- 3617 - SPACE X - satellites in a solar storm? Space weather forecasters are developing models that would help satellite operators prepare for bad “space weather“. But there is a problem, we lack measurements at altitudes where Earth's atmosphere meets outer space. SpaceX is now stepping in to help fill the gaps after its firsthand experience with an unexpected solar storm earlier this year.
--------------------- 3617 - SPACE X - satellites in a solar storm?
- In February 2022, 40 brand-new Starlink satellites plummeted to Earth when they encountered bad space weather right after launch. The solar storm that caused their demise wasn't even a bad one. The incident was a taste of things to come, as the sun, after a prolonged quiet period, is waking up to a more powerful cycle of activity than many satellite operators, including SpaceX, have experienced.
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- In 2019 NOAA launched what it calls the “Whole Atmosphere Model“, which extends the meteorological model that predicts weather on Earth to an altitude of up to 370 miles. This region includes the second-highest layer of Earth's atmosphere, the “thermosphere“, where thin, diffuse gases cause drag that slows satellites down.
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- This thin gas high above Earth's surface changes density when solar weather hits, and these density changes cause problems such as those the Starlink satellites experienced in February, 2022.
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- To improve NOAA’s forcasting model they really need to bring in more data and that's what SpaceX promised us. They will share with us the orbit information of their satellites to help us estimate the drag. Since they have so many satellites, they will give us a lot of data points.
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- Starlink currently, May, 2022, operates more than 2,200 satellites that orbit Earth at an altitude of 340 miles . However, the company launches the satellites into a much lower orbit of only 217 miles and raises their altitude using onboard propulsion units. It is at these lower altitudes that satellites are the most vulnerable to sudden space weather changes.
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- “Swarm satellites“, which monitor Earth's magnetic field, have been sinking 10 times faster since December, 2021 than in other years since their launch in 2013.
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- Space weather forecasters originally expected the current cycle of solar activity, which started last year, to be a mild one. However, the sun has been constantly outpacing predictions, producing many more sunspots, solar flares and eruptions, and triggering geomagnetic storms on Earth that make satellite operations more challenging.
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- On February 4, 2022, SpaceX launched 49 satellites as part of Elon Musk's Starlink internet project, most of which burned up in the atmosphere days later. The cause of this more than $50 million failure was a geomagnetic storm caused by the sun.
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- Geomagnetic storms occur when space weather hits and interacts with Earth. Space weather is caused by fluctuations within the sun that blast electrons, protons and other particles into space.
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- When space weather reaches Earth, it triggers many complicated processes that can cause a lot of trouble for anything in orbit. The sun is always releasing a steady amount of charged particles into space. This “solar wind” also carries with it the solar magnetic field. Sometimes, localized fluctuations on the sun will hurl unusually strong bursts of particles in a particular direction. If Earth happens to be in the path of the enhanced solar wind generated by one of these events and gets hit, you get a geomagnetic storm.
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- The two most common causes of geomagnetic storms are coronal mass ejections, explosions of plasma from the surface of the sun, and solar wind that escapes through coronal holes, spots of low density in the sun's outer atmosphere.
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- The speed at which the ejected plasma or solar wind arrives at Earth is an important factor, the faster the speed, the stronger the geomagnetic storm. Normally, solar wind travels at roughly 900,000 mph. But strong solar events can release winds up to five times as fast.
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- The strongest geomagnetic storm on record was caused by a coronal mass ejection in September 1859. When the mass of particles hit Earth, they caused electrical surges in telegraph lines that shocked operators and, in some extreme cases, actually set telegraph instruments on fire. Research suggests that if a geomagnetic storm of this magnitude hit Earth today, it would cause roughly $2 trillion in damage.
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- Emissions from the sun, including the solar wind, would be incredibly dangerous to any life form unlucky enough to be directly exposed to them. Thankfully, Earth's magnetic field does a lot to protect us.
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- The first thing solar wind hits as it approaches Earth is the magnetosphere. This region surrounding the Earth's atmosphere is filled with plasma made of electrons and ions. It's dominated by the planet's strong magnetic field. When solar wind hits the magnetosphere, it transfers mass, energy and momentum into this layer.
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- The magnetosphere can absorb most of the energy from the everyday level of solar wind. But during strong storms, it can get overloaded and transfer excess energy to the upper layers of Earth's atmosphere near the poles. This redirection of energy to the poles is what results in fantastic “aurora”events, but it also causes changes in the upper atmosphere that can harm space assets.
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- The different layers of Earth's atmosphere are all affected by solar storms differently.
When the atmosphere absorbs energy from magnetic storms, it heats up and expands upward. This expansion significantly increases the density of the “thermosphere“, the layer of the atmosphere that extends from about 50 miles to roughly 600 miles above the surface of Earth. Higher density means more drag, which can be a problem for satellites.
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- Starlink satellites are released in batches, and 40 were destroyed in early February because of a geomagnetic storm. This situation is exactly what led to the demise of the the SpaceX Starlink satellites in February.
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- Starlink satellites are dropped off by Falcon 9 rockets into a low-altitude orbit, typically somewhere between 60 and 120 miles above Earth's surface. The satellites then use onboard engines to slowly overcome the force of drag and raise themselves to their final altitude of approximately 350 miles.
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- The latest batch of Starlink satellites encountered a geomagnetic storm while still in very low-Earth orbit. Their engines could not overcome the significantly increased drag, and the satellites began slowly falling toward Earth and eventually burned up in the atmosphere.
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- Drag is just one hazard that space weather poses to space-based assets. The significant increase in high-energy electrons within the magnetosphere during strong geomagnetic storms means more electrons will penetrate the shielding on a spacecraft and accumulate within its electronics. This buildup of electrons can discharge in what is basically a small lightning strike and damage electronics.
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- Penetrating radiation or charged particles in the magnetosphere can also alter the output signal from electronic devices. This phenomenon can cause errors in any part of a spacecraft's electronics system, and if the error occurs in something critical, the entire satellite can fail. Small errors are common and usually fixable, but total failures, though rare, do happen.
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- Geomagnetic storms can disrupt the ability of satellites to communicate with Earth using radio waves. Many communications technologies, like GPS rely on radio waves. The atmosphere always distorts radio waves by some amount, so engineers correct for this distortion when building communication systems.
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- But during geomagnetic storms, changes in the ionosphere, the charged equivalent of the thermosphere that spans roughly the same altitude range, will change how radio waves travel through it. The calibrations in place for a quiet atmosphere become wrong during geomagnetic storms.
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- This makes it difficult to lock onto GPS signals and can throw off the positioning by a few meters. For many industries like aviation, maritime, robotics, transportation, farming, military and others, GPS positioning errors of a few meters are simply not acceptable. Autonomous driving systems will require accurate positioning as well.
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- Satellites are critically important for much of the modern world to function, and protecting space assets from space weather is an important area of research.
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- The ability to accurately forecast storms would make it possible to preemptively safeguard satellites and other assets to a certain extent by shutting down sensitive electronics or reorienting the satellites to be better protected.
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- The sun is like a child that often throws tantrums. It's essential for life to go on, but its ever-changing disposition make things challenging.
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July 1, 2022 SPACE X - satellites in a solar storm? 3614
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