Landsat-9 image of London and South East, UK on 18th July 2022. Courtesy of U.S. Geological Survey/NASA.
Landsat will celebrate fifty years of Earth Observation (EO) this weekend. The first Landsat mission was Earth Resources Technology Satellite 1 (ERTS-1), which was launched into a 570-mile sun-synchronous near polar orbit on the 23 July 1972 by a Delta Rocket from the Vandenberg Air Force Base in California. It wasn’t renamed Landsat-1 until 1975. It had an anticipated life of 1 year and carried two instruments: the Multi Spectral Scanner (MSS) with a 60-metre spatial resolution with four spectral bands with red and green visible bands and two near-infrared bands; and the Return-Beam Vidicon (RBV).
False colour image of Dallas, Texas. The first fully operational Landsat image taken on July 25, 1972, Image courtesy: NASA’s Earth Observatory
The very first Landsat image was a false colour image of the Dallas-Fort Worth area of Texas in the United States, acquired two days after the launch, which is shown to the right.
Landsat Data Continuity
In total there have been nine Landsat missions to date, unfortunately Landsat 6 failed to reach its designated orbit and never collected any data. As technological capabilities have developed the instruments on consecutive missions have also been improved. The missions have been:
- Landsat 1 launched on 23 July 1972 with 60-metre spatial resolution and four spectral bands.
- Landsat 2 launched on 22 January 1975 with 60-metre spatial resolution and four spectral bands.
- Landsat 3 was launched on 5 March 1978 with 60-metre spatial resolution and five spectral bands
- Landsat 4 launched on 16 July 1982 with 30-metre spatial resolution and seven spectral bands.
- Landsat 5 launched on 1 March 1984 with 30-metre spatial resolution and seven spectral bands.
- Landsat 7 launched on 15 April 1999 with 30-metre spatial resolution and seven spectral bands.
- Landsat 8 launched on 11 February 2013 and is still active. It offers 30-metre spatial resolution and eight spectral bands.
- Landsat 9 was launched on 27 September 2021 and is still active. It offers 30-metre spatial resolution and nine spectral bands.
Whilst such a series of missions would indicate that data continuity was at the heart of the programme, that’s not always been true. In the 1980’s there was an attempt to privatize the Landsat programme which led to a six-fold increase in the cost of satellite data and made it more expense that other competitors such as the French Spot 1 satellite. There were fears the Landsat programme might end, but global objections, and objections in the US Congress saved it.
Open Data
The decision that made Landsat the world’s go to satellite imagery occurred in 2008 when the Landsat data archive was made free-to-access to anyone and everyone around the world, and this change in approach effectively kick-started the EO industry, beyond the large players and space agencies. Without the open data policy, companies like Pixalytics, would struggle to be able to provide cost effective services for smaller clients.
Of course, other programmes now offer open data, most notably the European Union’s Copernicus Programme. However, Landsat remains a go-to source for satellite data, it is the trail blazer and has the biggest archive of satellite data in the world!
Facts About the Landsat You Might Not Know
- Landsat 5 officially set a new Guinness World Records title for the ‘Longest-operating Earth observation satellite’ with its 28 years and 10 months of operation when it was decommissioned in December 2012.
- Landsat Island is a small, uninhabited island off the northeast coast of Labrador, Canada. It was discovered during analysis of imagery from Landsat-1, and was named in honour of the satellite.
- In August 1975, a joint research mission between NASA and Jacques Cousteau’s team tested whether Landsat could measure water depths in clear oceans. This mission determined that in clear water, with a bright seabed, depths of up to 22 metres could be measured by Landsat. This effectively gave birth to satellite-derived bathymetry.
- The 100 millionth Landsat scene was downloaded from the Landsat archive on the 9 March 2020. The image showed the southwest part of New Zealand’s North Island, including Mount Taranaki, and the image had been acquired on 27 May 2017.
Future for Landsat
The future for Landsat programme is bright with the next satellite known as Landsat Next, rather than Landsat 10, already in the planning stage. It is hoped that this satellite will launch in 2029/2030.
Landsat has been a game changer for the remote sensing and EO industries both in terms of the data continuity approach and free-to-access data. It provides an unrivalled archive of the changing planet enabling scientists, researchers and businesses like Pixalytics to effectively go back in time and see what was happening over the last 50 years.
We salute Landsat and wish it many more future years!
