- 3649 - SUN - solar storms? 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 is called the “solar wind“.
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--------------------- 3649 - SUN - solar storms?
- 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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- 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” which are explosions of plasma from the surface of the sun, and, solar wind that escapes through coronal holes which are 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 humanity.
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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 atmospheric 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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- There a few different ways geomagnetic storms threaten orbiting satellites that serve people on the ground daily. 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, 2022, because of a geomagnetic storm. 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.
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- Finally, geomagnetic storms can disrupt the ability of satellites to communicate with Earth using radio waves. Many communications technologies, like GPS rely on radio waves.
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- The atmosphere always distorts radio waves by some amount, so engineers correct for this distortion when building communication systems. 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 the wrong ones 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, aviation, maritime, robotics, transportation, farming, military, GPS positioning errors of a few meters are simply not tenable. Autonomous driving systems will require accurate positioning.
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- Some of the risks can be minimized by shielding electronics from radiation, or developing materials that are more resistant to radiation. But there is only so much shielding that can be done in the face of a powerful geomagnetic storm.
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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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- But while the modeling and forecasting of geomagnetic storms has significantly improved over the past few years, the projections are often wrong. The National Oceanic and Atmospheric Administration had warned that, following a coronal mass ejection, a geomagnetic storm was "likely" to occur the day before or the day of the February Starlink launch. The mission went ahead anyway.
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- 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. The change coincided with the onset of the new solar cycle, and experts think it might be the beginning of some difficult years for spacecraft orbiting our planet.
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- In the last years, the satellites were sinking about 1.5 miles a year. But since December, 2021, they have been virtually diving. The sink rate between December and April has been 12 miles per year.
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- Satellites orbiting close to Earth always face the drag of the residual atmosphere, which gradually slows the spacecraft and eventually makes them fall back to the planet. They usually don't survive this so-called re-entry and burn up in the atmosphere. This atmospheric drag forces the International Space Station's controllers to perform regular "reboost" maneuvers to maintain the station's orbit of 250 miles above Earth.
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- 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.
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- The last cycle, which 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.
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- Denser air means higher drag for the satellites. Even though this density is still incredibly low 250 miles above Earth, the increase caused by the upwelling atmosphere is enough to virtually send some of the low-orbiting satellites plummeting.
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- The “Swarm constellation“, launched in 2013, consists of three satellites, two of which orbit Earth at an altitude of 270 miles , about 20 miles above the International Space Station. The third Swarm satellite circles the planet somewhat higher, about 320 miles above ground.
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- The two lower-orbiting spacecraft were hit more by the sun's acting out than the higher satellite was. The situation with the lower two got so precarious that by May, operators had to start raising the satellites' altitude using onboard propulsion to save them.
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- In February, SpaceX lost 40 brand-new Starlink satellites that were hit by a solar storm just after launch. In such storms, satellites suddenly drop to lower altitudes. The lower the orbit of the satellites when the solar storm hits, the higher the risk of the spacecraft not being able to recover, leaving operators helplessly watching as the craft fall to their demise in the atmosphere.
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- Starlink satellites have operational orbits of 340 miles, which is above the most at risk region. However, after launch, Falcon 9 rockets deposit the satellite batches very low, only about 217 miles above Earth.
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- All spacecraft around the 250-mile altitude are bound to have problems. That includes the International Space Station, which will have to perform more frequent reboost maneuvers to keep afloat, but also the hundreds of cubesats and small satellites that have populated low Earth orbit in the past decade. Those satellites are a product of the new space movement spearheaded by private entrepreneurs pioneering simple, cheap technologies are particularly vulnerable.
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- Many of these new satellites don't have propulsion systems. They don't have ways to get up. That basically means that they will have a shorter lifetime in orbit. They will reenter sooner than they would during the solar minimum.
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- 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. The solar cycle 25 that we are entering now is currently increasing very steeply.
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- Our Sun routinely blows off parts of its tenuous outer atmosphere, the corona, in an event known as a Coronal Mass Ejection (CME). But the Betelgeuse SME blasted off 400 billion times as much mass as a typical CME!
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- The monster star Beteleuse is still slowly recovering from this catastrophic upheaval. Betelgeuse continues doing some very unusual things right now; the interior is sort of bouncing.
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- These new observations yield clues as to how red stars lose mass late in their lives as their nuclear fusion furnaces burn out, before exploding as supernovae. The amount of mass loss significantly affects their fate. However, Betelgeuse’s surprisingly petulant behavior is not evidence the star is about to blow up anytime soon. So the mass loss event is not necessarily the signal of an imminent explosion.
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- The titanic outburst in 2019 was possibly caused by a convective plume, more than a million miles across, bubbling up from deep inside the star. It produced shocks and pulsations that blasted off the chunk of the photosphere leaving the star with a large cool surface area under the dust cloud that was produced by the cooling piece of photosphere. Betelgeuse is now struggling to recover from this injury.
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- Weighing roughly several times as much as our Moon, the fractured piece of photosphere sped off into space and cooled to form a dust cloud that blocked light from the star as seen by Earth observers. The dimming, which began in late 2019 and lasted for a few months, was easily noticeable even by backyard observers watching the star change brightness. One of the brightest stars in the sky, Betelgeuse is easily found in the right shoulder of the constellation Orion.
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- Though our Sun has coronal mass ejections that blow off small pieces of the outer atmosphere, astronomers have never witnessed such a large amount of a star’s visible surface get blasted into space. Therefore, surface mass ejections and coronal mass ejections may be different events.
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- Betelgeuse is now so huge now that if it replaced the Sun at the center of our solar system, its outer surface would extend past the orbit of Jupiter.
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- NASA’s Webb Space Telescope may be able to detect the ejected material in infrared light as it continues moving away from the star?
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August 13, 2022 SUN - solar storms? 3649
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