PHISAT2 Data Specification
PHISAT2 (also known as ɸ-Sat-2) is an Earth observation CubeSat mission from the European Space Agency (ESA) platform capable of running AI apps directly on board. It has been designed and manufactured by Open Cosmos. It is planned to launch in 2023 in a sun-synchronous orbit at 500km altitude, the satellite carries a multispectral payload capable of capturing 8 bands (7+PAN) at 5m resolution.
Technical Specifications Overview
- 1 satellite
- Ground Sampling Distance (GSD): 4.75m at Nadir
- Swath Width: 19 km
- Bit Depth: 8 or 12 bits
- Sun-Synchronous Orbit (SSO)
- Swath Resolution: 4096 pixels wide
Spectral Bands
The multispectral payload captures 8 channels in the visible and near infrared spectral range. These channels are designed to align with the corresponding channels in Sentinel 2 imagery. The range of each channel is given below:
- Band 0: 625nm - Panchromatic from 550.0nm to 750.0nm, 250nm wide
- Band 1: 490nm - Blue from 457.5nm to 522.5nm, 65nm wide
- Band 2: 560nm - Green from 542.5nm to 577.5nm, 35nm wide
- Band 3: 665nm - Red from 650.0nm to 680.0nm, 30nm wide
- Band 4: 705nm - Red Edge 1 from 697.5nm to 712.5nm, 15nm wide
- Band 5: 740nm - Red Edge 2 from 732.5nm to 747.5nm, 15nm wide
- Band 6: 783nm - Red Edge 3 from 773.0nm to 793.0nm, 20nm wide
- Band 7: 842nm - Near Infra-Red from 784.5nm to 899.5nm, 115nm wide
File Naming Convention
The file names for PHISAT2 data products follow a standard convention as defined in the table below. This convention captures high level metadata in the name to allow for quick and easy visual identification.
Example: phisat2_L0_raw_000000000X_20211001101205_20211001101210_E72EFC12.extension
| Name | Description | Example |
|---|---|---|
| Mission | Name of Mission in string format | phisat2 |
| Level | The corresponding processing level of the image | L0, L1A |
| Type | Type of image data, typically the frequency of the band, defined in the Key column in the assets section | R, RE2, NIR, TCI, raw... |
| Session | 9 characters used internally at Open Cosmos | 000000000 |
| Ownership | A single character that indicates ownership of the image, can be O for Open Cosmos or C for customer. | C, O |
| Start | Datetime of the start of image capture | 20221224012812 |
| End | Datetime of the end of image capture | 20221224012817 |
| CRC | Cyclic Redundancy Check (CRC32-c) | E72EFC12 |
L0 Data
Collection ID: phisat2-l0
This collection consists of PHISAT2 Level-0 data products, which are unprocessed outputs from the satellite payload. Level-0 products are the basis from which all other higher level products are produced. This collection contains assets that might not be processable to a higher level product, this normally happens when an acquisition was carried out to test, calibrate, or commission some part of the satellite.
STAC Properties
Information about the assets, geometry, and bands can be accessed in STAC via the following standard extensions:
- Electro-Optical Extension
- Item Assets
- View Geometry
- Raster Extension (only
bits_per_sample)
In addition, the following custom properties have been added:
opencosmos:compression:none,lossless, orlossyopencosmos:capture_mode: which mode was used to capture the image, can besnapshotorlinescanopencosmos:processable: boolean that indicates if the file can be processed to L1A level. Some configurations, like snapshots, cannot be processed to level 1A
Assets
All PHISAT2 L0 Items in the Collection have the following assets with the corresponding asset field key, file format and descriptions.
| Title | Key | File Format | Description |
|---|---|---|---|
| Raw data | raw | binary raw | Binary raw format outputted by the payload, also known as "the session file" |
| Metadata | metadata | json | JSON file containing an extract of the metadata present in the binary. It also contains whether or not the item is processable to L1A. |
| Thumbnail | thumbnail | webp | A low resolution image for quick visualisation of imagery data. Either an snapshot or a non-aligned true colour image |
| Ancillary | ancillary | json | An extract of relevant telemetries from the satellite platform |
| Application Output | app_out | compressed tar.gz | An output file from an application. The format is defined by the application. Only present if an AI application was run. |
| Intermediate Output | intermediate | compressed tar.gz | Intermediate output from the on board AI processing chain. Only present if an AI application was run. |
Metadata
This file is included for ease of access to the metadata without needing to decode the binary file. Most of the information contained in this file is also contained in the binary file.
Ancillary
See the common Open Cosmos Ancillary Format.