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Unexpected solar weather is accelerating satellites' orbital decay

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Re: Unexpected solar weather is accelerating satellites' orbital decay

#81

Post by nomel »

colechristensen wrote: post #48
BitwiseFool wrote: post #46

Earlier quoted context omitted.

I think the primary objection is that to the vast majority of people 'plummet' implies the satellite is suddenly and violently falling from the sky - it's the kind of word people would describe an airplane crash with. However unless the author happens to know a lot about orbital mechanics (or they've played Kerbal Space Program) they probably just picked an expressive word for the sake of a compelling article rather…

It's a dumb objection. A mission manager was quoted using the word "diving". It isn't the journalist but the nitpicking commentors who are clueless. The headline accurately enough conveys what is happening and the article articulates it well. Orbital mechanics isn't intuitive enough for there to be perfect fit words given human experience, human timescales, "plummet" is fine.

The definition of the word, that everyone is probably familiar with, strongly disagrees: https://www.merriam-webster.com/dictionary/plummet

    Plummet:
    
    1. to fall perpendicularly
    
    2. to drop sharply and abruptly
Or, Google's scraped definition from Oxford dictionary:

    fall or drop straight down at high speed.
If you google "satellite plummeting", you'll notice that almost all of the results also include "fireball", "burning up" and/or "reentry".

Re: Unexpected solar weather is accelerating satellites' orbital decay

#83

Post by walrus01 »

FunnyBadger wrote: post #70

This is simply part of the solar cycle. And it's a standard part of satellite planning when it comes to operational quality and reliability to account for solar cycle radiation effects. This is an ignorant fear article and/or an article written by someone who knows NOTHING about space launch and design. (I used to be a military rocket scientist specializing in radiation effects on space electronics many moons ago).

I concur with this, and also, one possible solution to this from a technical perspective is to increase the amount of fuel carried for ion/hall effect and similar thrusters (high specific impulse, low thrust) for periodic orbit raising maneuvers to extend lifetime.

Theoretically, as $ per kg launch costs come down with things like reusable falcon 9, it makes it much less costly to equip medium sized LEO satellite with more fuel than it might have costed 10 or 15 years ago.

Or if you have something that needs to orbit really low and minimize drag/maximize lifespan, you could design it to be particularly aerodynamic and shaped like this:

https://en.wikipedia.org/wiki/Gravity_Field_and_Steady-State...

Re: Unexpected solar weather is accelerating satellites' orbital decay

#84

Post by adolph »

mirashii wrote: post #47
perihelions wrote: post #32

Earlier quoted context omitted.

They also say Starlink fully lost 40 satellites to solar weather (were decelerated rapidly enough to burn up in the atmosphere, before their orbits could be rescued). There's a range of outcomes. Thread about that: https://news.ycombinator.com/item?id=30267587 (488 comments)

For those who don’t click through to the other thread, I’d say that solar weather contributed, but the root cause was more an overzealous safe mode induced by the operations team that didn’t leave time to recover. A better operations plan would’ve shortened the safe mode duration to ensure that they attempted to raise their orbit even if it meant deploying during the solar event. Letting safe mode destroy the satelli…

> Take the chance and deploy anyways and hope you get lucky.

If they got unlucky they might have spiked a space in which another satellite could have orbited (no pun intended).

Re: Unexpected solar weather is accelerating satellites' orbital decay

#85

Post by colechristensen »

GekkePrutser wrote: post #66
colechristensen wrote: post #39

Earlier quoted context omitted.

Yes, orbit decay having gone up by a factor of ~10 is indeed plummeting. You park things in low earth orbit so that they don't stay up forever and indeed come down in reasonably small human-scale timeframes. Usually on the time scale of decades, sometimes more, sometimes less. If you designed a satellite to stay up for 10 years, it'll suddenly only be able to stay up a year, that's the scale of these things. Again it…

But this space 'weather' won't last forever right? Won't it go back to the old decay rate after this? So if it lasts a week, the lifetime will be reduced by 10 weeks? Still a lot but something you can cope with.

There are events measured in minutes, hours, and years (or decades).

We’re ramping up to a maximum which should happen in a few years but activity has been above predictions. We don’t understand the Sun dynamics all that well, but what’s happening now is a little weird beyond expectations and might be something that continues for years.

Re: Unexpected solar weather is accelerating satellites' orbital decay

#86

Post by jhgb »

zackees wrote: post #74

So this effect is caused by more solar wind slamming into the atmosphere at 100’s of km/hr and is so powerful that it’s CAUSING THE ATMOSPHERE TO HEAT UP AND EXPAND? Does the global warming models take this into effect? This seems like an unfathomable amount of energy.

It's causing the uppermost layers of atmosphere to expand. That's less than an unfathomable amount of energy because the uppermost layers of atmosphere are extremely rarefied, to the extent they don't even behave like gases.

Re: Unexpected solar weather is accelerating satellites' orbital decay

#87

Post by KennyBlanken »

FunnyBadger wrote: post #70

This is simply part of the solar cycle. And it's a standard part of satellite planning when it comes to operational quality and reliability to account for solar cycle radiation effects. This is an ignorant fear article and/or an article written by someone who knows NOTHING about space launch and design. (I used to be a military rocket scientist specializing in radiation effects on space electronics many moons ago).

The article at length describes how this solar cycle is different from prior cycles and forecasts.

> This drag also helps clean up the near-Earth environment from space junk. Scientists know that the intensity of this drag depends on solar activity — the amount of solar wind spewed by the sun, which varies depending on the 11-year solar cycle. The last cycle, which officially ended in December 2019, was rather sleepy, with a below-average number of monthly sunspots and a prolonged minimum of barely any activity. But since last fall, the star has been waking up, spewing more and more solar wind and generating sunspots, solar flares and coronal mass ejections at a growing rate. And the Earth's upper atmosphere has felt the effects.

> In late 2021, operators of the European Space Agency's (ESA) Swarm constellation noticed something worrying: The satellites, which measure the magnetic field around Earth, started sinking toward the atmosphere at an unusually fast rate — up to 10 times faster than before.

> By coincidence (or beginner's luck), the onset of the new space revolution came during that sleepy solar cycle. These new operators are now facing their first solar maximum. But not only that. The sun's activity in the past year turned out to be much more intense than solar weather forecasters predicted, with more sunspots, more coronal mass ejections and more solar wind hitting our planet.

> "The solar activity is a lot higher than the official forecast suggested," Hugh Lewis, a professor of engineering and physical sciences at the University of Southampton in the U.K. who studies the behavior of satellites in low Earth orbit, told Space.com. "In fact, the current activity is already quite close to the peak level that was forecasted for this solar cycle, and we are still two to three years away from the solar maximum."

> Stromme confirmed those observations. "The solar cycle 25 that we are entering now is currently increasing very steeply," she said. "We do not know if this means that it will be a very tough solar cycle. It could slow down, and it could become a very weak solar cycle. But right now, it's increasing fast."

Re: Unexpected solar weather is accelerating satellites' orbital decay

#88

Post by daniel-cussen »

mirashii wrote: post #47
perihelions wrote: post #32

Earlier quoted context omitted.

They also say Starlink fully lost 40 satellites to solar weather (were decelerated rapidly enough to burn up in the atmosphere, before their orbits could be rescued). There's a range of outcomes. Thread about that: https://news.ycombinator.com/item?id=30267587 (488 comments)

For those who don’t click through to the other thread, I’d say that solar weather contributed, but the root cause was more an overzealous safe mode induced by the operations team that didn’t leave time to recover. A better operations plan would’ve shortened the safe mode duration to ensure that they attempted to raise their orbit even if it meant deploying during the solar event. Letting safe mode destroy the satelli…

Come on, 40 satellites is not all that much for Spacex.

Re: Unexpected solar weather is accelerating satellites' orbital decay

#89

Post by jtbayly »

dang wrote: post #62
jtbayly wrote: post #24

Earlier quoted context omitted.

It's spelled "pedantry." :)

That has to have been a trap.

Lol. That was certainly on my mind. And then I decided it was such a lovely trap that I wanted to be the one that fell in it.
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