NASA Starliner astronauts Sunita Williams and Butch Wilmore won't be coming back home on the Boeing spacecraft. Starliner will return uncrewed by September 6, while the two astronauts will reach Earth on a SpaceX craft in February next year. What might have prompted the US space agency to take such a step? Past mistakes and two space shuttle disasters are cited as the reasons.
"We have had mistakes done in the past. We lost two space shuttles as a result of there not being a culture in which information could come forward...," NASA Administrator Bill Nelson said on August 24. Nelson said this when he announced that NASA astronauts Sunita Williams and Butch Wilmore would be ditching Boeing's Starliner to return home on SpaceX Dragon Crew spacecraft.
By "two space shuttles", Nelson may have been referring to the space shuttle Challenger in 1986 and the space shuttle Columbia in 2003.
The Columbia disaster is said to "have changed NASA forever." The mission was called STS-107, and Kalpana Chawla was part of it. Mission Specialist Chawla was among seven astronauts who lost their lives minutes before landing on Earth in 2003. She was the first Indian-American astronaut and first Indian woman in space.
STS-107 was the first shuttle mission in 2003. Columbia space shuttle lifted off on January 16, 2003. It was a 17-day mission featuring numerous microgravity experiments. It was "strictly a multidiscipline microgravity and Earth science research mission" and involved 80-plus International experiments.
All went well until the disaster ensued during the return mission. Upon re-entry to Earth, the orbiter and its seven crew members were lost approximately 15 minutes before Columbia was scheduled to touch down at Kennedy Space Center (KSC) in the US, NASA said.
The landing was planned on February 1, 2003. NASA explained that upon re-entering, the Shuttle orbiter, Columbia, suffered a "catastrophic failure due to a breach that occurred during launch...". The Columbia and crew were lost during reentry over East Texas at about 9 am EST.
"Communication and tracking of the shuttle was lost at 9 am at an altitude of about 2,03,000 feet above north central Texas while traveling approximately 12,500 miles per hour (Mach 18). No communication and tracking information was received in Mission Control after that time," NASA had then said.
The then Nasa Administrator Sean O'keefe had said, “This is indeed a tragic day for the NASA family, for the families of the astronauts who flew on STS-107, and likewise is tragic for the Nation.”
NASA had investigated a foam strike that took place during the launch. Space.com explained that around 82 seconds after Columbia left the ground, a piece of foam fell from a "bipod ramp" that was part of a structure that attached the external tank to the shuttle.
"Video from the launch appeared to show the foam striking Columbia's left wing. It was later found that a hole on the left wing allowed atmospheric gases to bleed into the shuttle as it went through its fiery re-entry, leading to the loss of the sensors and eventually, Columbia itself and the astronauts inside," the report added.
Just before the mishap, Columbia was travelling 18 times the speed of sound near Dallas. Mission Control made several attempts to contact the astronauts, but they were unsuccessful.
Twelve minutes later, a mission controller received a phone call. The caller said a television network showed a video of the shuttle breaking up in the sky, Space.com reported.
Following the incident, an investigation took place for seven months and a four-month search was conducted across Texas to recover debris. During the months that followed, searchers recovered more than 83,000 pieces of debris.
"Nearly 85,000 pieces of orbiter debris were shipped to KSC and housed in the Columbia Debris Hangar near the Shuttle Landing Facility," NASA said. "About 38 per cent of the orbiter Columbia was eventually recovered," the US space agency added.
Scientists have repeatedly reiterated that human spaceflights are risky and that re-entry into atmosphere is even riskier. “Spaceflight is risky, even at its safest and most routine. A test flight, by nature, is neither safe, nor routine," said NASA Administrator Bill Nelson on August 24.
Indian Space Research Organisation (ISRO) Chairman S Somanath had earlier explained that the return journey "is more dangerous than the onward journey".
While explaining the process of landing of India's future Moon mission, Chandrayaan 4, back on Earth, Somanath had said that landing on Earth is "much more difficult" and "equally challenging than landing on the lunar surface".
This is because "there's no atmosphere on the Moon, but there's an atmosphere on Earth," Somanath said, adding that "we have to overcome the atmospheric heat, etc...," during the return mission.
Taking a lesson from previous failures and risky re-entry process, Bill Nelson said, “The decision to keep Butch and Suni aboard the International Space Station and bring Boeing’s Starliner home uncrewed is the result of our commitment to safety: our core value and our North Star.”
The launch of Boeing's Starliner spacecraft, which carried NASA's Sunita Williams and Butch Wilmore to the International Space Station on June 5, was delayed twice. Despite the issues with the spacecraft, it was launched on June 5 and suffered anomalies during the journey.
Starliner, initially scheduled to launch on May 6, 2024, was delayed "due to a suspect oxygen relief valve on the Atlas V rocket’s Centaur second stage", NASA said.
During its journey to the International Space Station on June 5, NASA reported that some of the spacecraft’s thrusters did not perform as expected, while several leaks in Starliner’s helium system were observed.
Meanwhile, in Kalpana Chawla's mission, a breach had also occurred during the launch – when falling foam from the External Tank struck the Reinforced Carbon Carbon panels on the underside of the left wing. This eventually led to tragedy.
At a time when NASA and Boeing are still working to identify the root cause of the Starliner problems and fully understand the spacecraft, it would be a risk to bring astronauts aboard the same capsule that suffered anomies during the launch and even prior to the launch.
ISRO chief Somanath, while reacting to Sunita Williams' mission, had said that the Starliner "showed some anomalies, and [it appears to me that] they [NASA] don't want to take risks...because it has shown some issues in the past, even before launch," he said.
NASA and Boeing will proceed with undocking of the uncrewed Starliner spacecraft no earlier than 6:04 pm EDT (3:30 am) on Friday, September 6, from the International Space Station, pending weather and operational readiness.
After undocking, Starliner will take about six hours to reach the landing zone at White Sands Space Harbor in New Mexico. "The spacecraft will touch down about 12:03 a.m. on Saturday, Sept. 7, descending under parachutes and with inflated airbags to cushion the impact," NASA said.
Meanwhile, Sunita Williams and Butch Willmore will return on the SpaceX Crew-9 mission in February 2025.
