[meteorite-list] Asteroids - Meteorites

[Pete Pete]

http://www.cornellsun.com/vnews/display.v/ART/2005/11/11/437449e7625bb

Prof Lectures on Meteor, Asteroid Connection
November 11, 2005
By Mariel Bronen
Sun Contributor

Spaced out. Prof Richard P. Binzel, planetary science, Massachusetts 
Institute of Technology, speaks last night at the Space Science Building on 
the connections between meteors, comets and asteroids.
“What makes me want to be a planetary scientist is that you have a chance in 
your lifetime to fly missions that get real data,” said Prof. Richard P. 
Binzel, planetary science, Massachusetts Institute of Technology. Binzel 
gave a lecture to a group of graduate students and professors in the 
astronomy department yesterday.
Binzel’s lecture focused on the connections between meteors, comets and 
asteroids.

“I’m very interested in the intersecting spaces,” he said, referring to the 
commonalities between the three.

Binzel addressed two main questions. The first involved the “ordinary 
chondrite problem”: why S-type asteroids don’t match the most common 
meteorites found. The second was, what are the origins of these meteorites?

The studies he covered in the lecture focused on near-earth objects, which 
he defined as anything within 1.3AU (astronomical units) of the earth.

“Near-earth objects (NEOs) are the most accessible objects to study. You can 
go to these objects and land on them …. We’ve made some progress because 
we’ve been able to get measurements on about 400 near-earth objects.”

He said that the “holy grail” is to “determine what fraction of near-earth 
objects are coming from the asteroid belt, and what fraction are coming from 
comets.” He estimated that about 90 percent of NEOs were coming from 
asteroid belts and that about 10 percent originated as comets.

His conclusions came from a three-step analysis. First, the studies involved 
showing a continuous transition from meteorites to asteroids, which he 
accomplished with data on the divergence of their spectral properties.

Second, he explored how the transition depended on the age and size of the 
near-earth object. Finally, he concluded with an examination of the 
probability of the source of the objects.

Overall, Binzel’s research supported previous hypotheses on why S-type 
asteroids do not match the most common meteorites, as well as providing new 
insights into the origins of meteorites.

Prof. Jim Bell, astronomy, said, “I’m interested in the work he’s doing, 
making connections between a lot of the mission work we do here and 
telescope work that is done around the world.”

Binzel also discussed his part in sending a mission to Pluto. The launch 
window opens on January 11, 2006.

Binzel said, “We expect that in July 2015 it will arrive at Pluto,” and that 
“we think our power supply will last until 2020-2025.”

Astronomy student Julia Deneva grad said, “I was mainly interested in the 
Pluto mission because it’s the first of its kind. No one has sent a space 
craft targeting specifically Pluto before.”

Deneva also expressed interest in “the way they planned to study the 
atmosphere by beaming out a signal through the atmosphere before the craft 
gets there.” She wondered what telescope they would use to send the signal, 
and mentioned that Cornell has a telescope capable of this.

Binzel’s discussion of what he referred to as the “planet Pluto” provoked a 
friendly debate among the faculty present.

Prof. Jean-Luc Margot, astronomy, said that “Pluto is not a planet” and that 
“there are eight major planets in the solar system.” Bell disagreed.

“Pluto is a planet; the solar system has about 28 planets. I count them all 
— anything that is big enough to be round, have its own geographic features 
and gravity.” He provided the example of Ganymede, which rotates around 
Jupiter. “It’s bigger than Mercury,” he said.

With a smile on his face, Margot responded that “It does not rotate around 
the sun.”

The lecture was part of space science colloquium series. Margot, the 
organizer of the lecture, said, “We try to reach a balance of topics 
throughout the series. We’ve had four lectures on planetary science, some on 
theoretical astronomy, radio astronomy, infrared astronomy. Those are the 
four strengths in the department.”