The Columbia Glacier descends the Chugach Mountains into Prince William Sound in Alaska. Landsat allows scientists to monitor the changing fronts of such ice streams

17 January 2013 Last updated at 22:55 ET

Jonathan Amos
Science correspondent

Landsat aims to maintain gold standard

One of the very best ways to understand the changes taking place on Planet Earth is to make observations from space.

And to get a true sense of any trends, you really need those measurements to be long-term and unceasing.

Preferably, you use the same type of instrument to make the observations, and when, inevitably, you’re required to replace aging equipment, you do so in such a way that the new system can be cross-calibrated with the old.

Few Earth observation programmes get as close to this gold standard as Landsat, the cooperative space mission run by US space agency (Nasa) and the US Geological Survey.

For 40 years now, the Nasa/USGS satellites have maintained a permanent eye on Earth.

It was during the Apollo preparations – when astronauts would also take pictures of their home planet as they tested their Moon technologies – that the idea was born for a dedicated imaging system to observe the Earth.

It led to the development of the Earth Resources Technology Satellite (ERTS), launched on 23 July 1972 and operated for six years. Subsequent platforms picked up the baton. Today, Landsat-7 maintains the watch, with its successor, Landsat-8, being readied for lift-off next month.

The latest incarnation will go up from California’s Vandenberg Air Force base on an Atlas rocket, and, after a few weeks of checks, assume the lead role of imaging the planet from an altitude of 705km.

The Landsat spacecraft view the Earth in visible and infrared wavelengths, and track details as small as 30m across.

Read more: BBC News – Landsat aims to maintain gold standard.

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