Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cluster listens to the sounds of Earth

30.06.2008
The first thing an alien race is likely to hear from Earth is chirps and whistles, a bit like R2-D2, the robot from Star Wars.

In reality, they are the sounds that accompany the aurora. Now ESA’s Cluster mission is showing scientists how to understand this emission and, in the future, search for alien worlds by listening for their sounds.

Scientists call this radio emission the Auroral Kilometric Radiation (AKR). It is generated high above the Earth, by the same shaft of solar particles that then causes an aurora to light the sky beneath. For decades, astronomers had assumed that these radio waves travelled out into space in an ever-widening cone, rather like light emitted from a torch. Thanks to Cluster, astronomers now know this is not true.

By analysing 12 000 separate bursts of AKR, a team of astronomers have determined that the AKR is beamed into space in a narrow plane. This is like placing a mask over the torch with just a small slit in the middle for light to escape.

“We can now determine exactly where the emission is coming from,” says Robert Mutel, University of Iowa, who conducted the three-year study with colleagues. For each of the AKR bursts they analysed, the astronomers pinpointed its point of origin to regions in Earth’s magnetic field just a few tens of kilometres in size. These were located a few thousand kilometres above where the light of the aurora is formed.

“This result was only possible because of the Cluster mission’s four spacecraft,” says Mutel. Consisting of four nearly identical spacecraft flying in formation, Cluster allowed the scientists to precisely time when the AKR washed over each of the satellites. Using this information, the scientists triangulated the points of origin, in a similar way to the way GPS navigation works.

AKR was discovered by satellites in the early 1970s. It is blocked from reaching the ground by the ionosphere, the upper reaches of Earth’s atmosphere. This is just as well because otherwise it would overwhelm the transmissions from all our radio stations. It is 10 000 times more intense than even the strongest military radar signal. “Whenever you have aurora, you get AKR,” says Mutel. That includes aurorae on other planets, too. Visiting spacecraft have seen aurorae and detected AKR on Jupiter and Saturn, the two largest gas giants in our Solar System.

Not only will this new understanding of how the AKR is beamed into space help astronomers understand the magnetic environment of those gas worlds, it will also help them search for similar planets around other stars.

Although looking for AKR from extrasolar planets will require much larger radio telescopes than are currently available, these instruments are on the drawing boards. Once these planets have been identified, the AKR can be monitored for how it winks on and off, allowing astronomers to calculate how long the planet takes to rotate.

It also provides new routes of investigation into the magnetic fields of other stars, many of which have magnetic fields thousands of times stronger than the Sun. They too, will produce radiation similar to AKR and these can be monitored.

The result is a major scientific breakthrough that gives astronomers a new tool with which to investigate both planets and stars.

Philippe Escoubet | alfa
Further information:
http://www.esa.int/esaSC/SEMLX5SHKHF_index_0.html

More articles from Physics and Astronomy:

nachricht Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State

nachricht What do Netflix, Google and planetary systems have in common?
02.12.2016 | University of Toronto

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: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

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...

Im Focus: Quantum Particles Form Droplets

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...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

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,...

Im Focus: Molecules change shape when wet

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...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

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...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

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

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>