Abstract's details

SMASH: a Constellation of Small Altimetry Satellites Dedicated to Hydrology



Alexandre Guérin (CNES, France); Alain Lamy (CNES, France); Alexandre Couhert (CNES, France); Alexandre Piquereau (CNES, France); Baptiste Palacin (CNES, France); Florian Rouzies (CNES, France); Alain Mallet (CNES, France); Sylvain Biancamaria (LEGOS, France); Sophie Le Gac (CNES, France); Thierry Amiot (CNES, France); Eric Boussarie (CNES, France); Philippe Maisongrande (CNES, France); Selma Cherchali (CNES, France); Sophie Coutin-Faye (CNES, France)

Event: 2019 Ocean Surface Topography Science Team Meeting

Session: The Future of Altimetry

Presentation type: Type Poster

Contribution: not provided


The monitoring of water resources at the global scale is already a major challenge whose importance will increase in the next years. Continental waters are essential components of the water, energy and carbon cycles. The rivers and lakes water levels are identified as essential climate variables by the GCOS which recommends daily measurements of these variables. Traditionally, this information was provided by gage data. However, the availability of these in situ measurements is very heterogeneous and is declining (GDRC).
For the last twenty years, numerous research teams have demonstrated that measurements from space altimeters could be used to mitigate this lack of in situ measurements even if these instruments where mainly designed for measurements over the oceans. However, all the historic and current altimetry missions, based on repeat track orbits with cycle durations of 10 days (T/P, Jason), 27 days (Sentinel3), 35 days (ERS2, ENVISAT, AltiKa) and more (CryoSat) cannot provide these daily measurements.
As the performance of altimetry missions applied to inland water surfaces improves constantly, the next frontier is to increase the frequency of temporal revisit. A “flash” study was performed by CNES to propose altimetry missions which could provide this daily revisit. The constellation of SMall Altimetry Satellites for Hydrology (SMASH) is the result of this study.
This is a constellation of ten small satellites of the class 50 kg / 50 W / 27 U put on a Sun Synchronous Orbit. Each satellite carries a nadir altimeter and a precise orbit determination subsystem which provide the targeted end to end altimetric performance of 10 centimeters. The payload will allow us to monitor rivers as narrow as 50 meters wide and lakes as small as 100 meters x 100 meters and the orbit provides a latitude coverage that is largely sufficient to monitor inland waters. The constellation provides a daily revisit for each point on the earth overflight by a satellite. The altimetry products should be provided with a short time latency in order to make full use of the high temporal frequency of the measurements.
The SMASH constellation is very complimentary to the Wide Swath altimetry missions like SWOT (launch planned in 2021) and WiSA (ongoing phase A) which provide almost complete spatial coverage at a lower temporal frequency.
The presentation will provide more details on the SMASH study and its continuation in CNES.

Poster show times:

Room Start Date End Date
The Gallery Tue, Oct 22 2019,16:15 Tue, Oct 22 2019,18:00
The Gallery Thu, Oct 24 2019,14:00 Thu, Oct 24 2019,15:45