Featured Research

from universities, journals, and other organizations

Cassini makes first dive inside Saturn’s radio aurora

Date:
September 25, 2010
Source:
Europlanet Media Centre
Summary:
The Cassini spacecraft has made the first observations from within the radio aurora of another planet than Earth. The measurements, which were taken when the spacecraft flew through an active auroral region in 2008, show some similarities and some contrasts between the radio auroral emissions generated at Saturn and those at Earth.

Image of Saturn's aurora seen at ultraviolet wavelengths. The spiral shape seen here is similar to the distorted radio aurora visualised by the team and also indicates enhanced auroral activity.
Credit: ESA/NASA/Hubble

The Cassini spacecraft has made the first observations from within the radio aurora of another planet than Earth. The measurements, which were taken when the spacecraft flew through an active auroral region in 2008, show some similarities and some contrasts between the radio auroral emissions generated at Saturn and those at Earth. Results were presented this week by Dr Laurent Lamy at the European Planetary Science Congress in Rome, and recently published in Geophysical Research Letters.

Related Articles


"So far, this is a unique event," said Lamy (Observatoire de Paris, France). "Whereas the source region of Earth's radio aurora has been studied by many missions, this is our first opportunity to observe the equivalent region at Saturn from the inside. From this single encounter, we have been able to build up a detailed snapshot of auroral activity using three of Cassini's instruments. This gives us a fascinating insight into the processes that are generating Saturn's radio aurora."

Cassini encountered the auroral region at a distance of 247 million kilometres from Saturn's cloud tops (about 4 times Saturn's radius). High above the spectacular visible-light displays of Saturn's Northern and Southern Lights, auroral emissions occur this far from the planet at radio wavelengths. The emissions are generated by fast moving electrons spiralling along Saturn's magnetic field lines, which are threaded through the auroral region.

On 17 October 2008, Cassini's MAG (magnetometer), RPWS (radio) and CAPS (electrons) instruments detected three successive curtains of active auroras. An international team of scientists has now combined magnetic, radio and particle in situ observations to build up a picture of the local radio source properties and the surrounding auroral plasma. They also identified the magnetic field lines along which radio aurora are emitted.

"The instrument that measures radio waves, RPWS, can tell us the direction that each radio wave detected is travelling. By mapping this information onto magnetic field lines, we can work out the location of each radio source. In addition, we can project the source locations along the field lines that curve down to Saturn's southern pole and visualise a radio oval comparable to the auroral features commonly seen at ultraviolet wavelengths. Unusually, the oval observed during this event is strongly distorted, which indicates a particularly enhanced auroral activity," said Lamy.

Earth also has radio auroral emissions and these new results show that the process that generates radio aurora appears to be the same at both planets. Interestingly, there are two minor differences between the aurora at Earth and Saturn. At Earth, there is a cavity in the plasma above the auroral oval that rises for several thousand kilometres. The new observations show that this is not seen at Saturn. Secondly, radio sources were crossed at much further distances from the planet. These discrepancies reflect intrinsic differences between the two magnetospheres, in terms of dimensions and planetary rotation speed.

Cassini crossed high latitude auroral field lines during 40 orbits in 2008, but this is the only time that the instruments detected unusually strong electric currents in that region in space with in situ evidence of an active aurora.

"We think that the unusual conditions responsible for these intense electric currents might have been triggered by a solar wind compression squeezing Saturn's magnetic field and producing the observed auroras," said Emma Bunce, a team member from the University of Leicester in the UK.

Animation: Visualisation of the sources of a radio aurora at Saturn. The animation is based on Cassini observations using the RPWS instrument. On the left hand side are the radio sources as seen from Cassini. The right hand side shows the projection of the radio sources down onto the southern pole of the planet.


Story Source:

The above story is based on materials provided by Europlanet Media Centre. Note: Materials may be edited for content and length.


Journal Reference:

  1. Mutel, R. L., D. J. Menietti, D. A. Gurnett, W. Kurth, P. Schippers, C. Lynch, L. Lamy, C. S. Arridge, and B. Cecconi. CMI growth rates for Saturnian kilometric radiation. Geophysical Research Letters, 2010 DOI: 10.1029/2010GL044940

Cite This Page:

Europlanet Media Centre. "Cassini makes first dive inside Saturn’s radio aurora." ScienceDaily. ScienceDaily, 25 September 2010. <www.sciencedaily.com/releases/2010/09/100924084612.htm>.
Europlanet Media Centre. (2010, September 25). Cassini makes first dive inside Saturn’s radio aurora. ScienceDaily. Retrieved November 28, 2014 from www.sciencedaily.com/releases/2010/09/100924084612.htm
Europlanet Media Centre. "Cassini makes first dive inside Saturn’s radio aurora." ScienceDaily. www.sciencedaily.com/releases/2010/09/100924084612.htm (accessed November 28, 2014).

Share This


More From ScienceDaily



More Space & Time News

Friday, November 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Scientists Find Invisible Space Shield Protecting Earth

Scientists Find Invisible Space Shield Protecting Earth

Newsy (Nov. 27, 2014) An invisible barrier is keeping dangerous super fast electrons from interfering with our atmosphere, but scientists aren't entirely sure how. Video provided by Newsy
Powered by NewsLook.com
NASA's First 3-D Printer In Space Creates Its First Object

NASA's First 3-D Printer In Space Creates Its First Object

Newsy (Nov. 26, 2014) The International Space Station is now using a proof-of-concept 3D printer to test additive printing in a weightless, isolated environment. Video provided by Newsy
Powered by NewsLook.com
Feast Your Eyes: Lamb Chop Sent Into Space from UK

Feast Your Eyes: Lamb Chop Sent Into Space from UK

Reuters - Light News Video Online (Nov. 25, 2014) Take a stab at this -- stunt video shows a lamb chop's journey from an east London restaurant over 30 kilometers into space. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Soyuz Spacecraft Docks With International Space Station: NASA

Soyuz Spacecraft Docks With International Space Station: NASA

AFP (Nov. 24, 2014) A Russian Soyuz spacecraft carrying Italy's first female astronaut safely docks with the International Space Station, according to NASA. Duration: 00:40 Video provided by AFP
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:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

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