XM SIGNS THE WEATHER CHANNEL, WORLD'S PREMIER WEATHER BROADCASTER

National, August 24, 1999 -- XM Satellite Radio today announced that The Weather Channel, the world's most relied upon source of information about the weather, will be the exclusive provider of weather forecasts and related information for a number of XM's channels. The announcement was made by Hugh Panero, President and CEO of XM Satellite Radio Inc.

"We are enthusiastic about reaching a new mobile listening audience from coast to coast," said Norm Zeller, Vice President of Syndication for The Weather Channel. "XM Satellite Radio is giving us an opportunity to expand our audience and to meet people's need to know about weather conditions while they travel."

Since 1982, The Weather Channel has brought timely weather information to the world. Beginning as a 24-hour, seven-day-a-week television network devoted entirely to weather, it has expanded across several mediums to bring breaking weather to its viewers and users. Available in more than 72 million US homes, The Weather Channel also owns and operates a 24-hour all-weather network in Latin America. In addition, The Weather Channel radio network is heard in more than 250 radio markets across the country; its newspaper service provides customized weather packages to print publications. The Weather Channel website, located at www.weather.com, is the leading weather provider on the web and offers current conditions and forecasts for over 40,000 locations worldwide as well as local radar, satellite and special lifestyle features.

XM Satellite Radio, a wholly owned subsidiary of American Mobile Satellite Corporation (NASDAQ:SKYC), is developing a new band of radio. The system will use direct satellite-to-receiver broadcasting technology to provide listeners in their cars and at home with crystal-clear sound seamlessly from coast-to-coast. The subscription service is scheduled to start during the first half of 2001 for $9.95 a month. Through its XM Originals programming unit, XM plans to offer an innovative mix of music, talk, news, sports and children's formats. To complement its original programming, XM has signed programming agreements with a number of premier content providers, including USA TODAY, the BBC World Service, Black Entertainment Television, the Hispanic Broadcasting Corporation (formerly Heftel), Bloomberg News Radio, C-SPAN Radio, CNN/Financial Network, CNN/Sports Illustrated and many others.

XM is partnering with industry leaders to build its service. General Motors will distribute and market the XM service in its vehicles; Alpine, Delphi Delco, Pioneer and Sharp will design, manufacture and market AM/FM/XM radios; and, Hughes and Alcatel are building XM's satellites, the most powerful commercial satellites ever ordered. XM's investors include industry leaders Clear Channel Communications Inc.; DIRECTV, Inc., a unit of Hughes Electronics Corporation; the General Motors Corporation; and a private investment group comprised of Columbia Capital, Telcom Ventures L.L.C., and Madison Dearborn Partners, which together recently invested $250 million in the company. XM Satellite Radio obtained one of two satellite digital audio radio service (SDARS) licenses from the Federal Communications Commission in October 1997. First there was AM, then FM and soon. . . XM Satellite Radio. For more information, please visit www.xmradio.com.

Factors that could cause forward-looking statements in this news release to differ materially from actual results are discussed in XM's Registration Statement on Form S-1 (No.333-38619) filed with the Securities and Exchange Commission on July 23, 1999, as the same may be amended, and other periodic filings the company will make with the Securities and Exchange Commission.