Historical Satellite Images: Accessing The Old Data
Collections of historical satellite images allow comparing the present and the past to detect changes, make predictions, and mitigate losses. There are multiple sources with commercial historical images or granting access for free, with the downloading option or just for online view. The richest catalogs are often the most helpful, and EOSDA LandViewer offers historical aerial or satellite images from nearly a dozen sources.
Old Satellite Images: Timeline Of Earth Observation Missions
The Landsat program is the longest-ever mission that has been retrieving imagery from space for over 50 years by now. It can flaunt the biggest data collection so far (billions of historical satellite images). The oldest of them is dated 1972 when Landsat-1 was launched.
Six more Landsat satellites joined their predecessor over time thanks to USGS and NASA to provide glimpses from space every 14 to 16 days. The last ones, Landsat-7 and Landsat-8, have been operating since 1999 and 2013, respectively.
Landsat 1-5 have completed their missions, contributing to the precious database of historical satellite imagery. The others are still on-orbit enriching historical collections with the latest remote sensing data (optical and radar).
The infographic below provides a better idea of when the launches and completions occurred.
Nearly all satellite-derived imagery is black and white initially. They gain colors only after processing with certain filters (color transformations in spatial analysis). For example, false color imagery is assigned conditional colors. Natural color imagery is processed with RGB filters (red, green, and blue) – as perceived by the human eye.
Where To Find Old Satellite Images?
Most databases to get historical satellite data are devoted to a separate mission. Still, services like EOSDA LandViewer provide old images from different collections in one place.
Historical satellite imagery in EOSDA LandViewer dates back to 1982 and is obtained from ten sources.
The old imagery from each source has its specifics, so the collection can fit everyone’s needs:
- location – historical satellite images of Earth globally;
- revisiting time – from several days to two weeks;
- spatial resolution – free satellite historical images of low and medium with a 100 to 10 m/pixel grid and hi-res imagery by request).
Apart from satellite-derived data, there are historical datasets captured by another medium – aircraft. Aerial imagery covers a smaller territory but has a better resolution. For example, EOSDA LandViewer includes 1-meter detailed and free historical satellite images of a location from the U.S. NAIP Program (2010-1017).
How To Get Historical Satellite Images In EOSDA LandViewer
There are multiple online services providing the required data for the past periods. Some of them are commercial, and the others grant access to historical satellite imagery for free. EOSDA LandViewer is among such services.
Its navigation is pretty easy, so after selecting the AOI and date (or period) you will get the full list of available historical images meeting the criteria. The filters like the image type, cloudiness, Sun elevation, AOI coverage, and sensor type allow users to narrow down the query and view historical satellite images quicker.
There are several types of historical imagery in EOSDA LandViewer:
- passive (day / night / low resolution);
- terrain tiles (to build 3D images / models of an AOI);
- high-resolution images (for detailed analytics).
The following sensors and sources have been retrieving the collection of historical satellite images in EOSDA LandViewer:
- Sentinel-2 MSI (Multispectral Instrument);
- Landsat-8 OLI (Operational Land Imager) and TIRS (Thermal Infrared Sensor);
- Landsat-7 ETM+ (Enhanced Thematic Mapper);
- Landsat 4-5 MSS (Multi-Spectral Scanner);
- Landsat 4-5 TM (Thematic Mapper);
- CBERS-4 MUX (Multispectral Camera);
- CBERS-4 WFI (Wide-Field Imager);
- CBERS-4 PAN5 (Panchromatic and Multispectral Camera);
- CBERS-4 PAN10 (Panchromatic and Multispectral Camera);
- NAIP (film and digital cameras).
Where Can One Download Old Satellite Images Of Earth?
Unlike search, downloading old data from space is not that easy. First, not all resources provide such an option. Second, the ones that offer it, don’t always do it for free. However, all low and medium-resolution images in EOSDA LandViewer are for open access. It means that downloading past satellite images is also free and available as JPEG, KMZ, or GeoTIFF files.
How To Use Historical Satellite Imagery: Get The Most From EOSDA LandViewer Features
For enhanced user experience, EOSDA LandViewer is equipped with a number of features that can be employed either out of mere interest, scientific research, or commercial use.
Natural disasters like tornadoes, forest fires, tsunamis, floods, or volcano eruptions are impossible to prevent, but timely tracking of the least changes can help mitigate losses. For a regular user, it might be interesting to see how their city looked like a century before. EOSDA LandViewer can provide either insight with the Change detection tool of the same AOI for different dates. Users can also embed the results on websites or share them on social media.
Time Series Analysis allows for data dynamics visualization with a spatiotemporal time-series vegetation index graph based on NDVI, as well as index graphs for NDWI and NDSI. The feature can be applied to monitor vegetation growth, changes in land use, identification of crop development stages, and more.
Visualization graphs of historical satellite imagery are generated after filtering the sensor (mostly often Sentinel-2 and Landsat-8) and the time interval for analysis. A specified AOI must not exceed 200 square kilometers. A graph allows for tracking the dynamics of changes in index values. Each point on the graph corresponds to a certain image within the selected time frameworks. To view historical satellite imagery online in detail, zoom in at any point by clicking.
The Change detection feature shows the dynamics of events over a span of time, be it centuries, decades, or years. However, an animated presentation gives a more vivid – and fun – picture than a still observation. EOSDA LandViewer offers such an opportunity with the Time-lapse animation tool. Generated GIFs or videos are applicable in commercial and scientific fields, as well as in everyday use. Thus, the historical timelapse of satellite images provides valuable insights on oil spills, urban growth, deforestation, ice sheet cracking and melting, and more.
Historical satellite images are in demand in many industries nowadays, and agriculture is among the oldest ones to benefit from the comparison of the past and present. Access to old satellite images about crop production seasons allows generating historical NDVI time-series and concluding on the field productivity, identifying trends, and predicting yields.
Commercial Historical Satellite Images
Historical imagery of low and medium resolution is often insufficient for proper analysis, and the purchase of historical satellite images with high resolution opens up more opportunities for detailed research. Hi-res imagery is particularly useful when it comes to environmental monitoring (including natural disasters), nature pollution, or environmental effects of climate change. High resolution also provides numerous benefits for mining, building and construction, and other spheres.
The resolution of historical hi-res images in EOSDA LandViewer is 0.4 to 2 meters/pixel, and they are available for downloading as GeoTIFFs.
Learn more on historical satellite images in EOSDA LandViewer at firstname.lastname@example.org. Our experts will gladly answer all your questions regarding our collection and the product’s features.
About the author:
Kateryna Sergieieva joined EOS Data Analytics in 2016. She has a Ph.D. in information technologies and a 15-year experience in remote sensing.
Kateryna is a Senior Scientist at EOSDA. Her specialty is the development of technologies for satellite monitoring of natural and artificial landscapes and surface feature change detection. Kateryna is an expert in the analysis of the state of mining areas, agricultural lands, water objects, and other features based on multi-layer spatial data.
Kateryna is an Associate Professor conducting research at the Dnipro University of Technology. She is the author of over 60 scientific papers.
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