Radar altimeters on TOPEX/Poseidon, Jason-1, Jason-2, Jason-3, and Sentinel-6 Michael Freilich have provided a global mean sea level record since 1992, showing a rise of about 3.3 millimeters per year and roughly 10 centimeters over 30 years. Arctic summer sea ice extent has declined by about 12% per decade since the 1980s, with the Arctic…
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Geostationary orbit sits at about 35,786 km above the equator and completes a sidereal day (~23h56m), so satellites appear fixed over one longitude; Arthur C. Clarke popularized it in 1945, giving the region the nickname the Clarke Belt. A GEO satellite remains stationary relative to the ground, allowing ground antennas to point at a fixed…
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By 2024, small satellites accounted for over 95% of all satellites launched annually. SpaceX’s Starlink operates the world’s largest constellation with over 7,000 active satellites in orbit as of late 2024. Starlink’s initial shell consisted of about 4,400 satellites at roughly 550 km altitude and 53° inclination, with FCC approval for about 12,000 satellites and…
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August 2022: SpaceX and T-Mobile announced a partnership to provide direct-to-cell connectivity via Starlink satellites, with texting expected in 2023–24 and voice/data thereafter. January 2024: SpaceX achieved the first SMS directly via satellite, enabling a two-way text conversation between ordinary smartphones relayed entirely through space after the first batch of D2C-equipped satellites launched. Gen2 Starlink…
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