William Atkins
Wednesday, 18 March 2009 03:54
Science -
Space
Page 2 of 3
Because the mass of the Earth is not uniformly distributed and the shape of the Earth is not a perfect sphere (it’s an oblate spheroid---more bulging in the middle more than a perfect sphere), the gravitational field of the Earth varies.
That is, the gravity created by the mass of Earth is not constant. It varies depending on your location on the surface of the Earth.
Gravity is measured with Newton's Theory of Universal Gravitation, which you may have studied in school.
English mathematician and physicist Sir Isaac Newton said in his theory that two objects (like the Earth and the GOCE satellite) will attract each other with a force proportional to their masses and inversely proportional to the square of distance between them.
The Universal Gravity Equation is stated in equation form as F = GMm/R², where F is the force of attraction between any two objects with masses m and M, G is the universal gravitational constant; G = 6.67*10-11 N-m²/kg², and R is the distance between the objects, as measured from their centers.
The GOCE mission will measure the gravitational field of the Earth in detail never before tried. The best measurement of gravity attempted before was by the U.S. GRACE satellites that were launched in 2002.
This NASA mission was only able to detail the gravity field of Earth one-third as well as the ESA GOCE mission.
Jean-Jacques Dordain, the ESA Director General, stated,
"GOCE is ESA’s first science satellite dedicated to Earth observation since Envisat in 2002. The size has changed, but the rationale remains the same: to provide the best science our technology can deliver for the maximum benefit of the science community and ultimately the citizens of Europe and the world.” [ESA: “
ESA launches first Earth Explorer mission GOCE”]
Page three talks about the benefit that this gravity mapping mission will have here on planet Earth.
