Celestri

The Celestri Multimedia LEO System was a planned Low Earth orbit (LEO) satellite constellation, which was intended to offer global, low-latency broadband Internet services via Ka-band radio links[1]. It was planned by Motorola circa 1997-1998 as one of the earliest "Internet in the sky" constellations, and as a successor to the company's Iridium satellite constellation, but never built or launched.

The Celestri constellation was envisioned to consist of 63 operational satellites in 7 orbital planes, inclined at 48° with respect to the Equator, plus up to 7 in-orbit spares[1]. Satellites in each plane would follow circular orbits at an altitude of 1400 kilometers[1]. Each satellite was envisioned to contain all hardware and software needed to route traffic throughout the network, including Earth-to-space in the 28.6-29.1 GHz and 29.5-30.0 GHz bands, space-to Earth in the 18.8-19.3 GHz and 19.7-20.2 GHz bands, and space-to-space connections via optical inter-satellite links[1]. Satellites were expected to employ phased array antennas supporting 432 uplink beams and 260 downlink beams per satellite[2], provided by Raytheon[3], to communicate with Celestri ground stations, which would have equivalent antenna aperture sizes from 0.3 to 1 meter to support communications at rates from 2.048 to 155.52 Mbps.

Celestri's anticipated cost was $12.9 billion[4]. In May 1998, Motorola announced that it was dropping its plans for the Celestri system, and instead would invest $750 in the rival Teledesic constellation[5]. The combined project was ultimately abandoned in 2003[6].

References
  1. Application for Authority to Construct, Launch and Operate the Celestri Multimedia LEO System, A Global Network of Non-Geostationary Communications Satellites Providing Broadband Services in the Ka Band, filed June 1997 with the Federal Communications Commission, Motorola Global Communications, Inc., Chandler, Arizona.
  2. Satellite Earth Stations and Systems (SES); Broadband satellite multimedia; Part 1: Survey on standardization objectives, ETSI Technical Report TR 101 374-1 V1.2.1 (1998-10), page 50.
  3. "Motorola to Give Raytheon Satellite-Antennae Contract", Wall Street Journal, October 30, 1997.
  4. "Motorola to build $12.9 billion global satellite network Celestri, a direct challenge to Teledesic, SkyBridge", Bloomberg News, June 18, 1997.
  5. "Motorola decides to drop Celestri satellite project, Will invest $750 million in rival Teledesic", Bloomberg News, May 22, 1998.
  6. de Selding, Peter B. "Teledesic Plays Its Last Card, Leaves the Game". Space News, July 14, 2003.
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