Researchers have revealed that during the intense four-day solar storm in May, satellites and space debris in low Earth orbit fell towards Earth at an alarming rate of 590 feet (180 meters) per day, as was reported by Space.com on June 12 in a pre-print paper published on arXiv. This sudden change forced thousands of spacecraft to ignite simultaneously in order to reclaim their original positions, according to Space.com.
The authors from the Massachusetts Institute of Technology namely William Parker and Richard Linares pointed out the potential dangers associated with such satellite movement. They noted that there may not have been enough time for collision avoidance systems to compute diverging paths for these satellites.
The authors explained that this was a G5 event which is the highest level on NOAA’s five-step scale. It was the most powerful solar storm since 2003. However, they emphasized that over the last two decades, space has changed significantly. While about a few hundred satellites were orbiting Earth twenty years ago only now there are nearly 10000 “active payloads at [low Earth orbit].”
“The growth of commercial small satellites has transformed how we operate in LEO,” said an author.
Solar storms cause disruption in earth’s magnetic field by ejecting massive amounts of charged gas from the sun into its atmosphere; these charged particles can penetrate deep into it. As a result, when they collide with air molecules, this leads to beautiful northern and southern lights. Conversely, they heat up our atmosphere causing it to stretch.
Thus, sparse leftover gases at satellite heights cause them lose altitude due to increased resistance from thick medium resulting from greater density.
As such, forecasting accuracy concerning severity or duration of May solar storms was considerably hampered by existing space weather prediction systems making it almost impossible before hand to anticipate chances for collision among satellites.
“This meant low Earth orbit had disturbances that were large and unpredictable compared to previous conjunctions while posing severe threats towards orbital trajectories of satellites,” wrote the authors. “Nearly half of all active satellites in [low Earth orbit] completed simultaneous station keeping, especially from the Starlink constellation due to the storm. The act of unpredictability in satellite drag and bulk manoeuvring made possible identification of potential conjunctions throughout the period when there was a storm and even days after.”
However, the storm’s major effect was on space debris removal as dead satellites and fragments fell deeper into the atmosphere. Thousands of space debris objects were estimated by the report’s authors to have come down several kilometers during that tempest.
As we approach late 2024 and early 2025, stronger solar storms are expected during this current solar cycle peak. This fluctuations in occurrence rates of sunspots, flares and eruptions define an eleven-year cycle.
