ONE REASON no one has invested in a "mediasat" is that it would be very expensive to do so, particularly if a legal challenge is part of the deal, and most news executives see no great need for the images it would produce. In a report last May ("Commercial Newsgathering from Space"), the Office of Technology Assessment cited an estimate by Hughes Aircraft that it would cost at least $215 million to set up an independent, high-resolution system for the media.

Hughes also guessed it could cost as little as $20 million to piggyback a sensor on someone else's spacecraft, although this would mean some loss of autonomy. The author of those figures, Stillman Chase of Hughes' Santa Barbara office, now agrees that the job "probably can be done for less" and that this first look was "pretty superficial." But there still is no concensus on what it would cost. Some estimates hover around $50 million; others, from the builders of lightweight systems called "cheapsats" or "lightsats," are lower.

One builder whose main customer is the military (and who wanted to remain anonymous) said it is "realistic" to think a high-resolution media satellite could be built for $5 million to $10 million. This could be done by using less exact geocoordinating equipment, since TV viewers do not require the same precision researchers do. Great uncertainty about the cost remains, however, because no one has commissioned a thorough study.