This weekend, a Chinese rocket booster, weighing nearly 23 tons, came rushing back to Earth after spending more than a week in space—the result of what some critics, including NASA Administrator Bill Nelson, have attributed to poor planning by China. Pieces of the rocket, dubbed Long March 5B, are believed to have splashed down in the Indian Ocean near the Maldives, and no one was injured.

But the event has shown the potential dangers that come from humanity's expanding presence in space, said Hanspeter Schaub, professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences.

Schaub is an engineer with an eye for the myriad bits of junk that circle our planet—from meteors the size of grains of dust to manmade rocket stages as big as school buses. As humans launch more objects into space, he said, this debris may increasingly threaten the safety of satellites and human astronauts in orbit. In 2009, a decommissioned Russian satellite crashed into an active satellite called Iridium 33, sending a cloud of shrapnel hurtling around the planet.

Your smartphone may be able to sense space weather and even get a little disoriented by it, according to researchers, who tested how geomagnetic storms affect the magnetic sensors in cell phones. The new research suggests that apps being developed to use cell phone magnetometers to pinpoint locations could be susceptible to space weather errors. On the other hand, millions of phones sensing changes in Earth's magnetic field could potentially create a vast observatory to help scientists understand these geomagnetic storms.

Cell phone magnetometer chips are being explored as a backup for GPS, which uses satellite signals to triangulate location and thus is often inaccurate or unavailable in places where signals can't penetrate, such as inside large buildings or underground.

"Smartphone magnetometers are being commercially explored for applications as diverse as locating customers in shopping malls for targeted advertising, to precision needle-guided surgery," wrote Sten Odenwald, of NASA's Space Science Education Consortium at Goddard Space Flight Center in Maryland, in Space Weather.