Weather conditions are 90-percent-favorable for Wednesday’s next attempt to get the snakebitten Crew Flight Test (CFT) of Boeing’s CST-100 Starliner spacecraft airborne. This initial crewed mission to the International Space Station (ISS)—flown by Commander Barry “Butch” Wilmore and Pilot Suni Williams—will rise atop a United Launch Alliance (ULA) Atlas V rocket from storied Space Launch Complex (SLC)-41 at Florida’s Cape Canaveral Space Force Station, during an “instantaneous” window at 10:52 a.m. EDT.
Wilmore and Williams will spend at least eight “docked” days aboard the ISS, conducting a wide range of critical flight test objectives, before returning to a parachute-and-airbag-aided landing in the southwestern United States. In so doing, they will become the first NASA astronauts to return from an orbital space mission to land on solid ground in America since the final voyage of the Space Shuttle Program in July 2011.
The key weather watch-word for tomorrow’s launch attempt and a backup opportunity at 10:29 a.m. EDT Thursday is a potential violation of the Cumulus Cloud Rule. “A mid-level trough will begin to approach the Deep South tomorrow,” noted the 45th Weather Squadron at Patrick Space Force Base in a Tuesday update, “causing weak steering winds to begin shifting westerly.
“Atmospheric moisture will also begin to increase,” it was added. “The sea breeze boundary should develop near the time of the launch window, possibly triggering cumulus clouds that pose a risk, but the threat appears low as most convective development should occur after the launch window.”
And that launch window at 10:52 a.m. EDT is an instantaneous one, with ULA, Boeing and NASA targeting just a single moment in time to get the 172-foot-tall (52.4-meter) Mighty Atlas—flying in its rarely used “N22” configuration, equipped with a Common Core Booster (CCB), a pair of Aerojet Rocketdyne-furnished AJ-60 solid-fueled boosters, a Dual-Engine Centaur (DEC) upper stage and a Launch Vehicle Adapter (LVA) for Starliner—off the ground. With a liftoff thrust of 1.6 million pounds (725,750 kilograms) of thrust, this mission marks the 100th outing by an Atlas V since August 2002 and the first time a member of this rocket family has carried humans in over six decades.
Flying in a variety of configurations, with two different-sized payload fairings and none or as many as five strap-on solid-fueled boosters (dependent upon mission requirements), the Atlas V has delivered commercial geostationary communications satellites, classified payloads for the National Reconnaissance Office and the U.S. Space Force, a flotilla of military weather, surveillance and early-warning assets, five X-37B Orbital Test Vehicles (OTVs) and a smorgasbord of exploratory voyages to learn more about the Sun, the Moon, visit distant Pluto for the first time, orbit, land and rove on the ochre-hued plains of Mars, circle giant Jupiter and investigate its Trojan minor bodies and visit and gather microscopic surface grains from the carbonaceous asteroid Bennu.
In its N22 configuration, it also launched Starliner on a pair of uncrewed Orbital Flight Tests (OFTs) in December 2019 and May 2022. But the crew-carrying CFT—which will enable Boeing and NASA to complete final certification of Starliner before regular astronaut rotation missions to the ISS—has already met with a multitude of delay as thermal control system issues and software glitches caused its launch to slip from late 2022 until mid-2023, before being indefinitely stood down last summer in response to parachute-line concerns and ultimately rescheduled for 2024’s opening half.
An opening launch attempt back on 6 May was scrubbed two hours prior to liftoff, by which time Wilmore and Williams were aboard Starliner and working through communications and pressure checks. The cause of the scrub was traced to a faulty oxygen relief valve on the Atlas V’s second stage, but despite quick replacement and testing hopes to fly as early the 17th came to nought when a small helium leak was discovered in Starliner’s service module, an issue which teams have since managed to mitigate.
The result was a movement in the No Earlier Than (NET) date for launch firstly to 21 May, then no sooner than the 25th and eventually to the opening day of June, with a targeted T-0 point at 12:25:40 p.m. EDT. Agonizingly, last Saturday’s countdown was scrubbed less than four minutes before liftoff, when the Ground Launch Sequencer (GLS) was unsuccessful in its attempt to verify necessary redundancy.
Hopes to enter a 24-hour recycle and launch at 12:03 p.m. EDT Sunday were skipped to enable ULA to fully assess the GLS issue and teams realigned for the second pair of launch opportunities at 10:52 a.m. EDT Wednesday and 10:29 a.m. EDT Thursday.
“The ULA team identified an issue with a single ground power supply within one of the three redundant chassis that provides power to a subset of computer cards controlling various system functions, including the card responsible for the stable replenishment topping valves for the Centaur upper stage,” it was noted on Sunday. “All three of these chassis are required to enter the terminal phase of the launch countdown to ensure crew safety.
“On Sunday, the chassis containing the faulty ground power unit was removed, visually inspected and replaced with a spare chassis,” ULA continued. “No signs of physical damage were observed. A full failure analysis of the power unit will be performed to better understand root cause.”
Seconds after tomorrow’s launch, Wilmore will be heard making the “Roll Program” radio call, straight off the pad, as the Atlas V rolls onto the proper heading for injection into low-Earth orbit. The behemoth will pass through peak aerodynamic turbulence (colloquially termed “Max Q”) and exceed the speed of sound at just past a minute into the flight and the twin AJ-60 boosters will be jettisoned at T+140 seconds.
Riding onward under the RD-180, Wilmore and Williams will experience Booster Engine Cutoff (BECO) at 4.5 minutes into the flight. Multiple abort options, ranging from St. John’s, Newfoundland, to Shannon, Ireland, are available to the crew, as well as a notable Abort to Orbit (ATO) profile that enables Starliner—if needed in a serious contingency—to burn its engines and limp into a low 120-mile-high (200-kilometer) orbit.
After BECO, the Centaur will ignite its dual RL-10A engines for a lengthy “burn” of seven minutes and 15 seconds to push Starliner into orbit. Fourteen minutes and 55 seconds into the mission, the spacecraft—which Williams named “Calypso”, honoring the former British naval minesweeper made famous by French oceanographer Jacques Cousteau—will separate from the Centaur and enter a preliminary orbit inclined 51.62 degrees to the equator.
The astronauts will follow a 25-hour, 16-orbit rendezvous to reach the ISS, with docking anticipated at the forward port of the station’s Harmony node on Thursday. During their transit, Wilmore and Williams will be tasked with multiple test objectives, including manually repositioning their spacecraft, manually reacquiring Tracking and Data Relay Satellite System (TDRSS) assets, manually operating Starliner’s thrusters and commanding their vehicle in the close vicinity of the station itself.
After docking and following pressurization and leak checks, hatches will open and the newcomers will be welcomed by Expedition 71 Commander Oleg Kononenko, his Russian crewmates Nikolai Chub and Aleksandr Grebenkin and NASA astronauts Matt Dominick, Mike Barratt, Jeanette Epps and Tracy Dyson. An initial safety briefing and doffing of their customized “Boeing Blue” launch and entry suits will kick off an ambitious schedule of flight test activities expected to be completed in no fewer than eight docked days.
Several notable tasks will occur during that tightly timelined period. Wilmore and Williams will perform a “Safe Haven” period of isolation inside Starliner to demonstrate procedures for an emergency departure, including the powering-up and rapid checkout of spacecraft systems if an imminent undocking becomes necessary.
They will also complete pilot-proficiency training in support of future Starliner crews, which are expected to expand to four members on operational, long-duration missions. Since there are only two crew members aboard CFT, they expect to pull over two members of the Expedition 71 team to assist with their evaluations of four-crew operations. “If they’re nice,” Williams joked, “we’ll let them in”, adding that all four U.S. members of Expedition 71 are chomping at the bit to get an insider’s view of Starliner.
Undocking is set to occur after a minimum of eight “docked” days, about 6.5 hours prior to landing, a little sooner than it would happen on operational missions in order that Wilmore and Williams can perform additional tests. CFT will perform a minute-long deorbit “burn” over the Pacific Ocean, with four landing zones—two areas at White Sands, N.M., plus two others at Willcox Playa, Ariz., and Dugway Proving Grounds, Utah—available to the crew.
Starliner’s landing sequence will commence at an altitude of 30,000 feet (9,000 meters), with a set of drogue parachutes and later the main canopies “reefed” at 8,000 feet (2,400 meters). Touching down under parachutes and airbags, Wilmore and Williams will be extracted from the spacecraft, helicoptered to a landing field and then flown back to NASA’s Johnson Space Center (JSC) in Houston, Texas.
I feel very proud to see astronauts flight to the ISS as been privatized..
All the very best to Sumita and Butch
for the great success of their mission and
and to the team for their dedication and hard work.
Good luck to you all.
Godspeed.
Dipak Talapatra
Retired NASA Liaison
Manager to Canadian Space