Historic Axiom-1 mission returned from ISS as Crew-4 prepares for launch

by Haygen Warren

The first all-private astronaut mission to visit the International Space Station (ISS), Axiom-1, has successfully returned to Earth. Crew Dragon Endeavour undocked from the station’s Node 2 zenith (or space-facing) docking port at 01:10 UTC Monday (9:10 PM EDT Sunday), with reentry and landing off the coast of Florida at 17:06 UTC Monday (1:06 PM EDT).

As Axiom-1 and its crew complete their mission, NASA’s Crew-4 astronauts and SpaceX continue to prepare for the launch of Crew Dragon Freedom to the ISS.

Axiom-1 Return

Following a launch to the ISS on April 8 atop Falcon 9 B1062-4, Crew Dragon Endeavour docked to Node 2 on the ISS Harmony module on April 9 and the crew entered the orbiting laboratory shortly afterward — signifying the start of the Axiom-1 (Ax-1) mission aboard the station. Over the course of the past two weeks on the ISS, the Ax-1 crew completed various science experiments while also participating in public engagement activities, such as speaking with students at Mission Control in Houston, Texas.

The multinational crew aboard Endeavour consists of American commander Michael López-Alegría and pilot Larry Connor, Israeli mission specialist Eytan Stibbe, and Canadian mission specialist Mark Pathy. López-Alegría is a former NASA astronaut, making his fourth trip to the ISS. Ax-1 has been the first flight into space for the three other astronauts.

The Axiom-1 crew: (left to right) Mark Pathy, Larry Connor, Michel López-Alegría, Eytan Stibbe. (Credit: SpaceX)

Unlike other missions to the ISS, each crew member was largely able to select which experiments they wanted to perform while on the ISS. The four crew members performed experiments researching stem cells, chronic pain and sleep disturbances during space travel, and many other subjects. Additionally, crew members partnered with many institutions and agencies on Earth who assisted with the completion of each experiment.

At the conclusion of their research, the crew worked to pack up their belongings and experiments, which were then placed inside of Crew Dragon Endeavour for return to Earth. On the day of undocking, the crew said their goodbyes to the NASA, ESA, and Roscosmos crew members of Expedition 67 before entering Dragon.

Before closing the hatch, the crew donned their SpaceX flight suits and prepared for undocking. This includes securing items inside Dragon and strapping themselves into their respective seats in the spacecraft.

The Axiom-1 crew then closed the hatch between their capsule and the ISS, while on the ISS, Expedition 67 crew members worked to close the hatch on the ISS side and depressurize the area between the Harmony module and Dragon.

Once the hatches are confirmed to be closed, the space between the hatches has been depressurized, and all crew on both the ISS and Dragon are in their planned positions, the command for Endeavour to undock was sent. Undocking followed shortly afterward.

As Dragon slowly backed away from the docking port, it used its Draco thrusters to maintain the proper orientation and trajectory. Endeavour performed a series of maneuvers using its thrusters to move away from the station. After undocking, Endeavour and the Ax-1 crew remained in low Earth orbit for almost 17 hours before re-entering Earth’s atmosphere.

Dragon is designed to splash down at sea, with multiple landing sites designated for each mission. Shortly before Dragon undocks, SpaceX teams closely evaluated each of the seven possible landing sites for the Ax-1 mission. These are located off the coast of Pensacola, Panama City, Tallahassee, Tampa, Cape Canaveral, Daytona, and Jacksonville, Florida. Teams factored in weather, wave height, visibility, and more when deciding Endeavour‘s landing location, and ultimately selected Jacksonville as the primary landing zone for Dragon.

The seven possible splashdown locations for Axiom-1. (Credit: NASA)

For the return of Ax-1, SpaceX positioned Megan (formerly known as GO Searcher) off of the eastern coast of Florida near the primary Jacksonville landing zone. In the Gulf of Mexico, Shannon (formerly GO Navigator), was waiting near the Panama City and Tallahassee landing zones as a backup.

Shortly before deorbit, the crew once again donned their SpaceX flight suits and strapped into their seats for the beginning of Dragon’s re-entry process. Before the start of the deorbit burn, Endeavour jettisoned its trunk, a part of the Dragon spacecraft that houses unpressurized cargo and Dragon’s solar panels. Once trunk jettison was complete, Endeavour fired its Draco motors for a 15-20 minute deorbit burn, lowering its orbit on a trajectory towards the chosen splashdown site.

Following the completion of its deorbit burn, Endeavour reoriented itself to the proper re-entry angle. Dragon’s protective nosecone, which protects Dragon’s docking port during ascent and re-entry, was also closed following the burn.

As Dragon screamed into Earth’s upper atmosphere, the air outside began to heat up to extreme temperatures of 1,930 degrees Celsius, forming an envelope of ionized air around the capsule. This blocks all communications between Endeavour and the ground, so a communications blackout period occurs during the first phase of Dragon’s re-entry.

Splashdown of Crew Dragon Resilience during the private Inspiration4 mission in September 2021. (Credit: SpaceX)

Communications was regained by the time Endeavour began its parachute deployment sequence. Initially, the spacecraft deployed two drogue chutes, descending under them for 30-60 seconds before deploying the four main parachutes that are used to slow it to an acceptable velocity for splashdown.

Endeаvour splashed down in the Atlantic Ocean, concluding the first private-astronaut mission to the International Space Station. The SpaceX recovery ship Megan will raise Endeavour out of the water and place it onto a platform where crews will work to extract the crew from their capsule.

Crew-4 Launch Preparations

The next crewed mission to the International Space Station will be the joint NASA/SpaceX Crew-4 mission, the fourth operational crew rotation mission to the ISS as part of the Commercial Crew Program.

The crew of Crew-4 consists of NASA astronauts Kjell Lindgren (commander), Robert Hines (pilot), Jessica Watson (mission specialist), and European Space Agency astronaut Samantha Cristoforetti (mission specialist). Upon their arrival at the ISS, the crew will begin a six-month-long science mission as part of Expedition 67 and later Expedition 68.

The astronauts arrived at the Kennedy Space Center on Monday, April 18, for the final week of preparations before launch. Throughout the week, the crew will complete various tasks and activities, including rehearsals with simulators and the actual flight vehicle. Additionally, the crew will likely participate in press conferences and public engagement activities in the lead-up to the launch.

The launch of Crew-4 is currently scheduled for 3:52 AM EDT (07:52 UTC) on Wednesday, from Launch Complex 39A at the Kennedy Space Center. With a tight schedule and the return of Axiom-1 having already been delayed due to bad weather before undocking, the launch of Crew-4 could slip a day or two depending on when exactly Axiom-1 returns.

Crew Dragon Freedom will be the Dragon capsule flying the Crew-4 mission, making its first journey to the ISS. The docking of Freedom and Crew-4 is expected to occur about a day after launch.

(Lead image: Crew Dragon Endeavour docked to the International Space Station during Axiom-1. Credit: NASA)

Related Articles