September 2008: Falcon 1 reached orbit on its fourth flight, becoming the first privately developed liquid-fuel rocket to orbit Earth. December 2008: NASA awarded SpaceX a $1.6 billion Commercial Resupply Services contract to deliver cargo to the ISS. May 2012: Dragon cargo capsule became the first commercial spacecraft to rendezvous with and deliver cargo to…
Read more
The Nancy Grace Roman Space Telescope is planned to launch in late 2026 (latest commitment by May 2027) aboard SpaceX’s Falcon Heavy to a halo orbit around the Sun-Earth L2, about 1.5 million kilometers from Earth. Roman uses a 2.4-meter primary mirror repurposed from Hubble and a 300-megapixel Wide Field Instrument that covers about 0.28…
Read more
As of mid-2025, Starlink is available in over 110 countries and territories. In the United States, Starlink began with limited trials in August 2020 and the public beta “Better Than Nothing Beta” in November 2020, and now has nationwide commercial coverage including Puerto Rico and the U.S. Virgin Islands, with over 2.5 million subscribers as…
Read more
The first space images were captured in 1946 from a sub-orbital U.S. V-2 rocket at about 105 km altitude. The first actual satellite photograph of Earth was taken on August 14, 1959 by the U.S. Explorer 6 satellite. In 1960, TIROS-1 transmitted the first television image of Earth from orbit, a milestone for weather observation.…
Read more
About 75% of the planet is obscured by cloud cover or darkness at any moment, making optical imaging inaccessible. Synthetic Aperture Radar (SAR) satellites actively illuminate the ground with microwave radar and synthesize a large aperture by moving the antenna to produce high-resolution images. SAR can operate day or night and in all weather, providing…
Read more
Iridium operates about 66 LEO satellites at roughly 780 km, offering truly global coverage including the poles with a one-way latency around 0.1–0.2 seconds. Inmarsat uses 3–4 GEO satellites at about 35,786 km, delivering near-global coverage (roughly ±70° latitude) with about 0.5 second latency, and IsatPhone 2 offers up to 8 hours of talk and…
Read more
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…
Read more
DGNSS improves GNSS accuracy by using stationary reference receivers to broadcast corrections to rovers, transforming standalone GPS accuracy from about 5–15 m to sub-meter or centimeter levels, with SBAS like WAAS (USA) and EGNOS (Europe) delivering about 1–3 m for aviation. Real-Time Kinematic (RTK) uses carrier-phase measurements and double-differencing to fix integer ambiguities, delivering centimeter-level…
Read more
GPS III, first launched in 2018, delivers three times the accuracy and eight times the anti-jamming performance of previous GPS generations, with a GPS III satellite named Katherine Johnson launched by SpaceX in 2025. GPS modernization includes the L1C common civil signal for interoperability with Galileo and a Next Generation OCX ground system to handle…
Read more
GSSAP-1 and GSSAP-2 were launched on July 28, 2014 aboard a Delta IV M+(4,2) from Cape Canaveral, accompanied by the ANGELS experimental satellite. The GSSAP satellites operate in near-geosynchronous orbit roughly 35,900 km (22,300 miles) above Earth and function as a “neighborhood watch” for the GEO belt, providing space situational awareness to USSPACECOM. Built by…
Read more
