Russia puts ISS on the scales

Weighing the weightless: Russia puts ISS on the scales

How do you calculate the weight of a gigantic man-made object floating
around in the supposed "weightlessness" of space?

With a big rocket and a little brainpower, according to Russian
scientists who have announced plans to use their Progress space
resupply ship to measure the mass of the orbiting International Space
Station (ISS).

"We do not know the mass of the ISS precisely enough," said Vladimir
Solovyov, chief of the Russian mission control team supervising the
current Progress mission to the ISS.

"The station is refuelled from time to time, something new is brought
aboard and something is taken away," he was quoted by Interfax news
agency as saying.

The Progress vessel, which docked with the ISS to deliver fresh
supplies to its two-man crew, will be used to weigh the
problem-plagued station, resulting in more efficient and economical
use of it, he said.

In physics, thrust is equal to mass multiplied by acceleration.

Since Russian scientists know the precise weight of Progress and can
gauge both the thrust of its engines and the acceleration of the ISS,
they can determine its mass, he added.

The resulting measurement of the orbiting station will be accurate
within a tolerance of two per cent, Mr Solovyov explained.

http://www.abc.net.au/news/newsitems...8/s1176676.htm