February 24, 2015 – Mission controllers at NASA’s Jet Propulsion Laboratory in Pasadena, California, today sent commands to unfurl the massive 20-foot-wide (6-meter) reflector antenna on NASA’s new Soil Moisture Active Passive (SMAP) observatory which was launched atop a United Launch Alliance (ULA) Delta II rocket on January 31. The deployment of the mesh reflector antenna, which supports the collection of SMAP’s radar and radiometer instrument measurements in space, marks a key milestone in commissioning the satellite. SMAP will soon begin its three-year science mission to map global soil moisture and detect whether soils are frozen or thawed.
SMAP will help scientists understand the links in Earth’s water, energy and carbon cycles, help reduce uncertainties in predicting weather and climate, and enhance our ability to monitor and predict natural hazards such as floods and droughts.
Today, an onboard pyro was fired to open restraints on the furled antenna, which then sprang partially open through the force of stored energy. A motor then wound a cable to pull the reflector open to its full circular configuration. The total procedure took approximately 33 minutes.
Initial data indicate the antenna deployment went as planned. Mission managers are downloading onboard inertial measurement unit data and other telemetry to confirm the antenna successfully deployed. The assessment of this more detailed data and telemetry is expected to be completed later this week.
The reflector antenna and its boom, which holds the reflector in position and reduces deflections caused by the antenna as it spins, were designed and built by Astro Aerospace, a Northrop Grumman Corporation company located in Carpinteria, California, under subcontract to JPL.
In about a month, after additional tests and maneuvers to adjust the observatory to its final science orbit, the antenna will be spun up to nearly 15 revolutions per minute in a two-stage process. By rotating, the antenna will be able to measure a 620-mile (1,000-kilometer) swath of Earth below, allowing SMAP to map the globe every two to three days.
SMAP is managed for NASA’s Science Mission Directorate in Washington by the agency’s Jet Propulsion Laboratory (JPL) in Pasadena, California, with instrument hardware and science contributions made by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. JPL is responsible for project management, system engineering, radar instrumentation, mission operations and the ground data system. Goddard is responsible for the radiometer instrument. Both centers collaborate on science data processing and delivery to the Alaska Satellite Facility, in Fairbanks, and the National Snow and Ice Data Center, at the University of Colorado in Boulder, for public distribution and archiving. NASA’s Launch Services Program at the agency’s Kennedy Space Center in Florida is responsible for launch management. JPL is managed for NASA by the California Institute of Technology in Pasadena.
To view an animation of the reflector antenna unfurling, click here.