Sentinel-2B carries an oversized camera to image all land surfaces and coastal waters in visible and actinic radiation.
It joins the same artificial satellite, Sentinel-2A, already in orbit.
The pair are flown on identical path however a hundred and eighty degrees apart so they will give an entire map of Earth - clouds allowing - each 5 days.
The Sentinels represent the area section of the eu Union's Copernicus environmental observation programme.
A suite of sensors is being lofted over consequent few years to assemble crucial data on the state of the world and to accumulate the information required to tell and enforce EU policies.
Applications vary from urban designing and air-quality observation to following deforestation and ice mass retreat.
Sentinels 2A and 2B area unit, in several senses, the centrepiece of this effort as a result of their free and open image resource can nearly actually notice the widest use.
"To say they are the 'heartbeat' is a good way to describe them because they take the images that are most easily understandable," Josef Aschbacher, the director of Earth observation at the European Space Agency (Esa), told BBC News.
The lift-off aboard a Vega rocket occurred on cue at exactly 22:49 local time, Monday (01:49 GMT, 02:49 CET, Tuesday).
Ejection of the satellite happened about an hour later, roughly 775km above the Earth.
Controllers in Darmstadt, Germany, were waiting to pick up a signal and begin early operations.
"We will slowly acquire the reference orbit (786km altitude) over the next two weeks," explained Bianca Hoersch, Esa's mission manager for the Sentinel-2 spacecraft.
"Then we have the commissioning phase; that takes us to early June. At that point we should be producing lots of data, and after a short ramp-up, around the October timeframe, we should be in full constellation readiness."
The cameras on the Sentinel-2 pair are designed to see colour features as small as 10m across.
Together, they will be producing something like four terabytes of data daily. It is a prodigious volume that will lean on the assistance of a laser relay link.
For a 10-minute spell on each orbit, the artificial satellite can every fireplace their pictures not down to Earth however higher into the sky, to a fixed satellite which will then bounce them to the bottom.
Thousands of users have registered to possess access to the photographs. Downloading them from the varied distributed servers has been created easier by chopping the "scenes" up into a lot of manageable chunks.
"With Sentinel-1A, we tend to had at the start immense merchandise that were 8GB to 9GB per file, that were extremely arduous to access and transfer," aforesaid Dr Hoersch.
"In Sept, we tend to switched to single tiles, a product of 100km by 100km, and that i assume that has LED to Associate in Nursing explosion in knowledge access. We've had a pair of.7 million merchandise downloaded within the last 2 months."
Sentinel one could be a measuring system platform and has its pair totally operational in orbit since last year. watcher a pair of is that the next to complete its pairing; watcher three, that carries preponderantly ocean sensors, ought to have Associate in Nursing orbiting try aloft return next year.
Sentinels four and five, that study the atmosphere, and watcher six, to live ocean height, haven't any presence in orbit however.
But even if the programme continues to be to complete its initial roll-out, the EU and Esa have already begun to debate a way to extend it.
In this future-scoping, watcher seven is envisaged to be a constellation of satellites that monitors carbon dioxide; watcher eight can be a thermal infrared device, helpful for understanding phenomena like drought; and watcher nine may be polar mission, either to check the extent and thickness of ice surfaces or 2 give higher weather imaging and communications at high latitudes.
"But I ought to stress that every one these candidate missions area unit a piece current and can need to be consolidated through an intensive consultation method, each on the user aspect and on the technical aspect," aforesaid Dr Aschbacher.
"And we tend to even have to place along a full theme, not simply on content however however conjointly in terms of value and funding."
