The GOES-R test program includes several types of integrated system tests between the satellite and operational ground system. These tests are supplementary to the segment-level tests necessary to verify functional and performance requirements of the Flight system and Ground system individually.
5.13.1 Mission Operations End-To-End Tests
Since the pre-launch development effort of GOES-I in 1992, the GOES Program has prescribed a series of spacecraft-to-ground system End-To-End (ETE) test sequences for each satellite. ETE tests focus on the validation and compatibility of flight and ground hardware, software, and communications interfaces in a mission operations context. It is important to note that the ETE test program does not replace any aspect of segment level testing and should not be used at the Project level to fulfill segment level test
requirements2. The ETE test program is intended to supplement the Project level V&V programs using “as flown” configurations and procedures.
ETE testing verifies the interoperability of the Space and Ground Segments in a configuration as close to flight as possible. ETE testing is mainly functional, but may include limited performance verification. The elements involved in the ETE test are the fully-integrated satellite (in flight-like configuration or as close to flight configuration as practicable), the fully integrated ground system at the operational sites, and all operational network elements that are practical to exercise. For GOES-R, ETE tests will be conducted during the pre-launch phase from the operational sites (NSOF or RBU) by a dedicated mission operations team, supplemented with spacecraft, instrument, and ground system developer personnel. The series of ETE tests reflect each phase of the GOES-R mission.
Objectives of the ETE test program include:
Full demonstration of the operational compatibility of the satellite, government operations control center, ground systems, and associated network elements
Validation of spacecraft and instrument databases
Validation of “as-flown” routine, special, and contingency operations procedures
Discover and solve design issues before launch, for example: o Interface inconsistencies
o Unintended design or operational features o Database errors (values and inconsistencies) o System timing errors
Familiarization of the satellite and ground systems by the mission operations team
For these tests, one “end” is the actual flight-configured satellite (spacecraft & instruments), and the other “end” is either a component of or the full operational ground system (i.e. the full end-to-end ground system may not be involved depending on the scope of the test). All testing will be planned and conducted by the Mission Operations Support Team, who are the engineers developing the mission operations procedures and responsible for flight. ETE test plans and procedures are developed jointly by the MOST, spacecraft, instrument, and ground system vendors. All ETE test sequences are validated by the MOST through the high fidelity satellite simulator prior to execution. ETE test scheduling is done at the Program level.
The content of the first ETE test may be dependent on component and system readiness at that time (both spacecraft and ground). It is also possible that one or more tests may be segmented. One ETE test will occur during spacecraft thermal vacuum environmental testing, where instrument raw data acquired during flight sequence testing will be recorded for playback in stand-alone radiometric calibration validation and INR characterization testing. An ETE test later in the series may include a protracted period of continuous operations (2 or more days) where routine, contingency, and special operations procedures and schedules are run for confirmation and where data may be collected for system performance verification.
2 For instance, bandwidth limitation in the ETE test configuration may make it impractical to acquire instrument scene
measurements and flow raw data through the entire Product Generation system to generate products in a real time “photons- to-products” test. This test would be conducted as a stand-alone Ground Segment system-level test using recorded raw data or other instrument data source.
The ETE test program begins roughly 2 years before launch, when the satellite has been integrated and the ground system installed at the operational site(s), and continues until shortly before launch. Note that the ETE test schedule may not necessarily be “Launch-minus”, but based on a ground-storage date. It may be advisable to repeat some functional ETE sequences after a protracted period of ground storage prior to launch.
5.13.2 Special Integrated Tests
Other special system-level tests may be performed that require an integrated Flight and Ground system configuration. These include instrument radiometric calibration and image navigation performance testing. Special Integrated Tests are conducted using an end-to-end configuration much like the mission operations ETE tests, but data may be recorded be for playback where it is not practical to flow high rate data directly to the ground system. Some special tests may exploit data captured under flight
configuration during a particular mission operations ETE test.
Instrument Calibration Tests
For Earth-referenced instruments requiring radiometric calibration to meet product specification, raw data will be collected from the fully integrated satellite and processed through the operational ground system. For the ABI, this test will verify end-to-end calibration performance from the actual detector response through Level 1b processing. These data will most likely be acquired during ETE thermal vacuum testing where actual flat plate emissive and cold space targets will be sampled in the chamber using typical on-orbit scanning scenarios.
Satellite Optical Tests
The purpose of these tests is to characterize the optical pointing performance and the interoperability of each of the Earth-referenced instruments on the fully integrated spacecraft. A collimated Earth target will be used to measure instrument performance during typical on-orbit scenarios and acquiring data for processing by the ground system and for off-line analysis. In the case of ABI, performance assessment will include the following:
Verify correct Mode 3 & 4 scanning
Characterization of star measurement features
Characterization of internally generated ABI correction signals
An overall assessment of the ABI performance over the entire ABI field of regard
System Functional and Performance Test
The purpose of this test is to verify the interoperability of the flight and ground systems by executing various operational scenarios using procedures, command and imaging schedules as close to flight operations as possible. The System Functional and Performance Test (SFPT) configuration and commanding will be similar to a functional ETE test, but will also verify the optical pointing
performance of the Satellite system for Earth-referenced instruments using a collimated Earth target. Data will be collected to process through the ground system to acquire as much image navigation and registration performance data as possible. High fidelity simulations will be provided of known noise and disturbance sources that are possible to produce physically in the test configuration, as well as dynamic effects necessary to mimic the on-orbit environment. The SFPT will be run for a duration of
several days and include all routine, housekeeping, and orbit maneuver scenarios expected in nominal operations.