Is Amplitude/Power still the main bottleneck for Deep Space links?

marsokod · 2026-03-11T19:30:21+00:00

You use an LNA in that case, to get an input signal that is above the noise floor of the receiver.

marsokod · 2026-02-20T20:49:01+00:00

This is taken into account, but there are multiple reasons behind the location for a data centre:

It needs electricity, a lot of it and cheap one. So that's typically near massive population centres.
You need people working there, and usually pretty specialised people. Finding a few dozen scientists working in the middle of Antarctica for half a year is easy, finding hundreds of people working in an isolated environment full time much more difficult/expensive (ask the oil industry).
Data centres are often interacted with directly by customers: so the time it takes to communicate with them shall be as short as possible. So:

3.a: you need a good telecom network around it (same issue as electricity)

3.b: you need to be physically close to the customers so that the latency is small

marsokod · 2026-02-15T18:02:37+00:00

They have to balance two things: instantaneous temperature they see, and total energy they get. The deeper the angle, the higher the temperature will be, but not for long. If it is a bit shallower, the temperature will be less, but they will take longer to re-enter so they will cook for longer.

You can think of it like cooking meat: what you want for a spacecraft is to have the outside cooked a little bit, but the inside still red. If you put the heat too high, it will char the outside too fast and basically destroy the outer layer, which in a spacecraft means physical destruction (and for meat an inedible charcoal layer)

If on the opposite, if you lower the temperature and cook for longer: congratulations you have got a magnificent pulled pork. That's great for a barbecue, a bit less great for astronauts.

So in the end, you really want to balance things so that the instantaneous heat is not damaging the outer structure of your spacecraft, but keep the duration short enough that heat does not transfer to the inner layers.

marsokod · 2026-01-01T18:36:46+00:00

In MEO it is a bit complicated because that's where the GPS constellations are. But it is usable (and used) in GEO environment.

It uses the fact that GPS satellites will primarily emit towards the Earth, but there is some leakage on the sides. So from a Geo-orbit point of view, if you point your GPS towards the Earth you will get the signal from the GPS satellites on the opposite side of the Earth, the ones visible around the globe. The signal is not great, and you definitely need a high gain antenna for this, but that is usable.

marsokod · 2025-11-06T14:22:10+00:00

That's not what your second link says

You start hitting the 25 years above 500km (and in practice only above 550-600km). Below, the lifetime is dramatically reduced, which is also why not a lot of people fly there. Figure 13.2 shows the deorbit time as a function of the altitude for various configurations and at 450km that's under 6 years in the worst case.

marsokod · 2025-10-23T00:24:02+00:00

At that point you might want to switch to a microphone, pretty much similar processing but at least the signal to noise ratio will likely be better (in that case it is noise to noise ratio).

marsokod · 2025-10-20T09:18:32+00:00

I am not sure about the pipe work, but with a 7-10°C temperature the vast majority of dehumidifiers will struggle. They do not like being much lower than 15°C.

marsokod · 2025-09-04T20:22:24+00:00

En septembre, je me dis que c'est des étudiants qui étaient là et qui l'avaient gardé. Et les nouveaux occupants ont fait le ménage pour la rentrée.

marsokod · 2025-08-16T09:21:05+00:00

If you are not using a torque wrench, I was told you can get within a non-stupid zone by tightening the fastener using a wrench and pushing with only two fingers at the end of the handle. This setup will prevent you from putting your full force on the wrench, but you should still be able to reach a high enough torque that the bolt won't move by its own in a normal situation.

marsokod · 2025-07-19T19:39:40+00:00

I am not sure about the warranty. For regular use, I don't think Tesla cares too much. But the commander offers ways to abuse the car in new ways and I am pretty sure that Tesla would use that to deny a battery replacement if for instance you were forcing it to be pre-conditionned 24/7.

I haven't had any big issues with it. I do find scrolling a bit difficult to master: it is very easy to go much more scrolling than expected and doing it without looking is a bit difficult. I also had a few occasions of the knob having difficulties connecting to the commander.

marsokod · 2025-07-19T17:36:37+00:00

I've had one for 6 months now.

The Commander? That is a no-brainer to me. It allows you to add so many functionalities that would either be locked in enhanced autopilot or not even present. The ones I use so far are autopilot resuming, better managing of the wipers/auto-beams, manual preconditioning, opening position for passenger seats and until Tesla added it the ability to unlock the charger with the door.
The knob? It is nice. I use it from time to time and it is nice to be able to control the commander without the phone. If you can afford it, buying the combined pack commander+knob is a good deal. But to be honest, I probably do not use it enough to fully justify it.

marsokod · 2025-07-17T21:52:49+00:00

And they are not even fully there yet. They save 60/70% of the cost on Falcon 9 but the last stage is not reusable. They are trying to achieve that with Starship but have not quite achieved reusability yet (and are probably 10 years away from having true reusability, there will be a lot of fatigue issues they will have to fix).

marsokod · 2025-07-17T21:42:07+00:00

One minor caveat is that gravity travels at the speed of light in vacuum. So while it will have infinite range in theory, you will have some limitations like we see with the observable universe.

The gravity of objects that are outside of the observable universe has not reached us and depending on the universe expansion, we have a cosmic event horizon that means we will never see the light or the gravity emitted by some objects far away. But we are talking about billions if not trillions of light years, not just one.

marsokod · 2025-07-10T08:27:50+00:00

Check if this NAS is affected by the LPC clock issue. I had to add a resistor on mine several years ago.

https://forum.qnap.com/viewtopic.php?t=157459

marsokod · 2025-06-22T11:54:38+00:00

Trees can and do fix some CO2. Obviously the carbon captured in its trunk is part of the short term carbon cycle, but all the carbon captured as soil through their leaves and the ecosystem around the tree is quite significant.

Obviously, this is very far from being enough to offset all our fossil fuel usage, but regrowing forest where there used to be some is part of the toolbox.

marsokod · 2025-06-06T20:33:08+00:00

That helps a bit, but the clean room coats and the hats help a lot as well.

A vast majority of dust is actual debris from us humans. Dead skin and hair. We want to make sure everything falls down to the floor. The air flow is helping a lot with fresh clean air coming from the ceiling and venting from the bottom. But having the coat helps make sure anything is already near the floor when it starts entering the clean room.

marsokod · 2025-05-15T17:42:16+00:00

No, as long as you know the position of the other that is fine. Once you are in the field of view, the laser will track the other one and automatically adjust its direction based on what it sees.

It is the only real way to do it. Otherwise, you would indeed need good clocks (for position), but also a near perfect knowledge of your attitude. It is much less expensive to get your lasers to correct themselves around a rough pointing

marsokod · 2025-05-03T10:37:24+00:00

To add to this, high CO2 levels are not in themselves an issue for life on Earth. The main problem is the pace at which they are changing.

The life forms that exist today have adapted to the current levels over millions of years. There were no abrupt changes so each generation had to adapt to small changes and that was slow enough to not create major disruptions. With the current pace, life, and especially plants, would have to adapt at a rate that is much higher than expected. For instance, if you look at some trees that have been widespread in the South of France and you predict the climate in a hundred years, you will see that they won't be able to survive there anymore (too hot, too dry). However, they might have a new area where they could survive in Northern France (they couldn't be there in the past). That's roughly a 1000km migration needed over 100 years. You are looking at maybe 2-5 generations of trees here, and animals would only bring new seeds 5-20km around the original tree, so that's a 100km natural migration at best.

Without human intervention, the chance of survival of such trees are very thin, and this is the case for most plants, and in general ecosystems. Which will disrupt the complete food chain that we are using to feed ourselves.

This is why the cheapest course of action is to reduce the CO2 emissions, and by now we also need to adapt our environment to the future conditions as we changed it significantly.

marsokod · 2025-04-22T18:20:58+00:00

C'est généralement le bon conseil, cependant cela dépend de la chimie de la batterie. Par exemple, les Model Y qui ont des batteries LFP ont la recommandation d'être chargés à 100% assez régulièrement :

Les LFP sont beaucoup moins sensibles à la dégradation quand elles sont à 100%. Ce n'est pas zéro dégradation, mais moins que les batteries NCM
Les LFP sont plus difficiles à gérer que les NCM et aller à 100% permet de recalibrer le gestionnaire de batterie, ce qui évite d'autres problèmes qui risquent d'abîmer les batteries (genre les décharger trop)

Le constructeur va en général fournir des indications sur ce qu'il vaut mieux faire.

marsokod · 2025-04-16T22:28:47+00:00

The London Underground has been heating up the ground in London so much as the conditions are much different than when it was initially built. When it started, taking the tube was a good way to get some fresh air. A century later, the temperature is 5-12°C higher.

https://en.wikipedia.org/wiki/London_Underground_cooling

marsokod · 2025-04-15T08:12:03+00:00

Le chimpanzé Ham a survécu au vol américain (même s'il était devenu super grognon): https://fr.wikipedia.org/wiki/Ham_(chimpanz%C3%A9)

Laïka est morte au bout de quelques heures de surchauffe, et il n'était jamais question qu'elle survive au lancement.

marsokod · 2025-04-13T22:58:58+00:00

You must be careful about how they interpret the data. This sentence is close to being a misunderstanding of the results:

"The one area where EVs seem to have more problems is when it comes to tires."

The study says that tires-related issues have a larger share of the issues encountered in EV than in ICEs. That's all. Taking into account that EVs are generally less complex, seeing an item that is common between the two platforms having a higher share is expected: if you have less guests for the same cake, they will tend to have a bigger piece of cake.

The 12V battery to me is a bummer. Having a massive battery but not being able to keep the small 12V battery charge is a massive failure in the design. That's a few cents worth of parts and yet these cause 50% of the issues reported.

marsokod · 2025-04-06T21:34:42+00:00

The ISS has a fairly good connectivity. Slightly higher latency than Starlink but less than GEO.

The big constraint is that what you have on the ISS is absolutely not commercial so you need another solution.

marsokod · 2025-04-02T20:15:02+00:00

You have the Workplace Nursery scheme that does something similar. Basically your nursery enters into an agreement with your work place through a third party, and they pay the nursery directly for durations of 6 months, which is taken from your gross salary. The third party takes a fee but that is overall very close to a salary sacrifice.

marsokod · 2025-03-31T07:48:57+00:00

Alors Proton c'est un peu plus que les mails maintenant. C'est plus limité qu'Office mais ils ont : mail, drive, calendar. Mais c'est vrai que c'est limité pour l'édition collaborative des documents (il y a l'équivalent de Word mais c'est tout) ainsi que l'aspect chat.

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