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marze

2,011 karma · joined June 23, 2009

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marze··on Nancy Grace Roman Space Telescope
For some tasks, surveys in particular, field of view is critical. You would need many Hubble telescopes to do what Roman can do mapping everything out there.

"What really makes Roman stand out is that it is designed for wide-field imaging. The cameras on telescopes can often only detect objects in a very small patch of sky. If we use the size that the full moon appears in the sky as our guide, Hubble’s field of view is often smaller than that —meaning each picture it takes is of a patch of sky smaller than the full moon. Webb’s instruments often are even smaller than Hubble’s. Each picture taken by Roman, however, will be larger than the full moon, allowing it to survey more of the sky much faster than Hubble or Webb."

https://science.psu.edu/news/ask-expert-will-roman-help-reve...

marze··on Tesla’s 4680 battery supply chain collapses as partner writes down deal by 99%
"Tesla, where we make the impossible late"
marze··on Ask HN: What Are You Working On? (December 2025)
Astrophysics
marze··on A supersonic engine core makes the perfect power turbine
If China had "no regulations" and was building out 100% coal, no one would be worrying that China industry would have an advantage due to low electricity cost vs rest of world.
marze··on Trillions spent and big software projects are still failing
So I haven't looked through the comments, and assume this has been discussed, but the simple solution is to limit contracts to, say, $4M, and pay only on successful completion. Then build a large project through a series of smaller steps.
marze··on The Perplexing Appeal of the Telepathy Tapes
I was interested to learn recently that Alan Turing believed telepathy was a real thing. At least that is what someone wrote.
marze··on Analysis of Hedy Lamarr's Contribution to Spread-Spectrum Communication
To me, the interesting question is, were they the first to come up with the concept of communicating while jumping around on a random-like sequence of frequencies. What was the prior art?
marze··on These Men dove to the Edmund Fitzgerald shipwreck decades ago. Their stories
It may have been 15 minutes to both go down and explore, it mentioned 4 minutes at the bottom. The quote: "15-minute descent and exploration"
marze··on Why Sam Altman Won't Be on the Hook for OpenAI's Spending Spree
It will be interesting to see who owns all the compute hardware in a few years, that cost billions now, and what becomes of it. With an expected useful lifetime so short the depreciation rate is insane.
marze··on Analysis of Hedy Lamarr's Contribution to Spread-Spectrum Communication
I find the article unconvincing, although I'm open to being convinced. With historical hindsight, it should be easy to see if the Lamarr et al patent seems novel. Just because an examiner doesn't allow a claim, I don't see that as strong evidence it wasn't novel at the time. They always are rejecting claims, sometime for good reason, sometimes not.

A more convincing article would focus on purported prior art patents, and let the reader judge if really anticipated frequency hopping.

marze··on Leatherman (vagabond)
It might just be that there are a lot more cheap pizza locations than fancy ones.

This fellow also stays with friends.

marze··on Leatherman (vagabond)
My brother has a friend who is the modern day equivalent. He travels North America by bike, eats pizza from cheap pizza restaurant dumpsters.
marze··on Solar power has begun to transform the world’s energy system
Once there are 50M electric cars parked here and there, the solution will be even more obvious.
marze··on Preliminary report into Air India crash released
Also, it took 10 and 14 seconds to switch them back on. If it was an accidental switch, you would think it would have been quicker to switch them back.
marze··on Preliminary report into Air India crash released
You mention "brain fart". There is certainly a long history of pilots selecting the wrong lever, or wrong switch. So, it is possible the pilot who denied switching the fuel off thought he had switched something else.
marze··on Solar power has begun to transform the world’s energy system
As in, "an electric vehicle fleet that charges during the day and powers the grid at night if the owner opts in"?
marze··on Solar power has begun to transform the world’s energy system
Transmission lines are a interesting idea, but expensive.

Once solar is cheap (like now, as it already is), you can put in 3x what is needed on a sunny day, and power everything on cloudy days. Solar runs on cloudy days. Night obviously requires a different solution. Start by installing solar over all parking lots.

To think that you won't be able to run a 100% solar/wind grid is a bet against human ingenuity. If generation in excess of peak demand was installed of solar/wind, there are many promising approaches to deal with generation shortfalls. Batteries, load shifting, an electric vehicle fleet that charges during the day and powers the grid at night if the owner opts in, precooling a home with AC during the day to a low set point so AC isn't needed at night, H2 storage in salt caverns, pumped hydro, aluminum smelters that operate during excess power periods, the possibilities are infinite.

It won't be hard. Don't bet against human ingenuity.

marze··on A Review of Aerospike Nozzles: Current Trends in Aerospace Applications
Against the cost of a lower payload fraction. Say you get 4% with TSTO, 2% with SSTO. And if you run into trouble with the design, the SSTO payload moves towards 0%. Your operational savings need to compensate for a doubling of cost per unit mass payload, possibly much more.

And even though full reusability is much easier with two stages, and has not been achieved yet.

marze··on Ada and SPARK enter the automotive ISO-26262 market with Nvidia
References?
marze··on Ada and SPARK enter the automotive ISO-26262 market with Nvidia
Wasn't a correlation with elderly drivers and the unintended accretion found in the Toyota cases?
marze··on My quest to make motorcycle riding that tad bit safer
A legal mandate should be made to require this on all motorbikes.
marze··on Blue Origin New Glenn Mission NG-1 (video)
Oops, you're right!

So legacy launch vehicles with the exception of Shuttle lift of leisurely.

marze··on Blue Origin New Glenn Mission NG-1 (video)
That is incorrect. Shuttle liftoff thrust was 5.7 million pounds, giving a ratio of 1.25.

At liftoff, each SRB produces 2.65 million pounds thrust [1]. Using Wikipedia numbers instead (2.8 million pounds for SRB thrust at liftoff [2]) gives a liftoff thrust to weight ratio of 1.33. The 3xSME produce 0.4 million pounds thrust at liftoff. The SRB thrust did increase as the burn progressed, then ramped down for max Q.

People are accustomed to SpaceX rockets rapid acceleration, since they conduct most launches these days, but historic rockets (and New Glenn) accelerated more slowly off the pad.

[1] https://www.nasa.gov/reference/the-space-shuttle/

[2] https://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Boo...

marze··on Blue Origin New Glenn Mission NG-1 (video)
Historic rockets around 1.2, including Shuttle, check your numbers. Starship is not a "historic rocket". It and Falcon 9 fly a trajectory that is optimized for something else, not max payload for a set first stage thrust.
marze··on Blue Origin New Glenn Mission NG-1 (video)
That is a trajectory optimized for payload mass, with a set amount of first stage thrust. It is quite typical, historically. It just looks extra slow since the New Glenn rocket is quite enormous relative to historic rockets.

An impressive first flight by any measure!

marze··on The case for letting Malibu burn (1995)
This one looks fine to me from the outside:

https://x.com/camoPirate_xXx/status/1877749643465134141

marze··on Why the Getty Center Is the Safest Place for Art During a Fire (2019)
Everyone with a fire-hardened house should be feeling good. If all Pacific Palisades houses were fire-hardened, the fire would have burned vegetation but few houses.

Even modest fire hardening would help. If a wood-frame house burns, it is a danger to all nearby houses. Hardening reduces the chain reaction potential.

marze··on The case for letting Malibu burn (1995)
One would certainly hope that reconstruction would involve houses with concrete exteriors, or masonry. It would be silly to build a bunch of wood houses. Especially for luxury homes, a concrete shell should only add 1% to the overall cost. And technology exists to build hurricane-proof houses.

Shouldn't this be mandated, if a "natural disaster" destroys a home, to not replace it with a similarly vulnerable structure?

marze··on The case for letting Malibu burn (1995)
Does anyone know if the insurance companies gave discounts to houses that had fire resistant improvements, in the areas that burned in these fires?
marze··on The case for letting Malibu burn (1995)
Probably a more pertinent question would be: can you construct houses that would not burn in a Santa Ana if all the vegetation and landscaping nearby burned.

If you have fire resistant structures and only vegetation burned, not any structures, it would be much less expensive to replace just the landscaping plants.

In a 80 mph wind, it would be very challenging to design a structure that would survive a wooden house burning next door.

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