An eight-year effort to repatriate millions of Landsat scenes locked away in ground station outposts around the world reached a milestone in March 2018 when the 5 millionth such scene was recently ingested and placed in the archive at EROS.
Landsat Global Archive Consolidation Initiative Ingests 5 Millionth Scene
The data came from the Riyadh Ground Station in Saudi Arabia and was acquired by Landsat 5 on April 16, 1989. It shows an area over Bahrain, Qatar, and Saudi Arabia.
Since 2010, the USGS has been combing the planet through its Landsat Global Archive Consolidation (LGAC) initiative, repatriating millions of scenes that had never made it into the archive at the Earth Resources Observation and Science (EROS) Center near Sioux Falls, SD. Officials estimate that roughly two-thirds of Landsat data collected between 1972 and 1999 remained largely untapped at ground stations across the planet.
The earliest Landsat missions had recording limitations in that they had none of the robust on-satellite storage from which to eventually transmit data to a centralized storage and distribution facility, as Landsat 8 does. Fortunately through the years, the U.S. had offered other countries the opportunity to build International Ground Stations and operate them as International Cooperators (ICs) as a goodwill gesture to encourage friendly use of outer space.
Those ground stations installed suitable antennae to acquire Landsat data, paid a fee to receive and distribute the data, then set up their own archives. Twenty-two ICs operating 35 International Ground Stations agreed to periodically forward metadata to the USGS. But with no systematic process in place to enable the transfer of data acquired by the ICs back to EROS, those metadata transfers were rarely enforced.
Locked away, and in some cases degrading in less than pristine storage conditions, that data went untapped until 2008, when the USGS decided to make Landsat data downloads free. Interest in Landsat data quickly spiked, and users clamored to find out what was in the archive.
When studies revealed that there were potentially 4 to 5 million unique Landsat scenes around the world that could fill in the archival record, the Landsat Science Team formally requested that the USGS consolidate the global archive, and LGAC was born.
“The result of that is a doubling of the amount of data in the global Landsat archive,” said Tom Loveland, who recently retired as chief scientist at EROS and co-chaired the Landsat Science Team. Now LGAC is helping to fuel “investigations of many, many types all around the world, because we now have imagery we didn’t have access to many years ago,” Loveland added.
It’s been estimated that there are 6.5 million scenes potentially available to repatriate through the LGAC initiative, said Jerad Shaw, a contract systems engineer with USGS. Of those, roughly 4 million to 5 million scenes are unique. “It’s been holding steady at 70 percent,” Shaw said of unique images.
Data is still coming in from places like Argentina, the European Space Agency, and South Africa, Shaw added. “We’ve got a lot of data in-house that we’re still working on ingesting as well,” he said. “There’s additional data from Saudi Arabia. There’s data from Thailand. There’s data from India, Indonesia, and a few other places that we have gotten data in here and just have to work through getting it ingested.”
To Shaw’s knowledge, every country where Landsat data was downlinked has been open to an arrangement to return the data they have. That includes Landsat 7 data that is still being collected and downlinked to International Ground Stations because of storage limitations on that satellite’s recorder.
“Five million is kind of a neat milestone,” Shaw said. “It shows how far we’ve come in filling the holes in the archive.”