[meteorite-list] Burned-Up Meteors Add to Martian Atmosphere

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Fri Nov 4 14:06:21 2005
Message-ID: <200511041904.jA4J4uX19661_at_zagami.jpl.nasa.gov>

http://www.newscientistspace.com/article/dn8264-burnedup-meteors-add-to-martian-atmosphere.html

Burned-up meteors add to Martian atmosphere
Kelly Young
New Scientist
November 3, 2005

A previously unknown layer has been detected in the atmosphere of Mars,
which scientists believe is created when meteors burn up high above the
planet's surface.

Scientists in Germany and the US found the new layer between 65 and 110
kilometres above the Martian surface. It constitutes a third part of the
planet's ionosphere - a region of ionized particles - and lies just
beneath two layers already known to exist.

The new layer was detected all around the planet in 10 out of 120
observations, and was not spotted in 20 measurements during the Martian
night.

The two main layers of the planet's ionosphere are created by
ultraviolet and X-ray radiation from the Sun, which dislodges electrons
from oxygen molecules in the atmosphere.

Scientists believe the third layer is formed as meteors crash through
the atmosphere, colliding with molecules and atoms. This process is
thought to knock electrons away from magnesium and iron particles within
the rocky bodies as they break up, leaving a thin new layer of charged
metallic particles in the atmosphere.

Martin Paetzold at the Institute for Geophysics and Meteorology at the
University of Cologne, Germany, and colleagues discovered the region
using the Mars Radio Science Experiment (MaRS) instrument on the
European Space Agency's Mars Express spacecraft, currently orbiting the
Red Planet.

Quiet nights

Paetzold's team was not able to measure these ionized particles
directly. Instead, they measured electron density in this layer of the
atmosphere by analysing interference to the MaRS instrument's radio
signal. They found an increased density of electrons suggesting the
creation of ionised particles.

One way to verify that this layer actually comes from meteors would be
to send a spacecraft through the atmosphere with an ion spectrometer
that could measure the mass of the ions to identify them.

Scientists detected the new layer in both the northern and southern
hemisphere. But one curious aspect was that they did not see the layer
during their 20 night-time observations. "Meteors do hit at night," says
Michael Mendillo, an astronomer at Boston University, US, who was not a
part of this study. "So why don't they see them [then]?"

The Mariner 4 spacecraft, which visited Mars in 1964, first glimpsed the
main layer of the Martian ionosphere. The Viking spacecraft spied the
second layer in 1977.

Scientists predicted the existence of this third layer because part of
Earth's ionosphere is also created by meteors blazing through the sky.
This layer lies above an altitude of 95 kilometres. The new Mars layer
is lower than Earth's because the Martian atmosphere is less dense at
higher altitudes, meaning less friction for incoming meteors until they
get closer to the planet's surface.

Journal reference: Science (vol 310, p 837)
Received on Fri 04 Nov 2005 02:04:56 PM PST