  Sugars of extraterrestrial origin have been observed in the interstellar
medium (ISM), in at least one comet spectrum, and in several carbonaceous
chondritic meteorites that have been recovered from the surface of the Earth.
The origins of these sugars within the meteorites have been debated. To explore
the possibility that sugars could be generated during shock events, this paper
reports on the results of the first laboratory impact experiments wherein
glycolaldehyde, found in the ISM, as well as glycolaldehyde mixed with
montmorillonite clay, have been subjected to reverberated shocks from ~5 to >25
GPa. New biologically relevant molecules, including threose, erythrose and
ethylene glycol, were identified in the resulting samples. These results show
that sugar molecules can not only survive but also become more complex during
impact delivery to planetary bodies.
