Landsat aims to maintain gold standard

Columbia Glacier 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

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.

Matt Larsen, USGS: "A library card to Planet 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.

Penguin guano on ice sheet It is not possible to see individual birds from space but we can recognise their habitats. The brown staining (centre) on the white ice is a consequence of guano, or penguin poo, dropped by a colony of emperors.
Beetle damage Insect damage: Two views of Rocky Mountain National Park in Colorado in 2003 (left) and 2010 (right). Spot the areas of tree death caused by the mountain pine beetle. The insect has been spreading its range to the north.
The Aral Sea is shown receding over 30 years Water watch: The Aral Sea in central Asia was once the fourth largest lake in the world, but poor irrigation practice severely depleted its water reserves as seen in these Landsat images from 1977, 1989 and 2006.
Byrd Glacier Antarctica's Byrd Glacier: The satellite series has produced some of our best maps of the White Continent. We now have a complete pictorial view thanks to the Landsat Image Mosaic of Antarctica (LIMA) project.
Etna Violent Earth: With a 16-day repeat to every place on the land surface, there is a good chance that a volcanic eruption will be recorded. This picture shows Mount Etna, Italy, blowing its top once again, this time in 2001.
Kuwait fires War scene: Landsat saw the devastating environmental fall-out from the end of the Gulf conflict in 1991 when retreating Iraqi forces set fire to Kuwaiti oil wells. The fires raged for months.
Mississippi The meandering Mississippi River in all its glory. The blocks are towns, fields and pastures. Evident in this view are the countless oxbow lakes and cut-offs that trace the length of the North American river.

It's true there are imaging sensors up there now that will return pictures of Earth with far better resolutions (in the tens of centimetres), but for the job Landsat is trying to do, the 30m/pixel view is perfect.

Over its 40-year history, Landsat has catalogued the growth of the megacities, the spread of farming and the changing outlines of coasts, forests, deserts and glaciers. It has monitored fires and volcanic eruptions. It has even detailed the behaviours of Antarctic penguins and North American beetles.

"One [application] that we're particularly proud of is the use of something we call the thermal band," explained Matt Larsen, the associate director for climate and land-use change at the USGS.

"This is a technique by which we can estimate the temperature of the surface of the Earth from the sensors on the Landsat satellite, and from that we can measure evapotranspiration (the conversion of water to water vapour).

"Why do we care about that? That's a key part of agricultural activity, and in the western US where we have a huge amount of land in irrigated agriculture, it allows us to better understand how much water we are using, how much water we need and how that might be affected in the future because of changing stream flows because of changing temperatures," he told the BBC World Service's Science In Action programme (listen to our feature).

Landsat-8 will carry an additional thermal band that will lead to more precise measurements.

Iceland This Landsat-7 image from 1999 shows Eyjafjordur, a deep fjord on the northern coast of Iceland. Many have likened the shape of the coast and the colours used to render the image as looking like a tiger’s head

The uses of Landsat data really are innumerable.

Paul Donald, a conservation scientist with the UK's Royal Society for the Protection of Birds (RSPB), gives a great example of how these pictures can be used to understand the geographical distribution of very poorly known avian species. You cannot see the birds from space, obviously, but you can map their likely habitat.

"One of the ways we can do this is to use a modelling technique, where we take Landsat data and we match that with areas where we know the birds are; and that will then give us a very good description of where the bird may be where people have never even been to look for it," he told us.

"The results have been extraordinary. We've generated maps using Landsat imagery which have predicted areas we never thought suitable for this bird. We've gone there, and we've found the bird."

Landsat-8 is more formally called the Landsat Data Continuity Mission (LDCM). This mouthful reflects the rather tortured route the mission had to take to get budget approval. It's a perennial problem for Earth observation missions - getting a timely sign-off from the politicians so that an enduring presence in orbit can be maintained. Even with Landsat, it is as if each satellite was born an only child, and the next mission had to fight for justification as if there had been no heritage.

Nasa, USGS and the Federal Office of Management and Budget (OMB) are now seeking a long-term solution that would see Landsat-9 and all following spacecraft arrive on a predictable track.

It is the sort of assurance Earth observation seeks in Europe, also. At the end of this year, the European Space Agency will start to roll out the multi-billion-euro Sentinel fleet of satellites, which aim to echo the Landsat philosophy but with many more types of sensor. However, even as the first mission is prepared for launch, politicians are still arguing over how the project should be funded.

Landsat-8 Ready to go: Landsat-8 will launch in February from California on an Atlas rocket
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  • rate this

    Comment number 27.

    Perhaps they could programme it to look for the OZONE which was the Great Talking Point in the1970s?
    Remember"experts"surmised that the ozone depletion they "observed" would result in parts of earth being "uninhabitable by 2000".
    Send up another satellite by all means.It will join all the other 6000 plus already orbiting. Science is sure giving Mother Earth a "Good Looking at" for sure! Relevance?

  • rate this

    Comment number 26.

    Although the U.S. military can use Landsat, they get a much better resolution from their Big Bird satellites, due to the latter's much lower altitude. On the plus side, they can see smaller objects, but on the negative side they have to be replaced much more often due to the tiny mount of atmospheric drag causing them to have a shorter life before burning up on reentry.

  • rate this

    Comment number 25.

    Let's hope the European Space Agency can secure long-term funding for their Earth Observation. Without the proof that these images provide far too much energy will be spent proving global warming, instead of addressing it.

  • rate this

    Comment number 24.

    I find that satellite images, no matter where they are pointing, are the most fascinating. If we did not have satellites pointed towards the outer reaches of space, we would still blindly believe that there was only one galaxy. And if we didn't have satellites pointed towards Earth, many archaeological sites and geological changes would be missed.

  • rate this

    Comment number 23.

    I don't suppose they've spotted any buried Spitfires, have they?

  • rate this

    Comment number 22.

    17.Mike Mullen

    Military and intelligence agencies have their own satellites, they hardly need Landsat

    Ok, but I didn't say the military needed Landsat, rather that these technologies are vulnerable to governments (and corporattions).

    But prove to me the military won't, or don't use Landsat.

  • rate this

    Comment number 21.

    were creating the anthropcene event and have been for probobly 500 years...ultimatly we will die out as a species and eveidence of our anthropcene event will be found in millions of years times by the then scientists.theres no stopping it its evolution.

  • rate this

    Comment number 20.

    I have been watching Landsat 4 passing over U.K. these past few evenings.
    Easily visible to the unaided eye.

    Nice to spy on the satellites that are watching us.

  • rate this

    Comment number 19.


    It i because of space taken pictures that we could see the massive extent of sea ice loss in the Artic last year - how else could you measure it?

    If you can't measure it you don't know how bad the problem is.

    If you don;t know how bad the problem is you do not know how much needs to be done to address it.....

  • rate this

    Comment number 18.

    Satellites are a crucial part of any developed, even developing countries. But problem is who controls them. Current we use American GPS satellites, with the Eu and China launching their own. But what happens if a war break out and the controlling country blocks them?

    Will we soon have a war over who controls space in the near future?

  • rate this

    Comment number 17.


    Military and intelligence agencies have their own satellites, they hardly need Landsat

    #12 -Bluesberry

    How do you think people found out about those problems and obtained accurate information about them?

    Landsat is providing vast amounts of date and its long history provides a detailed record of changes over time. This is pure science as well as providing some very pretty pictures.

  • rate this

    Comment number 16.

    Re. BluesBerry's comment below-have you read the article? Yes we do need all this equipment to tells us landscapes are changing. It is through the use of "all this equipment" that we can acurately measure the rate of change and this is called "evidence". What is more likely to get people motivated to do something - a placard saying SAVE THE NORTH POLE or detailed scientific data?

  • rate this

    Comment number 15.

    "Is science pretty pictures or solutions to help us survive in OUR OWN WORLD?"

    Both. Although it would help if a certain degree of personal responsibility were taken as well.

  • rate this

    Comment number 14.


    " Is science pretty pictures or solutions to help us survive in OUR OWN WORLD?"

    Those "pretty pictures" give an enormous amount of information!

  • rate this

    Comment number 13.

    As beautiful as these pictures are, I think we need more images showing the Earth as a little blue dot in space.

    It's those remote images that truly show how isolated we are, and how far away we are from any back-up home should (when?) we totally destroy the home we already have.

  • rate this

    Comment number 12.

    Did we need all this equipment to tell us Arctic & Antarctic Landscapes are changing, melting will cause sea levels to rise, rising sea levels will wipe out coastal cities & cause Noah's-Flood-type misery, fresh water is becomig a valued commodity, or that fracking will fracture faultlines? Is science pretty pictures or solutions to help us survive in OUR OWN WORLD?

  • rate this

    Comment number 11.

    Beautiful. They look like abstract art paintings, especially the Mississippi one. And some penguin poo too: thanks BBC! Who else would show us penguin poo from space?

  • rate this

    Comment number 10.

    Fantastic images, thanks.

  • rate this

    Comment number 9.

    It's great that people are getting a proper appreciation for our home planet. Our planet may be small but it is a good one. We need to ensure the Earth's lasting presence as humanity is dependent on it. We may travel to other worlds and in the future, inhabit them. But this is OUR home, this is OUR planet. We must take care of it as it has taken care of us and landsat is a good start

  • rate this

    Comment number 8.

    @4 littleoldme
    A hurricane has, according to the Beaufort scale 12, wind speeds in excess of 74mph. The highest recorded wind speed in Gorleston Norfolk was 122 mph. When I witnessed the old heavy metal dustbins cartwheeling to the height of my bedroom window, it was as bad as the Typhoon I have actually experienced in Hong Kong.


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