In what could prove a big embarrassment to Bill Gates, plans to build a global, broadband Internet-in-the-sky by the satellite industry may be significantly held back by problems with TCP/IP – the core communications protocol of the Internet. Scientists at the National Aeronautics & Space Adminstration have been finding out that the vast distances covered by the data to reach the satellites and get back again involves enough delay – often as long as half a second – to cause the Transmission Control Protocol to think there is an error on the network, and to begin its process of checking, duplicating and re-transmitting lost segments. That results in a major loss of performance. In NASA trials, data that would have been reaching transmission rates up to 155 Megabits per second over fiber optics slowed to just 10 Megabits per second using a satellite network. TCP was originally developed specifically for the reliable delivery of data. Downgrading the current performance of TCP/IP to improve its performance on satellites would not be an option, according to chairman of the Internet Engineering Task Force Fred Baker, quoted in an article last week in the Los Angeles Times. Huge sums are being invested in attempts to marry together the Internet and satellite communications systems, one of the most prominent efforts being Teledesic Corp, based in Kirkland, Washington, set up by telecommunications pioneer Craig Mc-Caw and backed personally to the tune of $10m by Gates. The company is planning to have a two-way, broadband connection using an 840-satellite Teledesic Network intended for speech, data, video conferencing and high-performance Internet access by the year 2002. The multi-satellite distributed architecture, with dynamic routing and robust scalability, was even modeled on the Internet, while supposedly providing the added benefits of real-time capability and location-insensitive access. Teledesic has responded to the findings, spearheaded by Daniel Glover, a Cleveland-based project engineer with NASA, by issuing its own white paper, claiming it will be able to work around the problem. It also points out that its low earth orbit satellites will be less susceptible to delay than geostationary satellite