LONGBOTTOM JOINS TEAM DEVELOPING INNOVATIVE NATIONWIDE SATELLITE-DELIVERED RADIO SERVICE

National, December 14, 1999 -- XM Satellite Radio (NASDAQ:XMSR), an innovator in radio entertainment, today announced that Penelope Longbottom has joined its senior staff as Vice President, Corporate Communications. A veteran communications executive, Longbottom takes charge of XM's media, public and investor relations functions. She reports to XM President and CEO Hugh Panero.

"Penelope has amassed over 15 years experience with companies on the cutting edge of satellite and wireless communications," said Panero. "She brings a wealth of communications knowledge and experience to XM as our plans to deliver the next generation of radio move into high gear. We are delighted to welcome her to our sterling senior management team."

Prior to joining XM, Longbottom was Vice President, Communications and Branding, for Lockheed Martin Global Telecommunications (LMGT). Based in LMGT's London office, she was a key player in founding and establishing a global presence for LMGT's Russian satellite partnership, Lockheed Martin Intersputnik. Previously, Longbottom was Vice President, Corporate Communications for Washington, DC-based SPACEHAB, Inc.

Longbottom gained significant industry experience during her 12-year tenure with Hughes Electronics, Inc., in Los Angeles. From 1996-97 she was Vice President, Communications and Brand Management, for Hughes' DIRECTV International unit, which subsequently became part of the company's flagship US DIRECTV, Inc., unit. Joining Hughes in 1985, she was the principal architect in shaping the identity and directing external and internal communications for Hughes Communications, Inc., the world's leading private satellite operator that merged with PanAmSat in 1996. HCI conceived and developed DIRECTV before it became a separate Hughes Electronics operating company in 1993. DIRECTV is now a major XM investor.

During her Hughes tenure, Longbottom was instrumental in forming the Satellite Industry Association, now a respected trade organization representing satellite manufacturers, operators and major suppliers. She was elected and served as SIA founding chairman from 1995 to 1996.

Prior to joining Hughes, Longbottom held senior communications management positions with Toyota Motor Sales, USA, Torrance, California, and the National Automobile Dealers Association in Washington, DC.

XM Satellite Radio Inc. is developing a new band of radio. It will use direct satellite-to-receiver broadcast technology to provide listeners in their cars and at home with crystal-clear sound seamlessly from coast-to-coast. XM will create and package up to 100 channels of digital-quality music, news, sports, talk and children's programming at its Washington, DC, broadcast facility. The service will be uplinked to XM's two powerful satellites and transmitted directly to vehicle, home and portable radios across the country. XM is scheduled to launch its service during the first half of 2001 for a monthly subscription rate of $9.95.

In October 1999, XM Satellite Radio (NASDAQ:XMSR) completed a successful public offering on the Nasdaq Stock Market. American Mobile Satellite Corporation (NASDAQ:SKYC) holds controlling interest in the company. XM's other 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 invested $250 million in the company in July 1999. XM Satellite Radio obtained one of only two satellite digital audio radio service (SDARS) licenses from the Federal Communications Commission in October 1997. Alpine, Clarion, Delphi-Delco, Mitsubishi Electronics Automotive America, Motorola, Pioneer and Sharp have announced that they will manufacture and market XM-capable radios. First there was AM, then FM and soon ... XM Satellite Radio. For more information, please visit XM's new website: xmradio.com

Factors that could cause actual results to differ materially from those in the forward-looking statements in this press release include uncertainties associated with the launch of our satellites, our dependence on third party equipment vendors, our continuing need for additional financing, as well as other risks described in our registration statement on Form S-1 (File No. 333-83619) with the Securities and Exchange Commission. Copies of the filing are available upon request from our Investor Relations Department.