Table of Contents
The Smallsat Data Explorer (SDX) is being developed as part of NASA’s Commercial Smallsat Data Acquisition (CSDA) Program to search, discover, and access Commercial Small Satellite (or Smallsat) data that has been acquired by NASA. Currently, this tool supports search, discovery and access to Planet Labs PBC, Spire Global, Inc., EarthDEM produced by the Polar Geospatial Center, and Airbus U.S. Access to these data products is restricted to NASA-funded projects. This document is intended to provide a detailed overview of the tool and its functionality.
Additional information on the Commercial Smallsat Data Acquisition Program, data availability, and the technical specifications of the commercial data can be found at the CSDA Program information page.
To request access to data through the Commercial Smallsat Data Acquisition Program, please complete the CSDA Program Authorization Request Form.
For any general questions about the Smallsat Data Explorer that are not addressed in this guide, please email firstname.lastname@example.org.
The Smallsat Data Explorer consists of three web pages accessible directly by the navigation links provided below or by a convenient navigation panel found on the left side of the webpage.
- Welcome (Home icon)
- The SDX landing page provides a brief explanation of the purpose of the tool for end users and describes currently supported data vendors.
- Explore (Map icon)
- The explore page allows the public to search, discover and order satellite data acquired by the CSDA Program. Ordering of data is only available for approved NASA-funded projects and researchers. A complete guide on how to use the features on this page are found in the Data Exploration section of this User Guide.
- User Guide (Information icon)
- The SDX User Guide is provided on this page. This guide presents a brief description of the CSDA Program, the context of this tool within the program, and a detailed description of how the SDX supports search, discovery and distribution of commercial vendor data.
- View Coverage Map (Marker icon)
- This map displays the geographic coverage of SDX vendors’ data. The user can filter the display by date (month, year) for one or more vendors.
In addition to these options in the navigation panel, it is possible to login to the tool directly by clicking the login icon (Login icon). User login is described in detail in the next section.
3. Authorization and Login
Commercial data discoverable through the SDX is made available only to NASA funded researchers who have been approved for access. Authorized data users will be able to log into the SDX and submit requests for data archived by the CSDA Program. The authentication and authorization process that must be completed prior to accessing data is described in the following sections.
3.1 Authentication and Authorization Process
Data access is restricted to current NASA-funded researchers that are classified as a NASA employee, related entity, and/or authorized user. Instructions for gaining authorization to order data can be found at CSDA Program Smallsat Data Explorer. The CSDA Program Data Management Team (DMT) will review and verify that the requestor is funded by NASA and make the determination whether or not the user is authorized to request and access data. After review by the DMT, the user will be notified of authorization status. An authorized user can proceed to order data. Unauthorized users can search for but not order data.
3.2 User Login
A user must be logged into the SDX to be able to order data. As discussed in Section 2, clicking the login icon (Login icon) directly prompts a user for login to the SDX. The initial attempt will redirect a user to Earthdata Login, where the user will be prompted to enter Earthdata credentials and accept an End User License Agreement (EULA). Clicking the login icon for subsequent logins produces a login prompt without redirection from the user’s current page.
3.3 End User License Agreement
A user’s initial login to the SDX following authorization will prompt the user with EULAs pertaining to the commercial vendors available in the SDX. The user must agree to the terms of the EULA before proceeding to order any data. When the EULA is updated, the user will be prompted at the next login to the SDX.
4. Vendor Data Products
This section describes data products supported in the SDX. This includes data products from Planet Labs PBC (Planet), Spire Global, Inc. (SPIRE) Airbus U.S. , and EarthDEM data producted by the Polar Geospatial Center. Please refer to the vendor websites or the CSDA Program Commercial Dataset page for more information.
The SDX provides access to PlanetScope, RapidEye, and SkySat data products from Planet Labs Inc., including:
- PlanetScope 4-band radiometric and sensor correct imagery orthorectified and UTM projected
- PlanetScope 3-band Basic and orthorectified scenes
- PlanetScope 4-band Basic and orthorectified scenes
- PlanetScope 8-band Basic and orthorectified scenes
- RapidEye 5-band radiometric and sensor correct imagery orthorectified and UTM projected
- RapidEye 5-band radiometric and sensor corrected Basic scenes
- SkySat orthorectified scenes composed into segments (typically about 60 scenes)
- SkySat 4-band Basic (includes both raw and radiometrically corrected) and orthorectified scenes
The following Global Navigation Satellite Systems (GNSS) Radio Occultation data products from Spire Global Inc. are available through the SDX:
- L2 Atmospheric Profile
- Atmospheric Profile is the bending angle, neutral refractivity, and dry temperature as a function of mean sea level altitude and an impact parameter. The Atmospheric BUFR is the derived bending angle, refractivity, and dry pressure and dry temperature formatted for ingestion into standard operational weather models.
- L1B Excess Phase
- Excess Phase includes the occultation excess phase delay computed from excess phase processing.
- L1A High Rate Occultation
- High-rate Occultation Observation consist of two files containing raw measurements from the occulting GNSS satellite and two or more files containing raw phase data from one or more reference GNSS satellites.
- L1A Attitude and L1B Navigation
- The Attitude product contains raw quaternion information given at 1-Hz and 0.1-Hz samplings describing the actual pointing of the spacecraft. The Navigation product contains pseudorange and carrier phase observables at 1-Hz sampling rate, coarse positions and velocities of a given Spire satellite computed from the onboard receiver, and precise positions and velocities computed from POD software.
- L2 Grazing Angle GNSS-R Altimetry
- This product contains the results of relative surface measurements along each signal track, at the point of reflection on the surface of the Earth. Height measurements are relative to the mean of the model reflecting surface along the track.
- L2 Grazing Angle GNSS-R Sea Ice
- This product contains the results of sea ice detection and ice-type classification along each signal track, at the point of reflection on the surface of the Earth. The data are derived from the grazing angle altimetry Level 1B.
- L1 GNSS Bistatic Radar Cross-Section
- This product contains tracks of land and sea ice observations.
- L1 GNSS Bistatic Normalized Radar Cross-Section
- This product contains tracks of ocean observations.
The following Polar Geospatial Center (PGC) Digital Elevation Model (DEM) data products produced by the Polar Geospatial Center at University of Minnesota are available through the SDX:
- EarthDEM Strip Tiles
- The EarthDEM Strip DEM tiles are 2-meter spatial resolution DEMs constructed from individual stereoscopic pairs of submeter (0.32 to 0.5 m) resolution DigitalGlobe (Maxar) satellite imagery.
- EarthDEM Mosaic Tiles
- EarthDEM Mosaics are 50 km x 50 km mosaics of EarthDEM Strip Tiles in non-polar regions at 2-meter spatial resolution.
More information is available at www.pgc.umn.edu/data/earthdem.
4.4 Airbus U.S.
The following synthetic aperture radar (SAR) data products produced by Airbus U.S. are available through the SDX:
- Single Look Slant Range Complex (SSC)
- The SSC product, closest to the recorded raw data, is the single look product of the focused radar signal. This product includes amplitude and phase information, appropriate for applications that require full bandwidth and phase.
- Geocoded Ellipsoid Corrected (GEC)
- The GEC product is a multi-look detected product, corrected to the reference WGS84 ellipsoid..
- Enhanced Ellipsoid Corrected (EEC)
- The EEC product is a multi-look detected product projected and resampled to the WGS84 reference ellipsoid and terrain corrected using an external Digital Elevation Model.
- Coregistered Single Look Slant Range Complex (CoSSC)
- The CoSSC product consists of two SSC products that have been geometrically aligned in preparation for interferometric analysis.
These products are available in the following instrument modes:
- Staring Spotlight (ST)
- The Staring Spotlight instrument mode provides between 0 and 0.25-meter spatial resolution with single polarization (VV or HH).
- High Resolution Spotlight (HS)
- The HS instrument mode provides between 0 and 1-meter spatial resolution with Single (VV or HH) or Dual (HH and VV) polarization.
- Spotlight (SL)
- The SL instrument mode provides between 0 and 2-meter spatial resolution with Single (VV or HH) or Dual (HH and VV) polarization.
- Stripmap (SM)
- The SM instrument mode provides between 0 and 3-meter resolution with Single (VV or HH) or Dual (HH and VV, HH and HV or VV and VH)) polarization.
- ScanSAR (SC)
- The SC instrument mode provides between 0 and 18.5-meter spatial resolution with Single (VV or HH) polarization.
- Wide ScanSAR (WSC)
- The WSC instrument mode provides between 0 and 40-meter spatial resolution with Single (VV, HH, HV, or VH) polarization.
More information is available at www.pgc.umn.edu/data/earthdem.
5. Data Exploration
This section provides in-depth explanations and examples of how to use features within the Explore page of the SDX tool.
An overview of the SDX Explore page with major features labeled is provided in Figure 1. Descriptions of each feature are provided below.
- Navigation Panel—Facilitates fast navigation between the Welcome, Explore, User Guide, and Heat Map as well as a link to the user login interface. More details are found in Section 2.
- Map Features/Navigation—Map exploration features, including the ability to search for locations, toggle on the Mapbox high-resolution true-color satellite base map, and buttons for zooming in and out of an area of interest. Holding the cursor down within the display pane is used to pan/drag the map view. More details are provided in the Additional Map Features section 5.4 below.
- Map Explorer/Display Pane—The data exploration window. Facilitates identifying regions of interest and thumbnail display of selected data scenes for search and exploration of Smallsat data. The default basemap is Mapbox Streets.
- Data Type Filter Panel—Filter by data type. Allows users to select the collection type (e.g., imagery, DEM, etc.). More details are provided in Data Type Filters section 5.2.3.
- Area of Interest (AOI) Filter Panel—Filter by AOI. Allows users to draw, upload, manually enter, modify, or delete areas of interest. More details are provided in the AOI Filter section 5.2.1 below.
- Date Filter Panel—Filter by an observation date(s). Allows users to select a date or range of dates to search for available data. More details are provided in the Date Filters section 5.2.2 below.
- Metadata Filter Panel—Filter by metadata feature. More details about these filtering capabilities are provided in the Metadata Filters section 5.2.4 below.
- Product Filter Panel—Filter by product type. See Product Filters section 5.2.5 below for additional details.
- Results Pane—Results of search and discovery filters are provided here. Users can sort the results and select those to be ordered. More details are provided in the Scene Results section 5.3 below. This pane will also display the number of selected data items and details on your remaining quota.
Filters in the SDX are utilized to refine the search and discovery of commercial Smallsat data within NASA’s data holdings. The result of these filters are displayed in the tool’s Results Pane and described further in section 5.3.
5.2.1 Area of Interest (AOI) Filter [Required]
There are three methods available for defining an area of interest (AOI) in the SDX to spatially filter the available data, which are described below. By default, there is no AOI filter applied in the tool; however, an AOI is required for scene results to be returned by the tool.
Draw an AOI—Select the “Draw an AOI on map” icon (Square icon) in the AOI Filter Panel to draw a bounding box on the map. The cursor will change to the crosshairs symbol in the map drawing area. Click once to define the first corner of the AOI, move the cursor to expand and define the area, click the Apply button to complete. Once defined, the AOI can be edited by clicking inside the bounding box or by selecting the AOI icon again. While in edit mode you can click and drag any of the corners, or move the entire box by clicking and dragging inside the bounds. Double clicking the icon will automatically zoom to the active AOI (Figure 2).
If the “Draw an AOI on map” is selected when an AOI exists, the current bounding rectangle will be selected and available for edit by dragging one of the corners to the desired location.
Upload an AOI—The tool supports upload of a GeoJSON file from a user’s local machine to the tool. Selection of the “Upload an AOI (GeoJSON)” icon (Upload icon) will prompt a local directory file search window from which a valid GeoJSON file may be selected (Figure 3). When the GeoJSON contains multiple AOIs, the tool will automatically extract the full extent of coordinates and produce an AOI that encompasses all shapes.
- Enter coordinates—Selection of the “Edit AOI bounds” icon (Pencil icon) will produce an Edit AOI prompt from which latitude and longitude values may be entered as decimal degrees for the Northeast and Southwest coordinates of a bounding rectangle (Figure 4).
- Edit AOI prompt from which latitude and longitude values may be entered as decimal degrees for the Northeast and Southwest coordinates of a bounding rectangle (Figure 4). If an AOI currently exists, either from a previous manual entry, uploaded file, or drawn on the map, the existing coordinates will be available for editing by the user. The Apply button must be clicked in order for a new AOI to appear or to update existing bounds.
When an AOI is in active edit mode, it will appear as a light blue rectangle bound by dashed lines with filled circles at the corners. Otherwise the rectangle is bound by solid blue lines. Any AOI can be removed by clicking on the “Clear defined AOI” icon (Trashbin icon).
For the defined AOI, an estimate of the area covered is also provided in the AOI panel in square kilometers (km²) or millions of square kilometers (M km²) depending on the size of the area. This provides users with awareness of the scale of their AOI.
5.2.2 Date Filter [Required]
Temporal filtering in the SDX is available through a date selection interface. A valid date, or range of dates, is required for scene results to be returned. The current date is provided as a default. The date selection interface is prompted by clicking the “Select a date range” icon (Pencil icon). The “Edit date” interface initially presents the user a one month calendar (Figure 5).
Date navigation may be conducted forward and back one month at a time through the use of the arrows at the top right and left of the interface (Left chevron iconRight chevron icon). The fast navigation icon (Horizontal arrow icon) may be selected such that any month is selectable and arrows move forward and backward by year. To quickly specify the date range, select the Input option and enter the start and end dates in the specified format (Figure 6).
Selected dates are highlighted in blue. Once the desired start and end date are selected, click the “Apply” button to refresh results; the range will now appear on the main explore page. The “Clear” button (Clear icon) removes all dates. (Note: This button does not revert back to the default setting.)
5.2.3 Data Type Filter
Data type filtering is possible in the SDX using the data type filtering panel. This feature prompts the user to select the collection type(e.g., imagery, GNSS science data, DEM, SAR, etc.). Selection of the “View edit option” icon (Pencil icon) displays the data type options (Figure 7). Currently, the imagery data type supported by the SDX includes Planet Labs, Inc. products while the GNSS science data option includes products from Spire Global, Inc., and the SAR (Synthetic Aperture Radar) option includes products from Airbus U.S.
5.2.4 Metadata Filter
Additional data filters are provided to support a more comprehensive search and discovery experience. These filters are supported by the metadata associated with each data file made available by the commercial data providers. Users can filter satellite imagery by the amount of cloud cover in a scene. By default, all imagery with cloud cover from 0 to 100% are returned. Selection of the “View edit option” icon (Pencil icon) will pop up a slider widget that users can move to adjust the acceptable maximum amount of cloud cover (Figure 8), or they can manually enter in the maximum amount of acceptable cloud cover. After the value is selected, click “Apply” in order to refresh results with the new value.
Users can filter SAR data products by multiple filters (Figure 9), including resolution, instrument mode, orbit direction, track number, instrument type, and polarization. By default, all data with resolution between 0 and 50 meters are returned. Selection of the “View edit option” icon (Pencil icon) will pop up a slider widget that users can move to adjust the acceptable resolution range. By default, all instrument modes are selected. Selection of the “View edit option” icon (Pencil icon) will pop up a toggle widget that users can click to select or deselect relevant instrument modes. By default, both ascending and descending orbit directions are selected. Selection of the “View edit option” icon (Pencil icon) will pop up a toggle widget that users can click to select or deselect relevant orbit directions. By default, data with all track numbers are returned. Selection of the “View edit option” icon (Pencil icon) will pop up a slider widget that users can move to select the appropriate track number. By default, all instrument types are returned. Selection of the “View edit option” icon (Pencil icon) will pop up a toggle widget that users can click to select or deselect the relevant toggle type, TanDEM-X, TerraSAR-X, or PAZ. By default, all polarizations are returned. Selection of the “View edit option” icon (Pencil icon) will pop up a toggle widget that users can click to select or deselect the required polarization (HH, VV, HH/VV, VV/VH, HH/HV, or HH/HV/VH/VV).
5.2.5 Product Filter
Multiple products are available based on the vendor, sensor, and the processing applied to the data (Figure 10). If the user wishes to search for data from only a subset of available products, click the “View edit options” (Pencil icon) to view and select from the pop up window of products. Click “Apply” to refresh results. All available products are selected by default.
5.3 Scene Results
An AOI and date (or range of dates) are required in order for scenes to be returned. Any valid AOI and date range that encompasses data currently available will automatically return scene results. For every scene returned, users will initially see in the Results pane a thumbnail, the product type, the data collection date, and the data type as well as icons to return additional information about the scene, zoom to the results, and view the thumbnail in the Map Display pane (Figure 11). Additional details on these features are provided below.
Clicking on a returned item will display all assets contained within that item (Figure 12). For each asset, its specific name, file type, file size, and area are also shown.
5.3.1 Quick View
The tool supports visualization of scene thumbnails for satellite imagery data and point icons for GNSS science data within the Map Display pane. Users are able to view the location of results using the toggle button to the right of each result. Selecting the “Zoom to Scene” button (Eye icon) will zoom the Map Display pane to the full extent of the scene selected (Figure 13).
5.4 Additional Map Features
- Search (Magnifying glass icon)
- Users can zoom to specific regions quickly by entering place names in the search panel. These place names may include, but are not limited to, cities, states, and countries. The map will then zoom to the location entered.
- Map Layers (Stack icon)
- In addition to the Mapbox Streets base layer, users may instead select a satellite basemap (derived from a variety of open source satellite imagery) through a toggle widget from the layers icon.
- Zoom and pan(Plus icon/Minus icon)
- Users may use standard zoom capabilities enabled by the buttons found in the lower left of the navigator pane, and pan (move) the map at any time by clicking the cursor in the map at any zoom level to move the map pane. Double click within the map to zoom to any region.
5.5 Downloading Data
Users can download data discovered through the SDX by selecting the desired data from the Results pane and clicking the “Download selected” button.
Individual data results can be selected by clicking on the results tile, which will then display a white checkmark on a blue background in the upper right-hand corner (Figure 14). The .csv file provides the user with the necessary information to download the data. The Get Download Script button next to the Download selected button, links to a Python script on a public Github repository that allows users to (1) download all files associated with a data order or (2) filter, select, and download specific files. The repository includes a readme file with instructions for how to run the script. The use of this download option is encouraged for data orders that consist of many files.
After selecting data, there is an information callout in the bottom left that shows the details of the user’s quota (Figure 15).
It is also possible to download all data returned from the provided search parameters. To do so, do not select any of the individual data file records. Clicking the Download Inventory button with no data files selected will download a csv file of all the items in the current search (Figure 16).
Below the data results is a summary of the number of items selected and information on current quota details for the user. Note that a data file may only be downloaded once for each user.
5.5.1 User Profile
Clicking the login icon (User icon) redirects to the user’s CSDA Program profile for managing data orders.
For registered and logged in users, clicking the login icon (User icon) redirects to the user’s CSDA profile for reviewing quotas and the data download history (Figure 17). The Overview tab displays each of the user’s quotas, how much of the quota remains and the remaining time until the quota expires. The Data tab shows the user’s download history, including total assets downloaded and the downloads per provider.