Ixlr8 writes "BBC news is running a story that suggests up to half of Mars may have ice. From the article:
Up until now, scientists had been able to search for water deposits using a spectrometer fixed to the orbiting Mars Odyssey spacecraft. However, only readings that are accurate to within several hundred kilometres can be obtained.
By comparing seasonal changes in thermal infrared patterns, detected by the same Odyssey spacecraft, (scientists)[ed] can make readings accurate to within just hundreds of metres."