Space Weathering

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Space Weathering

• By Maxwell Justice

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What is it?

• What is Space Weathering?
• It is like erosion on earth but in space
• What causes Space Weathering?
• Collisions of galactic and solar cosmic rays
• Irradiation, implantaion, and sputtering from
  solar wind particles
• The bombardment by all sizes of meteorites and
  micrometeorites

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Whatever gave you that idea?

• Much of the knowledge on space weathering comes
  from the lunar samples returned from the Apollo
  program.
• What was found to help support the idea was in
  the regolith a crystal formation called
  Agglutinates was discovered which is created from
  impacts on the surface by high velocity
  micrometeorites. They turn a portion of the
  regolith to glass and contain inside the glass
  nanophase iron.
• Nanophase iron is formed from the vapor caused by
  the impacts and give agglutinates its black
  appearance.

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Micrometeorite Bombardment

• Micrometeorites constantly bombard the lunar
  surface
• Many are smaller than the size of a pencil head
• They can have an impact velocity of 100,000 km/h
  and using the E(mv2), they have enough energy
  to vaporize the lunar soil glassy coat or
  agglutinates

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Background

• Q. What are solar winds?
• A. Solar wind is an ejection of charged
  particles from the Suns upper atmosphere or the
  Corona. The solar winds extent the very edge of
  the solar system to create what is known as the
  heliosphere. The winds are full of harmful
  particles that can affect biology and technology.

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How to recognize Space Weathering

• The physical effects of space weather
• Become darker because the albedo (or the
  reflectivity of an object) is reduced caused by
  the cosmic and solar radiation
• Becomes redder ( the reflectance increases with
  increasing wavelength) caused by the micrometeor
  bombardment
• The depth of diagnostic absorption bands (the
  portion of the spectrum that an element absorbs)
  are reduced

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The Differences in the Earth and Moon from the
Effects of Solar Winds

• Earth

• Moon

• The earths magnetic field prevents the solar
  winds from reaching the planets surface and in
  that, allows an atmosphere that supports and
  develops life.

• The moon has no detectable magnetic field to
  deflect the harmful solar winds and allows the
  charged particles to collide and collect in the
  lunar surface. Solar winds also prevents a life
  supporting atmosphere from developing.

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Apollo Missions

• The Astronauts discovered in their missions were
• The deposits from the winds are of potential
  resources for future mission to the moon such as
  the element Helium 3
• Lunar dust is positively charged so clings to
  everything and gets into equipment
• The dust that snuck into the Lander caused a
  irritation in the lungs of the astronauts
  Harrison Schmitt called it lunar dust hay fever

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Space weathering on Mercury

• Mercury being the closet planet to the sun is
  constantly bombarded with solar radiation and
  winds. The impact velocity of micrometeorites is
  also much higher then that of lunar impacts.
• The closeness to the sun and higher impacts
  velocity on Mercury make it more efficient in
  creating the melt and vapor that form
  agglutinates on the surface.

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Space Weathering on Mercury

• One effect from space weathering is not found on
  Mercury like the Moon. It is the red-ing of the
  soil. Because of this it is speculated that
  there is no iron composition on surface.

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Space Weathering on Asteroids

• Ceres, Pallas, Vesta, and Juno

• Asteroids have no atmosphere and very little
  gravitational attraction but space weathering is
  thought to occur on these bodies as well.
• The asteroid belts distance from the Sun mean
  fewer particles from solar winds and radiation
  reach them so less red-ing is noticeable.
• The little gravity asteroids have mean fewer
  impacts from micrometeorites so fewer vapor and
  melt surface compositions that form agglutinates

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How did they determine space weathering on
asteroids then?

• The redden portion of the spectrum given off by
  the moon, mercury and meteorites did not match up
  to ones in the asteroid belt. The S-type
  asteroids in particular.
• S-type asteroids are silicaceous composition.
• Asteroids that have come close to the earth have
  been noticed to have the same spectrum matching
  other known weathered objects, suggesting an
  ongoing process that actually flip-flops the
  spectral characteristics of the asteroids back
  and forth depending on where they are.
  

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Space Weathering on Asteroids

• More data to suggest space weathering is taking
  place on asteroids are the fly-bys of probes to
  asteroids.
• The spectral analysis of impacts on the surfaces,
  particularly the fresh ones show a red-ing of the
  surface on S-types, showing the effects of solar
  radiation on the iron.

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Citation

• http//antwrp.gsfc.nasa.gov/apod/image/0309/aldrin
  swc_apollo11_big.jpg
• http//science.nasa.gov/headlines/y2008/10apr_moon
  dustinthewind.htm
• http//science.nasa.gov/headlines/y2006/28dec_true
  fake.htm
• http//en.wikipedia.org/wiki/Space_weathering
• http//en.wikipedia.org/wiki/Solar_winds