ALCATEL SPACE DELIVERS FIRST PAYLOAD FOR XM SATELLITE RADIO

Delivery represents the first fruits of Alcatel Space's industrial cooperation with Hughes Space & Communications

National, April 17, 2000 -- Alcatel Space, Europe's leading satellite exporter, today announced the completion and delivery to Hughes Space & Communications Company of the first of two state-of-the-art communications payloads for XM Satellite Radio (NASDAQ:XMSR). The second payload is scheduled for delivery in May 2000.

The XM payload was manufactured and integrated onto its module at Alcatel Space's Toulouse, France, facility. On Friday, April 14, 2000, it was shipped to Hughes' spacecraft factory in El Segundo, CA, where the 3,500-pound payload module will be integrated into Hughes' 702 spacecraft bus. Hughes Space & Communications (HSC), the world's leading manufacturer of commercial communications satellites, will conduct functional, antenna range and environmental testing on the spacecraft in preparation for launch later this year.



In making the announcement, Alcatel Space President and CEO Jean-Claude Husson stated, "We designed the largest payload ever made, and we successfully demonstrated our capabilities to meet the challenge of its very high-power requirement. Our collaboration with Hughes went extremely well, and I am proud of the confidence placed in us by both Hughes and XM Radio."

Hugh Panero, XM's President and CEO commented, "Completion of this payload module represents a tremendous milestone in XM's development. XM is on schedule and well on its way to launching its satellites later this year. It has taken an enormous engineering and manufacturing effort to produce the most powerful payload in the world, and everyone, from XM's space segment team to crews at Hughes and Alcatel Space, can be proud of this achievement."

"We call the Hughes 702 satellite our 'powerhouse,' and thus it is particularly well-suited for the XM Satellite mission," said HSC President and CEO Tig H. Krekel. "With 18 kilowatts total spacecraft power at beginning of life, these will be the most capable satellites Hughes has built."

The XM payload provides two very powerful S-band downlink channels over the contiguous United States with an equivalent radio-frequency (RF) transmit power more than 7 megawatts per channel, a first in the satellite industry.

The payload benefits from several innovative developments from Alcatel Space in paralleling power amplifiers. XM's high channel transmission power is obtained by combining sixteen 228-watt S-band traveling wave tube amplifiers through a multi-stage configuration. This power level is needed to allow digital radio satellite signals to be received with ample margin in cars or at home throughout the contiguous United States, thereby offering excellent sound quality and a large reception footprint.

XM's Hughes 702 satellites, dubbed "XM-Rock" and "XM-Roll," will operate in geostationary orbit, positioned on either side of the United States at 115° West Longitude and 85° West Longitude, respectively. XM's uplink facility, provided by Calian's SED Systems, will be collocated with the company's Washington, DC, studios and broadcast center, and Telesat Canada will provide in-orbit operations.

Alcatel Space's involvement in the field of Satellite Digital Audio Broadcasting started back in 1994 with the company's cooperation with WorldSpace, today the world's first operational digital audio broadcasting system. With WorldSpace's AfriStar satellite launched in 1998 and in service since October 1999, and the second satellite, AsiaStar, launched this past March 21, the WorldSpace program continues to progress under the prime contractorship of Alcatel Space. For WorldSpace, Alcatel designed sophisticated payload solutions using on-board baseband digital processing techniques, allowing easy uplinking of radio programs and the possibility of bandwidth-on-demand to broadcasters. XM Radio's satellite system technology and design capitalize on Alcatel's experience.

About XM Satellite Radio
XM Satellite Radio is developing a new band of radio. Starting the first half of 2001, XM Radio will beam up 100 channels of digital quality music, news, sports, talk and children's programming directly from its two powerful satellites to vehicle, home and portable XM-Ready radios coast to coast. Listeners will be able to drive from New York to Los Angeles, Chicago to Corpus Christi while continuing to listen to their favorite XM channels without searching the dial as they travel through unfamiliar parts of the country.

The XM sound will combine leading brand-name channels with distinctive formats produced in XM Radio's fully digital Programming Center by some of the country's leading artists, producers, programmers and radio format designers. XM-ready radios will be manufactured by such household names as Sony, Alpine, Pioneer Electronics Corporation, Delphi Delco Electronic Systems, Audiovox, Clarion, Mitsubishi Electronic Automotive America, Motorola and the Sharp Corporation.

The service will be easy to order, with XM-Ready radios available at car dealerships and consumer electronics stores across the country. The company has a long-term distribution agreement with General Motors to integrate XM-Ready radios into its vehicles commencing in 2001. XM will be available to truckers, boaters and airplane passengers through deals with Freightliner and Pana-Pacific, Marine Audio, and LiveTV respectively.

American Mobile Satellite Corporation (NASDAQ:SKYC) holds a controlling interest in the company, which is also backed by General Motors, Clear Channel Communications and DIRECTV, respectively, the leading car, radio and satellite TV companies in the US.

First there was AM, then FM and soon ... XM Satellite Radio. For more information, please visit XM's new website: www.xmradio.com.
About Hughes Space and Communications:
HSC is the world's leading manufacturer of commercial communications satellites, having built nearly 40 percent of those in operation. It also is a major supplier of spacecraft and equipment to the U.S. government, and a builder of weather satellites for the United States and Japan.

HSC introduced the 702 model spacecraft in 1995 to meet customer requirements for satellites with more than 10 kilowatts of power, and with flexible payload capacity. A total of ten of these powerhouses have been ordered by such customers as PanAmSat Corporation, XM Satellite Radio, Telesat Canada, and Hughes SpacewayTM. This year three more Hughes 702s are scheduled for launch.



HSC is a unit of Hughes Electronics Corporation. The earnings of Hughes Electronics, a unit of General Motors Corporation, are used to calculate the earnings per share attributable to the General Motors Class H common stock. For more information about HSC, visit its website www.hughespace.com.

About Alcatel Space:
Alcatel Space, Europe's leading satellite exporter, ranks among the world's leading space systems industries. With expertise in civil and military applications, Alcatel Space develops satellite technology for telecommunications, navigation, optical and radar observation, meteorology, science. With partners around the world, subsidiaries throughout Europe, and a strong commitment to R&D, Alcatel Space plays an important role -- as prime contractor, operator, investor, or service provider -- in a majority of ongoing space programs. An affiliate of Alcatel (51%) and Thomson-CSF (49%), Alcatel Space generated a 1999 turnover of 9.3 billion francs (1.6 billion Euros). The Company employs 5,500 people. For more information, please visit our Web site on www.alcatel.com/telecom/space.

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, the company's dependence on third party vendors, its continuing need for additional financing, as well as other risks described in XM Satellite Radio Inc.'s Form 8-K filed with the Securities and Exchange Commission. Copies of the filing are available upon request from XM Radio' s Investor Relations Department.

Press Contacts
Jennifer Markham
(202)380-4315 Phone
jennifer.markham@xmradio.com