No sooner has the dust cleared from its most recent launch in January, United Launch Alliance (ULA) has successfully delivered the latest Geostationary Operational Environmental Satellite—currently known as “GOES-T”, but set to be numerically redesignated “GOES-18” when it enters active service—into orbit from Space Launch Complex (SLC)-41 at Cape Canaveral Space Force Station, Fla.
Liftoff of ULA’s rarely-used Atlas V 541 rocket with a 17-foot-wide (5-meter) Short Payload Fairing (SPF), four strap-on solid-fueled boosters and a single-engine Centaur upper stage occurred on time at 4:38 p.m. EST Tuesday, 1 March, incidentally four years to the day since the launch of the previous satellite in the constellation, the problem-prone GOES-S.
From its eventual geostationary orbital perch at an altitude of about 22,300 miles (35,900 kilometers), the Lockheed Martin-built GOES-T will mark the third and penultimate member of the fourth generation of Earth-watching spacecraft which have revolutionized our understanding of the Home Planet since the 1970s. It was ULA’s second launch of the year, following the USSF-8 mission for the U.S. Space Force in January.
Weather for launch proved favorable, with a 70-percent probability of acceptable conditions on both the prime (Monday) and backup (Tuesday) targets. Scattered showers and a “possible” isolated thunderstorm—the result of a cool front, stalled in south-central Florida—were predicted for Monday afternoon.
Those conditions were expected to linger into the backup launch day on Tuesday, with the principal issues of concern being a potential violation of the Cumulus Cloud Rule and Surface Electric Fields Rule. As circumstances transpired, conditions improved to 90-percent favorable by T-0.
Operated by the National Oceanic and Atmospheric Administration’s (NOAA) National Environmental Satellite, Data and Information Service (NESDIS), the multi-spacecraft GOES network is responsible for weather forecasting, storm tracking and meteorological research from geostationary orbit. It became customary for each satellite to be alphabetically identified before launch and renamed with a number after entering service. As such, GOES-T will be redesignated “GOES-18” when it commences operations.
Contracts to fabricate instruments for this latest incarnation of GOES were awarded back in 2006 and Lockheed Martin was selected by NASA in December 2008 to build and integrate an initial pair of spacecraft, each with an option for one additional spacecraft, at an total cost (including exercised options) of $1.09 billion. Those spacecraft—GOES-R and GOES-S—were launched atop ULA Atlas V boosters in November 2016 and March 2018.
The additional spacecraft option was subsequently activated in May 2013 to build GOES-T and GOES-U. In December 2019, NASA awarded a $165.7 million contract to ULA to launch GOES-T and in September 2021 the agency’s Launch Services Program (LSP) picked SpaceX to deliver GOES-U to orbit atop a Falcon Heavy booster in April 2024.
Based upon Lockheed Martin’s A2100A “bus”, GOES-T weighs some 11,500 pounds (5,200 kilograms) and its unfurlable solar arrays will produce around four kilowatts of electrical power. Aboard the spacecraft, in pride of place sits the Advanced Baseline Imager (ABI) which will acquire terrestrial imagery across 16 spectral bands, including two visible, four near-infrared and ten infrared channels.
This will enable observations of cloud formation, atmospheric motions, convections, land-surface temperature mapping, ocean dynamics and aerosols and air quality. The ABI’s sensitivity represents a twofold enhancement over earlier GOES incarnations.
Alongside the ABI, the Geostationary Lightning Mapper (GLM) will observe lightning emissions at near-infrared wavelengths, helping to alert forecasters to severe weather, developing storms and tornadoes. First utilized aboard GOES-R, this instrument can detect lightning by day and night, with a detection rate of 70-90 percent of all strikes within its viewing area.
A group of solar and space environment sensors also reside aboard the GOES-T bus. The Extreme Ultraviolet and X-ray Irradiance Sensors (EXIS) will examine solar irradiance upon Earth’s atmosphere, whilst the Solar Ultraviolet Imager (SUVI) will produce full-disk images of the Sun at extreme ultraviolet wavelengths.
Rounding out the GOES-T payload are the Magnetometer (MAG) and Space Environment In-Situ Suite (SEISS). The former will furnish generalized data on geomagnetic activity as part of ongoing efforts to predict solar storms and facilitate large-scale space environment modeling, whilst the latter comprises four sensors to monitor proton, electron and heavy ion fluxes in the magnetosphere.
Original plans called for GOES-T to be launched in May 2020 for an anticipated 15-year active operational lifetime. Development and testing of the spacecraft proceeded smoothly and in August 2017 the EXIS and SUVI instruments had been installed at Lockheed Martin’s facility in Littleton, Colo. A few weeks later, on 22 September, GOES-T’s system module and core propulsion module were mated to begin the satellite-level integration and test phase of the mission.
However, a few weeks after the March 2018 launch of GOES-S, a cooling issue arose with the ABI when its infrared detectors could not be properly maintained at their requisite operating temperatures under certain seasonal and orbital conditions. The net result was a drop in the instrument’s availability throughout the course of a year.
And this corresponded to a loss which exceeded its key design requirements. An investigative board, chaired by David McGowan, chief engineer at NASA’s Langley Research Center (LaRC) in Hampton, Va., was convened to determine the root cause and identify corrective actions.
In its October 2018 report, the board traced the problem to the Loop Heat Pipe (LHP), which was meant to transfer waste heat from the ABI electronics to GOES-S’s radiators. Due to the existence of probable foreign object debris within the heat pipe, the flow of coolant to the instrument was blocked.
Mr. McGowan’s board recommended changes to the ABI radiators on future satellites—including GOES-T—with a simpler hardware configuration and ammonia, rather than propylene, as a coolant. GOES-T was structurally complete by late summer 2018 and had just been ensconced in Lockheed Martin’s Thermal Vacuum Chamber (TVC) to commence environmental testing, when NOAA ordered its ABI to be removed and returned to its manufacturer, Harris Corp.
Unsurprisingly, the GOES-T launch slipped from May 2020 to December 2021 as engineers dug into the ABI rebuild. Finally, in March of last year the spacecraft—with its new ABI and an upgraded MAG—in place, completed its TVC campaign, which included thermal, vibration, acoustic and shock tests.
By last summer, the GOES-T launch had moved to 8 January 2022, in order “to optimize launch schedules” from SLC-41. And last September, that date moved again to no sooner than 16 February.
In the meantime, late last fall GOES-T was transported via truck from Littleton, Colo., to Buckley Space Force Base in Aurora, Colo., before being airlifted aboard a C-5M Super Galaxy to Florida. It arrived at the Launch and Landing Facility (LLF) at the Kennedy Space Center (KSC) last 10 November, after which it was moved to Astrotech Space Operations in nearby Titusville for checkout.
In tight lockstep with the arrival of GOES-T, the Atlas V Common Core Booster (CCB) and Centaur upper stage were delivered from ULA’s facility in Decatur, Ala., to the Space Coast last November, arriving aboard the R/S RocketShip vessel on 15 November. The four Graphite Epoxy Motor (GEM)-63 strap-on boosters were delivered to Florida earlier this spring.
“Rocket boosters packed up and on the road,” prime contractor Northrop Grumman Corp. tweeted on 18 January. By this stage, the GOES-T launch had moved to a two-hour “window”, set to open at 4:38 p.m. EST on 1 March.
Over the next few weeks, efforts for this mission entered high gear. The last day of January was officially Launch Vehicle On Stand (LVOS) Day, when the 107-foot-long (32.6-meter) Atlas V CCB was raised upright inside the Vertical Integration Facility (VIF) at SLC-41.
Over the next four days, the four GEM-63 boosters were attached around its base. And on 7 February, the upper part of the vehicle—an interstage, the Centaur and the lower halves of the payload fairing—were hoisted into place.
More recently, on 17 February the SPF, containing GOES-T itself, was added to the stack, topping off the Atlas V at 196 feet (59.7 meters). This particular configuration of the rocket is nicknamed “The Dominator”.
And with this bulbous fairing in place, the vehicle looked comically top-heavy as it rolled the quarter-mile (400-meter) distance from the VIF to the SLC-41 pad surface on Monday. The Launch Readiness Review (LRR), led by NASA Launch Manager Tim Dunn, had previously been concluded on Saturday.
The Atlas V’s Russian-built RD-180 engine roared alive at T-2.7 seconds, quickly ramping up to 860,000 pounds (390,000 kilograms) of thrust. At zero, the four GEM-63s ignited, punching the stack airborne with a propulsive yield of 2.3 million pounds (1.1 million kilograms).
Passing Mach 1 at 35 seconds into flight, the vehicle encountered peak aerodynamic turbulence (known as “Max Q”) on its airframe shortly thereafter. The four GEM-63 boosters burned for 110 seconds, before separating in pairs, with each separation event timed 1.5 seconds apart.
With the boosters gone, the Atlas V continued powering uphill under the raging thrust of the RD-180. At 3.5 minutes, the SPF was discarded, exposing GOES-T and the Centaur to the space environment for the first time.
Finally, the RD-180 shut down at 4.5 minutes and the stack coasted, before the CCB was jettisoned. The stage was now set for no fewer than three “burns” by the Centaur’s restartable RL10C-1 engine, which would position GOES-T for separation at three hours and 32 minutes into flight.
The spacecraft’s orbital parameters at separation were predicted to carry an apogee of 21,925 miles (35,286 kilometers) and a perigee of 5,515 miles (8,875 kilometers). Over the next few months, GOES-T will undergo an extensive orbital checkout campaign, before assuming the “GOES West” operational location by January 2023.Missions » GOES-R »