Cyborg from Earth

The Messina Dust Cloud is home to a flourishing human population seeking independence from Earth and rumored to be illegally experimenting with nanotechnology to create warrior cyborgs. The misfit heir to a transportation empire, Jefferson Kopal, is sent out to the Cloud in spite of nearly failing his qualification tests for the Space Navy. Once there, he undergoes a classic process of coming of age and of learning that things are not what they seem--things including his family, the Space Navy, the Cloud and, above all, the Cloud's technologies. Young Jeff is an appealing protagonist, embodying a plausible mixture of virtues and vices. Perhaps he's too appealing: Sheffield focuses so closely on him that other interesting and even essential aspects of the story (such as the climactic space battle and the confrontation over control of the Kopal transportation empire) are undeveloped, even somewhat jumbled by comparison. In any case, the novel--the most ambitious yet of the Jupiter series (Putting Up Roots, etc.)--succeeds as the edifying entertainment it, and the series, is meant to be. (Mar.)