GOES-16


GOES-16, formerly known as GOES-R before reaching geostationary orbit, is the first of the GOES-R series of Geostationary Operational Environmental Satellites operated by NASA and the National Oceanic and Atmospheric Administration . GOES-16 serves as a backup for NOAA’s operational geostationary constellation. GOES-16 provides high spatial and temporal resolution imagery of the Earth through 16 spectral bands at visible and infrared wavelengths using its Advanced Baseline Imager. GOES-16's Geostationary Lightning Mapper is the first operational lightning mapper flown in geostationary orbit. The spacecraft also includes four other scientific instruments for monitoring space weather and the Sun.
GOES-16's design and instrumentation began in 1999 and was intended to fill key NOAA satellite requirements published that year. Following nearly a decade of instrument planning, spacecraft fabrication was contracted to Lockheed Martin Space Systems in 2008; construction of GOES-16 began in 2012 and lasted until 2014 when the satellite entered the testing phase. After several launch delays, GOES-16 launched from Cape Canaveral on 19 November 2016 aboard a United Launch Alliance Atlas V. The spacecraft reached an initial geostationary orbit several days later, beginning a yearlong non-operational checkout and validation phase. In November 2017, GOES-16 began a drift to its operational GOES East position, and was declared fully operational on 18 December 2017. The satellite is expected to have an operational lifespan of ten years, with five additional years as a backup for successive GOES spacecraft.

Background

Instrument conceptualization

The Geostationary Operational Environmental Satellite program began as a joint effort between the National Aeronautics and Space Administration and the National Oceanic and Atmospheric Administration in 1975 to develop geostationary weather satellites following the success of the Applications Technology Satellite and Synchronous Meteorological Satellite programs beginning in 1966. In the 1999 Operational Requirements Document for the Evolution of Future NOAA Operational Geostationary Satellites, NOAA listed instrument requirements for the next generation of GOES imager and sounder. Top priorities included continuous observation capabilities, the ability to observe weather phenomena at all spatial scales, and improved spatial and temporal resolution for both the imager and sounder. These specifications laid the conceptual foundations for the instruments that would eventually be included with GOES-16.
More concrete development of GOES-16 began with the initial designs of an Advanced Baseline Imager, which started in June 1999 under the direction of Tim Schmitt of the National Environmental Satellite, Data, and Information Service. At its inception, ten spectral bands were considered for inclusion in the new ABI, derived from six instruments on other satellites. In September 1999, the NOAA Research and Development Council endorsed the continued development of the instrument with the suggested bandwidths and frequencies. As the instrument became further realized, the number of potential spectral bands increased from the initial ten, to twelve by October 1999. Alongside the ABI, development also began on the Advanced Baseline Sounder, which would form a part of a Hyperspectral Environmental Suite of instruments on the next generation GOES satellites. Like the ABI, the HES also marked significant improvements in resolution and spatial coverage. Initial forecasts were for the ABI to be included as part of GOES beginning with the projected launch of GOES-Q in 2008.
In 2001, NOAA planned for the GOES-R generation of GOES satellites to commence with the expected launch of GOES-R in 2012, with the ABI and ABS as expected instrumentation. GOES-R and its sister satellites were to lead to substantial improvements in forecast accuracy and detail by providing new operational products for users. Four years later, the number of proposed spectral bands on the ABI instrument increased to 16, covering a swath of visible and infrared wavelengths. In September 2006, NOAA dropped plans to include the HES aboard GOES-R, citing a lack of sufficient testing and major cost overruns in the development of the National Polar-orbiting Operational Environmental Satellite System. Although the GOES-R series was expected to cost in total, increased instrument complexity, revised inflation assumptions, and program reserves led to the Government Accountability Office estimating a much higher US$11.4 billion cost for the program in 2006.

Construction

In December 2008, NASA and NOAA selected Lockheed Martin Space Systems as the contractor for the fabrication of the first two satellites of the GOES-R generation, including GOES-R, for an estimated value of contract at US$1.09 billion. Preliminary design review was completed just over two years later, with critical design review being completed in May 2012. Construction of the satellite bus was contracted out to Alliant Techsystems and work began shortly thereafter, with the core structure becoming test-ready in January 2013. The Extreme Ultraviolet and X-ray Irradiance Sensors became the first installation-ready instruments for GOES-R in May 2013, while the ABI became integration-ready in February 2014; spacecraft propulsion and system modules were delivered three months later, finalizing the initial construction phase and allowing for complete spacecraft integration and testing at Lockheed Martin's facilities in Colorado. The satellite was then transferred to Kennedy Space Center on 22 August 2016 to undergo additional tests and ready the spacecraft for launch.

Spacecraft design

GOES-16 and other satellites of the GOES-R generation are based around a derivative of Lockheed Martin's A2100 spacecraft bus capable of supporting up to dry mass with power capabilities exceeding 4 kW until the spacecraft's end-of-life. With propellant, GOES-16 had a total mass of, with a dry mass of. The spacecraft has dimensions of. GOES-16 is powered by a solar array containing five solar panels that were folded at launch and unfurled after deployment. GOES-16 was designed to have a service lifetime of 15 years, including 10 years as an operational satellite and 5 additional years as a backup for successive GOES satellites. GOES-16's command and data handling subsystem is based around the SpaceWire bus; a modified version of the SpaceWire protocol was developed specifically for GOES-16 as a cost and risk reduction measure, with the associated application-specific integrated circuit being developed by British Aerospace. The GOES Reliable Data Delivery Protocol complements preexisting SpaceWire capabilities and includes packet loss detection and recovery. The satellite's instruments collect and transfer payload data to the spacecraft at 10-100 Mbit/s. Spacecraft stability and accuracy is maintained by several reaction wheels, gyrometers, and a star tracker. GOES-16 is also the first geostationary civilian spacecraft to use GPS to assess its orbit. Such calibration equipment is intended to establish the satellite's position within a radius with a confidence of 3σ.

Instruments

Earth-facing

The Advanced Baseline Imager and Geostationary Lightning Mapper make up GOES-16's Earth-facing, or nadir-pointing, instruments. These are positioned on a stable precision-pointed platform isolated from the rest of the spacecraft.

Advanced Baseline Imager (ABI)

The Advanced Baseline Imager is the primary imaging instrument on GOES-16, providing over 65 percent of all GOES-16 data products. A multi-channel passive imaging radiometer, ABI takes images of the Earth with 16 spectral bands, including two visible channels, four near-infrared channels, and ten infrared channels. The individual bands are optimized for various atmospheric phenomena, including cloud formation, atmospheric motion, convection, land surface temperature, ocean dynamics, flow of water, fire, smoke, volcanic ash plumes, aerosols and air quality, and vegetative health. ABI's "red" visible band 2 has the highest resolution among the 16 bands at per pixel. The other visible light and near-infrared bands have a resolution of, while the infrared bands have a resolution of per pixel.
The sensors on the ABI are made of different materials depending on the spectral band, with silicon used for sensors operating in visible light and mercury cadmium telluride used for sensors operated in the near-infrared and infrared. An ABI electronics unit and cryocooler control electronics complement the sensor unit to power the imager and keep the instrument at cryogenic temperatures; all electronics and the sensor array are redundant to ensure operation longetivity. Development of the ABI was contracted to Harris Corporation of Fort Wayne, Indiana. Several other companies were involved in the development and fabrication of the ABI, including BAE Systems, BEI Technologies, Babcock Corporation, DRS Technologies, L3 Technologies SSG-Tinsley, and Northrop Grumman Space Technology.
The ABI takes images with three different geographic extents, with each image produced as a combination of stitched west-to-east narrow image scans made by the instrument. In the default "flex" mode of operation, the ABI produces full-disk images of the Earth every 15 minutes, with a spatial resolution of. However, the ABI can also operate on continuous disk mode, whereby full disk images are recorded every 5 minutes. Full-disk images are composed of 26 image strips, making it more efficient than the preceding GOES imager, which was made with 1,300 image strips. The instrument also images a area centered on the continental United States every five minutes at a resolution of. Where possible, the ABI can also image mesoscale phenomena over two selected areas every 60 seconds at a resolution of. The variable scanning modes make GOES-16 the first GOES satellite to be configurable while in orbit. In addition, a solar diffuser new to GOES-16 allows for calibration of the ABI imaging data. On 2 April 2019, the GOES-16 ABI was reconfigured to use scan mode 6 as a default, allowing full disk scans every 10 minutes.
The ABI onboard GOES-16 represents a significant improvement over the imager onboard previous GOES satellites. The sixteen spectral bands on the ABI, as opposed to the five on the previous GOES generation, represents a two-fold increase in spectral information. In addition, the ABI features up to four times greater spatial resolution and five times greater temporal resolution over the previous GOES imager. The ABI is nearly identical to the Advanced Himawari Imager first used on the Japan Meteorological Agency's Himawari 8, which launched on 7 October 2014. The two instruments share 15 of the same spectral bands and have one spectral band unique to either instrument, with the ABI featuring a 1.37 μm near-infrared band for cirrus cloud detection while the AHI uses a 0.51 μm band optimized for reflectance around the green portion of the visible spectrum. Lacking an explicit band for green light, true-color imagery for ABI is created using the combination of the ABI's red and blue visible bands along with a synthesized green band; the simulated green band is created by applying algorithms based on MODIS and AHI onto existing ABI spectral bands.
Bandλ Central
λ 		Pixel
spacing 		NicknameClassificationPrimary functionSource
10.45-0.490.471BlueVisibleAerosols
20.59-0.690.640.5RedVisibleClouds
30.846-0.8850.8651VeggieNear-infraredVegetation
41.371-1.3861.3782CirrusNear-infraredCirrus
51.58-1.641.611Snow/IceNear-infraredSnow/ice discrimination, cloud phase
62.225-2.2752.252Cloud Particle SizeNear-infraredCloud particle size, snow cloud phase
73.80-4.003.902Shortwave WindowInfraredFog, stratus, fire, volcanism
85.77-6.66.192Upper-level Tropospheric Water VaporInfraredVarious atmospheric features
96.75-7.156.952Mid-level Tropospheric Water VaporInfraredWater vapor features
107.24-7.447.342Lower-level Tropospheric Water VaporInfraredWater vapor features
118.3-8.78.52Cloud-Top PhaseInfraredCloud-top phase
129.42-9.89.612OzoneInfraredTotal column ozone
1310.1-10.610.352Clean Infrared Longwave WindowInfraredClouds
1410.8-11.611.22Infrared Longwave WindowInfraredClouds
1511.8-12.812.32Dirty Infrared Longwave WindowInfraredClouds
1613.0-13.613.32 Longwave InfraredInfraredAir temperature, clouds