# SMOS
*missions*

## Specifications
- **operator**: esa
- **actual launch**: 2009-11-02
- **planned launch**: 2009-11-02
- **current status**: extended
- **orbit type**: Sun-synchronous dusk-dawn, 758 km mean altitude, inclination 98.44 degrees, LTAN 06:00, 23-day repeat cycle, 3-day sub-cycle, 100.1-minute period
- **swath km**: 1050
- **revisit days**: 3
- **tasking supported**: false
- **archive depth years**: 16
- **current geographic priority**: Global
- **entity type**: mission
- **last verified date**: 2026-06-05
- **verified by**: agency-doc
- **claim status**: unclaimed
- **provider**: esa
- **mass kg**: 658
- **attributes**: {"operator":"esa","actual_launch":"2009-11-02","planned_launch":"2009-11-02","current_status":"extended","orbit_type":"Sun-synchronous dusk-dawn, 758 km mean altitude, inclination 98.44 degrees, LTAN 06:00, 23-day repeat cycle, 3-day sub-cycle, 100.1-minute period","swath_km":1050,"revisit_days":3,"tasking_supported":false,"archive_depth_years":16,"current_geographic_priority":"Global"}

## Editorial
SMOS (Soil Moisture and Ocean Salinity) is an ESA Earth Explorer mission launched on 2 November 2009 from Plesetsk Cosmodrome, Russia, aboard a Rockot/Breeze-KM vehicle [^esa-smos-facts]. It is the second ESA Earth Explorer Opportunity mission (EE-2) [^esa-smos-facts]. ESA describes MIRAS as the first satellite instrument to carry a 2D interferometric synthetic-aperture radiometer in orbit [^esa-smos-facts]. The spacecraft is built on the Proteus bus developed by Thales Alenia Space and CNES, with a total launch mass of 658 kg [^esa-smos-facts].

The sole instrument is MIRAS (Microwave Imaging Radiometer using Aperture Synthesis), a Y-shaped interferometric array built by a consortium of more than 20 European companies led by EADS CASA Espacio (Spain). MIRAS carries 69 L-band receivers distributed across three arms and a central hub, operating at 1.413 GHz (21 cm wavelength) [^esa-smos-facts]. Aperture synthesis combines signals across the array to reconstruct brightness temperature images with a spatial resolution of 35 to 50 km over a swath of approximately 1050 km [^esa-smos-facts]. Global coverage repeats on a 3-day sub-cycle within a 23-day exact repeat orbit [^esa-smos-facts].

SMOS flies in a sun-synchronous dusk-dawn orbit at a mean altitude of 758 km, with a 98.44 degree inclination and a 06:00 ascending node [^esa-smos-facts]. Primary science products include Level-2 and Level-3 surface soil moisture (0-5 cm depth) at 35 to 50 km resolution, Level-2 and Level-3 sea surface salinity, a Level-3 soil freeze-thaw state product, sea ice thickness estimates, and ocean surface wind speed [^esa-smos-eogateway]. Near-real-time products are available for operational users [^esa-smos-eogateway]. Data are distributed through the ESA SMOS Online Dissemination service and the Copernicus Data Space Ecosystem [^esa-smos-eogateway].

Designed for a five-year mission (three-year nominal plus a two-year extension) [^esa-smos-facts], SMOS has operated significantly beyond its design life and continues to return science data as of June 2026 [^esa-smos-extension]. ESA has extended the mission multiple times; a new Level-3 soil freeze-thaw product was published in June 2025, confirming continued operations [^esa-smos-extension]. ESA is the mission operator.

## Compositional position
- SMOS --[mission_payloads]--> miras (products)
- SMOS --[related-topic]--> soil-moisture (topics)

## Sources
- [esa-smos-facts] | SMOS Facts and Figures, ESA | https://www.esa.int/Applications/Observing_the_Earth/SMOS/Facts_and_figures | tier=agency-doc | accessed=2026-06-05
- [esa-smos-eogateway] | SMOS Mission Overview, ESA Earth Online | https://earth.esa.int/eogateway/missions/smos | tier=agency-doc | accessed=2026-06-05
- [esa-smos-extension] | Overachieving SMOS mission primed for continued success, ESA Earth Online | https://earth.esa.int/eogateway/news/overachieving-smos-mission-primed-for-continued-success | tier=agency-doc | accessed=2026-06-05
- [eoportal-smos] | SMOS Mission, eoPortal Directory | https://www.eoportal.org/satellite-missions/smos | tier=community | accessed=2026-06-05

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Source: https://eo-atlas.org/missions/smos
Maintainer: SpectraWorks B.V. (CC-BY 4.0)