Sentinel-1A, a satellite designed to scan the Earth with cloud-penetrating radar, lifted off at 2102 GMT aboard a Soyuz rocket from Kourou, French Guiana, the European Space Agency (ESA) said yesterday.
The 2.2-tonne satellite is the first of half a dozen orbital monitors that will be built and launched under the USD 5.19-billion Copernicus project, a joint undertaking of ESA and the European Union (EU).
Sentinel-1A separated from the rocket's upper stage 23 minutes and 24 seconds after launch.
Operating 180 degrees apart, at an altitude of about 700 kilometres , between them the pair will be able to take a radar picture of anywhere on Earth within six days.
Radar scanning has a range of uses, from spotting icebergs and oil slicks to detecting rogue logging and ground subsidence.
The data will be widely accessible to the public, and is likely to have uses that go beyond the environment, such as in construction and transport.
By mapping areas stricken by flood or earthquake, the monitors will also be able to help emergency teams identify the worst-hit areas and locate roads, railway lines and bridges that are still passable, ESA says.
The goldmine of data expected to be thrown up by the satellite constellation will be more accessible to the public than any previous Earth-monitoring programme.
The potential applications go beyond stewardship of the environment. They could help shipping firms, farmers and construction companies, too.