CARBONIC-ACID ON MARS

For a long time carbonic acid (H2CO3) had defied many efforts for its detection by IR spectroscopic techniques. Recently H2CO3 has been synt hesized at low temperature (similar or equal to 10-80 K), and stabiliz ed up to similar or equal to 250 K, by energetic ion irradiation of fr ozen targets made of H2O:CO2 ice mixtures (Moore and Khanna, Spectroch im. Acta 47, 255-262, 1991; Moore et al., J. Geophys. Res. 96(2), 17,5 41-17,545, 1991; DelloRusso et al., Geophys. Res. 98(E3), 5505-5510, 1 993; Brucato et al., Icarus 1996 (in press)) and by protonation of bic arbonate (Hage el al., J. Am. Chem. Soc. 115, 8427-8431, 1993; J. Chem . Soc. Faraday Trans. 91(17), 2823-2826, 1995). Its IR spectrum has be en obtained. A comparison between the IR laboratory spectrum of H2CO3 with some spectra of Mars suggests that carbonic acid could be present on the surface and/or atmosphere of the red planet. Its firm identifi cation requires the acquisition of better astronomical data possibly f rom space missions (e.g. Mars 96) and would be of primary relevance fo r both the organic and inorganic chemistry taking place on Mars. Copyr ight (C) 1996 Elsevier Science Ltd