Charting Axiom-4’s 28-hour flight path from Earth to Station    

Ten minutes and four seconds after the scheduled lift-off from the Kennedy Space Center (KSC) in Florida on Wednesday, which is noon in India, the Dragon C-213 spacecraft carrying four astronauts, including an Indian, will separate from the Falcon-9 launch vehicle and begin a 28-hour journey to the International Space Station (ISS).

The separation from the Falcon rocket’s second stage booster will take place at an altitude of approximately 200 km, roughly midway between the Earth’s surface and the orbit of the ISS, which lies at about 415 km.

During its cosmic voyage, the Dragon will encircle the Earth at least twice, increasing its altitude in phases to match that of the ISS and adjusting its speed before docking with the manned orbital outpost.   The mission, christened Axiom-4, is being executed jointly by the National Aeronautics and Space Administration (NASA), a US government agency, SpaceX, and Axiom Space, both of which are US-based private space technology companies.

“All systems are looking good for Wednesday’s launch of @Axiom_Space’s Ax-4 mission to the @Space_Station, and weather is 90% favorable for liftoff,” SpaceX posted on its handle a few hours ahead of the launch at Florida’s 6:31 AM Eastern Daylight Time (EDT). The docking is expected on Thursday at 7 AM EDT, which would be 4:30 PM in India.

“Looking good, #Ax4!” Axiom Space posted on its handle on Wednesday morning in response to a post by an astronaut showing the four crew members just before they head to the suit-up facility at around 8 AM India time.

The mission was initially scheduled to launch on May 29, but was postponed several times because of unfavorable weather conditions or technical glitches like a leak on the Falcon’s liquid oxygen tank and loss of pressure in an ISS module.

Group Captain Shubhanshu Shukla, a seasoned fighter pilot and test pilot, is the designated pilot of the Dragon, a partially reusable spacecraft developed by SpaceX that will transport the crew back into the Earth’s atmosphere after about 14 days. Other crew members include the mission commander, Peggy Whitson, among the US’ most experienced astronauts, and mission specialists Sławosz Uznański-Wiśniewski, a scientist from Poland, and Tibor Kapu, an engineer from Hungary.

Shukla will be involved in key phases of the flight, including launch, orbital insertion, docking and undocking at the ISS, and the return journey. While the Dragon’s flight operations are mostly automated, Shukla will supervise the automated processes, handle any glitches, and take over the overriding manual control systems if needed. He is also responsible for coordinating communication with mission control on Earth.

According to details released by SpaceX, the Dragon will execute a series of fuel burns that will position the spacecraft progressively closer to the ISS before it performs the final docking maneuvers.

The entire sequence involves:  

1. Lift-off: The Falcon-9’s first stage lofts the Dragon crew module to orbit. The Falcon’s first and second stages separate at an altitude of around 70 km after a flight of two minutes and 28 seconds. The second stage then accelerates the Dragon to orbital velocity.
2. Orbit activation: The Dragon separates from the Falcon’s second stage nine minutes and 38 seconds after lift-off and performs initial orbit activation and checkouts of propulsion, life support, and thermal control systems.
3. Phasing burns: Delta-velocity orbit raising maneuvers are performed with the Dragon’s thrusters to catch up with the ISS. Delta-velocity, which represents a change in speed, is crucial for planning and executing space missions as it determines the amount of propellant needed for various maneuvers like orbital transfers, planetary landings, and interplanetary trajectories.
4. Approach initiation: The visiting spacecraft establishes a communication link with the ISS and performs its final orbit raising delta-velocity fuel burn.
5. Proximity operation: The Dragon establishes relative navigation to the ISS and arrives along the docking axis, initiating an autonomous approach.
6. Docking and pressurisation: Performs the final approach; the Dragon docks on the ISS’ Harmony module, followed by pressurization of the vestibule, hatch opening, and crew ingress.

According to NASA, two women flight engineers onboard the ISS, Anne McClain and Nichole Ayers, will be on duty on Thursday, monitoring the Dragon during its automated approach and rendezvous.   Both are NASA astronauts. While Anne is a Colonel in the US Army, Nichole is a Major in the US Air Force. In fact, on May 1, they had jointly undertaken a spacewalk for six hours and 35 minutes to undertake maintenance activities on the exterior of the ISS.

Less than two hours after docking, the Dragon’s hatches will open, and the Axiom-4 crew will enter the space station. They will meet with the seven members presently stationed on the ISS as part of Expedition 73, call down to Earth for welcoming remarks, participate in a safety briefing, and complete other formalities before settling down to their tasks.

The seven ISS residents sharing space with the four visitors are led by Takuya Onishi, an astronaut from the Japan Aerospace Exploration Agency, who is on his second trip. The others include three from NASA and three from Russia’s Roscosmos.

Over the next two weeks, the Axiom-4 crew will conduct around 60 scientific studies and activities. These cover a wide range of topics such as medical support for diabetic astronauts, the effects of microgravity on the brain and body, and the collection of vital health data. The impact of space travel on joints, blood flow, stem cells, cancer growth, and radiation exposure are other areas of research.

The Indian Space Research Organisation (ISRO), which has an expansive program on space research, in collaboration with NASA and the European Space Agency, is focusing on advancing microgravity research aboard the ISS to enhance understanding of biological processes in microgravity and develop strategies for long-duration space missions.

ISRO’s research studies include investigating the physical and cognitive impact of computer screens in microgravity, studying the growth, metabolism, and genetics of three microalgae strains in microgravity as compared to that on Earth, and comparing the growth, cellular responses, and biochemistry of two cyanobacteria strains in microgravity.

Also, on the academic agenda are identifying pathways of skeletal muscle dysfunction in microgravity and exploring therapies, examining spaceflight impacts on six crop seed varieties, investigating the impacts of spaceflight on the germination and growth of crop seeds, and identifying molecular mechanisms of resilience in extreme environments.

The Axiom‑4 mission is also a critical marker for ISRO’s human spaceflight program, referred to as Gaganyaan. The programme envisions sending a three-man crew into an orbit of about 400 km above the earth. Some test flights of components and validation of critical technologies have already been undertaken, and the manned flight is expected to take place in 2027. Group Captain Shukla’s experience in manned space flight would be an important element in the research, planning, and execution of the programme.