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Lost data: What impact does Landsat 7's Scan Line Corrector failure have on scientific research?
Landsat 7 satellite, since its launch on April 15, 1999, has always played an important role in earth observation. The main goal of this satellite is to update the global satellite photo archive and provide the latest cloud-free images. As the seventh satellite of the Landsat program managed by the United States Geological Survey (USGS), the data collected by Landsat 7 is distributed by the United States Geological Survey (USGS) and can be freely navigated and viewed through NASA's WorldWind project.
However, since May 31, 2003, the satellite has faced a major technical challenge: the Scan Line Corrector (SLC) failure. This failure had a profound impact on the data quality of Landsat 7 and its applications.
Causes and effects of Scan Line Corrector failure
Scan Line Corrector is a crucial component of Landsat 7's ETM+ instrument. Its function is to compensate for the movement of the satellite during its advancement through a rotating small mirror. After the Scan Line Corrector malfunctioned, the instrument showed a zigzag pattern when photographing the Earth, resulting in overlapping images in some areas and no image data at all in other areas. As a result, approximately 22% of data became unavailable without functioning properly.
"Despite the loss of data caused by the failure of the Scan Line Corrector, scientists still believe that there are many ways to make up for this loss."
Judging from the post-failure assessment, despite the missing data, many scientific applications can still use the data obtained this time. Many scientists emphasized that data processing can make up for some of the deficiencies and provide information similar to the data accumulated in the previous period.
Scientific applications of satellite data
Landsat 7 is more than just a satellite, it provides valuable data for scientific research. These data include monitoring of global land cover changes, analysis of agricultural productivity, studies of urban development, and assessment of the impact of climate change on the natural environment. Even after the Scan Line Corrector failure, Landsat 7 data still plays an important role in these research areas.
“With the advancement of science and technology, how to deal with and remedy these data incompleteness problems caused by failures has become a major challenge faced by current scientists.”
Therefore, Landsat 7 data remains an important resource for scientists in many data analysis and simulation applications, especially when conducting long-term trend analysis.
The future of Landsat 7
The future of Landsat 7 is also uncertain as its orbit is lowered. After the last orbital operation in February 2017, the satellite's orbit began to gradually lower, and by 2021 it had changed from the original 10:00 AM local mean time (LMT) to 9:15 AM. With the launch of Landsat 9 on September 27, 2021, Landsat 7 will soon be replaced by the enabled satellite.
“With the launch of Landsat 9, Landsat 7 data will face more intense challenges, which also means that the continued use of its long-term data must be more cautious.”
While NASA has sought to refuel Landsat 7 through its OSAM-1 mission to achieve better scientific significance, these plans have been delayed multiple times. Under the current circumstances, Landsat 7's subsequent image collection and processing operations still require continuous monitoring, and future operations and maintenance also face considerable challenges.
Conclusion
In general, the Scan Line Corrector failure of Landsat 7 undoubtedly poses a challenge to scientific research, and scientists must find new ways to remedy the data gap. However, what the accident revealed also prompted the scientific community to gain a deeper understanding of the importance of satellite data and the maintenance of data integrity. In the future development of science and technology, can we come up with better solutions to such failures to ensure the continuity and integrity of scientific research?
