Planet(Scope) satellite imagery: a technical introduction
Exploring our planet in detail is key for researchers who study the Earth’s environment. Planet Labs offers a special way to look at Earth from space with its PlanetScope satellites. This post is your guide to getting access to this valuable satellite data.
The PlanetScope satellite constellation includes a variety of Dove satellites equipped with cameras that operate in different spectral bands. The standard configuration for the older Dove satellites (PS.2 and PS2.SD) captures images in four spectral bands: blue, green, red, and near-infrared (NIR). The next-generation Dove satellites, referred to as SuperDoves (PSB.SD), offer eight bands in coastal blue (431–452 nm), blue (465–515 nm), green I (513–549 nm), green (547–583 nm), yellow (600–620 nm), red (650–680 nm), red edge (697–713 nm), and NIR (845–885 nm). Table 1 below lists the spectral bands of the different Dove satellite types.
The older PS.2 and PS2.SD Doves have a native spatial resolution of 4.1 meters, while the SuperDoves’ native resolution is 3.7 meters. They are both resampled to 3.0 meters, which is the resolution of the images as you download them. This high resolution is achieved through a combination of the satellites’ optical sensor characteristics, altitude, and the imaging technology employed. The Dove satellites operate in a sun-synchronous orbit, typically at altitudes ranging from 400 to 600 kilometers, which allows for consistent lighting conditions for the images they capture.
Temporal resolution is a critical aspect of the Dove constellation’s capabilities, with the entire fleet capable of imaging the Earth’s entire landmass on a near-daily basis. This is facilitated by the large number of Dove satellites in orbit, which work in a coordinated manner to ensure frequent revisits to any given point on the Earth’s surface. The near-daily revisit rate is made possible by the constellation’s orbital parameters, including the sun-synchronous orbit that ensures consistent time of day for imaging opportunities, and the phasing of individual satellites within the constellation to maximize coverage.
The technical design and operational strategy of the Dove satellites are focused on providing a balance between spatial resolution, which is sufficient for detecting and analyzing medium-scale features on the Earth’s surface, and temporal resolution, which allows for monitoring changes over time with high revisit frequency. This combination of spatial and temporal resolution, underpinned by the technical attributes of the satellites and their orbital mechanics, makes the Dove constellation a versatile tool for Earth observation across a range of scientific, environmental, and commercial applications.
Under the Education and Research Program, qualified researchers and academic institutions can gain access to a substantial subset of Planet’s data archives. The basic (personal) license is free and allows free access to up to 5000 square kilometers of data per month, often sufficient for small to medium-sized research projects.
For more practical information about how to get your hands on the PlanetScope image archive, check this post:
