Over the past three years, SpaceX has placed thousands of satellites into low Earth orbit as part of its efforts to bundle high-speed Internet services from space. But the company’s latest deployment of 49 new satellites after a February 3 launch didn’t go as planned.
Due to a geomagnetic storm caused by a recent solar outburst, up to 40 of the 49 newly launched Starlink satellites have been taken out of service. They are in the process of re-entering the Earth’s atmosphere, where they will be burned.
The incident highlights the dangers facing numerous companies that plan to launch tens of thousands of small satellites into orbit to provide internet services from space. And it’s possible that more solar outbursts will knock some of these newly placed orbital emitters out of the sky. The sun has an 11-year cycle in which it fluctuates between hyperactive and quiescent states. Currently, it is rising to its peak, which is expected to arrive around 2025.
This recent solar storm was relatively moderate by the standards of the sun. “I’m very confident that in the next cycle we’ll see an extreme event because that’s typical of what happens during a solar maximum,” said Hugh Lewis, a space debris expert at the University of Southampton in England. If a milquetoast outburst can knock out 40 Starlink satellites hovering at low orbital altitudes, a more powerful solar scream could do more damage to the megaconstellations of SpaceX and other companies.
SpaceX announced the impending destruction of as many as 40 of its satellites in a company blog post Tuesday night. The company said the satellites were released into their intended orbit after launch, about 130 miles above Earth.
This height was chosen in part to avoid possible future collisions with other satellites. If the satellites don’t work properly after being deployed at that altitude, and are unable to move their orbits to more safe altitudes, “the atmosphere reclaims the failed technology very quickly,” said Dr. Lewis. “And that’s a really good security measure.”
But on January 29, before these satellites were launched, a violent outburst from the sun of highly energetic particles and magnetism was detected, known as a coronal mass ejection. Those emissions arrived on Earth sometime around Feb. 2 and created a geomagnetic storm in Earth’s magnetic bubble.
The powerful storm added kinetic energy to particles in Earth’s atmosphere. “The atmosphere gets a bit inflated and expands because of that,” said Dr. Lewis. That expansion causes an increase in the density of the atmosphere, which in turn increases the drag experienced by objects moving through it, including satellites. This resistance reduces the size of their orbits, bringing them closer to the thick, lower atmosphere in which they burn up.
According to SpaceX, the rate of escalation and severity of the storm caused air resistance to be up to 50 percent higher during the recent Starlink deployment than during previous launches. This caused as many as 40 of the 49 satellites to eventually succumb to gravity and perish.
There are currently a total of 1,915 Starlink satellites in orbit, so for SpaceX a loss of up to 40 “isn’t a big deal from their point of view,” it said. Jonathan McDowellan astronomer at the Harvard and Smithsonian Center for Astrophysics in Cambridge, Massachusetts, who also catalogs and tracks artificial space objects.
But dr. Lewis said, “That probably accounts for potentially up to $100 million in hardware, if you factor in the cost of launch.”
The dangers that solar eruptions and geomagnetic storms pose to objects in low Earth orbit, from electrical damage to communication failures, are well known. The National Oceanic and Atmospheric Administration ranks geomagnetic storms on a scale from minor to extreme. The latter, a “moderate” storm, is noted by the agency as potentially leading to changes in atmospheric drag that could alter orbits.
Now that these risks are known, has SpaceX considered this danger during this Starlink deployment?
“I’m just a little baffled. said Samantha Lawler, an astronomer at the University of Regina in Canada. “Really? Didn’t they think of that?”
“It’s a bit of a surprise,” said Dr. McDowell. “They should have been ready for this, you would think.”
When contacted via email, a SpaceX media representative said no one was available to answer questions, noting that “it’s an incredibly demanding time for the team.”
That these satellites seem to be entering the atmosphere quickly, rather than hovering in low Earth orbit, is a good thing. They also pose no threat to anyone on the ground. “From a safety point of view, the system functioned exactly as it should,” said Dr. Lewis. “The satellites went out of orbit and nothing else was compromised.”
Most satellites orbit at higher altitudes and can avoid the dangers of atmospheric expansion. But the threat to satellites orbiting at lower altitudes is far from over, and it raises the question of whether SpaceX can continue to deploy spacecraft at these low altitudes.
“As the sun becomes more active, it releases an increasing amount of extreme ultraviolet, which is absorbed into our atmosphere,” said Dr. Lewis. That atmosphere will expand significantly, and “atmospheric density is expected to increase by one or two orders of magnitude. That’s a much bigger change compared to what we’ve just seen with this particular event. †
Many astronomers have criticized Starlink and other satellite constellations, which reflect sunlight and potentially interfere with telescope research on Earth. And some see this incident as symbolic of SpaceX’s attitude to issues arising in low Earth orbit.
“When things fail, they fix them and do better next time,” said Dr. Lewis. “This is another example of that” – a policy of sticking to hindsight, not looking ahead.
The death of these satellites is “a hard lesson for SpaceX,” said Dr. Lewis. What happens next is up to them.
dr. Lawler added, “I hope this will knock some sense into them.”
