Sunday evening looks likely to be the best of a bad bunch, at least as far as “ideal” launch days go, with a brand-new Falcon 9 booster and the once-before-used Dragon Freedom currently targeting a 5:37 p.m. EDT liftoff from historic Pad 39A at Florida’s Kennedy Space Center (KSC). The ten-day Ax-2 mission, flying on behalf of Houston, Texas-based AxiomSpace, Inc., has a crew of four—Commander Peggy Whitson, Pilot John Shoffner and Mission Specialists Ali Al-Qarni and Rayyanah Barnawi of Saudi Arabia—who will support more than 20 scientific research, technology and educational outreach investigations aboard the International Space Station (ISS).
According to the 45th Weather Squadron at Patrick Space Force Base, there exists a 60-percent likelihood of acceptable conditions for tonight’s launch, although that is expected to deteriorate sharply to only 20-percent-favorable for the backup opportunity at 5:14 p.m. EDT Monday and 30-percent-favorable on Tuesday. The arrival of a boundary layer in North Florida later today may provide “ingredients for an earlier start and greater coverage of convection”, the 45th noted in its L-1 update on Saturday, but weak flows make it likely that most storms will be clear of the launch site by Sunday evening.
Conditions are predicted to worsen for Monday’s backup launch attempt, with a “messy pattern” across Central Florida and “widespread convection likely”. At last week’s post-Flight Readiness Review (FRR) news conference, NASA leaders identified Sunday and Monday as the primary opportunities—although a backup date on Tuesday may also be available—after which Ax-2 would nominally need to stand down to make way for the month-long CRS-28 Cargo Dragon research mission, scheduled to launch to the ISS on 3 June.
No Autonomous Spaceport Drone Ship (ASDS) will be on duty tonight, as Ax-2 attempts SpaceX’s first Return to Launch Site (RTLS) of a crew-carrying Falcon 9 core. After powering the 230-foot-tall (70-meter) booster uphill for the opening 2.5 minutes of flight, B1080 will alight on Landing Zone (LZ)-1 at Cape Canaveral Space Force Station, trialing a new ascent profile which SpaceX Vice President of Build and Flight Reliability Bill Gerstenmaier expects will furnish “a little bit of extra Falcon performance”. An RTLS is also planned for the Crew-7 booster when it flies in mid-August.
In readiness for tonight’s post-sunset launch of Ax-2, B1080 was rolled out from the Horizontal Integration Facility (HIF) to Pad 39A on Thursday. Whitson, Shoffner, Al-Qarni and Barnawi participated in a Dry Dress Rehearsal (DDR) of their launch day practices and processes early Friday. And later that day, after the astronauts had disembarked and returned to their crew quarters, B1080’s nine Merlin 1D+ engines were ignited for a Static Fire Test that is customarily performed prior to the maiden outing of any new booster.
Although B1080 has not flown before, the Crew Dragon for this mission certainly has. Dragon Freedom will embarking on her second orbital trek, having previously supported the 170-day Crew-4 increment of NASA astronauts Kjell Lindgren, Bob “Farmer” Hines and Jessica Watkins, together with Italy’s Samantha Cristoforetti, which took place between April and October of last year.
An on-time launch tonight will see Dragon Freedom separate from the Falcon 9’s second stage and enter orbital flight about 11 minutes and 58 seconds into the flight, with the spacecraft’s nose cone unfurled a minute or so later to expose its rendezvous and other sensors. Whitson, Shoffner, Al-Qarni and Barnawi will follow the second-shortest launch-to-arrival transit of any Crew Dragon so far, with autonomous docking at the space-facing (or “zenith”) port of the station’s Harmony node expected at 9:24 a.m. EDT Monday, less than 16 hours after liftoff.
The new arrivals will be welcomed aboard the orbital complex by the incumbent Expedition 69 crew—Commander Sergei Prokopyev, his Russian colleagues Dmitri Petelin and Andrei Fedyayev, U.S. astronauts Steve Bowen, Warren “Woody” Hoburg and Frank Rubio and Sultan Al-Neyadi of the United Arab Emirates (UAE)—and will participate in a safety briefing, before heading directly into work. Ax-2 will support more than 20 multidisciplinary experiments spanning the life sciences, human research, physical sciences and technology, as well as about 130 hours of National Lab Science.
They also plan to carry several personal items with them. Whitson will fly her wedding necklace, Shoffner a toy spaceman from a Gemini spacecraft model he built as a child, Barnawi’s grandmother’s earrings and Saudi coffee and dates, courtesy of Al-Qarni.
Ax-2 is particularly significant, as it will mark the first time that any Saudi astronauts have visited the ISS and Barnawi is set to become the first female Saudi spacefarer. Al-Qarni is the second Saudi man to enter space, following Prince Sultan Salman Abdul Aziz Al-Saud, who flew aboard shuttle Discovery way back in June 1985.
Originally timelined as a 12-day flight, ten of which would be docked to the ISS, Ax-2 has been shortened to ten days, with eight of them docked, to make the mission “fit” into a busy ISS manifest, prior to the CRS-28 Cargo Dragon’s arrival. The shortened duration will prioritize Ax-2’s scientific payloads, with several low-priority activities, including some media events, deleted from the timeline.
On-orbit, the Expedition 69 has busily been preparing for Ax-2’s arrival. Last week, Bowen gathered and staged emergency hardware to accommodate the new arrivals and Al-Neyadi reviewed procedures and set up computers in the multi-windowed cupola and the U.S. Destiny lab to support Dragon Freedom’s inbound approach and docking.