An artist rendering of the Soil Moisture Active Passive spacecraft.
|Mission type||Earth observation|
|Mission duration||3 years (nominal) |
Elapsed: 5 years, 11 months, 19 days
|Manufacturer||Jet Propulsion Laboratory|
|Launch mass||944 kg|
|Payload mass||79 kg|
|Dimensions||1.5 x 0.9 x 0.9 m|
|Start of mission|
|Launch date||31 January 2015, 14:22UTC|
|Rocket||Delta II 7320-10C |
|Launch site||Vandenberg, SLC-2W|
|Contractor||United Launch Alliance|
|Entered service||August 2015|
|Perigee altitude||680.9 km|
|Apogee altitude||683.5 km|
|Epoch||15 October 2019, 23:39:39 UTC|
Soil Moisture Active Passive (SMAP) is a NASA environmental monitoring satellite launched on 31 January 2015. It was one of the first Earth observation satellites developed by NASA in response to the National Research Council's Decadal Survey.
NASA's investment is of US$916 million (design, development, launch, and operations).
SMAP provides measurements of the land surface soil moisture and freeze-thaw state with near-global revisit coverage in 2-3 days. SMAP surface measurements are coupled with hydrologic models to infer soil moisture conditions in the root zone. These measurements enable science applications users to:
SMAP observations are acquired for a period of at least three years after launch, and the 81 kg of propellant that it carries should allow the mission to operate well beyond its design lifetime. A comprehensive validation, science, and the application program are implemented, and all data are publicly available through the NASA archive centers.
The SMAP observatory includes a dedicated spacecraft and instrument suite in a near-polar, Sun-synchronous orbit. The SMAP measurement system consists of a radiometer (passive) instrument and a synthetic-aperture radar (active) instrument operating with multiple polarizations in the L-band range. The combined active and passive measurement approach takes advantage of the spatial resolution of the radar and the sensing accuracy of the radiometer.
The active and passive sensors provide coincident measurements of the surface-emission and backscatter. The instruments sense conditions in the top 5 cm of soil through moderate vegetation cover to yield globally mapped estimates of soil moisture and its freeze-thaw state.
The spacecraft orbits Earth once every 98.5 minutes and repeats the same ground track every eight days.
The satellite carries two scientific instruments: a radar and a radiometer, that share a single feed and deployable 6 m reflector antenna system, built by Northrop Grumman, that rotates around the nadir axis making conical scans of the surface. The wide swath provides near-global revisit every 2-3 days.
|Frequency||1.2 GHz||1.41 GHz|
|Polarizations||VV, HH, HV||V, H, U|
|Resolution||1-3 km[a]||40 km|
|Antenna diameter||6 m|
|Rotation rate||14,6 rpm|
|Swath width||1000 km|
|Orbit||Near Polar, Sun-synchronous|
|Local time des. node||06:00|
|Local time asc. node||06:00|
Educational Launch of Nanosatellite X (ELaNa X), consisting of three Poly Picosatellite Orbital Deployers containing four CubeSats (three CubeSat missions), mounted on the second stage of the Delta II launch vehicle:
The CubeSat projects are deployed at a minimum of 2,896 seconds after the separation of the Soil Moisture Active Passive observatory, into a 440 x 670 km, 99.12° inclination orbit.
SMAP is a directed mission of the National Aeronautics and Space Administration. The SMAP project is managed for NASA by the Jet Propulsion Laboratory, with participation by the Goddard Space Flight Center. SMAP builds on the heritage and risk reduction activities of NASA's cancelled ESSP Hydros Mission.
SMAP observations are used to characterize hydrologic and ecosystem processes including land-atmosphere exchanges of water, energy, and carbon. Among the users of SMAP data are hydrologists, weather forecasters, climate scientists and agricultural and water resource managers. Additional users include fire hazard and flood disaster managers, disease control and prevention managers, emergency planners and policy makers. SMAP soil moisture and freeze-thaw information directly benefit several societal applications areas, including:
Initialization of numerical weather prediction models and seasonal climate models with accurate soil moisture information extend forecast lead times and enhance prediction skill.
SMAP soil moisture information improves the monitoring and forecasting of drought conditions, enabling new capabilities for mitigating drought impacts.
Improved seasonal soil moisture forecasts directly benefit famine early warning systems. Benefits also are realized through improved predictions of heat stress and virus spread rates, and improved disaster preparation and response.
In August 2015, scientists completed their initial calibration of the two instruments on board, however, SMAP's radar stopped transmitting 7 July due to an anomaly that was investigated by a team at JPL. The team identified the anomaly to the power supply for the radar's high-power amplifier. On 2 September 2015, NASA announced that the amplifier failure meant that the radar could no longer return data. The science mission continues with data being returned only by the radiometer instrument. SMAP's prime mission ended in June 2018. The 2017 Earth Science senior review endorsed the SMAP mission for continued operations through 2020, and preliminarily, through 2023.
As SMAP was emerging from the ashes of HYDROS in 2007, CSA exchanged with NASA on the possibility of renewing their partnership. CSA, in collaboration with other Canadian Government Departments, is currently developing plans regarding possible scientific and technical contributions to the new mission. The scientific activities would include both government and academic partners.