User Guide

1. Introduction

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 Inc. and Spire Global, Inc. 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.

2. Pages

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. This 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.

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 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, Inc. (Planet) and Spire Global, Inc. (SPIRE). Please refer to the vendor websites or the CSDA Program Commercial Dataset page for more information.

4.1 Planet

The SDX provides access to PlanetScope, RapidEye, and SkySat data products from Planet Labs Inc. including:

PSOrthoTile
PlanetScope 4-band radiometric and sensor correct imagery orthorectified and UTM projected
PSScene3Band
PlanetScope 3-band Basic and orthorectified scenes
PSScene4Band
PlanetScope 4-band Basic and orthorectified scenes
REOrthoTile
RapidEye 5-band radiometric and sensor correct imagery orthorectified and UTM projected
REScene
RapidEye 5-band radiometric and sensor corrected Basic scenes
SkySatCollect
SkySat orthorectified scenes composed into segments (typically about 60 scenes)
SkySatScene
SkySat 4-band Basic (includes both raw and radiometrically corrected) and orthorectified scenes

4.2 Spire

The following Global Navigation Satellite Systems (GNSS) Radio Occultation data products from Spire Global Inc. data 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

4.3 EarthDEM

The following Polar Geospatial Center (PGC) Digital Elevation Model (DEM) data products produced by the Polar Geospatial Center at University of Minnesota is 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 Mosaic’s are 50 km x 50 km mosaic of EarthDEM Strip Tiles in non-polar regions at 2-meter spatial resolution.

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.

5.1 Overview

An overview of the SDX Explore page with major features labeled is provided in Figure 1. Descriptions of each feature are provided below.

Figure 1 Overview
Figure 1. Overview of the SDX Explore page. Features numbered here are described in the text below.
  1. Navigation Panel—Facilitates fast navigation between the Welcome, Explore, and User Guide as well as a link to the user login interface. More details are found in Section 2.
  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.
  3. 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.
  4. 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.
  5. 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.
  6. Data Type Filter Panel—Filter by data type. Allows users to select between satellite imagery and GNSS data types. More details are provided in Data Type Filters section 5.2.3.
  7. Metadata Filter Panel—Filter by metadata feature. More details about these filtering capabilities are provided in the Metadata Filters section 5.2.4 below.
  8. Product Filter Panel—Filter by product type. See Product Filters section 5.2.5 below for additional details.
  9. 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.
  10. Order Panel—Shows the number of selected data items and the approximate amount of selected data (in square kilometers). Requests to order the selected data are made by clicking the “Request selected data” button which only places a request for individually selected data items or “Request all matching data” button which places a request for all data matching the provided faceted search criteria.

5.2 Filters

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.

  1. 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 again 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).

    Figure 2 Draw AOI
    Figure 2. Example of an AOI drawn on the Map Navigation pane. The area selected is shown by the blue filled rectangle.

    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.

  2. 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.

    Figure 3 Upload AOI
    Figure 3. Prompt to upload AOI (geojson) from your local machine.
  3. 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).
  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).

Figure 4a Enter new AOI
Figure 4b Edit existing AOI
Figure 4. Edit AOI prompt without an existing AOI (enter new coordinates: top) and with an existing AOI (blue filled rectangle) available for editing (bottom).

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 to 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 two-month window surrounding the current date (Figure 5).

Figure 5 Select Date
Figure 5. Selection of a range of dates using the date selection interface. The range of dates selected are highlighted in blue.

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). To quickly navigate months or years, the fast navigation icon (Horizontal arrow icon) may be selected such that any month is selectable and arrows move forward and backward by year (Figure 6).

Figure 6 Select Date
Figure 6. Date selection interface with quick navigation by year and month.

Selected dates are highlighted in blue. Once the desired start and end date are selected, click the “Apply” to refresh results; the range will now appear on the main explore page. The “Clear” button 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 data products that are either satellite imagery or GNSS science data. 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.

Figure 7 Type Filter
Figure 7. Data type filtering interface to filter between imagery and GNSS science data.

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. Currently, only the filtering of satellite imagery data by the amount of cloud cover in a scene is available. 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.

Figure 8 Cloud Cover Filter
Figure 8. Cloud cover filtering interface.

Note that in general it is program policy that only scenes with less than 20% cloud cover are ordered from the commercial vendor. However, there are cases for which exceptions have been made. Therefore, users will likely notice a minimal reduction in resulting scenes when the filter is above 20%.

5.2.5 Product Filter

Multiple products are available based on the vendor, sensor, and the processing applied to the data (Figure 9). 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.

Figure 9 Product Filter
Figure 9. Product filtering interface with toggle options for all available products.

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 10). Additional details on these features are provided below.

Figure 10 Initial Results
Figure 10. Results pane with return from valid AOI and temporal filter.

5.3.1 Scene Information

Clicking the information icon (Information icon) next to a returned scene will provide users additional information about that scene including (Figure 11):

File Name
Unique name of the scene following the naming convention found in the provider’s product documentation (Planet Labs, Inc.).
Cloud Cover
Percent of cloud cover (in percent) in a scene as provided in the commercial provider metadata.
Product (item) Type
Provider supplied product type. For Planet Labs Inc. this is based on the platform and processing applied. Product Type names will be one of those listed in section 4.1.
Provider
Commercial data provider.
Ground Sampled Distance (GSD)
Spatial resolution of the scene.
Figure 11 Results Info Imagery
Figure 11. Results pane with additional information for the selected imagery scene.
Figure 12 Results Info Gnss
Figure 12. Results pane with additional information for selected GNSS science data scene.

The following information is provided with the GNSS science data scenes (Figure 12):

Title
Unique scene name following the naming convention provided by Spire Global, Inc.

5.3.2 Sorting Results

Search results may be sorted by selecting the “Sort By” icon (Vertical arrows icon), to more quickly explore results (Figure 13). By default, scenes are sorted in ascending order by date. Current sorting options will be denoted by blue text and checkmark. Results will automatically be updated when a different sort option is selected.

Figure 13 Sorting Results
Figure 13. Results pane showing options to sort results. The current selection shows the default of sorting by ascending date.

5.3.3 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. If an image thumbnail exists, overlays are placed or removed from the map when toggling on or off respectively (Figure 14 and Figure 15). When multiple scenes overlap each other, scenes with the highest sort priority will be overlaid on the other scenes at that location on the map. Selecting the “Zoom to Scene” button (Crosshair icon) will zoom the Map Display pane to the full extent of the scene selected (Figure 16).

Figure 14 Quick View Imagery
Figure 14. Map navigator pane with imagery thumbnails overlain for select results.
Figure 15 Quick View GNSS
Figure 15. Map navigator pane with GNSS science data point icon overlain for selected result.
Figure 16 Zoomed Quick View
Figure 16. Map navigator pane with zoom to specific scene using the Zoom to Scene feature.

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.
Toggle 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 Requesting Data

Data discovered through the SDX is distributed to users upon request and review of the order. Users can request data by selecting the desired data from the Results pane and placing an order via the “Request data” button. The SDX currently limits the initial Results pane to 20 or fewer results.

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 17). If a data result cannot be selected for an order, a tooltip containing an explanation will appear when the selection pointer hovers above the result tile (Figure 18). After selecting the desired data result(s), clicking the “Request selected data” button submits an order to the CSDA DAT. The user may also click the “Request all matching data” button which will submit an order for all data results that match the query filters.

Figure 17 Select Data
Figure 17. The tiles of selected data results are indicated by a white checkmark on a blue background in the upper-right corner.
Figure 18 Tooltip
Figure 18. An explanatory tooltip will appear over any tile that is not available for ordering through the SDX.