At least 30.000 freshwater level measurement points will be made available from space sensors, allowing for a high-revisit (daily updates) system.
Existing continental freshwater altimetry missions have disadvantages, such as slow repeat cycles resulting in hydro-climatic disaster blindness. Rivers and lake water levels are essential variables according to the Global Climate Observing System (2024), which recommends their daily measurements.
The BWI constellation, of high temporal resolution, is the perfect complement to large-swath hydrological satellites such as SWOT. For example, the soon-to-be Sentinel-3 TOPO NG has much higher spatial resolution but lower temporal frequency.
1-day revisits will revolutionize Earth Observation, given that current satellites’ repeat cycles are between 10 and 90 days! Global water level data points, updated daily, will help advance the state-of-the-art on our understanding of the water cycle.
Significantly inspired by the SMASH concept (Small Altimetry Satellites for Hydrology), born at LEGOS & designed at CNES (Phase A completed). French Space Agency CNES has a long history of contributing to altimetry missions. They range from TOPEX-Poseidon launched in August 1992 to SWOT launched in December 2022 – two satellites co-developed with NASA’s JPL. LEGOS (Laboratory of Space Geophysical and Oceanographic Studies) is a joint research unit (UMR5566) under the auspices of CNES, CNRS, IRD, and UT3 at the Midi-Pyrénées Observatory in Toulouse (France). The LEGOS research and teaching scientific fields include oceanography and the water cycle in the broadest sense, with the physics of the oceanic, hydrological, cryospheric, and atmospheric components, including coastal and climatic components, as well as marine biogeochemistry and geochemistry. The SMASH mission specification was written by a scientific group led by Pr. Denis Blumstein at LEGOS, and SMASH was then developed at CNES until the completion of Phase A in late 2022.
Optimized launch & maintenance costs as our architecture requests just 1 launch to set all 10 nanosatellites on the same orbital plane.
First, a demonstrator of 2 nanosatellites will be launched to validate scientific, technological, and commercial assumptions. Afterward, we expect to launch a constellation of 10 nanosatellites to be extended to 80 nanosatellites. The extension of coverage would span over a decade by shrinking inner tracks and increasing revisit rates.
A virtual station is located at the crossing of satellite tracks (500km intertracks with 2 satellites, 300km intertracks with 10 satellites) and freshwater bodies. It will measure the water height of the same water body daily.
Up to 50.000 virtual stations will provide global daily water level measurement data with a constellation of 10 nanosatellites.
In the long term, BWI wants to reach the number of 80 nanosatellites in orbit to maximize global geographic coverage
Ground measurement stations cost approximately 5000€ per year (incl. installation & maintenance). One virtual measurement station (acquired by a space sensor) costs approximately 250€ per year (excl. downstream hosting, sales & marketing costs), assuming a global network of 30.000 virtual stations. The BWI constellation will divide existing freshwater height monitoring costs by a factor of 20!
BWI constellation partners
NRT snapshot of water surface elevations for all the basin (70 min for Congo basin).
Every 24 hours for ascending and descending tracks (separated by ~12 hours).
BWI’s constellation will provide inland water level data for free to the scientific community, and the data will be made available after the purchase of subscription plans to governments and businesses.
They support the mission
BWI specializes in providing near real-time estimates and forecasts of inland surface water bodies around the globe. It combines in-situ data, spaceborne observations, and machine learning to feed and empower hydrological and hydrodynamical models. Through an online, subscription-based service, BWI aims to make scalable – across space and time – hydrological software to address climate change-induced water stress.BWI also strives to launch a constellation of 10 smallsats equipped with miniaturized altimeters to monitor inland water levels globally.
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