to contradict basic material intuition – at least some of the stainless steel SpaceX is examing would be a special (presumably SpaceX-engineered) alloy that has undergone what is known as cryogenic treatment, in which metals are subjected to extremely cold conditions to create some seriously unintuitive properties. Ultimately, cold-formed/worked or cryo-treated steel can be dramatically lighter and more wear-resistant than traditional hot-rolled steel.
Elon Musk hinted at a "delightfully counter-intuitive" redesign in November, which was almost certainly a reference to the use of stainless steel instead of carbon fiber composites. Here's a video (10m14s) which offers some speculation about how a steel Starship could effectively conduct and radiate away heat.
Also at Business Insider.
During a press conference at his company's Hawthorne, CA headquarters, SpaceX CEO Elon Musk announced the first planned private passenger to travel into deep space and around the Moon. Yusaku Maezawa, a billionaire fashion entrepreneur and art collector, paid an undisclosed amount to become one of the first people to fly on a SpaceX Big Falcon Rocket (BFR), with a target date of 2023. If the launch happens, he won't be going alone. Maezawa (aka "MZ") plans to invite at least six to eight artists to accompany him on a journey around the Moon. The passengers chosen may be painters, sculptors, musicians, fashion designers, dancers, film directors, architects, etc. and are intended to represent the Earth and participate in an art exhibition after returning to Earth. Musk himself has also been invited. The project is called #dearMoon.
Yusaku Maezawa approached SpaceX and made a contribution that will pay for a "non-trivial" amount of the BFR's development costs. During the Q&A, Musk estimated that the entire development of BFR would cost around $5 billion, or no less than $2 billion and no more than $10 billion. Other potential sources of funding for BFR development include SpaceX's top priority, Crew Dragon flights to the International Space Station (ISS), as well as satellite launches and Starlink satellite broadband service.
Maezawa (along with a guest) was a previously announced anonymous customer for a Falcon Heavy ride around the Moon. SpaceX currently has no plans to human-rate the Falcon Heavy. The switch from Falcon Heavy to BFR will substantially increase the maximum number of passengers and comfort level attainable on a nearly week-long mission, since the Crew Dragon 2 has a pressurized volume of just 10 m3, about 1% of the volume of the BFS.
SpaceX CEO Elon Musk's use of cannabis during an interview with Joe Rogan has led to safety reviews at both SpaceX and Boeing:
In addition to spurring problems for the car company Tesla, Elon Musk's puff of marijuana in September will also have consequences for SpaceX. On Tuesday, The Washington Post reported that NASA will conduct a "safety review" of both of its commercial crew companies, SpaceX and Boeing. The review was prompted, sources told the paper, because of recent behavior by Musk, including smoking marijuana on a podcast.
According to William Gerstenmaier, NASA's chief human spaceflight official, the review will be "pretty invasive" and involve interviews with hundreds of employees at various levels of the companies, across multiple worksites. The review will begin next year, and interviews will examine "everything and anything that could impact safety," Gerstenmaier told the Post.
[...] One source familiar with NASA's motivations said the agency has grown weary of addressing questions about SpaceX's workplace culture, from the long hours its employees work to Musk's behaviors on social media. "SpaceX is the frat house," this source said. "And NASA is the old white guy across the street yelling at them to 'Get off my lawn.'"
The "Big Falcon/Fucking Rocket" (BFR) has been renamed. The upper stage will be called Starship, while the booster will be called Super Heavy:
SpaceX CEO Elon Musk tweeted late Monday night that he has renamed the company's largest (and yet to be built) BFR rocket to Starship. Or more precisely, the spaceship portion will be called Starship. The rocket booster used to propel Starship from Earth's gravitational grasp will be called Super Heavy.
Plans to add a "mini-BFS" second stage to the Falcon 9 were scrapped less than 2 weeks after they were announced. Yet another design change for the BFR/Starship was also hinted at:
Popular Mechanics has interviewed SpaceX CEO Elon Musk about his decision to move to a stainless steel design for Starship Super Heavy (formerly BFR). The interview reveals new details about the design, including micro-perforations on the outside of the windward side of the rocket that can bleed water or fuel for cooling:
Ryan D'Agostino: How does stainless steel compare [to carbon fiber]?
Elon Musk: The thing that's counterintuitive about the stainless steel is, it's obviously cheap, it's obviously fast—but it's not obviously the lightest. But it is actually the lightest. If you look at the properties of a high-quality stainless steel, the thing that isn't obvious is that at cryogenic temperatures, the strength is boosted by 50 percent.
Most steels, as you get to cryogenic temperatures, they become very brittle. You've seen the trick with liquid nitrogen on typical carbon steel: You spray liquid nitrogen, you can hit it with a hammer, it shatters like glass. That's true of most steels, but not of stainless steel that has a high chrome-nickel content. That actually increases in strength, and ductility is still very high. So you have, like, 12 to 18 percent ductility at, say, minus 330 degrees Fahrenheit. Very ductile, very tough. No fracture issues.
[...] [Here's] the other benefit of steel: It has a high melting point. Much higher than aluminum, and although carbon fiber doesn't melt, the resin gets destroyed at a certain temperature. So typically aluminum or carbon fiber, for a steady-state operating temperature, you're really limited to about 300 degrees Fahrenheit. It's not that high. You can take little brief excursions above that, maybe 350. Four hundred, you're really pushing it. It weakens. And there are some carbon fibers that can take 400 degrees Fahrenheit, but then you have strength knockdowns. But steel, you can do 1500, 1600 degrees Fahrenheit.
SpaceX has nailed its 24th Falcon booster reuse and 44th Falcon booster landing with Falcon 9 B1056's flawless Landing Zone-1 recovery, setting the booster up to become the first SpaceX rocket NASA has flown on three times.
According to NASASpaceflight.com, NASA had already moved from a conservative "maybe" to a much firmer "yes, but..." on the second-reuse question, pending – of course – the successful completion of B1056's second launch and landing. As of now, the Block 5 booster has indeed successfully completed its second orbital-class mission, setting itself up for a milestone NASA reuse that could happen as early as December 2019 on CRS-19, Dragon 1's second-to-last planned International Space Station (ISS) resupply mission.
Starhopper has completed its first untethered flight ever, simultaneously a small step for the awkward prototype and a giant leap for SpaceX's Starship/Super Heavy program as the next-gen launch vehicle is carried into a new phase: flight testing.
Despite the spectacular and reportedly successful hover and divert test, Starhopper's powerful Raptor engine appears to have started a significant fire, placing SpaceX's Starhopper pad in a precarious position per the fire's apparent adjacency to full liquid oxygen tanks. Ironically, despite Starhopper's seeming predilection as of late towards catching itself on fire, the large rocket testbed appears to be entirely unscorched as a brush fire burns around a few hundred feet distant.
[...] According to Elon Musk, the SpaceX CEO will present an update on the company's progress designing, building, and testing Starship and Super Heavy soon after Starhopper's first successful flight, meaning it could potentially happen within the next week or two. Additionally, Musk deemed Starhopper's July 25th flight a success and indicated that SpaceX would attempt to put Starhopper through a more ambitious 200m (650 ft) hop in a week or two, continuing what is expected to be an increasingly arduous serious of tests for the prototype.