New Delhi: The Axiom-4 crew is set to start its journey back to Earth from the International Space Station on 14 July, said NASA officials in a press conference Friday. The Axiom Space website pegs the ‘splashdown’ time and date for 4.35 pm IST, 14 July. This would make the mission an 18-day-long one, 4 days more than initially planned.
The NASA press conference was discussing the upcoming launch of the Crew 11 Mission to the ISS on 31 July, for which the Axiom-4 Mission will first need to be undocked. In his address to the media, NASA Commercial Crew Programme Manager Steve Stitch said they are monitoring the Axiom-4 mission closely.
“Of course, we’re working with the station programme and watching the Axiom-4 Mission carefully, of course we need to undock that mission (before Crew 11), and the target time for that is July 14,” said Stitch Friday.
The Axiom-4 Mission piloted by Shubhanshu Shukla and carrying veteran astronaut Peggy Whitson, European mission specialists Slawosz Uznanski-Wiśniewski (Poland) and Tibor Kapu (Hungary), reached the ISS on 26 June for a 14-day mission at the ISS. Shukla, Kapu and Uznanski-Wiśniewski are first visitors to the ISS and are the first people to fly to space in 40 years from their respective countries.
Aboard the ISS, Shukla has spent the last 2 weeks working on eight different research experiments by various Indian institutes, including the Indian Institute of Science (IISc) Bengaluru, National Institute of Plant Genome Research, and University of Agricultural Sciences in Dharwad. The experiments range from muscle regeneration to cyanobacteria to growing sprouts in space.
Shukla also spoke to Indian PM Narendra Modi Saturday, 28 June, where he assured him that he was “absorbing the learnings” on the mission.
“As we speak, we are moving at a speed of nearly 28,000 km/hour. This speed is somewhat symbolic of the speed at which our country is progressing. We have reached here. But there is still a long way to go,” Shukla said in his conversation.
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Why the delay?
The NASA press conference discussed the launch timings and date for the SpaceX Crew 11 mission, which is a long-duration science experiment mission where the astronauts are expected dock at the ISS until 2026. For the 4 astronauts of Crew 11 to reach and dock at the ISS, the Axiom-4 Mission will first need to undock to have enough space up on the ISS, explained NASA in the press conference.
14 July is the target date for Axiom-4’s undocking because it will be after the “high beta period” of the ISS, said Stitch.
The high beta period is a period when the ISS is facing the sun and absorbing maximum sunlight, for its solar panels. Usually, the high beta period peaks around the summer solstice which is 21 June, and lasts for about two weeks. High beta periods also heat up the spacecraft and require the ISS to do thermal management carefully, and it is also the time when the ISS is visible to most countries on Earth.
According to a 2019 article in Universe Today, arrivals and undocking of missions are usually avoided during the high beta period, which explains why Ax-4 Mission’s return is scheduled after the period ends.