November 11, 2005

Prof Lectures on Meteor, Asteroid Connection

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“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.”

Archived article by Mariel Bronen
Sun Contributor