Subscribe free to our newsletters via your
  Mars Exploration News  




Subscribe free to our newsletters via your




















Mars Express Creates First Global Map Of Martian Ionosphere

After some two years of operation, an international team of scientists has been able to analyse more than 750 000 echoes from MARSIS in order to make the first direct measurement of the global distribution of electrons in the Martian ionosphere - or the total electron content (TEC).
by Staff Writers
Paris, France (ESA) Nov 19, 2007
With ESA's Mars Express, scientists continue to gain new insight into the mysterious Martian environment. Some of the most exciting results are being sent back by the MARSIS (Mars Advanced Radar for Subsurface and Ionospheric Sounding) experiment. MARSIS transmits low frequency radio waves towards the planet's surface and records the echoes of the different layers.

Although Mars is sometimes described as the most Earth-like of all the planets, there are many differences between the two worlds which scientists are trying to understand. One of the less familiar aspects of both planets is that they possess an ionosphere - a layer of ionised (electrically charged) particles - in their upper atmospheres.

Earth's ionosphere has been studied intensively and is invaluable as a reflector of radio waves, but, until recently, little was known about the Martian ionosphere.

Previous measurements indicated that Mars' ionosphere generally lies about 110 to 130 km above the planet. In this region, high-energy solar radiation and particles in the solar wind split the atoms and molecules in the upper atmosphere, releasing free electrons. One of the most surprising results from Mars Express has been the discovery of an ionosphere above the planet's hemisphere which is in the dark.

Although the main task of MARSIS is to probe beneath the planet's surface in search of unseen geological materials and structures, the radar is also a valuable tool for learning about the ionosphere. This is because the radio waves from MARSIS are reflected and modified as they pass through the ionised layer.

Now, after some two years of operation, an international team of scientists has been able to analyse more than 750 000 echoes from MARSIS in order to make the first direct measurement of the global distribution of electrons in the Martian ionosphere - or the total electron content (TEC).

The distribution of the TEC has been determined by using a novel 'transmission-mode' technique to sound the ionosphere, instead of the more common 'reflection mode'. In the transmission mode, the radar transmits a pulse that travels through the ionosphere twice, once on the way down to the surface and again on the way back.

The received echoes are weakened, delayed and dispersed, depending on the electron density in the ionosphere directly below the spacecraft. In the process of correcting the radar signal, the team has been able to estimate the TEC and its global distribution with an unprecedented spatial resolution of about 5 km.

"We have been able to analyse the MARSIS data to obtain the first large-scale coverage of the ionosphere above the planet's night side," said Ali Safaeinili of NASA's Jet Propulsion Laboratory, lead author on a scientific paper presenting the new results. "The ionosphere on the night side of Mars has never been mapped before."

The mapping of the geographical variations in the night side TEC data reveals an intricate web of regions with high electron density. One of the most interesting discoveries has been the close correlation between the number of electrons in the night-side ionosphere and the direction of the local Martian magnetic field.

"We confirmed that the regions of high electron density are associated with strongly magnetised areas, especially south of the equator, near places where the magnetic field lines are perpendicular to the surface," said Wlodek Kofman of the Laboratoire de Planetologie de Grenoble, CNRS a co-author on the paper.

"On Earth, this situation is only found at the two magnetic poles," he added.

The draping of the solar wind around the planet presumably allows the ionosphere to form above the night-side. The interaction with the solar wind energises the atmosphere and produces a population of free electrons.

In the coming years, as the low point of the spacecraft's orbit drifts further into the night side, MARSIS is expected to provide an even more precise map of the ionosphere and the regions where the solar wind connects to the Martian magnetic field.

Community
Email This Article
Comment On This Article

Related Links
Mars Express
Mars News and Information at MarsDaily.com
Lunar Dreams and more



Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News


Rover Finds Way To Brush Rock Surfaces Despite Setbacks
Pasadena CA (JPL) Nov 15, 2007
Opportunity is still parked in front of the rock layer known as "Smith" inside Victoria Crater. The rover has now lost two encoders that operate motors on the rock abrasion tool during the grinding and brushing of surfaces. Science team members and engineers have been working in test beds and computer sequencing rooms to devise creative ways of using the rock abrasion tool without the grind and revolve encoders.









  • Nuclear Power In Space - Part 2
  • Outside View: Nuclear future in space
  • Nuclear Power In Space
  • Could NASA Get To Pluto Faster? Space Expert Says Yes - By Thinking Nuclear

  • First China Lunar Probe To Activate Observation Payloads On Monday
  • Scientist In Texas Runs NASA's Lunar Laser Program
  • NASA Tests Lunar Habitat In Extreme Antarctic Environment
  • Japan shoots first high-definition of Earth rising

  • Orbital Outfitters Debuts IS3C - First-Ever Fully Functional Commercial Pressure Spacesuit
  • Europe's comet-chasing probe completes key flyby
  • Boeing Completes Prototype Heat Shield For NASA Orion Spacecraft
  • Russia to stay at Baikonur until 2020

  • Data For The Next Generations
  • Goddard Instrument Makes Cover Of Science
  • Checking Out New Horizons
  • Pluto-Bound New Horizons Sees Changes In Jupiter System

  • Rethinking Jupiter
  • Jovian Magnetosphere Circulates Magnetic Field Very Differently From Earth
  • New Horizons' SWAP instrument Reveals Complex Structure, Diverse Plasma Populations In Jupiter's Magnetotail
  • Polar lightning - not just an earthly phenomenon: study

  • New Isotope Molecule May Add To Venus' Greenhouse Effect
  • 500 Days At Venus, And The Surprises Keep Coming
  • Up Up And Away To Venus
  • Spacecraft Tandem Provides New Views Of Venus

  • New CU-Boulder Study Confirms First-Known Belt Of Moonlets In Saturn Rings
  • Cassini Pinpoints Hot Sources Of Jets On Enceladus
  • Inspiring Views Celebrate Cassini's Diamond Anniversary
  • New Lakes Discovered On Titan

  • Dawn Checkout Going Out
  • Argonne Scientists Use Unique Diamond Anvils To View Oxide Glass Structures Under Pressure
  • YES2 Team Claims A Space Tether World Record
  • NASA Unveils New Antenna Network

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2007 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement