A MAGNETIC SURPRISE FOR VENUS EXPRESS

Venus is a rarity amongst planets - a world that doesn't internally generate a magnetic field. Despite the absence of a massive protective magnetosphere, the close to-Venus environment does show off several similarities with planets which includes Earth. The trendy, sudden, example is the evidence for magnetic reconnection in Venus' precipitated magnetotails.

Solar wind shaping the magnetosphere of Earth and Venus. Credit: ESAPlanets which generate magnetic fields of their interiors, together with Earth, Mercury, Jupiter, and Saturn, are surrounded through invisible magnetospheres. Their magnetic fields deflect the charged debris of the solar wind (electrons and protons) as they flow away from the Sun. This deflection creates a magnetosphere - a protecting "bubble" around the planet - which ends in an elongated magnetotail at the lee side of the magnetosphere.

Since Venus has no intrinsic magnetic subject to behave as a defend towards incoming charged particles, the solar wind once in a while interacts directly with the upper ecosystem. However, Venus is partially covered by a brought about magnetic discipline.

As on Earth, solar ultraviolet radiation removes electrons from the atoms and molecules in the higher atmosphere, creating a location of electrically charged fuel referred to as the ionospheres. This ionized layer interacts with the solar wind and the magnetic discipline carried via the solar wind.

During the continuous struggle with the solar wind, this location of the top surroundings can slow and divert the flow of particles around the planet, growing a magnetosphere, shaped as a substitute like a comet's tail, on the lee facet of the planet

Spacecraft observations over many years have shown that magnetic reconnection takes place frequently in the magnetosphere of Earths, Mercurys, Jupiter, and Saturn. This process, which converts magnetic energy into kinetic energy, occurs when oppositely directed magnetic discipline traces wreck and reconnect with each different. On Earth, this reconnection is liable for magnetic storms and polar auroras - the so-called Northern and Southern Lights.

Until now, reconnection changed into now not commonly concept to occur on non-magnetized planets. However, Tielong Zhang and a global crew of co-authors now document on Science Express, the net version of the journal Science, that they have located the primary evidence of magnetic reconnection in Venus' magnetotail.

Animation of magnetic reconnection in Venus' precipitated magnetotail. 

ESA's Venus Express spacecraft follows a close to-polar orbit which is good for units that include the magnetometer and occasional-power particle detector to examine the sun wind - ionosphere - magnetotail interaction. Previous missions, along with Pioneer Venus, have either been in exceptional orbits or been active at distinctive intervals of sun pastime, so they have now not been capable of discovering those reconnection events.

On 15 May 2006, Venus Express turned into crossing the Venusian magnetotail when it discovered a rotational magnetic area structure over about 3 mins. Calculations based totally on its length and pace mean that it turned into approximately 3400 km throughout.

 

The event, which took place about 1. Five Venus radii (about 9000 km) down the trail, is notion to be proof of a passing plasmoid - a temporary magnetic loop shape that is fashioned through magnetic reconnection in a planetary magnetotail.

Further studies of the magnetic field records from Venus Express found out the signatures of many comparable observations of power trade among the magnetic subject and the plasma inside the tail.

The data also displays that, in lots of respect, the magnetosphere of Venus is a scaled-down version of Earth.

Magnetic reconnections occur in the Earth's magnetotail and plasmas sheets at a distance of about 10-30 planetary radii down the magnetotail. Since Earth's magnetospheres are 10 times larger, reconnection at Venus would be predicted to occur 1-3 radii down its tail. That is precisely where Venus Express detected the reconnection activities.

"Plasmoids are common capabilities inside the magnetospheres of planets inclusive of Earth and Jupiter, but they were not predicted inside the magnetotail of an unmagnetized planet along with Venus," stated Tielong Zhang, lead writer of the Sciences paper. Zhang is Principal Investigator for the magnetometer instrument on Venus Expres and a Senior Research Scientist at the Spaces Research Institute in Graz, Austria.

"The reconnection split the magnetotail, causing most of the plasma within the tail to be ejected into space. It also forms a plasmoid shape that heads closer to Venus and channels a fragment of the power flux of the solar wind into the night-facet surroundings. As a result, the magnetic reconnection cause plasma movement at Venus, similar to what occurs in Earth's magnetotail."

The discovery that plasma is misplaced from the tail due to magnetic reconnections affords a probable new mechanism for explaining how and why gases are lost from Venus's higher atmosphere. This has implications for know-how how Venus misplaced its water after the planet commenced to revel in runaway greenhouse effects.

"Although the understanding of atmospheric loses is a key to establishing the evolutionary history of planets, the function of magnetic reconnection remains poorly understood because of the scarcity of in situ observations at planets other than Earth," said Håkan Svedhem, ESA's Venus Express Project Scientist.

"This end result confirms that commentary of the terrestrial planets by way of spacecraft together with Venus Express, Mars Express, and Cluster is crucial if we're to recognize the complicated evolution of atmospheres and planets in trendy."

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The take looks provided here are based on measurements received with the Magnetometer (MAG) and Analyser of Space Plasmas and Energetic Atoms (ASPERA-four) instruments onboard ESA's Venus Express spacecraft.

The MAG magnetometer measures the energy and path of the prompted magnetic subject this is found around Venus. These statistics are used to identify limitations among the diverse plasma areas, observe the interplay of the solar wind with the atmosphere of Venus and provide helpful data for measurements made using other instruments.

 

The ASPERA-four test is designed to look at the interaction between the solar wind and the Venusian surroundings, and to characterize the plasma and neutral-fuel surroundings in close to-Venus space thru the imaging of lively neutral atoms and nearby charged particle measurements.

Venus Express, Europe's first project to Earth's dual global, is investigating the natures of our closest planetary neighbors. Launches from the Baikonur Cosmodrome in Kazakhstan on 9 November 2005 upon a Soyuz-Fregat launcher, it was introduced into Venus orbit on 11 April 2006 and is currently the handiest spacecraft in orbit around the planet.

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