Featured Research

from universities, journals, and other organizations

Cluster Opens A New Window On 'Magnetic Reconnection' In The Near-Earth Space

Date:
March 13, 2007
Source:
European Space Agency
Summary:
Plasma physicists have made an unprecedented measurement in their study of the Earth's magnetic field. Thanks to ESA's Cluster satellites they detected an electric field thought to be a key element in the process of "magnetic reconnection."

This artist's impression shows the four ESA's Cluster satellites flying through the Earth's magnetosphere and observing the 'magnetic reconnection' process. Magnetic reconnection is a process that can occur almost anywhere that a magnetic field is found. In a reconnection event, the magnetic field lines are squeezed together somehow and spontaneously reconfigure themselves, releasing energy.
Credit: Image courtesy of European Space Agency

Plasma physicists have made an unprecedented measurement in their study of the Earth's magnetic field. Thanks to ESA's Cluster satellites they detected an electric field thought to be a key element in the process of 'magnetic reconnection'.

Thanks to these measurements, obtained by the eight PEACE electron sensors onboard the four spacecraft, scientists now have their first insight into magnetic reconnection's detailed behaviour.

Magnetic reconnection is a process that can occur almost anywhere that a magnetic field is found. In a reconnection event, the magnetic field lines are squeezed together somehow and spontaneously reconfigure themselves. This releases energy. When it occurs near the surface of the Sun, such an event powers giant solar flares that can release thousands of millions of tonnes of electrically charged particles into space.

The Earth's magnetic field creates a buffer zone, the magnetosphere, between our planet's atmosphere and the particles released during these eruptions. The Sun also releases a steadier flow of charged particles called the solar wind. On the large-scale, any heading this way buffet the magnetosphere, and are deflected by it. Plasma physicists describe this behaviour with a theory called 'magneto-hydrodynamics' (MHD).

On smaller scales, however, the picture becomes rather more complicated. The particles can actually flow across the magnetic field lines.This makes the mathematics of the behaviour more difficult. First to misbehave are the ions (positively charged particles). These break away from simple MHD on scales of less than a few hundred kilometres. On even smaller scales, less than 10 kilometres, the electrons (negatively charged particles) begin playing by other rules, too.

The new Cluster measurements reveal the electric field on the scale of a few hundred kilometres. "This is the first ever measurement of this term," says Paul Henderson, from University College London's Mullard Space Science Laboratory, UK, who led the investigation.

On 17 August 2003, Cluster was flying high above the night-time hemisphere of the Earth with an average separation of 200 kilometres between spacecraft. Data from several instruments shows that at 18:00 CET, a reconnection event took place and swept across the spacecraft.

Using data from Cluster's Plasma Electron and Current Experiment (PEACE) Henderson and collaborators calculated the pressure of electrons at each spacecraft and then calculated the difference between them and the variation with time. Using these quantities they calculated the electric field present near a reconnection site.

"This is an impossible calculation to make without four spacecraft," says Henderson. Now that the scientists can calculate the electric field in such a way, they have a new window into the process of magnetic reconnection.

Magnetic reconnection within Earth's magnetosphere regularly takes place on the night-time side of our planet, where the flow of the solar wind stretches out the magnetic field into a long tail. When the field reconnects in this region, it triggers jets of energetic particles that can cause auroral lights but can also damage satellites.

This new Cluster result takes scientists a step closer to seeing the precise details of magnetic reconnection. "When you think that the magnetosphere stretches over a million kilometres through space, we are actually looking at a minuscule part of it," says Henderson.

And that's exactly what plasma scientists want – the microphysics.


Story Source:

The above story is based on materials provided by European Space Agency. Note: Materials may be edited for content and length.


Cite This Page:

European Space Agency. "Cluster Opens A New Window On 'Magnetic Reconnection' In The Near-Earth Space." ScienceDaily. ScienceDaily, 13 March 2007. <www.sciencedaily.com/releases/2007/03/070312152102.htm>.
European Space Agency. (2007, March 13). Cluster Opens A New Window On 'Magnetic Reconnection' In The Near-Earth Space. ScienceDaily. Retrieved September 16, 2014 from www.sciencedaily.com/releases/2007/03/070312152102.htm
European Space Agency. "Cluster Opens A New Window On 'Magnetic Reconnection' In The Near-Earth Space." ScienceDaily. www.sciencedaily.com/releases/2007/03/070312152102.htm (accessed September 16, 2014).

Share This



More Space & Time News

Tuesday, September 16, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

NASA’s Curiosity Rover Finally Reaches Long-Term Goal

NASA’s Curiosity Rover Finally Reaches Long-Term Goal

Newsy (Sep. 15, 2014) — After more than two years, NASA’s Mars Curiosity Rover reached Mount Sharp, its long-term destination. Video provided by Newsy
Powered by NewsLook.com
SpaceX's Elon Musk Really Wants To Colonize Mars

SpaceX's Elon Musk Really Wants To Colonize Mars

Newsy (Sep. 14, 2014) — Elon Musk has been talking about his goal of colonizing Mars for years now, but how much of it does he actually have figured out, and is it possible? Video provided by Newsy
Powered by NewsLook.com
International Space Station Crew Returns Safely To Earth

International Space Station Crew Returns Safely To Earth

Newsy (Sep. 11, 2014) — The three-man crew touched down in Kazakhstan Wednesday after more than five months of science experiments in orbit. Video provided by Newsy
Powered by NewsLook.com
Solar Storm To Hit This Weekend, Scientists Not Worried

Solar Storm To Hit This Weekend, Scientists Not Worried

Newsy (Sep. 11, 2014) — Two solar flares which erupted in our direction this week will arrive this weekend. The resulting solar storm will be powerful but not dangerous. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins