# SMAP
*missions*

## Specifications
- **operator**: nasa
- **launch vehicle**: ula-delta-ii
- **planned launch**: 2015-01-31
- **actual launch**: 2015-01-31
- **current status**: extended
- **orbit type**: Sun-synchronous dawn/dusk, 685 km, LTAN 18:00, inclination 98 degrees, 8-day repeat, 98.5-minute period
- **swath km**: 1000
- **revisit days**: 3
- **tasking supported**: false
- **archive depth years**: 11
- **current geographic priority**: Global
- **entity type**: mission
- **last verified date**: 2026-06-05
- **verified by**: agency-doc
- **claim status**: unclaimed
- **provider**: nasa
- **attributes**: {"operator":"nasa","launch_vehicle":"ula-delta-ii","planned_launch":"2015-01-31","actual_launch":"2015-01-31","current_status":"extended","orbit_type":"Sun-synchronous dawn/dusk, 685 km, LTAN 18:00, inclination 98 degrees, 8-day repeat, 98.5-minute period","swath_km":1000,"revisit_days":3,"tasking_supported":false,"archive_depth_years":11,"current_geographic_priority":"Global"}

## Editorial
SMAP (Soil Moisture Active Passive) is a NASA Earth science mission launched on 31 January 2015 from Vandenberg Space Force Base aboard a Delta II 7320-10C rocket [^smap-description]. The spacecraft, built jointly by JPL (bus) and NASA Goddard Space Flight Center (radiometer instrument), flies in a sun-synchronous dusk-dawn orbit at 685 km altitude with an 18:00 local solar time ascending node, completing a full ground-track repeat every eight days (117 orbits) while achieving near-global coverage in approximately three days [^smap-observatory].

The mission carries two L-band instruments sharing a 6 m diameter rotating reflector antenna that spins at 14.6 rpm to produce a 1000 km conical swath [^smap-observatory]. The L-band radiometer operates at 1.41 GHz and measures brightness temperatures; surface soil moisture is retrieved at 36 km resolution, with an enhanced algorithm producing estimates at 9 km [^smap-observatory]. Historically, the mission also carried an L-band radar operating at 1.26 GHz, designed to retrieve soil moisture at 3 km resolution; that instrument suffered a power supply failure in July 2015 after collecting approximately three months of science data and has not operated since [^smap-timeline]. The radiometer remains the sole operational science instrument as of June 2026 [^smap-observatory].

SMAP's primary data products include Level-2 surface soil moisture at 36 km and 9 km (radiometer-only retrievals), Level-3 daily composite soil moisture maps, a Level-3 freeze-thaw state product at 36 km, Level-4 root-zone soil moisture derived by model assimilation, and a Level-4 carbon net ecosystem exchange product [^smap-description]. A combined SMAP and Sentinel-1 product (L2_SM_SP) provides soil moisture at 3 km by fusing SMAP brightness temperatures with Sentinel-1 C-band radar backscatter [^smap-description]. Data are distributed through the NASA National Snow and Ice Data Center with a near-real-time latency of approximately three hours [^smap-description].

eoPortal reports a spacecraft dry mass of 686 kg and a total launch mass of 944 kg [^eoportal-smap]. The three-year prime mission concluded in summer 2018; extended operations have continued since, reviewed on a three-year cycle [^smap-timeline]. NASA is the mission operator.

## Compositional position
- SMAP --[mission_payloads]--> smap-radiometer (products)
- SMAP --[related-topic]--> soil-moisture (topics)
- smap-rss-l3-sea-surface-salinity-8day (data_products) --[related]--> SMAP

## Sources
- [smap-observatory] | SMAP Observatory, NASA JPL | https://smap.jpl.nasa.gov/observatory/ | tier=agency-doc | accessed=2026-06-05
- [smap-description] | SMAP Mission Description, NASA JPL | https://smap.jpl.nasa.gov/mission/description/ | tier=agency-doc | accessed=2026-06-05
- [smap-timeline] | SMAP Mission Timeline, NASA JPL | https://smap.jpl.nasa.gov/mission/timeline/ | tier=agency-doc | accessed=2026-06-05
- [eoportal-smap] | SMAP Mission, eoPortal Directory | https://www.eoportal.org/satellite-missions/smap | tier=community | accessed=2026-06-05

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