China space station crash risk in Thailand remote
published : 10 Mar 2018 at 16:03
writer: Online Reporters
The country's space agency has allayed public concerns that a decommissioned Chinese space station could crash into Earth on Thailand, saying the probability is only 0.1%.
Tiangong-1, or "Heavenly Palace 1", China's first space laboratory, was launched into orbit in 2011 to carry out docking and orbit experiments as part of a programme that aims to place a permanent Chinese station in orbit by 2023.
The Geo-Informatics and Space Technology Development Agency (Gistda) has been monitoring the movement of the 8-tonne Tiangong-1, which is predicted to hit the earth in April, executive director Anond Snidvongs said on Saturday.
“Tiangong-1 is now 246 kilometres on average from Earth and is predicted to hit the planet on April 10," he said. "During its re-entry, most of its parts will burn up through the atmosphere, leaving only a few to land on Earth. The chance of it falling onto Thailand is 0.1%."
The scientist also dismissed reports from a "news" website that there was a risk that Tiangong-1 would land in Thailand and that cancerous hydrazine, the propellant it carries, would spread.
“Hydrazine is a commonly used in industries. To become affected, a person must touch or inhale it in large quantities for a long period,” he said.
Mr Anond explained further that when scientists design a satellite or space station, they will calculate the appropriate amount of hydrazine to be used throughout the journey.
“Normally, when a spacecraft goes through the earth’s atmosphere, the substance will be burned away, except when the structures are very large,” he said.
In any case, he said, his agency was coordinating closely with international peers and they have asked China how much hydrazine was left in the spacecraft.
“At this point, we can’t tell where Tiangong-1 will land. As an object comes into Earth’s orbit, its movement will be highly erratic, unlike those in space where their movements can be calculated more accurately," said Mr Anond.
Tiangong-1 is expected to pass over Thailand on March 16, when a Gistda team will observe it from Doi Inthanon, the country's highest mountain, in Chiang Mai.
While the station's movements will be more unpredictable as it moves closer to Earth, the agency is preparing a plan and draft guidelines including on the handling of hydrazine for all agencies despite the extremely remote chance of an incident.
China too has said that the space station is not out of control and does not pose a safety threat.
Tiangong-1 was originally planned to be decommissioned in 2013 but China repeatedly extended the length of its mission. The delay of re-entry into the earth's atmosphere, which Beijing said would happen in late 2017, had led some experts to suggest the space laboratory may be out of control.
Zhu Congpeng, a top engineer at the China Aerospace Science and Technology Corporation, told the state-backed Science and Technology Daily newspaper that the station was not crashing and did not pose a safety or environmental threat.
"We have been continuously monitoring Tiangong-1 and expect to allow it to fall within the first half of this year," Mr Zhu said.
"It will burn up on entering the atmosphere and the remaining wreckage will fall into a designated area of the sea, without endangering the surface," he said.
Re-entry was delayed in September 2017 in order to ensure that the wreckage would fall into an area of the South Pacific ocean where debris from Russian and US space stations had previously landed, the paper said.
The California-based Aerospace Corporation, a non-profit group that works with the US government, said Tiangong-1's re-entry was unlikely to be controlled but it was highly unlikely to hit people or damage property, according to a post on its website last updated on Jan 3.
"Although not declared officially, it is suspected that control of Tiangong-1 was lost and will not be regained before re-entry," it said. There may be hazardous material on board that could survive re-entry, it said.