In This Issue
Interstellar ices and prebiotic ribonucleotide intermediates
Ultraviolet processing of cosmic ice analogs.
In the dense molecular clouds from which stars and planetary systems form, interstellar ices represent the most abundant molecular species in the solid state. Subjected to various energetic and thermal processes, these ices undergo transformations that ultimately lead to new and complex molecules. Using laboratory experiments, Pierre de Marcellus et al. (pp. 965–970) reproduced the processes by which these ices evolve, and having previously identified amino acids in the organic residues, searched for different families of molecules of interest to prebiotic chemistry. The authors found 10 members of the aldehyde class of organic compounds, including glycolaldehyde and glyceraldehyde, two sugar-related species thought to be intermediates in the synthesis of ribonucleotides in planetary environments. This material, incorporated into planetesimals at the origin of the organic matter in the Solar System, represents a potential source of prebiotic chemistry on telluric planets. The findings represent a means by which comets and primitive meteorites could have seeded the Earth with organic material as early as 4.2 billion years ago, according to the authors. — T.J.
Estimating Greenland meltwater release
Supraglacial rivers on melt-prone areas of the Greenland Ice Sheet surface are an important component of Arctic climate change.
Every summer, melt-prone areas on the Greenland Ice Sheet form a complex system of supraglacial streams, rivers, and moulins that drain and transport surface meltwater to the ocean. Although this runoff contributes significantly to rising global sea level, few observational studies have examined the system in detail. Laurence Smith …
