By Maxwell Justice

• 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

• 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.

• 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=(m*v^2), they have enough energy to vaporize the lunar soil glassy coat or
“agglutinates ”

• Q. What are solar winds?
• A. Solar wind is an ejection of charged particles from the Sun’s 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.

• 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

Earth
• The earth’s magnetic field prevents the solar winds from reaching the planet’s surface and in that, allows an atmosphere that supports and develops life.
Moon
• 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.

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

• 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.

• 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.

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 belt’s 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

• 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.

• 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.

• http://antwrp.gsfc.nasa.gov/apod/image/030
9/aldrinswc_apollo11_big.jpg
• http://science.nasa.gov/headlines/y2008/10a pr_moondustinthewind.htm
• http://science.nasa.gov/headlines/y2006/28d ec_truefake.htm
• http://en.wikipedia.org/wiki/Space_weatherin g
• http://en.wikipedia.org/wiki/Solar_winds