Recognition Comes With His Own Asteroid : UCSD Chemist Searches for History of the Solar System
For Jim Arnold, life without outer space would be hard to fathom. The popular UC San Diego chemist even has an asteroid--”2143 Jimarnold”--named for him.
Arnold has spent most of his life--and more than a quarter century at UCSD--considering myriad questions about our universe, from cosmic rays to the future of space flight.
He believes strongly that the human quest for new frontiers mandates continued manned exploration and eventual space colonization.
His laboratory’s work on lunar rock samples has helped determine the age of the moon more precisely, and has helped trace millions of years of the sun’s history. As director of the statewide UC California Space Institute, Arnold identifies promising young scientists whose projects on the leading edge of new technologies can expand human exploits of the solar system. As a longtime consultant to NASA, Arnold attempts to shape government space policy, sometimes successfully, sometimes less so.
But even ahead of his professional career--which began at Princeton University in the mid-1940s--Arnold traces his interest in the non-terrestrial to his childhood. He keeps a well-worn copy of an omnibus collection of Jules Verne novels behind the desk in his Mayer Hall laboratory.
“I’ve owned it since I was 11, this collection of four science fiction novels,” the 63-year-old Arnold said during an interview last week. “The one particularly relevant here is the (1867) novel, “From the Earth to the Moon,” which had a profound impression on me.”
In addition, Arnold had a boyhood ambition to become an astronomer which developed, he said, “after I decided I was not going to be a fireman.”
“So from early on, I had a bias towards space.”
At Princeton, and then at the University of Chicago, Arnold geared his studies toward understanding the nuclei of chemical elements, which at the time represented the frontiers of science. He participated on the Manhattan (atom bomb) Project and then joined chemist William Libby at Chicago, where radioactive carbon dating was developed. That work earned Libby a Nobel Prize.
The technique, still widely used by anthropologists and paleontologists, looks at the radioactive decay of carbon isotopes that occurs in nature as a result of cosmic rays entering the earth’s atmosphere and causing nuclear interactions with nitrogen atoms. The decay takes place at a fairly constant rate, once the organism dies, in all organic matter that contains nitrogen. Approximate dating is possible when the rate of decay is known, then measuring how much of the isotope has decayed in a particular object.
Arnold expanded the research to look at the effects on meteorites of cosmic rays, which are very high energy nuclei entering the solar system at all times from interstellar space as a result of processes not yet fully understood.
By looking for isotopes that would have a long decay--millions of years or more--fossil records have become possible for a piece of the moon, or a meteorite.
“And you thus learn a lot about the history of the cosmic rays and how long a meteorite has been a rock in space and where it might have come from, all by exploiting the well-known properties of radioactive nuclei,” Arnold said.
In the past month, Arnold and his colleagues have determined, using powerful new techniques, the dates of terrestrial rocks by measuring isotopes in them that up until now could not be detected because their presence on earth was too weak to detect. The Earth’s atmosphere filters out most cosmic rays, protecting organisms from the most harmful effects of the powerful nuclei.
“We see it being used in the immediate future for measuring erosion rates, the rate of decay of mountains, on a worldwide or geographic scale, and think that is going to be one of the basic bits of information that one should know about the Earth,” he said.
The early work with cosmic rays took Arnold irretrievably into the arena of space.
Soon after his first work with meteorites, the Soviet Union began the space race with its Sputnik satellite in 1957 and attention among Arnold’s colleagues immediately focused on how to apply nuclear techniques in space. Arnold, with encouragement from Harold Urey--a giant in the field of nuclear chemistry and in the formulation of theories about the solar system’s origins--convinced the National Aeronautics and Space Administration to determine the composition of the moon by measuring cosmic ray effects there.
“By then, I was hooked,” Arnold said.
Also by then, Arnold had arrived at UCSD, where he became an associate professor of chemistry in 1958 and a full professor and first chairman of the chemistry department in 1960.
His ultimate research goal is to push the record of the universe back closer to its origins, and Arnold admits the philosophical impact can cause goose bumps.
“I am intensely curious, of course--a necessary condition for being in my business--and I always try to fantasize where we haven’t yet the wit, or tools, to unlock all the secrets of the solar system that I believe are already inside meteorites,” Arnold said.
“But I am also reminded that every day you have to do a day’s work and the experiments you can do on a given single day are always very small.”
Arnold calls himself a generalist, enjoying projects that can be applied across many fields of science, such as carbon-14 dating. In that context, he has weathered well the give-and-take of the nation’s space bureaucracy through almost 30 years of service on various NASA committees.
“My first committee was in January, 1959, only three months after the space agency was established,” Arnold said.
Arnold is critical of NASA’s tendency over the years to tie up promising new ideas in a web of reviews and other delays that have had the effect of dulling its early reputation as a “can-do” agency. In part, the increasing bureaucracy has resulted from the need to tighten procedures after disasters such as those that overtook Apollo 7 and Challenger, when astronauts died.
But Arnold thinks NASA could move more quickly to explore innovative space technology, including alternatives to chemical rockets that Arnold believes have reached the design limits of their potential to lift objects into space.
“We get some support from NASA for some of our studies (on new technologies), but after we finish, they say, ‘How would you like to do another study?’
“I do think that there is going to be more movement now that the President’s commission (on the future in space) has recommended that some of the next-generation technologies begin to come into their own.”
In his capacity as director of the California Space Institute, Arnold points to the mini-grant program, where seed monies are given to promising research projects using untested new ideas.
“One way to convince people to give you (a lot of) money is to show some results before they give it and the mini-grants have done that for many people,” Arnold said. “In addition, we have a lot of excitement in areas of ocean sensing from space--remote sensing--such as a new way of looking at monsoons (from space).”
Arnold also would like to see more international cooperation on space projects as a way to spur research. But he cautions that the United States should not allow its technical preeminence to erode.
“I’m an American and one likes to think well of one’s country,” he said. “The U.S. has been a leader since Apollo, although the Soviets have done better than we give them credit for, and I participate in these international technological olympics with a certain degree of national feeling and enthusiasm . . . and I would be very unhappy personally if the U.S. were to fall far behind.”
Arnold has a similar strong attachment to the idea of space colonization, harking back to his longstanding interest in the cosmos as well as in his involvement with former Princeton physicist Gerry O’Neill, who sponsored seminars on how to mine resources in outer space, and how and where colonies might be established.
While Arnold has no particular expertise in aerospace matters, he has tried to set up similar seminars at UCSD to encourage young scientists to pursue questions of man’s future in space.
“Call it Jules Verne stuff or whatever, this question of expanding life into the solar system is of very great value in itself and for itself,” he said.
“It is of great benefit to humanity in the long run and in some kind of sense, it is the only direction that the only intelligent life that I am aware of in the universe ought to go, exposing living things to environments very different from ours and creating civilizations elsewhere.”
At bottom, Arnold finds space issues the ultimate challenge.
“When I’m in Washington--and it’s been a grim time lobbying (with NASA and Congress)--I go to the National Air and Space Museum and watch people of every age marveling at . . . the Wright Brothers, Lindbergh, Goddard and Apollo and I recharge my own batteries and say, ‘It can be done!’ ”
