Contact/Source: Janice Nelson, USGS EROS
Landsat 9 Ground System development team members executed the first of a series of Ground Readiness Tests (GRTs) this week as they successfully simulated the communication of command and telemetry data between the Ground Network Element (GNE) at EROS and the Landsat Multi-Satellite Operations Center (LMOC) at the Goddard Space Flight Center.
In what was called GRT One, ground system engineers and operations team members used simulators to test the ability of the LMOC system and GNE system to talk with each other, communicating both simulated commands for actions by the spacecraft, but also retrieving and sharing with each other simulated telemetry data related to the health and safety of the satellite.
The GNE is the element of the ground system that includes the hardware, software, and networks necessary to receive data from the spacecraft. It relies on a variety of ground stations around the globe to assist with those communications, though this week’s test focused only on the station at EROS and the LMOC.
The LMOC is an element of the ground system as well. It receives and monitors spacecraft telemetry, ensures its health and safety, and sends commands to the satellite. While the LMOC utilizes some of the Landsat 8 software subsystems, the LMOC is new, and this initial test is a significant accomplishment for the incremental delivery of the Landsat 9 ground system.
That the exercise was a success didn’t surprise Brian Sauer, the USGS EROS Landsat 9 Project Manager. A significant amount of effort and preparation went into the test. The two elements conducted lower-level tests to verify their associated requirements.
Following element tests, the system was installed into the operations environment, and L9 Ground System staff conducted a series of Interface Connectivity Tests to ensure the systems could communicate with each other, commands could be sent, and data were able to flow. That was followed by several dry runs in January, and a Test Readiness Review conducted Feb. 8, Sauer said.
“We know what requirements are supposed to be verified from the tests, and we completed dry runs for the tests. So, if the run for the record (for the GRT) would not have been a success, that would have been a surprise,” he said.
The test wasn’t only about verification; it was also an early training opportunity for staff members who will operate the system. The test is conducted by ground system Integration and Test (I&T) engineers and executed by the staff who will operate the system when interfacing with the satellite. In fact, to the extent possible, it follows the “test as you fly” principle—operators run the system as they would when the spacecraft is in flight.
GRT One also included Quality Assurance monitors who ensured that processes and procedures were correctly followed for the test, and that documentation was appropriate for those processes and procedures.
Sauer said GRT One only covered initial commanding and did not include the full command suite. The additional tests will take place in upcoming GRTs, the next which is penciled in now for August. GRTs are expected to be ongoing for the next 14 months, he said.
“The success of this GRT truly is a credit to the all of the people on the Landsat 9 Ground System team,” Sauer said. “Contractors, government, everyone… it really is a team effort.”
Safeguarding freshwater resources is crucial, and while scientists use a variety of ground-based techniques to gauge water quality, the Landsat program has provided water quality data from orbit for decades.