166 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 64 



material from polar ice cores in search for extraterrestrial particles 

 and have collected particles on the slopes of the x\.rizona Meteorite 

 Crater for analysis and comparison with other matter that now seems 

 to be extraterrestrial. 



A particular problem has been the isolation of volcanic particles, 

 which may be confused with extraterrestrial material. To better 

 characterize volcanic particles, Dr. Wright is examining collections 

 made by personnel from the Baker-Nunn Stations: samples from 

 Kilauea Iki 1959 eruption, collected by D. V. Mechau ; samples from 

 Irazu 1963 eruption, collected by Ron La Count; and samples from 

 Ubinas 1954 eruption, collected by A. Oakes. 



Drs. Wright and Hodge have sampled these volcanic dust deposits 

 to search for and analyze microscopic spherules that might possibly 

 be similar to the supposed meteoritic spherules found in polar ice 

 sediments. In the size range of 10 to lOO/x, approximately 2X 10"^ of 

 volcanic particles are perfect or nearly perfect spherules, and 2X10"^ 

 are rough magnetic spheroids. In composition they are similar to 

 only a few of the polar glacier particles the two have analyzed. 

 They have concluded that since the numerical ratio of spherules to 

 irregular particles for the volcanic dust is so much different from that 

 for the ice sediments, a volcanic origin for the latter seems impossible. 

 Therefore a meteoroidal origin for the arctic and antarctic spherules 

 is the most reasonable hypothesis. 



Another place where cosmic dust might be expected to accumulate 

 is the sediment on the ocean floor. Dr. Craig M. Merrihue is explor- 

 ing this possibility. A mass-spectrometric search for extraterrestrial 

 material in a magnetic separate from a modern Pacific red clay 

 revealed the presence of He^ and an argon isotope anomaly, suggest- 

 ing the presence of cosmic dust. The cosmic gases are not cosmogenic 

 because the isotope pattern does not resemble that expected from 

 cosmic-ray-induced reactions. It appears that the most abundant 

 magnetic component of cosmic dust is saturated with gases picked up 

 from the solar wind. A computer program has been assembled to 

 solve the diffusion equation for gases from spheres, assuming an arbi- 

 trary nonuniform initial gas profile. This program will permit accu- 

 rate determinations of diffusion constants and activation energies for 

 meteoritic minerals. 



The Observatory's interest in dust goes beyond the earth's atmos- 

 phere. The joint research of Drs. Giuseppe Colombo and Don A. 

 Lautman, with Irving Shapiro of the M.I.T. Lincoln Laboratory, 

 concerning the concentration of cosmic dust around the earth has 

 established that the density of dust in the vicinity of the earth can 

 be enhanced by a factor of nearly 10^ over that in the zodiacal cloud. 



