This was somewhere between 4.49 pm today and 7.49 am tomorrow.

During this time Skylab will make its second, third and fourth orbits over Australia.

On the second orbit at 5.02pm it will cross the WA coast north of Carnarvon and move in a south-easterly direction over the Great Australian Bight.

At 11.18pm, on the third of the orbits the space station will cross the South Australian coast near Adelaide and move north-eastwards over Bundaberg on the Queensland coast.

The fourth orbit will take Skylab on a northeasterly path over Esperance at 12.46am tomorrow.

A spokesman for the Skylab communications centre in Canberra said that these were only three of 10 orbits Skylab was expected to make in that 15-hour period.

"This does not give it a very high probability rating of coming down in W.A." he said.

Of the 500 pieces expected to survive Skylab's fiery dive into the atmosphere, 10 should weight more than 450kg. Among these is a 2,290kg titanium protective shroud and 1,755kg lead safe used to shield film from radiation.

When they hit the earth the smaller pieces will be traveling about 50km/h and bigger pieces at almost 400km/h. likely to be affected had been put on standby.

A duty officer system had been set up with "watching brief" so that SES headquarters and the police could be given an immediate rundown on any assistance needed.

The regional director of the Department of Transportation, Mr. Ellis Kiel, said that his department was closely monitoring the situation with the U.S. Nation Aeronautics and Space Administration.

Once a definite path was known for the last stage of Skylab's life and if it took in WA the department would issue notices of area.

Skylab last night was averaging one orbit every 88 minutes sparking reactions varying between anguish in some countries and amused interest in others.