Space scientists are turning their eyes from the skies to begin a journey to the centre of the Earth. Just like in Jules Verne’s scifi classic, NASA wants to discover where lies the heart of the mass that makes up our own planet.
But forget any ideas of a manned mission, such as in the notorious Hollywood action movie The Core. Instead they will combine a sophisticated form of SatNav with observations of violent galaxies at the edge of the universe.
Scientists at NASA’s Jet Propulsion Laboratory, in California, say that pinpointing the centre of the Earth is vital to learning about changing sea levels, earthquakes, volcanoes and even ice ages.
But finding the so-called centre of mass is difficult because the Earth is wobbling like a jelly due to movements in its crust and climatic changes. These are believed to cause the point to move by a few millimetres every year.
Now NASA expert Donald Argus has developed a new technique to locate our centre of mass to within 1 millimeter. His technique uses data from a high-precision network of global positioning system receivers using laser beams to track high-orbiting satellites in the Lageos network.
This information is combined with measurements from a network of radio telescopes of our position in space compared to objects deep in the universe called quasars. Finally, more data is used from a French system called Doris – a network of precise satellite tracking instruments. (Doris is short for Doppler Orbit and Radiopositioning Integrated by Satellite.)
Dr Argus said: “The past two international estimates of the motion of the Earth system’s mass centre, made in 2000 and 2005, differ by 1.8 millimeters (.07 inches) a year. This discrepancy suggests the motion of Earth’s mass centre is not as well known as we’d like.” Details of the new study appear in the June issue of Geophysical Journal International.
The NASA images shows one of the Lageos satellites and an exaggerated relief image of the Earth produced from satellite data.
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