A Gem for Venus - John J. Culp

After noted space engineer Dr. Robert Deems is forcibly retired when his project is mysteriously canceled, he and niece Jillian move to the Black Forest region of Colorado. There he modifies his Geologic Exploration Module (GEM) named Diamond Two to look for water under the drought-stricken High Plains. Troubles arise when the probe inexplicably runs out of control and accidentally wreaks destruction, even as a secretive organization headed by the enigmatic Taras Tamonash schemes to seize and market it as an unstoppable secret weapon. With the help of their new friend Neil Rivera, Robert and Jillian strive to use the limited resources at hand to re-program and stop Diamond Two. However, given its artificial intelligence is it going to accept commands from Deems or from Tamonash, or does it have a mind of its own?