Places where China's 8.5-ton space station could fall
The Tiangong-1 space station is falling out of control with toxic chemicals on board that could hit one of the major cities, including New York.
| China's 8.5-ton space station is about to fall to Earth. |
China’s first experimental space station, Tiangong-1, will re-enter the atmosphere between March 30 and April 6, experts say. The areas most likely to fall are along a narrow strip between 43 degrees north and 43 degrees south latitude, including many populous cities such as New York, Barcelona, Beijing, Chicago, Istanbul, Rome and Toronto.Long Roomreport
Tiangong-1 is most likely to fall over these cities because it flies parallel to the equator. From Earth, the station appears to be flying more slowly over high-risk areas due to its position relative to the Earth, although its speed remains steady. Because it takes longer to cross the Earth’s surface at this latitude, the chance of a fall there is higher.
The 8.5-tonne space station hurtling towards Earth after it went out of control in 2016 is believed to contain the dangerous chemical hydrazine. Scientists only know the exact date and location of the debris in the final weeks of the station's descent. Explaining why, Dr Hugh Lewis, senior lecturer in aerospace engineering at the University of Southampton, likened the station's descent to crossing the road.
"The Chinese space station is flying in a roughly circular orbit, with the tip corresponding to the equator at 43°. If you plot this trajectory on a map of Earth, you get a sinusoidal graph, with a lower curve at the northern and southern latitudes and a straighter section running east to west," Dr Lewis explained.
"If you imagine the low-risk area on the map as the road we're trying to cross, the quickest way is to go straight across the road at a 90-degree angle. When the space station passes over the equator, it passes very quickly. As the station passes further north and south, it passes at a steeper angle, almost parallel to the road. It takes longer for the station to cross these latitudes, which is why the risk of the station falling there is higher," said Dr Lewis.
Most of the predictions for Tiangong-1’s impact location come from Aerospace, an American research organization in El Segundo, California, that advises governments and private companies on spaceflight. Aerospace said the station will enter Earth’s atmosphere on April 4, with a period of about a week. The station’s debris will not fall farther than 42.7° north latitude or 42.7° south latitude.
The safe zones that Tiangong-1 will not fly over cover about a third of the Earth's total surface area. Particularly at risk in the northern hemisphere are the northern United States, including Boston, Des Moines, Detroit, Milwaukee, Philadelphia and Salt Lake City. Florence, Italy, Monaco City and Sochi, Russia, are also in high-risk areas. In the southern hemisphere, other cities that could be affected include Trelew, Argentina, Christchurch, New Zealand, and Sapporo, Japan.
Experts from the European Space Agency (ESA) in Paris, France, are monitoring the Tiangong-1 station. ESA's Space Debris Division in Darmstadt, Germany, revised its forecast for the station's fall to between March 30 and April 6, narrowing it from a previous estimate of between March 29 and April 9.
While most of the spacecraft will burn up as it reenters the atmosphere, between 10 and 40 percent of the debris could survive and contain the chemical hydrazine. In recent months, Tiangong-1 has been falling at a rate of more than 6 kilometers per week. Last October, the station was falling at a rate of 1.5 kilometers per week.
