The world’s largest and most powerful rocket must wait at least “a few days” to fly, following Monday morning’s scrubbed launch attempt of a fully integrated Starship/Super Heavy “stack” out of Starbase in Boca Chica, near the southernmost point of Texas. After a smooth fueling and countdown process—with a full load of around 10 million pounds (4.5 million kilograms) of liquid methane and liquid oxygen having been pumped into the giant rocket’s tanks—a pressurization issue associated with the Super Heavy first stage forced SpaceX to call off this ambitious launch and recycle for at least 48 hours.
Late Monday, SpaceX announced that teams are now targeting a second launch attempt on Thursday. The 62-minute “launch window” extends from 8:28 a.m. CDT through 9:30 a.m. CDT.
Powered uphill by the Super Heavy’s 33 Raptor engines—with a thrust reportedly reaching 16.7 million pounds (7.5 million kilograms)—the vehicle stands to enter the record books as the most powerful rocket ever orbited, with a liftoff impulse more than twice as great as the Saturn V and almost twice as great as NASA’s Space Launch System (SLS). And standing 394 feet (120 meters) when fully stacked, it will also be the tallest, almost 10 percent higher than the Saturn V and 25 percent taller than the Block I SLS which lofted Artemis I on its historic around-the-Moon mission late last year.
When fully operational, the Starship/Super Heavy will be capable of lifting up to 330,000 pounds (150,000 kilograms) of payload to low-Earth orbit in its fully reusable configuration and as much as 500,000 pounds (250,000 kilograms) if expended. Earlier this month, the first fully integrated vehicle was confirmed fully stacked at Starbase, with SpaceX tracking towards a flight opportunity in April’s third week, which eventually coalesced to a No Earlier Than (NET) target Monday 17th, opening at 7 a.m. CDT (8 a.m. EDT).
Late Sunday, SpaceX noted that it was “keeping an eye on wind-shear” in the Boca Chica area, but that overall weather was “looking pretty good” for launch. The Hawthorne, Calif.-headquartered organization subsequently opted to move deeper in the test “window”, initially aiming for 8 a.m. CDT, then 8:20 a.m. CDT by early Monday.
Teams at Starbase completed their “Go/No-Go” poll at T-105 minutes, after which the Launch Director authorized the commencement of loading around 10 million pounds (4.5 million kilograms) of propellant and oxidizer into the tanks of the Super Heavy and the Starship. Fueling kicked off at T-99 minutes when liquid methane—chilled to -168 degrees Celsius (-272 degrees Fahrenheit)—and liquid oxygen began flowing into the propellant tanks of the Super Heavy and the Starship.
At 230 feet (70 meters) tall, the Super Heavy is about the same height as a full Falcon 9 “stack”, although its fuselage is more than twice the width at 30 feet (9 meters). And the Starship itself stands 164 feet (50 meters) tall, approximately 25 percent longer than NASA’s now-retired Space Shuttle orbiter.
Plans called for teams to complete wrapping up fueling at T-5 minutes, with all tanks fully loaded by T-3 minutes. One watch item as the minutes ticked away was the presence of an unauthorized boat in the launch danger area, although SpaceX noted that it was “closely co-ordinating” with the U.S. Coast Guard to ensure public safety.
But another issue soon reared its head. Shortly before T-17 minutes, the reassuring tones of SpaceX Principal Integration Engineer John Insprucker brought caution in the form of a pressurization issue pertaining to the Super Heavy first stage. It seemed, he explained, that teams would soon scrub the launch attempt, but would continue the count and treat it as a Wet Dress Rehearsal (WDR), running through the remaining pressurization steps to achieve “full validation for the team”, before halting the clock at T-10 seconds.
Prior to the scrub, SpaceX CEO Elon Musk described the cause of Monday’s scrub in further detail. “A pressurant valve appears to be frozen,” Mr. Musk tweeted at 8:11 a.m. CDT, “so unless it starts operating soon, no launch today.”
It was therefore with an air of disappointment that the minutes ticked away towards a T-0 that would not see a launch on Monday but would see a great wealth of data in support of a future launch. “With a test such as this,” SpaceX tweeted, “success is measured by how much we can learn, which will inform and improve the probability of success in the future”.
Shortly afterwards, Mr. Musk added that teams would aim for another launch attempt, “retrying in a few days”, with at least 48 hours required to remove and recycle the propellants. That currently places this long-awaited test flight at NET Thursday, with a launch window extending from 8:28 a.m. CDT through 9:30 a.m. CDT and an expectation that the Starship will complete almost an entire orbit of Earth, before splashing down in the Pacific Ocean, northwest of Kauai in Hawaii.
As SpaceX’s new rocket stands down for a few days, two other missions are gearing up for their own launches from the Florida Coast. Early Wednesday morning, the 11-times-flown B1067 Falcon 9 core—which last flew just four weeks ago—will rise from storied Space Launch Complex (SLC)-40 at Cape Canaveral Space Force Station, laden with 2023’s 12th “stack” of Starlink low-orbiting internet communications satellites.
Last Saturday, the Autonomous Spaceport Drone Ship (ASDS), “A Shortfall of Gravitas”, put to sea out of Port Canaveral, to recover B1067 from her forthcoming launch. The drone ship took up position about 400 miles (640 kilometers) downrange in the Atlantic.
Weather conditions for Wednesday are predicted to be 90-percent-favorable, according to the 45th Weather Squadron at Patrick Space Force Base, deteriorating to 75 percent in the event of a 24-hour slip to Thursday. “Sunny skies and good weather conditions” are expected for the opening of Wednesday’s launch window, with the only “distant” concern being a threat posed by Liftoff Winds.
It will also mark SpaceX’s 25th flight in the year’s 17th week, an achievement reached with 15 boosters, two of which have already logged three missions each so far. To put that into perspective, in 2022 it took SpaceX until the third week of June to pass 25 launches in a single year; two years ago, it took until the middle of November; and only as recently as 2020 did it first surpass a quarter-century of flights across an entire calendar year.
But with a significant uptick in launch cadence in 2023’s opening quarter, SpaceX has averaged a launch every 4.2 days. April, though—for all the drama associated with Starship—has proven a quieter month, at least in its first half, with “only” three Falcon 9 launches: the inaugural Tranche-0 of the Transport and Tracking Layer (TTL) for the Space Development Agency (SDA), the Intelsat 40e geostationary communications satellite with NASA’s “hosted” Tropospheric Emissions: Monitoring of Pollution (TEMPO) and last weekend’s 51-payload Transporter-7 “rideshare” mission.
Following Wednesday’s launch, attention will turn to historic Pad 39A at the Kennedy Space Center (KSC), where the year’s second triple-barreled Falcon Heavy stands ready to fly late next week. Delayed from an original launch date of Tuesday 18th, SpaceX announced on Monday that it is now targeting no sooner than Wednesday 26th to lift the first of three heavyweight ViaSat-3 ultra-high-capacity broadband satellites on the initial leg of its trek to Geostationary Earth Orbit (GEO).
The Heavy, which boasts a brand-new center core and two previously used side-boosters, will be expended on this mission, owing to the high-energy requirements of the payload. It was put through a Static Fire Test of its 27 Merlin 1D+ engines last week.