Harold C. Connolly Jr. on Bringing an Asteroid Sample Back to Earth
Harold C. Connolly Jr. is Founding Chair and Professor at the Department of Geology at Rowan University. His research focusses on the very oldest materials in the solar system, especially the tiny igneous rocks called chondrules that are the main structural component of stony meteorites. He explains what we hope to learn from a sample of the asteroid Bennu that the OSIRIS-REx spacecraft will return to Earth in 2023.
Here he is holding an example of a chondrite (stony) meteorite.
Listen to the podcast here or wherever you listen to podcasts.
Scroll down for illustrations that support the podcast.
Note - playing the podcast is not supported on Internet Explorer; please use any other browser, or listen on Spotify, Apple Podcasts, etc.
Podcast Illustrations
Asteroid Bennu is about half a kilometer across at its equator. It makes one orbit around the Sun every 1.2 years and completes a rotation on its axis every 4.3 hours. Each pixel in the image corresponds to 1/3 of a meter on Bennu’s surface.
Image courtesy of NASA
Size comparison courtesy of the University of Arizona
Bennu’s orbit intersects that of the Earth and is inclined to the ecliptic (the plane of the Earth’s orbit).
Courtesy of the Meteoritical Society
Artist’s impression of OSIRIS-REx with the collector arm extended.
Courtesy of Goddard Space Flight Center, University of Arizona, and NASA
Captured on Oct. 20, 2020, during the OSIRIS-REx sample collection event, this series of 2 images shows the surface of Bennu just before and after touchdown.
Courtesy of NASA, Goddard Space Flight Center, and the University of Arizona
The main asteroid belt lies just beyond the orbit of Mars. Ceres and Vesta are the two largest bodies in the asteroid belt, the former actually being classified as a dwarf planet.
Diagram courtesy of NASA
Thin section of the meteorite Allende, a carbonaceous chondrite that is similar to Bennu. The arrow points to a calcium-aluminum-rich inclusion that represents the oldest solids in the solar system, with radiometrically-determined ages going back to 4.567 billion years. The one shown here is not igneous, but rather an accumulation of accreted minerals, some of which are igneous minerals, i.e., crystallized from a melt. The round objects are chondrules, which are rich in olivine and pyroxene. Chondrules are igneous rocks that constitute the dominant structural component of chondrites (stony meteorites). The dark matrix is composed of micron-sized minerals, which can sometimes contain presolar grains. The slide is 2 cm in diameter and seen here in plane polarized light.
Courtesy of Dolores Hill and Harold C. Connolly Jr.
The same thin section seen with crossed polarizers. The olivine and pyroxene crystals display bright high-order interference colors. These minerals, which are common on Earth and constitute a major component of the mantle, are also common in the oldest rocks of the Solar System.
Courtesy of Dolores Hill and Harold C. Connolly Jr.