While 2018 features your standard mix of beautiful meteor showers to enjoy, there's one manmade version on the horizon that has a very small possibility of making more than just a visual impact.
The 34-foot-long, 8.5-ton Tiangong-1, China's first-ever space lab, is predicted to make an uncontrolled reentry into Earth's atmosphere sometime in March or early April. Unlike other orbiting spacecraft, which either burn up completely in Earth's atmosphere or feature a controlled descent into a remote "space graveyard" in the Pacific called Point Nemo, Tiangong-1's return is completely at the mercy of the laws of physics.
"You really can’t steer these things," Harvard astrophysicist Jonathan McDowell told the Guardian. "Even a couple of days before it re-enters we probably won’t know better than six or seven hours, plus or minus, when it’s going to come down. Not knowing when it’s going to come down translates as not knowing where it's going to come down."
China's space agency, which lost contact with the craft's telemetry services in September 2016, has estimated Tiangong-1 will reenter somewhere between latitudes 42.8° North and 42.8° South, an area largely covered by ocean, but also with some major population centers. Potential reentry locations include parts of the U.S., Southern Europe, China, the Middle East, South America, Australia and New Zealand.
Ground trace of Tiangong-1 over a period of one day. (Image: CNES)
While the chances are extremely small, 1 in 10,000 according the the Verge, that pieces of the space lab will impact any person or property, the event is still worth keeping an eye on. An estimated 10 to 40 percent of the spacecraft is expected to survive reentry, with some pieces weighing as much as 220 pounds hitting the Earth at high speeds.
"According to public sources, Tiangong-1 is a big cylinder of 10 meters long for a weight of 8.5 tons, a kind of big bus with solar panels on the sides," Stéphane Christy of the French space agency CNES said in an interview. "When the object gets closer to the 80 km altitude, it will begin to fragment into several pieces. Most of the pieces will be destroyed by the heat, but some (the tanks for example) can arrive more or less whole on the ground."
Using simulations that take into account the decaying orbit of Tiangong-1, as well as the impact of solar flux (solar activity increases friction, which hastens degradation of the space lab's orbit), Christy and his team at CNES predicted the craft will return to Earth March 11. (They were quick to add, however, that estimate comes with an "uncertainty of more or less 18 days.") More recently, the U.S.-funded Aerospace Corporation has estimated the return will occur April 3, give or take a week, while the European Space Agency estimates a return window between March 29 and April 9.
Possible light show
Depending on where Tiangong-1 re-enters, spectators may bear witness to a beautiful light show of its fiery destruction.
"It may be possible to see Tiangong-1 reentering depending on your location, the time of day, and visibility during reentry which will not be known until a few days prior to the event," the site Aerospace.org reports. "A more detailed predicted reentry region will be provided a few days prior to the reentry time frame. Visibly incandescent objects from this reentry will likely last tens of seconds (up to a minute or more) in contrast with the vast majority of natural meteors which last mere seconds."
You can see the spectacular end of the controlled 2015 deorbit of the European Space Agency's Jules Verne supply freighter in the video below for an example of how the T-1 might appear.
Should pieces of Tiangong-1 survive and impact the ground, scientists are urging the public not to seek out souvenirs.
"Potentially, there may be a highly toxic and corrosive substance called hydrazine on board the spacecraft that could survive reentry," they warn. "For your safety, do not touch any debris you may find on the ground nor inhale vapors it may emit."
Editor's note: This article has been updated with new information since it was originally published in January 2018.