China’s Tiangong-1 space lab is heading back to Earth. (Image: China Manned Space Engineering)

(CNSNews.com) – Chinese state media have been disputing reports that the country’s first experimental space station is out of control as it heads for Earth, but Western scientists tracking its movement are warning that its re-entry in the next few weeks could see a small amount of debris landing across a sizeable area of the planet, possibly emitting toxic vapor.

Roughly the size of a 64-passenger school bus, the Tiangong-1, is expected to make what’s known as an “uncontrolled re-entry” sometime in late March or early April, according to the Aerospace Corporation in the U.S. and the European Space Agency’s space debris office.

The Aerospace Corporation predicts contact in the first week of April, give or take a week, and the ESA predicts a window of around March 29 to around April 9.

Emphasizing the difficulties of preciseness in such predictions, both expect debris from Tiangong-1 to land somewhere in the wide swathe of the planet between roughly 42.8 degrees north and roughly 42.8 degrees south latitude.

Going further, both organizations indicate higher-probability points of landing based on the object’s orbital inclination (the yellow strips in the accompanying map). These include, in the northern hemisphere, the northern United States, parts of southern Europe, Central Asia, northern China and northern Japan; and in the southern hemisphere parts of Argentina, Chile and New Zealand.

The higher-probability crash zones also encompass large stretches of the Pacific, Atlantic and Indian Oceans, and the Aerospace Corporation and ESA both stress that the chances of anyone being hit by debris are miniscule (“10 million times smaller than the yearly chance of being hit by lightning,” says the ESA.)

They also say the Tiangong-1 will mostly burn up as it re-enters Earth’s atmosphere.

Still, “given the uncontrolled nature of this re-entry event, the zone over which fragments might fall stretches over a curved ellipsoid that is thousands of kilometers in length and tens of kilometers wide,” the ESA said in a FAQ blog post.

“[A]ny surviving debris would fall within a region that is a few hundred kilometers in size and centered along a point on the Earth that the station passes over,” the Aerospace Corporation said in a recent update.

The Aerospace Corporation has also drew attention to the possible presence onboard of a “highly-toxic and corrosive” propellant called hydrazine.

“For your safety, do not touch any debris you may find on the ground nor inhale vapors it may emit,” it cautioned.

In a letter to the U.N.’s Committee on Peaceful Uses of Outer Space last December, the Chinese government predicted re-entry between early February and late March, and said based on its analysis the “remaining small amount of fuel will be burned and destroyed along with its structural components during the course of re-entry and will therefore not cause any damage on the ground.”

‘Uncontrolled reentry’

China’s manned space program is run the People’s Liberation Army. In a significant achievement the 8.5-ton Tiangong (“Heavenly Palace”) -1 was launched on a Long March rocket in September 2011.

At 34 feet long and 11 feet in diameter, it includes a lab big enough for three astronauts to live and work, and both manned and unmanned vessels have docked with it.

ESA explained that the Chinese were originally planning a “controlled re-entry” at the end of its lifespan, with ground controllers guiding its fall towards the surface, typically in a large, unpopulated area of the South Pacific.

“However, in March 2016 the Tiangong-1 space station ceased functioning but maintained its structural integrity. In so far as can be fully confirmed, ground teams lost control with the craft, and it can no longer be commanded to fire its engines. It is, therefore, expected to make an ‘uncontrolled re-entry.’”

The Aerospace Corporation similarly said that “it is unlikely that this is a controlled re-entry. Although not declared officially, it is suspected that control of Tiangong-1 was lost and will not be regained before re-entry.”

The Chinese, however, have disputed this.

In January, a senior scientist at the China Academy of Space Technology, which built the space lab, told a Beijing publication affiliated with the science and technology ministry that Western media reports saying the space lab was “out of control” were wrong.

The state-run China Daily quoted Zhu Zongpeng as saying Chinese scientists were monitoring Tiangong I and would “make it fall back to the Earth” in the coming months.

Those parts of the object that did not burn out during re-entry, Zhu said, would land in a designated area of the ocean.

The Communist Party organ Global Times said unnamed aerospace experts had told it that Tiangong-1 “will splash down under control in the Pacific Ocean, denying Western media reports that it will hit Earth.”

“Spacecraft that return under controlled conditions will not threaten the Earth when they fall, he [an anonymous aerospace expert] said, noting that large low-Earth orbit spacecraft usually fall at a designated area in the southern Pacific.”

“Tiangong-1 will reach a proper speed and orbit with several breaks in space and return to the atmosphere, during which time most of its parts will be burned out, and the rest will fall in the southern Pacific,” it quoted the expert as saying. “No large remains nor toxic substance will be produced during the fall.”

In 2016, China launched the successor, the Tiangong-2. Beijing’s goal is to have a permanent space station in place by around 2022.