The PROBA-V mission, developed as part of ESA's PROBA Programme and in the frame of the ESA General Support Technology Program (GSTP) is an ESA EO mission providing global coverage, with latitudes 35-75°N and 35-56°S covered daily, and between 35°N and 35°S covered every 2 days. The Contributors to the mission are Belgium and Luxembourg.
The PROBA-V imager's continent-spanning 2250 km field of view collects light in the blue, red, near-infrared and mid-infrared wavebands, ideal for monitoring plant and forest growth as well as inland water bodies. The Vegetation instrument can distinguish between different land cover types and plant species, including crops, to reveal their health, as well as detect water bodies and vegetation burn scars.
The PROBA-V satellite has a mass of 140 kg is 1 cubic metre in size. The main PROBA-V payload is the Vegetation sensor: a multispectral pushbroom spectrometer with 4 spectral bands. The payload consists of 3 identical cameras, each with a very compact Three Mirror Anastigmat (TMA) telescope. Each TMA, having a FOV of 34°, contains 4 spectral bands: 3 bands in the visible range (Blue, Red and NIR) and one band in the SWIR spectral range.
The swath Total FOV is 103°. VGT-P is restricted to imaging land and dedicated calibration zones. On-board the spacecraft, there is for each camera a land sea mask that allow to remove the pixels that contain only sea and it dictates when each camera should be in imaging mode.The reference scientific paper providing description of the PROBA-V Space Segment is available here for download: M. Francois, et al., "The PROBA-V mission: the space segment", IJRS, 2014.
PROBA-V operates on a sun-synchronous near polar Earth orbit at about 820 km guaranteeing the required swath of 2250 km with an instrument field of view of 102 degrees, compatible with the geographical coverage.
The satellite’s ground segment and mission control centre are in Redu, Belgium complemented by a ground station for data reception and a processing and archiving centre at VITO in Belgium. The exploitation phase of PROBA-V is managed by ESA from ESRIN, ESA’s Earth observation centre in Italy.
The PROBA-V mission ended its operational phase on 30 June 2020. It was decided to end operations because the Solar Zenith Angle increased and resulted in a consequent change of equator crossing time due to the orbital drift of the satellite. By June 2020, this had become significant and impacted trend analysis, the consistency of the long-term archive, and the global coverage at high altitude would have become substantially reduced. It was also foreseen that by October 2021, two of PROBA-V's three on-board cameras would no longer receive sufficient illumination to perform acquisitions of Earth.
Because the satellite was still in good condition, ESA decided to continue the mission in an experimental phase rather than end the mission entirely. On 1 July 2020, PROBA-V's experimental phase began, with a focus on acquiring 100 m data over Africa and Europe. Test observations over the African Sahel will particularly help with early drought warnings. The satellite is not able to acquire as many acquisitions during this phase, but ESA have taken the opportunity to conduct other activities with PROBA-V. The satellite is conducting daily moon sensing, and yaw manoeuvres to test super resolution, which is a method for enhancing the accuracy of imagery by combining lower resolution images the satellite acquires over the same location.
This offers a way to continue acquiring imagery for this vegetation-monitoring mission, albeit in a more limited capacity, without the demands nominal operations would require. These acquisitions will support the more than 1800 research teams who make use of PROBA-V data. PROBA-V's 100 m imagery also serves as a midway point between Copernicus Sentinel-2 and 3 acquisitions, and is routinely used to cross-check other products such as the Copernicus Global Land Service.