Across the Universe: One Fix Leads to Another

First published in The Tablet in February, 2007

With my colleague Dan Britt from the University of Central Florida, for several years I’ve been measuring the densities and porosities of meteorites. The densities of different meteorite classes can be compared with their parent asteroids, to see how loosely packed they are; and the porosity of these rocks is an indication of how thoroughly their fabric has been cracked by the shock of the impacts that shattered those parent bodies.

We started with the collection I curate at the Vatican; but there are many meteorite types that are underrepresented there. When I came to New York last August for a year’s sabbatical at Fordham University, I had hoped to extend our data by looking at the nearby American Museum of Natural History’s extensive collection.

But things got off to a slow start. It took time to settle into Fordham; and Dan, who’d been storing our equipment in Florida, had new responsibilities too. Finally, in December, the equipment was shipped to New York. It arrived just in time for Christmas… and the holidays. Then I spent another week at my Jesuit province congregation. Finally, in mid-January, Dan himself came up to New York bringing the few last bits needed to get to work.

The key instrument we use is an Ultrachrome Pycnometer. It measures meteorite volumes on the same principle that had sent Archimedes running down the streets of Syracuse, naked from his bath, shouting “Eureka.” He’d realized that you could measure volumes by dipping a body into a pool of water and seeing how much water is spilled out of the pool. We don’t want to dip our fragile meteorites into water, however. We use inert helium gas.

Two chambers are pressurized with helium, one at a pressure higher than the other; we compare pressures beforehand, open a valve between them, and measure the final pressure. Then the meteorite is placed in the higher pressure chamber, and process repeated. The bigger the volume of the meteorite, the less room there is for the pressurized gas, and so the lower the final pressure. Comparing the final pressures of the two cases tells us the sample’s volume; this volume is divided into the meteorite’s mass to determine its density.

Helium, the gas with the tiniest molecules, will penetrate into the finest cracks and pores of the meteorite; this is good. It will also leak through the tiniest cracks in an experimental set-up; not so good. We could hear hissing from somewhere. Finally, pulling the pycnometer apart, we found a broken tube. Time to order a replacement from the manufacturer. Another month lost.

Last week, Dan returned to New York with the tube, and fixed that leak. But all that’s accomplished is to show up smaller leaks we hadn’t noticed before. The regulator that controls the pressure from the helium tank to the pycnometer is clearly not helium-tight; time to replace it. The outlet fitting is a quarter-inch, while the connecting pipe fitting is metric; another fix needed. Each patch we apply only reveals another leak further down the line. We’ve lost a quarter of our helium so far, without getting a single measurement. And I’ve less than three months left in New York.

These frustrations only remind me of my own spiritual state, this Lenten season. I’m not a terrible sinner; really, only one or two things need patching, right? But the only evidence I have that I’m making progress in my prayer life is my ability to constantly find faults that I hadn’t noticed before.

I know I will never eliminate all the leaks in my helium plumbing. My only hope is to get to a point where it’s good enough, where I can actually get something accomplished, some data collected, some good done in this world. With the grace of God, maybe I’ll get to that point by Easter.


Br. Guy Consolmagno

About Br. Guy Consolmagno

Brother Guy Consolmagno SJ is Director of the the Vatican Observatory and President of the Vatican Observatory Foundation. A native of Detroit, Michigan, he earned undergraduate and masters' degrees from MIT, and a Ph. D. in Planetary Science from the University of Arizona; he was a postdoctoral research fellow at Harvard and MIT, served in the US Peace Corps (Kenya), and taught university physics at Lafayette College before entering the Jesuits in 1989.

At the Vatican Observatory since 1993, his research explores connections between meteorites, asteroids, and the evolution of small solar system bodies, observing Kuiper Belt comets with the Vatican's 1.8 meter telescope in Arizona, and applying his measure of meteorite physical properties to understanding asteroid origins and structure. Along with more than 200 scientific publications, he is the author of a number of popular books including Turn Left at Orion (with Dan Davis), and most recently Would You Baptize an Extraterrestial? (with Father Paul Mueller, SJ). He also has hosted science programs for BBC Radio 4, been interviewed in numerous documentary films, appeared on The Colbert Report, and for more than ten years he has written a monthly science column for the British Catholic magazine, The Tablet.

Dr. Consolmagno's work has taken him to every continent on Earth; for example, in 1996 he spent six weeks collecting meteorites with a NASA team on the blue ice regions of East Antarctica. He has served on the governing boards of the Meteoritical Society; the American Astronomical Society Division for Planetary Sciences (of which he was chair in 2006-2007); and IAU Commission 16 (Planets and Satellites). In 2000, the small bodies nomenclature committee of the IAU named an asteroid, 4597 Consolmagno, in recognition of his work. In 2014 he received the Carl Sagan Medal from the American Astronomical Society Division for Planetary Sciences for excellence in public communication in planetary sciences.

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