Month: June 2025

New research suggests that heightened solar activity shortens the lifespans of SpaceX’s Starlink satellites, and may send them careening back to Earth at greater velocities. Perhaps unintuitively, this could increase the risk of satellite debris making landfall. 

This preprint study, which has yet to undergo peer review, adds to a wealth of evidence showing that solar storms wreak havoc on Elon Musk’s Starlinks. Over the last several years, the frequency and intensity of these storms have increased as the Sun approaches solar maximum—the peak in its 11-year cycle. At the same time, the number of satellites orbiting Earth has skyrocketed, largely due to the rise of private megaconstellations like Starlink. 

A team of researchers led by Denny Oliveira from NASA’s Goddard Space Flight Center tracked reentries of Starlink satellites between 2020 and 2024. This period coincided with the rising phase of the current solar cycle, when solar activity ramps up ahead of the solar maximum, which occurred in October 2024.

Over the course of those five years, 523 Starlink satellites reentered Earth’s atmosphere. Oliveira and his colleagues analyzed the orbits of these satellites using a statistical technique that identifies patterns in how their rates of orbital decay and reentry change during periods of high solar activity.

The researchers found that geomagnetic activity—disturbances in the upper atmosphere triggered by solar eruptions—causes Starlinks to reenter Earth’s atmosphere sooner than expected. These satellites are designed to remain in orbit for roughly five years. But during bouts of severe geomagnetic storms, their lifespans may be reduced by 10 to 12 days, Oliveira told Gizmodo. 

He and his colleagues believe this happens because geomagnetic activity heats the atmosphere and causes it to expand. This increases drag on satellites, shortening their lifespans and causing them to lose altitude more quickly as they interact with the upper atmosphere. What’s more, atmospheric drag may increase the chances of satellite-on-satellite collisions, as the orbital models that guide collision avoidance measures don’t fully account for the effects of geomagnetic activity. The team’s findings are currently available on the preprint server arXiv.  

A difference of 10 to 12 days may not sound like a big deal, but it could make it nearly impossible for SpaceX to ensure that Starlink satellites return to Earth via controlled reentry, Oliveira explained. What’s more, his analysis shows that increased drag causes satellites to reenter at higher velocities, which he believes could raise the chances of debris reaching the ground.

This may seem counterintuitive, since increasing the velocity of an object during reentry generally increases the likelihood of total disintegration. But Oliveira posits that Starlinks falling at greater speeds may have a better chance of surviving reentry due to reduced atmospheric interaction. Further research will need to confirm this hypothesis, as the study did not directly assess debris risks.

Starlinks are designed to fully burn up during reentry, but that doesn’t always happen. In 2024, a 5.5-pound (2.5-kilogram) chunk of Starlink debris made landfall on a farm in Saskatchewan, New Scientist reported. In February of this year, SpaceX said it is possible for Starlink debris fragments to fall back to Earth, but claimed that this poses “no risk to humans on the ground, at sea, or in the air.”

There are now more than 7,500 Starlinks in orbit, according to Harvard University astronomer Jonathan McDowell, who tracks the constellation. Eventually, SpaceX hopes to quintuple the size of this fleet, with a goal of launching 42,000 Starlinks in total, according to Space.com. This is in addition to the thousands of other satellites currently orbiting Earth. 

“[This is] the first time ever in history that we have so many satellites in orbit at the same time,” Oliveira said. “So, now, we have satellites reentering pretty much every week. And possibly, in the next months or years, every day.” Understanding how changes in solar activity impact their lifespans and their reentries will be critical as Earth’s orbit becomes increasingly crowded.

A new study has found a startling link between chronic cannabis use and increased risk of cardiovascular disease—regardless of whether you smoke it or consume edibles. The finding challenges commonly held beliefs about the health impacts of tetrahydrocannabinol (THC), which many see as a relatively harmless drug—especially when ingested.

The study, published Wednesday, May 28 in the journal JAMA Cardiology, found that THC smokers suffer from significantly worse artery function than non-users. They observed the same effect in edible consumers, though their arteries were not as severely affected. In either case, vascular function was reduced by roughly half compared to those who do not use cannabis, according to a statement from the University of California, San Francisco.

“Scientifically, this THC result is really interesting but boy does it screw up the public health messaging,’” co-author Matt Springer, a cardiovascular researcher at UCSF, reportedly said to lead author and UCSF physician-scientist Leila Mohammadi when he saw the data. 

These results add to a growing body of evidence that suggests long-term weed use can lead to cardiovascular damage and life-threatening events such as heart attacks and strokes, though experts still lack consensus on its precise impacts. A 2024 study published in the Journal of the American Heart Association found that people who consume cannabis daily had a 25% increased risk of heart attack and a 42% increased risk of stroke compared to non-users.

For this new study, researchers investigated how cannabis impacts vascular function. To isolate the effects of chronic cannabis use, they recruited 55 otherwise healthy adults aged 18 to 50 who did not use any form of nicotine and were not frequently exposed to secondhand smoke. 

These participants were sorted into three groups: marijuana smokers, edible users, and non-users. Those in the two cannabis user groups reported taking the drug at least three times per week, either exclusively through smoking or edibles.  

To assess the participants’ vascular function, the researchers measured dilation of the brachial artery—located in the upper arm—to determine whether it could properly expand in response to increased blood flow. To that end, they used an inflatable forearm cuff to briefly block blood flow to the artery, then used ultrasound to measure its diameter before and after inflating the cuff. 

Matt Springer, a cardiovascular researcher at UCSF whose lab led the study, told Live Science that his test offers a “window into the future.” When blood vessels cannot fully dilate, he said, the risk of heart attack and other poor cardiovascular outcomes increases.

Participants who did not consume cannabis showed an average vessel dilation—represented as the percent change from the baseline measurement of artery diameter—of 10.4%. This value was significantly reduced among weed smokers and edible users, who showed an average vessel dilation of 6.0% and 4.6%, respectively. For reference, average values for brachial artery dilation in healthy individuals typically range from 8.0% to 15%. In a previous study, Springer’s lab found similarly reduced levels of vessel dilation among e-cigarette and cigarette smokers. 

To better understand how THC causes this change, the researchers ran lab tests to determine how endothelial cells—which form the linings of blood vessels and release nitric oxide to trigger dilation—responded to the participants’ blood samples. These tests revealed that the blood of chronic cannabis smokers inhibited nitric oxide production in the cells, which may explain why these participants showed reduced vessel dilation. 

This effect was not observed in edible consumers, however, suggesting that ingestible THC may impact arterial function via an entirely separate mechanism. Figuring out what that mechanism may be will require further research. What’s more, subsequent studies will need to reproduce these findings in a larger population to validate the results. 

Within the last several years, cannabis use among U.S. adults has reached new heights, according to the NIH’s National Institute on Drug Abuse. As such, investigating the health effects of THC is more important than ever before—especially as mounting evidence challenges perceptions of weed as a harmless high.