HNHacker News
TopNewBestAskShowJobs

shazmosushi

43 karma · joined February 19, 2021

submissionscomments
shazmosushi··on FFMPEG from Zero to Hero
But why is that multi-step process even necessary?

There should be an quick command-line utility to concatenate multiple video files according to exactly the timestamps the user has provided. It's such a common operation.

There's no reason that the tool can't simply do a streaming decode of multiple different file formats and concatenate the video and sub-second precision. If input video resolutions are different, scaling the smaller video to the largest resolution is what the user almost always wants.

I get that FFMPEG is a "plumbing" CLI tool, but a "porcelain" wrapper would be amazing!

shazmosushi··on FFMPEG from Zero to Hero
I love FFMPEG, but it has truly awful handling of timestamps by default. You can't easily extract a clip using an exact timestamp because it rounds to the nearest keyframe, which may be many seconds earlier. It's such a powerful command-line tool, but I find the user-interface far more difficult than it needs to be. In "git" terminology, there's so much plumbing but not enough porcelain

I wish there was a scriptable / command-line interface for HandBrake (which is already based on FFMPEG) [1], where the user just provides the high-level commands: 99% of the time I want to specify high-level commands: extract clip from this timestamp, including SRT subtitles, crop to this geometry, and shift the audio by 3 seconds.

[1] https://en.wikipedia.org/wiki/HandBrake

shazmosushi··on Starship goes up. Starship goes down. But is the program moving forward?
True. I've been considering signing up for Ars Pro because I like their content, but haven't yet been able to pull the trigger yet
shazmosushi··on Starship goes up. Starship goes down. But is the program moving forward?
I think it's reasonable to bring up the upcoming Artemis Human Landing System down select in the context of where Starship development is at.
shazmosushi··on Starship goes up. Starship goes down. But is the program moving forward?
Yes, it's unlikely that SpaceX will use the flip maneuver for humans any time soon.

I believe they can just burn extra fuel margin to do a traditional vertical landing though. It costs payload, but it should be doable.

When maximizing cargo delivery to the surface of Mars, I'm sure they'll always do the flip.

shazmosushi··on Starship goes up. Starship goes down. But is the program moving forward?
Maybe this article is filler, but Eric Berger is a well-respected veteran space journalist, and generally his articles on Ars Technica are great.

He's just released a book on the early days of SpaceX [1] that appears to be the definitive account, according to the early reviews.

I'm not associated, but I have been wanting to read his book and am happy it has finally been released! :)

[1] https://www.amazon.com/Liftoff-Desperate-Early-Launched-Spac...

[2] https://twitter.com/SciGuySpace

shazmosushi··on Rocket Lab Unveils Plans for New 8-Ton Class Reusable Rocket
Good point on the carbon fiber thing. I forgot it's max operating temperature is 150 degrees Celsius (bursting to 180 degrees), while stainless steel can go to 820-870 degrees Celsius.

Rocket Lab never wanted to do first stage recover on the Electron, but they later chose to and have succeeded in soft ocean landings under parachutes and will soon try and catch the parachutes with helicopters.

I fully expect they're are running the numbers on second stage reusability but unlike SpaceX [1] they don't tend to announce things until they are sure that's what they will pursue.

Rocket Lab only promised the Neutron will do 8,000kg to low-Earth orbit, and people are suggesting the rocket tanks can be stretched for added performance.

If SpaceX wasn't pursuing Starship they would continue to spend resources on second stage reusability for the Falcon 9. Even less than 2 years ago Elon Musk was still talking about using a ballute to recover the Falcon 9 second stage [1], but they later decided to put all their resources into the Starship.

But yeah 2024 far enough away that Starship (and New Glenn) should be operational by then, so the competitive landscape may be different. But that's all the more reason for Rocket Lab to pursue second stage reusability.

[1] https://twitter.com/elonmusk/status/985655249745592320

shazmosushi··on Rocket Lab Unveils Plans for New 8-Ton Class Reusable Rocket
Second stage reusability on the Rocket Lab Neutron will be much easier than the Falcon 9 because the carbon fiber frame doesn't need a heatshield. I may be wrong on this, but I believe they can just slam the second stage into the atmosphere and bring it back without even a re-entry burn, like they already do with their first stage.

If Rocket Lab achieve second stage reusability while delivering a lot of payload to orbit it would be revolutionary. Like it will take hundreds of flights for a Starship to become as cost competitive to just a few flights of the Neutron rocket.

If I was SpaceX, I would be worried. Rocket Lab is SpaceX's most fearsome competitor.

shazmosushi··on Rocket Lab Unveils Plans for New 8-Ton Class Reusable Rocket
By selling his houses in California and moving to Texas he reportedly will save billions in taxes.
shazmosushi··on Rocket Lab Unveils Plans for New 8-Ton Class Reusable Rocket
Rocket Lab is an excellent company that makes innovative rockets: flying electric pump fed engines, carbon fiber frames and 3D printed Inconel engines all the way to orbit. They've achieved a high flight rate and a nice niche for themselves in a area where SpaceX themselves have moved away from.

Rocket Lab deserves the praise it receives. More so than Blue Origin, an older company whith grander ambitions but has been unable to execute on anything beyond a few small scale suborbital hops. Their methalox BE-4 engine is admittedly pretty cool though.

shazmosushi··on Rocket Lab Unveils Plans for New 8-Ton Class Reusable Rocket
Virgin Orbit launches their LauncherOne to orbit from a 747 Jumbo Jet. Virgin Galactic aspires to launches people for suborbital tourism on SpaceShipTwo. Different companies.
shazmosushi··on New Glenn’s Progress Towards Maiden Flight
Fascinating comment! Thanks for sharing.

Sucks for Red Dragon, but I'm looking forward to Starship!

shazmosushi··on New Glenn’s Progress Towards Maiden Flight
Source? My understanding is Elon Musk believes blunt body re-entry vehicles landing with SuperDraco thrusters is the wrong architecture for Mars colonization, so all funding has been redirected to Starship development.
shazmosushi··on New Glenn’s Progress Towards Maiden Flight
Musk has claimed imminent 24 hour turnaround times, Red Dragon on Mars every 2 years since 2018, second stage reusability etc.

So it's acceptable to have some skepticism that SpaceX intends to drop the Falcon 9's (already very cheap) marginal cost from $1000/kg by 100 times to $10-$20/kg through Starship's fully and rapidly reusable operation.

If anyone can do it, it's Elon Musk. But it's good to keep in mind his deep aversion to any sunken cost fallacies.

shazmosushi··on New Glenn’s Progress Towards Maiden Flight
Yes SpaceX's Raptor engines would be built in Hawthorne, CA and tested in McGregor, TX like the Merlin before it. But at Boca Chica, TX they are not just fitting the components into the an already completed fuselage, but welding the entire air frame together, including the pressure vessel bulkheads and stacking the stainless steel rings into Starship and Super Heavy. As far as I know Boca Chica receives stainless-steel sheet metal and turns it into the rings segments. The rings have a 9 meter diameter, so cross-country road transportation would be a problem.
shazmosushi··on New Glenn’s Progress Towards Maiden Flight
New Glenn is a case of "I don't have to outrun the bear, I just have to outrun you".

The Atlas V and Delta IV Heavy are being phased out in favor of ULA's Vulcan (which uses its BE-4 engines). Falcon 9 is otherwise dominant.

Despite sharing its BE-4 engines with ULA, New Glenn will eventually win a few national security payloads per year. If the economics of reusability pan out for them, they might eventually even beat the Vulcan!

We'll see if they can take their future taxpayer-funded first stages and launch commercial satellites with bargain basement internal costs, like SpaceX has achieved.

shazmosushi··on New Glenn’s Progress Towards Maiden Flight
It looks like the National Security Space Launch (NSSL) Phase 2 Launch Services Procurement (LSP) contract that Blue Origin refer to was awarded in August 2020 (six months ago).

https://www.afrc.af.mil/News/Article/2305576/space-force-awa...

shazmosushi··on The U.S. Air Force just admitted the F-35 stealth fighter has failed
> There is no VC who would have accepted a pre-SpaceX pitch for low cost launches, Starlink, or any of the rest of it. It would have been straight up "lol Iridium amirite, get out."

SpaceX was funded by Elon Musk and later, Draper Fisher Jurvetson and Peter Thiel's Founder's Fund. Starlink has been in part funded by a $1 billion investment from Google and Fidelity. And since then further funding rounds have been raised.

The DFJ and Founder's Fund investment was before SpaceX had any substantial NASA development contracts, let along their 2008 $1.6 billion launch contract.

shazmosushi··on The U.S. Air Force just admitted the F-35 stealth fighter has failed
> EASA has underestimated SpaceX from day one.

EASA is the European Union Aviation Safety Agency. I think you meant to say ESA, the European Space Agency? But ESA's not that relevant here, as the European governments fund and develop launch services through Arianespace, a consortium of space industry companies led by the French aerospace companies Airbus and Safran.

Correction aside, I agree with your point that Arianespace did underestimate SpaceX.

shazmosushi··on The U.S. Air Force just admitted the F-35 stealth fighter has failed
We know the Falcon 9's marginal cost for relaunch (with fairings reused is $15 million). Of this $10 million is for the second stage, $1 million is for booster refurbishment, the rest is for operations (including the landing barges) and fuel (which is $300,000 to $400,000 at the moment). These numbers are from Elon Musk's May 2020 Aviation Week podcast. I haven't yet found a good recent figure for the sticker price of relaunches though.

I did some analysis based on these numbers in this 8 minute video here: https://www.youtube.com/watch?v=36o4UrS9OS4

shazmosushi··on The U.S. Air Force just admitted the F-35 stealth fighter has failed
After the massively incorrect analysis by popular YouTuber Thunderf00t, I made a video analyzing SpaceX's reusability https://www.youtube.com/watch?v=36o4UrS9OS4 It's 8 minutes but I recommend watching at 2 times speed.

The latest numbers are that the marginal cost of relaunch is $15 million, with $10 million of that the second stage. Refurbishment cost is 27 days with a $1 million refurbishment cost (not $250,000 as I mistakenly said in the video, see description). The net effect is the cost of marginal cost of reflight is approximately 25% but the payload reduction is 30%, which leads to a break even point of 3 launches. After 10 flights, the cost to orbit per kilogram is halved. SpaceX has demonstrated 8 flights of a single booster.

Note, these are all using SpaceX's own numbers (but so was the payload reduction and original reuse cost figures). It depends on recovering the $6 million fairing (which does not happen every mission). All numbers are sourced from an Aviation Week May 2020 podcast that I linked to. Yes, the cost numbers are from SpaceX but the only public refurbishment cost analogue we have is their 27 day turnaround time.

SpaceX are currently operating at a sixth of the rest of the industry and use their cost advantage to launch 60 Starlink satellites at their $15 million marginal cost.

The traditional military-industrial complex with cost-plus accounting is "subcontractors all the way down", and the incentives weren't aligned to make an industry dominating rocket until arguably the 1990s commercial satellite boom (eg, the original Iridium constellation). Until 2008, there hadn't ever been a privately funded rocket reach orbit ever. Until SpaceX. Prior rockets we designed, owned and approved by the US government under World War 2-era cost-plus accounting arrangements.

shazmosushi··on Perseverance Rover lands on Mars [video]
Because you've posted a link containing a lot of misinformation multiple times in this thread, I am posting this video correcting the misinformation: https://www.youtube.com/watch?v=36o4UrS9OS4
shazmosushi··on Perseverance Rover lands on Mars [video]
The Thunderf00t video is wrong, see my video here: https://www.youtube.com/watch?v=36o4UrS9OS4
shazmosushi··on Perseverance Rover lands on Mars [video]
That video was incorrect on so many levels that I have made a rebuttal: https://www.youtube.com/watch?v=36o4UrS9OS4