Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Nasa Scientist Finds A New Way To The Centre Of The Earth

Humans have yet to see Earth's centre, as did the characters in Jules Verne's science fiction classic, "Journey to the Center of the Earth." But a new NASA study proposes a novel technique to pinpoint more precisely the location of Earth's centre of mass and how it moves through space.

Knowing the location of the centre of mass, determined using measurements from sites on Earth's surface, is important because it provides the reference frame through which scientists determine the relative motions of positions on Earth's surface, in its atmosphere and in space. This information is vital to the study of global sea level change, earthquakes, volcanoes and Earth's response to the retreat of ice sheets after the last ice age.

The accuracy of estimates of the motion of Earth's centre of mass is uncertain, but likely ranges from 2 to 5 millimeters (.08 to .20 inches) a year. Donald Argus of NASA's Jet Propulsion Laboratory, Pasadena, Calif., developed the new technique, which estimates Earth's center of mass to within 1 millimeter (.04 inches) a year by precisely positioning sites on Earth's surface using a combination of four space-based techniques. The four techniques were developed and/or operated by NASA in partnership with other national and international agencies. Results of the new study appear in the June issue of Geophysical Journal International, which is jointly published by the Royal Astronomical Society and the Deutsche Geophysikalische Gesellschaft.

Scientists currently define Earth's centre in two ways: as the mass centre of solid Earth or as the mass centre of Earth's entire system, which combines solid Earth, ice sheets, oceans and atmosphere. Argus says there is room for improvement in these estimates.

"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," he said. "This discrepancy suggests the motion of Earth's mass centre is not as well known as we'd like."

Argus argues that movements in the mass of Earth's atmosphere and oceans are seasonal and do not accumulate enough to change Earth's mass centre. He therefore believes the mass centre of solid Earth provides a more accurate reference frame.

"By its very nature, Earth's reference frame is moderately uncertain no matter how it is defined," Argus said. "The problem is very much akin to measuring the centre of mass of a glob of Jell-O, because Earth is constantly changing shape due to tectonic and climatic forces. This new reference frame takes us a step closer to pinpointing Earth's exact centre."

Argus says this new reference frame could make important contributions to understanding global climate change. The inference that Earth is warming comes partly from observations of global sea level rise, believed to be due to ice sheets melting in Greenland, Antarctica and elsewhere. In recent years, global sea level has been rising faster, with the current rate at about 3 millimeters (.12 inches) a year. Uncertainties in the accuracy of the motion of Earth's centre of mass result in significant uncertainties in measuring this rate of change.

"Knowing the relative motions of the mass centre of Earth's system and the mass centre of the solid Earth can help scientists better determine the rate at which ice in Greenland and Antarctica is melting into the ocean," Argus explained. He said the new frame of reference will improve estimates of sea level rise from satellite altimeters like the NASA/French Space Agency Jason satellite, which rely on measurements of the location and motion of the mass center of Earth's system.

"For scientists studying post-glacial rebound, this new reference frame helps them better understand how viscous [gooey or sticky] Earth's solid mantle is, which affects how fast Earth's crust rises in response to the retreat of the massive ice sheets that covered areas such as Canada 20,000 years ago," he said. "As a result, they'll be able to make more accurate estimates of these vertical motions and can improve model predictions."

Scientists can also use the new information to more accurately determine plate motions along fault zones, improving our understanding of earthquake and volcanic processes.

The new technique combines data from a high-precision network of global positioning system receivers; a network of laser stations that track high-orbiting geodetic satellites called Laser Geodynamics Satellites, or Lageos; a network of radio telescopes that measure the position of Earth with respect to quasars at the edge of the universe, known as very long baseline interferometry; and a French network of precise satellite tracking instruments called Doppler Orbit and Radiopositioning Integrated by Satellite, or DORIS.

More information on Lageos is at .

More information on NASA's global positioning system research is at .
Geophysical Journal International
JPL is managed for NASA by the California Institute of Technology in Pasadena.
Royal Astronomical Society

Robert Massey | alfa
Further information:

More articles from Physics and Astronomy:

nachricht Move over, lasers: Scientists can now create holograms from neutrons, too
21.10.2016 | National Institute of Standards and Technology (NIST)

nachricht Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>