rzimmerman

27 दिन पहलेdiscuss

The article mentions this, but it works on Macbooks as well! You can set up a shortcut key (press the fingerprint button 3x) to enable and disable it. I have a work shuttle I take and this makes it so much more tolerable to use my computer on the bus.

rzimmerman

7 माह पहलेdiscuss

Yeah the solar array on Starlink is held perpendicular to the velocity vector, so the cross section relative to the colliding body will invariably be smaller than the worst case.

rzimmerman

7 माह पहलेdiscuss

It's interesting to try to create a metric of collision avoidance "stress" and resiliency to outages. I don't think this is a particularly useful one (and the title is alarmist/flamebait), but it is a first cut at something new. A more nuanced aggregate strategy for different orbital altitudes would make sense. Maybe some can suggest (or has already suggested) a comprehensive way to keep the risk of cascading debris events low (and measured) that is useful for launch planning.

Complete loss of control of the entire Starlink constellation (or any megaconstellation) for days at a time would be an intense event. Any environmental cause (a solar event) would be catastrophic ground-side as well. Starlink satellites will decay and re-enter pretty quickly if they lose attitude control, so it's a bit of a race between collisions and drag. Starlink solar arrays are quite large drag surfaces and the orbital decay probably makes collisions less likely. I would not be surprised if satellites are designed to deorbit without ground contact for some period of time. I'm sure SpaceX has done some interesting math on this and it would be interesting to see.

Collision avoidance warnings are public (with an account): https://www.space-track.org/ But importantly they are intended to be actionable, conservative warnings a few days to a week out. They overstate the probability based on assumptions like this paper (estimates at cross-sectional area, uncertainty in orbital knowledge from ground radar, ignorance of attitude control or for future maneuvers). Operators like SpaceX will take these and use their own high-fidelity knowledge (from onboard GPS) to get a less conservative, more realistic probability assessment. These probabilities invariably decrease over time as the uncertainty gets lower. Starlink satellites are constantly under thrust to stay in a low orbit with a big draggy solar array, so a "collision avoidance manuever" to them is really just a slight change to the thrust profile.

Interesting stuff in the paper, but I'm annoyed at the title. I hate when people fear-bait about Kessler syndrome against some of the more responsible actors.

rzimmerman

10 माह पहलेdiscuss

If you're interested in building something, Planet released an open source hardware/software satellite radio that works over amateur radio bands for ~$50: https://github.com/OpenLST/openlst

rzimmerman

4 वर्ष पहलेdiscuss

Absolutely unacceptable to not give a developer local root on their own machine. Manage profiles and install logging all you want, but requiring a developer to ask permission to install docker/git/tools they need is not security, it's incompetence.

If your employer won't give you the tools you need to do your job you should find another one. If your IT/security department is there to block you instead of help you get work done, you should also find a new job. I'm not saying walk out the door today, just that you don't deserve to be treated like that.

rzimmerman

4 वर्ष पहलेdiscuss

At NASA I wrote a set of Python scripts to help with planning and telemetry for a Mars mission. I had to convert a lot of time data points between UTC and a Mars timezone/clock (specific to the rover itself). There was an officially blessed tool written in Java that ran from the command line for time conversion. It was too slow to call out for each data point, so I figured it would be generally useful to port the conversion to Python.

First I dug into the Java source, which it turned out called out to a C library. I believe the C library linked out to a Fortran library. It was a lot more complicated than a simple scale and calendar - there were corrections for special and general relativity. Converting times actually required propagating orbits and estimating some non-closed-form quantities. In the end is was more work than it was worth, so we just did an approximation ("only" good to a few milliseconds - fine for our case).

So I guess item number 100 on this list should be "time is experienced the same way by all observers" and maybe 101 "simultaneity depends on the reference frame" :)

rzimmerman

4 वर्ष पहलेdiscuss

My family has two cars - a 5 year-old Subaru and a relatively new Tesla. The Subaru has great physical controls for pretty much everything. It has a slightly janky touch-screen for changing audio sources (with nice physical buttons on the wheel for pause/skip/change channel). The touch screen is a little frustrating to use, but I rarely need it. I can imagine I'd be pretty annoyed if it was required for car functions or climate control. But the buttons and knobs are great.

The Tesla touchscreen is very good. I would be annoyed if I frequently had to use it while actually driving, but I don't. Everything in the Tesla is pretty much automatic, including climate control, windshield wipers, lights, and door locks. It's easy to use the touchscreen to raise or lower the temperature a degree - that's the main thing I find myself doing while driving that requires the screen. Everything else I do has a physical control on the wheel. The one frustrating exception is defog which the latest update put behind a menu. I have them shortcutted on the home screen but it is obnoxious.

I think having a big screen is nice. It does require thoughtful UX design and a few physical controls. Tesla probably errs a little too much on the side of automation + no buttons but it's generally well done. As driving becomes more automatic I think it really is less important to have tactile controls and more important to have screen real estate.

rzimmerman

4 वर्ष पहलेdiscuss

There are two forms of "summon". There's regular summon, where you have to hold down a button to make the car go forward or back. It does turn to avoid obstacles, but with a very nervous energy. Regular summon is super slow, 1-2 miles per hour. If you let go of the button the car stops, but not as quickly as you'd think. It takes about a full second.

Smart summon does have wild raccoon energy. In this case, you need to be within ~200 feet and the car uses its GPS location to plot a path to you. It will back out and turn around obstacles. But it goes kind of fast. Uncomfortably fast. I had my car whip around a turn and nearly hit a parked car. I don't think I've ever seen it work well. Or at least it has always ended with me letting go of the phone kill switch. Which again, takes around a full second to stop the car.

Like someone else commented, this is a very different system than "full self driving" (16 year-old that just got their license energy), which is also a different thing than "Autopilot" (works great on highways).

rzimmerman

4 वर्ष पहलेdiscuss

I have found a lot of value from putting up real code from our code base (maybe simplified with some parts removed) and asking the candidate to explain what a function does. It’s very fair, low stress, and you can ask open-ended questions about “why this way?” or “what are some other ways to do this?”

rzimmerman

5 वर्ष पहलेdiscuss

Rocket Lab | Operations Software Engineer | Full-time | Long Beach, CA | ONSITE (Currently remote due to COVID)

Rocket Lab is seeking a Software Engineer to support the development of Photon, with an emphasis on operations software. In this role, you will be working to develop our Space Operations Software that is responsible for commanding and data handling for all of Photon’s operations in space. This role will involve developing software to work with cloud technologies, mission & ground software, customer APIs, and large databases. Especially looking for DevOps + AWS experience.

https://www.rocketlabusa.com/careers/positions/operations-so...

rzimmerman

6 वर्ष पहलेdiscuss

A lot of people complain that Face ID doesn't work when they wear skiing gear or a mask. I'd argue that most humans can't identify me when I wear a mask, so it's a bit hard to expect my phone to do better.

I do prefer Face ID for almost everything except payments. Apple pay with Touch ID was a much better experience. The awkward double tap + stare at my phone for 2 seconds isn't great. Having an Apple Watch makes this much better but I do miss placing my phone near the reader and putting my finger on the sensor.

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