PhD student Erik Engwall of Uppsala University and the Swedish Institute of Space Physics led the study, which uses data from the European Cluster satellites and has just been published in Nature Geoscience.
The new observations show that the polar wind, a very dilute wind of hydrogen and oxygen, flows unimpeded to very high altitudes. The outflow has previously only been possible to study from satellites at low altitudes, so it was not clear if it actually continued far into space or if it spread out and soon returned to Earth. It is now clear that the particles are actually lost from Earth, as the Cluster measurements have followed them flow to an altitude of almost ten times the diameter of the Earth.
"The polar wind is no threat to the atmosphere", says study leader Erik Engwall, pointing out that an outflow of the magnitude observed will not make any dramatic change to our atmosphere even during the full expected lifetime of the solar system. But similar phenomena may be more important for other celestial bodies. "To understand how our atmosphere evolves is also important for understanding other atmospheres that can harbour life", adds Erik Engwall.
The discovery was made when the scientists tried to understand why the Cluster instrument provided by the Uppsala team seemed to give unrealistic results in space above the Earth's polar regions. "In regions of space where we expected to find very weak electric fields, we were surprised to find very strong fields in a direction that was just plain impossible", says Anders Eriksson, a scientist operating the Electric Fields and Waves instrument. By computer simulation, Erik Engwall could show that the unexpected results were due to the spacecraft encountering a supersonic wind of charged particles flowing away into space from the Earth's polar regions. The team could thus transform the apparent "measurement error" into a new method of observing the polar wind at unprecedented distances from the Earth. "In this region, the outflow was completely invisible to satellites until revealed by our new method", says Erik Engwall.
The paper "Earth's ionospheric outflow dominated by hidden cold plasma" by Erik Engwall, Anders Eriksson, Chris Cully, Mats André, Roy Torbert and Hans Vaith will appear in the January 2009 issue of Nature Geoscience, and was published online on 14 December. The results will also be presented at the fall meeting of the American Geophysical Union in San Francisco on Wednesday 17 December.
Cluster is a cornerstone project of the European Space Agency (ESA) and consists of four satellites, which have flown, in formation around the Earth since the summer of 2000. The Swedish Institute of Space Physics and the University of New Hampshire are responsible for two instruments measuring electric fields by very different methods on each of the satellites, and it was by comparing the two sets of results that the discovery was made. The Swedish group is financed by the Swedish National Space Board and the American group by NASA.
* Erik Engwall, PhD student, Department of Physics and Astronomy, Uppsala University, firstname.lastname@example.org, +46-70-765 9566.
* Anders Eriksson, scientist, Swedish Institute of Space Physics, email@example.com, +46-18-471 5945, +46-70-171 3029.
* Mats André, professor, Swedish Institute of Space Physics, firstname.lastname@example.org, +46-70-779 2072 (available at the AGU meeting in San Francisco).Weitere Informationen:
Rick McGregor | idw
Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State
What do Netflix, Google and planetary systems have in common?
02.12.2016 | University of Toronto
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy