Summary: ICARUS 119, 405426 (1996)
ARTICLE NO. 0027
Feasibility of Determining the Composition of Planetary Ices by Far
Infrared Observations: Application to Martian Cloud and Surface Ices
BRIAN R. JOHNSON AND SUSHIL K. ATREYA
Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109-2143
Received August 1, 1994; revised July 14, 1995
Ices in the atmospheres and on the surfaces of planets and
Ices are found in the atmospheres of many planets, asmoons are thought to play important roles in the evolution and
cloud and haze condensates, and on the surfaces of manystability of, and in radiative transfer in, planetary atmospheres.
In this paper, the capability of far-infrared spectral observations of their satellites, particularly in the outer solar system.
to determine the composition and characteristics of planetary The principal ices in the solar system include H2O, CO2 ,
ices is investigated with particular application to martian H2O CO, CH4 , C2H2 , C2H6 , N2 , NH3 , N2H4 , HCN, and NH4SH.
and CO2 ices. Thin film transmission spectra of crystalline (Ic) Planetary ices are believed to play important roles in the
and amorphous H2O ice and crystalline CO2 ice were measured origin, evolution, and stability of planetary atmospheres,
using a Fourier transform spectrometer. The far-infrared re- in the planetary radiative energy balance, and in surface-
fractive indices of these ices at temperatures from 77 to 150 K
atmosphere interchange processes (see for example Atreya