United Launch Alliance (ULA) will wait one more day to fly its Mighty Atlas on a highly secretive mission for the National Reconnaissance Office, following a technical issue which cropped up shortly after the vehicle completed its rollout from the Vertical Integration Facility (VIF) to the Space Launch Complex (SLC)-41 pad surface at Cape Canaveral Air Force Station, Fla., on Monday.
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“Upon arriving at the pad, we experienced an upper payload environmental control system flow rate reduction,” ULA announced. “The team is in the process of rolling the Atlas V back to the VIF to complete troubleshooting. The vehicle and payload are healthy.”
ULA swapped out a damaged ECS duct with a reinforced one, proclaimed the issue resolved and rolled the rocket back to its launch pad.
Current plans are for the mission to launch at 5:54 p.m. EST Wednesday, with weather predicted at 70-percent favorable. As outlined in AmericaSpace’s recent preview article, the Atlas V—sporting upgraded boosters—will carry the highly secretive NROL-101 payload uphill for ULA’s fifth flight of 2020.
Following a smooth Launch Readiness Review (LRR) on Saturday, led by ULA Launch Director Tom Heter III in the Atlas Spaceflight Operations Center (ASOC) at the Cape and via virtual teleconferencing, the mission was declared ready for launch on Tuesday, with a predicted 90-percent probability of good weather.
However, concerns were raised about the possibility of high ground-level winds impacting Monday’s rollout of the Atlas V on its Mobile Launch Platform (MLP) from the VIF to the pad. Strong winds from the north were expected to be sustained near 35 mph (56 km/h), gusting at up to 43 mph (68 km/h) throughout Monday morning, with a relaxation in the afternoon.
With scattered clouds and brisk, but acceptable winds, ULA Launch Conductor Scott Barney formally completed a readiness check of systems status and Mr. Heter authorized the rollout of the 206-foot-tall (62.8-meter) booster.
“Stand Engineer, proceed with MLP transport to the pad,” Mr. Barney radioed to Isaac Spence at the VIF.
Powered out of the 300-foot-tall (100-meter) VIF with the aid of undercarriage railcars and trackmobile machines, and led by payload support and ground support vans and trailed by a pair of portable Environmental Control System (ECS) trailers, the 1.7-million-pound (770,000 kg) vehicle trundled its way across the 1,800-foot (550-meter) distance between the VIF and the SLC-41 pad surface. It took less than an hour to complete the trip.
But shortly afterwards it became clear that a scrub would occur. “Going to roll back to the VIF,” ULA CEO Tory Bruno tweeted. “Very high winds at the pad. May have sustained damage to the upper ECS duct. Spacecraft is fine, but need to check it out.” Launch was rescheduled for Wednesday at 5:54 p.m. EST.
Weather conditions for tomorrow’s targeted launch attempt are expected to be around 70-percent favorable, with a risk of infringing the Ground Winds and Cumulus Cloud Rules.
“The pressure gradient tightens and winds increase from the east-northeast,” explained the 45th Weather Squadron at Patrick Air Force Base in its L-1 update, issued Monday morning. “Continued onshore flow will bring the potential for a few cumulus clouds.”
As previously detailed by AmericaSpace, the NROL-101 mission will mark a return-to-flight of sorts for ULA, as it ends more than three launchless months and multiple scrubbed or postponed attempts to get the beleaguered Delta IV Heavy and its NROL-44 payload off the ground.
Only four missions—most recently the launch of NASA’s Perseverance rover on its multi-month voyage to Mars in July—have occurred so far, making 2020 one of ULA’s “lightest” years on record in terms of launch cadence.
If the Atlas V flies tomorrow, it will tie with 2019 on five missions, although expectations remain high that a sixth mission may launch out of Space Launch Complex (SLC)-6 at Vandenberg Air Force Base, Calif., as soon as December. That will see another triple-barreled Delta IV Heavy boost the highly classified NROL-82 payload uphill.
But even six launches (if achieved) will make 2020 one of the lowest-flown years on record; apart from 2019, you would have to look all the way back to 2005 to see as few as six flights executed by the Atlas V or Delta IV product-lines.
As for NROL-101, few details have trickled into the public domain about the nature of this classified payload. Its presence atop the Atlas V in its rarely-used “531” configuration—equipped with a 17-foot-diameter (5-meter) payload fairing, three solid-fueled boosters and a single-engine Centaur upper stage—offer a clue, for this particular vehicle can lift 34,350 pounds (15,575 kg) into low-Earth orbit and up to 16,480 pounds (7,475 kg) into Geostationary Transfer Orbit (GTO).
That affords a perspective on the potential size, mass and/or energy requirements needed to get NROL-101 into space.
The 531 itself has only flown three previous missions, delivering the first three Advanced Extremely High Frequency (AEHF) military communications satellites to GTO in August 2010, May 2012 and most recently 18 September 2013. “It’s just a less frequent mass and orbit combination,” Mr. Bruno recently explained. “For perspective, Atlas and Delta together come in over 41 configurations, with most of those being Atlas variants. So small numbers (even zero) for some configurations is to be expected.”
But as outlined previously by AmericaSpace, this particular 531 will be distinctive in that its three solid-fueled boosters are uprated Graphite Epoxy Motors (GEMs), supplied by Northrop Grumman Corp., which will henceforth replace the AJ-60A boosters previously provided by Aerojet Rocketdyne.
Designated “GEM-63”, they measured 63 inches (1.6 meters) in diameter and stand 65 feet (20 meters) tall, making them the longest single-case solid-fueled rocket motors ever built by Northrop Grumman. Contracts for their design and construction were awarded to Orbital ATK in September 2015, with a key aim to significantly lower costs to ULA and the U.S. Government. An extended GEM-63XL will also fly next year aboard ULA’s new Vulcan-Centaur.
The GEM-63s and the Atlas V hardware—a Common Core Booster (CCB) and Centaur upper stage—were delivered to the Cape earlier in the summer and the Launch Vehicle On Stand (LVOS) milestone to integrate them in the VIF was completed in September. Last month, the complete rocket, minus its Medium Payload Fairing (PLF), was put through a Wet Dress Rehearsal (WDR).
This involved loading the Atlas V with its flight supply of 25,000 gallons (113,650 liters) of rocket-grade kerosene, known as “RP-1”, which will remain in its tanks until launch. Additionally, 66,000 gallons (300,000 liters) of cryogenic liquid oxygen and hydrogen were pumped into the rocket as part of WDR operations, but were drained at the end of the test. Finally, on 26 October, the PLF with NROL-101 snugly encapsuled inside, was attached to the giant rocket.
Tomorrow’s countdown is expected to formally commence about seven hours before the planned 5:54 p.m. EST launch. And with NROL-101 set to fly shortly after local sunset, the Atlas V promises to put on a spectacular light-show for spectators along the Space Coast.