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How a rather mundane space storm knocked out 40 SpaceX satellites

As the sun enters a more active phase, even minor geomagnetic activity could pose problems for smaller SpaceX satellites.

An aurora appeared near Rogart in Sutherland, Scotland, as a minor geomagnetic storm struck Earth’s atmosphere on Feb. 4, 2022. (Christopher J. Cogan)

In recent months, sky watchers have been treated to some of the most beautiful auroras in years as the sun enters a period of greater activity. Moderate and strong solar storms in October and November spurred the dancing purple and green lights in Earth’s atmosphere, delighting scientists and photographers.

But last week, SpaceX witnessed a different stunning impact of the charged particles hurtling through space when 40 of their small Starlink communications satellites were knocked out a day after they launched. The loss could cost the company tens of millions of dollars. Starlink ultimately will consist of tens of thousands of small satellites in low Earth orbit.

According to a SpaceX news release, 40 out of 49 Starlink satellites will reenter the atmosphere or already have entered after encountering a geomagnetic storm on Feb. 4. The satellite fleet, intended to bring low-cost Internet service to remote areas of the planet, was launched on Feb. 3 at the Kennedy Space Center in Florida. The company said the satellites are not expected to create debris or hit the ground on reentry, instead being incinerated during the fiery reentry.

“It is the first time this many spacecraft have been impacted at a single time that we’re aware of,” said Jim Spann, the space weather lead for NASA’s heliophysics division, which studies physics related to the sun.

Spann said that NASA and the National Oceanic and Atmospheric Administration (NOAA) are analyzing the exact nature of the event that caused the issue but that the conditions do not appear particularly special.

Two solar storms

On Jan. 30, satellites observed the sun undergo a coronal mass ejection — an expulsion of plasma and magnetic material. The stream was directed toward Earth and arrived around Feb. 2, sparking some aurora sightings in the northern United States, as shown above.

“That’s the solar storm we had predicted would hit. It was pretty much on time,” said Tamitha Skov, a research scientist at Aerospace Corp. “When we saw it, we went, ‘Oh, this is pretty mild.’”

Geomagnetic storms are rated on a scale of G1 to G5 by NOAA, but Skov said this storm registered as “only active conditions” — not even reaching the lowest G1 storm level. “We see lots of storms like this. They happen literally once a week.”

However, another solar storm was lurking behind this one, and it took scientists by surprise.

“We had essentially one observation that was line of sight, which means that we look from Earth to the sun and we see the structure that’s coming at us,” Skov said. “But if there are other things hidden inside that structure or just behind it, it’s very difficult to pull that out or discern.”

When SpaceX launched its satellites Feb. 3, the second storm was ramping up. The storm was rated G1, stronger than the first but still relatively weak.

Skov said the effects of the two successive storms, however, caused Earth’s atmosphere to inflate, or puff out.

Think of Earth’s atmosphere like a bicycle tire, Skov said. When the first solar storm hit, its magnetic field drove currents that caused Earth’s upper atmosphere and particles to move in one direction. The motion continued for nearly an entire day.

When the second surprise solar storm hit, however, it was oriented in such a way as to cause the motion of Earth’s upper atmosphere to reverse direction, Skov said. The friction and energy of the two opposing forces released heat in quantities more than models had anticipated — similar to the frictional heat released when trying to stop and reverse a moving bicycle tire with your hand.

“Your atmosphere is going to inflate a lot when you have to spin down the atmosphere and cause it to spin the other way,” said Skov, who also releases space weather forecasts regularly on her YouTube channel.

Spann said NASA and NOAA are still analyzing data and working to have a complete understanding of the event, but he also said there may have been a bit of build up from the first event that helped prime the environment by the time the G1 storm arrived.

“It’s kind of a normal G1 storm. It wasn’t anything exotic or extreme,” Spann said. He said his colleagues are working to “understand how this all happened, to make us more effective in the prediction and providing the support that the commercial and other entities might need for future launches.”

The second storm also spurred auroras in a handful of areas across the world, from near the Canada-U.S. border to Britain.

Low altitude

SpaceX stated in its news release that the storms caused the atmosphere to warm and increased atmospheric density at the altitudes at which the magnetic storm activity was occurring.

“The geomagnetic storms, when energy from the sun gets into the Earth’s magnetic field environment, it changes the upper atmosphere. ... The density of that changes,” said Elizabeth MacDonald, a space weather physicist at NASA. “When a lot of particles are coming into the atmosphere, that can cause increased drag.

Drag was up to 50 percent higher than in during previous satellite launches, according to the SpaceX news release. The Starlink team ordered the satellites into safe mode to minimize the effect, but the increased drag then prevented the satellites from leaving safe mode to begin maneuvers to enter correct orbit.

MacDonald said the atmospheric conditions led to a “perfect storm” in some sense. The timing of the flow of radiation from the sun and the effects of the storm on Earth’s upper atmosphere increased drag. But she added that that is not especially unusual, nor is the occurrence of two geomagnetic storms in close succession.

“What is unusual is the very low altitude of the Starlink satellites,” she said.

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SpaceX said the satellites were hovering at the intended 130 miles above Earth (the perigee of its orbit), although Skov said that is lower than expected for a stable orbit. Particle density also is higher at lower altitudes.

Skov said the design of the satellites also probably did not help to reduce drag. The satellites are impressively small, with a comparatively large solar panel — a recipe for drag if the atmosphere inflates. Imagine one of those plastic army man toys deploying its parachute.

Starlink had not encountered such a dense atmosphere in previous launches, but previous satellites launches occurred during very different conditions on the sun. Approximately every 11 years, the orientation of the sun’s magnetic field flips and activity waxes and wanes. The Starlink system came online while the sun was going through a period of low activity called a solar minimum. Recently though, the sun has begun to enter a period of increased activity, heading toward a solar maximum.

“Because the sun has been so quiet and all this technology being developed over the last several years, this is the first time that we are employing this sort of technology in this new environment,” Spann said.

Space climate will affect your weather — and technology

Space weather researchers say the sun’s activity is expected to increase, reaching solar maximum around 2025. In the past, Spann said, some of the most intense magnetic storms have occurred after the sun hit its peak and the solar maximum was declining — meaning Starlink’s engineers will have to learn how to adapt the system for these conditions for many years to come.

“This is something that Elon and crew are going to need to pay attention to, because this is not something that is an extreme event by any means,” Skov said, referring to SpaceX founder Elon Musk and the storm on Feb 4. “We are going to see more of them.”

In fact, in the week since the latest Starlink launch, sky watchers around the world have seen several auroras when another G1 storm reached Earth: