Out-of-control Chinese space station to smash into Earth today

An out-of-control Chinese space station the size of a school bus is due to smash into Earth on Monday.

Tiangong-1 is expected to re-enter the atmosphere sometime between 11am and 3pm (NZT), the European Space Agency (ESA) estimates.

"Just over an hour ago, ESA's space debris team provided their final estimate for re-entry," the ESA website reads.

It forecasts "a window of about four hours and centred on 01:07 UTC (03:07 CEST) on 2 April".

Previous estimates of its descent had suggested Sunday morning was most likely.

The ESA says not to expect "any more forecast updates with any higher accuracy".

"In other words, we're at the limit of what we can forecast.

"The high speeds of returning satellites mean they can travel thousands of kilometres during that time window, and that makes it very hard to predict a precise location of re-entry."

The nine-tonne space station will mostly burn up on descent and is unlikely to cause any damage, China Manned Space Engineering Office says in a statement.

But Andrew Abraham, a member of the The Aerospace Corporation, said there's a "10 percent to 40 percent" of it surviving its descent back to Earth.

Any remains could fall anywhere between Christchurch in the south and London in the north.

But the ESA says it is likely the re-entry will take place over water, meaning few people will see it for themselves.

Control of Tiangong-1 was lost two years ago, and its orbit has been decaying ever since.