# An Overview of the Applications of Earth Observation Satellite Data: Impacts and Future Trends
## 3 Results
### RSIF for Different Satellites  
The index that we created to assess the impact of the application of satellite data on scientific research and daily life and to predict possible future developments in the use of satellite data was called the RSIF. A series of indexes were derived from the formula given in Section 2.3: RSIF-A represents the satellite's average RSIF from the time of its launch until 2020, RSIF5 represents the average RSIF over the five-year period 2016-2020, and RSIFI-2020 represents the RSIF for 2020. These three indices provide overviews of the impact of satellite data applications in different periods. As shown in Figure 2, Landsat, MODIS and Sentinel have the highest impact factors among all the satellites that were considered. In terms of RSIF-A, Sentinel (50.16) > MODIS (25.82) > Landsat (13.75). The exploration of Landsat and MODIS data is still continuing, and the number of applications and countries that reference these data is still increasing. Although Sentinel was launched later than both Landsat and MODIS, Sentinel has a higher RSIF-A than both of these satellites, which indicates that there is still greater potential for the use of Sentinel data. In terms of RSIF5, Landsat (87.74) > MODIS (78.71) > Sentinel (59.69). For nearly 50 years, Landsat data have been indispensable in EO and remain essential to historical analyses and future predictions. The advantages of MODIS data include their wide spectral range and that most areas of the Earth are observed four times a day. MODIS data are traditionally used in global land monitoring and conservation studies [78]. In terms of RSIF1-2020, Landsat (236.20) > Sentinel (205.86) > MODIS (188.18), which means that, according to this measure and in contrast to RSIF5, the impact of Sentinel is greater than the impact of MODIS. Sentinel is undoubtedly the remote sensing data source with the most potential. However, Sentinel is a new satellite and the EO data provided by Sentinel missions will take time to accumulate. Figure 2: Derived RSIFs for Earth observation satellites. We also calculated the annual RSIF to explore the developments and future trends related to the use of data from different EO satellites. The annual RSIF can help with understanding the scope of the applications of different types of satellite data and their future potential uses from a more comprehensive perspective. As shown in Figure 3, Sentinel had a higher annual RSIF than MODIS in 2020. This indicates that Sentinel is preferred to MODIS in several research areas and in some user countries. In 2020, the number of Sentinel publications exceeded the number of publications related to MODIS. Sentinel is a series of missions that make comprehensive observations of the Earth including observations of the atmosphere, oceans, and land. Sentinel-1 is a radar imaging mission used for land and ocean services, Sentinel-2 is a multi-spectral high-resolution land-monitoring mission, and Sentinel-3 is a multi-instrument mission that supports ocean forecasting systems as well as environmental and climate monitoring. In addition, the increasing trend in annual RSIF for recently launched satellites such as Gaofen and WorldView is significant. These new satellites carry more advanced instruments and provide robust EO datasets that have a wide range of applications. We made estimates of the trends in RSIF over the next five years (2021-2025) based on the most recent five-year period (2016-2020) to explore some possible future developments in the use of EO satellite data. We predict that the satellites with the five highest RSIF values in the next five years will be Sentinel, Landsat, MODIS, Gaofen, and WorldView. Although the Gaofen and WorldView data are not yet open access, their predicted RSIF is higher than most of the satellites discussed such as ALOS and AVHRR. With the exception of MODIS, these five satellite missions have launch plans that will ensure instrument iteration and the continuous provision of EO data over this period.