Comment by areoform | Hacker News Reader

Comment by areoform | Hacker News Reader

Perhaps I am too paranoid, but I've been told to avoid doing any DIY in this field of study.

Apparently, or so I'm told, out of the many, many ways to end up on a list — building a working celestial navigation system can lead to some very inconvenient outcomes. Second, only to ordering large quantities of certain chemicals online.

Is this true?

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EDIT - from the paper, this is incorrect,

> The introduction of GPS caused the interest in celestial navigation to wither due to its relative inaccuracy. Consequently, celestial navigation is primarily seen only in space-based systems, whose orientation must be known to high levels of precision. Nonetheless, celestial navigation was identified as a desirable alternative to GPS [2], primarily due its robustness against potential jamming. Critically, few GPS-denied alternatives exist that are capable of using passive sensors to estimate global position at night or over the ocean. For this reason, celestial navigation remains an important topic of research.

The US and other militaries never stopped using these systems. They just stopped talking about them as much. Here's a literature search showing some of the slow & steady research on the topic,

https://scholar.google.com/scholar?q=astro-inertial+navigati...

Example systems that have been deployed in many (most? all???) American combat aircraft,

https://theaviationist.com/2021/09/10/lets-have-another-look...

https://www.gpsworld.com/honeywell-demonstrates-military-gra...

https://ieeexplore.ieee.org/document/290940

Alright. I'm ready to be on that list, Mr NSA agent.

You will likely raise a flag somewhere if you publicise what you are doing, but I highly doubt there would be any issues if you're working on this in private as a hobby.

As for chemicals, I can personally vouch that it is a terrible idea to order reagents (or even chemistry equipment) as an individual. I tried to teach myself organic synthesis in the summer before starting my doctoral studies, and ended up with MIB searching my house. Certainly on a list now :(

LLC or nonprofit, with a business address. At least for bio reagants, they won't ship to you otherwise.

Please tell me there is a blog post or something documenting this experience. Sounds like a fun read.

Afraid not. I don't have much of an online presence, so didn't think to write anything.

there's always a first time :)

I remember watching a video about a dude who was building a mothership-launched glide drone that could land using camera vision. The idea was something like "the highest egg drop" or something like that. He was speaking with academics about his idea, who quickly told him to stop whatever he was doing because that would effectively be a forbidden military device. Guided artillery, basically.

Sadly I don't remember who it was, it was a fun story. I thought it was maybe Mark Rober or Joe Barnard but I really can't find it anymore.

Edit: found it! It was launched from a weather balloon, and it was both Mark and Joe. https://youtu.be/BYVZh5kqaFg

Happened to codyslab, videos taken down now (but still on archive.org) of a uranium purification process and possibly nilered,no way to prove it but he had a 'making rocket fuels: part 1' that was never followed p on. Not totally sure though as people like BPS space on yt have some pretty in depth tutorials on solid rocket motors (does explicitly censor how to make the ignition component)

Uhm, there are plenty of videos about making solid rocket fuel. Model rocketry doesn't need any special permits until you get to launching large rockets.

I guess once you have the permits it doesnt matter. With the nilered vids, they were more of the more hypergolic variety

That is probably why Eric Schmidt (ex Google CEO) develops his AI combat drones in Estonia instead of US.

Can't find a source at the moment but cool side anecdote to this...working from memory

Honeywell was largely the driving force behind developing terrain avoidance systems for commercial aircraft. Those initial systems worked based on comparing the terrain below to the flight profile of an aircraft using a radar altimeter.

There was a CFIT (controlled flight into terrain) accident (I want to say AA in Peru?) where the mountains basically got to tall to fast to give the crew sufficient time to react because of that system. That caused Honeyweell to go back and look at ways to improve the system to be predictive rather than reactive - using a terrain database.

Honeywell bought/came into posession of a russian world wide terrain altitude database to do the first generation of this. I can only imagine the US had the same thing, or more accurate, but this was far enough ago that US Government wasn't sharing.

You're right! I actually know about the system you're talking about! The US data was classified and Donald Bateman, the engineer behind this and bought the data post Soviet Union collapse.

https://en.wikipedia.org/wiki/C._Donald_Bateman

https://www.flightsafetyaustralia.com/2023/05/don-bateman-en...

the amount of random 'stuff' like this that I've accummulated over the years could fill a book that is interesting only to me lol

Thanks for the link!

You're definitely on the list of people worried about being on lists now.

But that's the bestest list!

The only people not on any lists, are boring people.

They're just kept on the list of all people not on a list.

Peaceful, not harmless.

I've also been told learning too much about linux or the nuclear reactions in power plants or bombs puts you on a list. I just assume I'm on several.

Learning too much about Linux puts you on a list? That can't be a thing. Isn't Linux itself entirely a civilian project?

The rationale mentioned was it was under the subheading of people interested in strong encryption, people who care about being unobservable might have something to hide. Maybe it's a good list? People who you might want to ramp up a new Bletchley Park? Probably not.

Whatever you do, don't broadcast on the airwaves, as in pirate radio. That really does put you on the list.

I don't believe they have the people to monitor those that know 'how to use grep' and put them on a list. It stands to no reason, government civil servants are rarely from the top drawer.

Years ago, an acquaintance developed an autonomous flight controller for "real" helicopters. Cyclic-collective-tailrotor types. It would work on a full-size cargo helo just as well as an R/C model. He released it online, because why not? Drones are cool.

Some very nice gentlemen showed up and explained that he couldn't do that. He didn't get in any actual trouble that I'm aware of, but they "asked" him to take down the published code, and definitely not fix any of the bugs it had.

So, yeah, you're not wrong.

There are nuances to the rules, involving things that're openly published online, but I don't understand it in the least. A hacker's guide to ITAR would be an interesting document indeed.

> A hacker's guide to ITAR would be an interesting document indeed.

I suspect producing something called "a hacker's guide to ITAR" really would get you put on a list...

Knowing how stupid ITAR enforcement is, the guide would probably fall under ITAR :)

Not NSA - you'd have someone from US Bureau of Industry and Security tracking you down (no pun) for most likely violating export controls if you were to openly share information on building the technology.

Celestial tracking is a dual use technology (See 7A004 or 7A104) - https://www.bis.doc.gov/index.php/documents/regulations-docs...

Openly publishing information in e.g. a book (or presumably a website) does not count as exporting. Releasing software is a bit more hazy, but has been defended[1].

[1]: https://en.wikipedia.org/wiki/Pretty_Good_Privacy#Criminal_i...

I'm sure there are thousands of datasets of the night sky, and a camera, gyrometer (to get camera angles), clock, and basic image recognition/pattern matching is all you'd need.

yeah. Celestial navigation is a pretty standard thing to study if you're planning on taking up sailing or learning about satellite positioning. Celestial navigation with drones raises more interesting possibilities, but I don't think defence of key strategic assets against drones relies on the possibility it might be too difficult a problem to solve, and there are commercial solutions in the "drone navigation for GNSS denied environments" space. Don't even think the people that jailbreak consumer drones specifically to remove the geofences that prevent them flying near restricted areas get into trouble, at least not until someone spots them flying at the end of a runway or outside a military base.

Plenty of homework assignments in graduate level aerospace engineering courses that are right up the alley of this paper. Star trackers as backup for GNSS would be of great interest to maritime vessels worried about spoofing. So there are plenty of non-military use cases for these algorithms.

These days celestial navigation is trivial. See my comment here

https://news.ycombinator.com/item?id=42695079

I'm told quantum navigation is the new hotness for being on lists these days

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