GPM Core Observatory

GPM Performs Yaw Turn, Continues Calibration

On March 17, the team executed GPM's first scheduled yaw turn to turn the orientation of the spacecraft 180 degrees. Yaw is the left/right orientation in the horizontal plane of the spacecraft's motion. The spacecraft is now "flying backwards." Yaw maneuvers will be performed approximately every 40 days for spacecraft thermal control, as the angle between the spacecraft's orbit and the sun changes. This keeps the side of the spacecraft that is designed to remain cold from overheating. Yaw maneuvers are performed primarily using the spacecraft's reaction wheels.

Calibrating Thrusters, Verifying Science Data

The Global Precipitation Measurement mission's Core Observatory is performing normally.

On March 12, the GPM Core Observatory fired its thrusters for a 30-second check-out of their performance. The burn, called a delta-v, changes the velocity of the spacecraft to adjust the altitude of its orbit. This week's short maneuver did not greatly alter the satellite's orbit but was used instead for further calibration of the thrusters.

Functional checkout activities and internal calibration of the Dual-frequency Precipitation Radar continued this week.

DPR Activated, in Checkout

On Saturday, March 8, just after 10 a.m. EST, the second of the two science instruments aboard the Global Precipitation Measurement (GPM) mission's Core Observatory was activated, and the teams in the mission operations center and launch support room at NASA's Goddard Space Flight Center in Greenbelt, Md., began the instrument's checkout period.

GPM Science Check-Out

The Global Precipitation Measurement mission Core Observatory is performing normally. The GPM Microwave Imager (GMI) continues in science mode, and GMI data is being sent to the Precipitation Processing System (PPS) at NASA's Goddard Space Flight Center in Greenbelt, Md. Using the initial data, the instrument team has verified that GMI is working well on-orbit.  

GMI Spins Up, goes to Science Mode

The Global Precipitation Measurement mission Core Observatory is performing normally. Today, the GPM Microwave Imager (GMI) instrument started to spin at its normal rate and collect science data on rain and snowfall.

The GMI instrument is a multi-channel microwave radiometer that uses 13 channels to measure the intensity of the microwave energy emitted from Earth's surface and atmosphere. GMI will detect total precipitation within all layers of clouds, including snow and ice, and rain from drizzles to downpours.

GPM Checks Out Thruster Performance

Today, the Global Precipitation Measurement mission Core Observatory successfully fired its thrusters for five seconds to check out the thruster performance. This type of maneuver, called a delta-V, changes the velocity of the spacecraft to adjust the altitude of its orbit. Today's delta-V resulted in only a very slight change in the orbit, but will help the GPM team assess and calibrate the thruster performance.

GPM Core Activating Thrusters

Following yesterday’s activities with the two science instruments associated with the Global Precipitation Measurement core observatory, the flight control team’s attention today is focused on the observatory’s onboard maneuvering thrusters.

The satellite has a dozen thrusters: four forward and eight aft. The flight team is activating and initializing the thrusters over the course of today. A brief (5 second) propulsion burn to further calibrate the thrusters is planned for early this week.

GMI Reflector Deployed

Following activation and warm up of the Global Precipitation Measurement Microwave Imager (GMI) electronic systems, the team at NASA’s Goddard Space Flight Center in Greenbelt, Md., deployed the main reflector of the U.S. science instrument for the GPM Core Observatory.

A significant step was also achieved today in the activation of the science instrument provided by the Japan Aerospace Exploration Agency (JAXA) with the turning on of the controller for the Dual-Frequency Precipitation Radar (DPR).

Checkout of the GPM Core Observatory Continues Normally

Friday evening, GPM flight controllers at NASA Goddard began using the satellite’s High Gain Antenna system for high-rate data rate transmissions through NASA’s orbiting fleet of Tracking Data Relay Satellites.

Having high-rate data flowing through the TDRS system allows the spacecraft recorder to be downloaded more frequently. During science operations, TDRS communication will allow availability of science data within 3 hours of measurement.

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