NASA astronauts Sunita Williams and Butch Wilmore made headlines with their return to Earth on March 19 after an unexpected stay of over nine months at the International Space Station (ISS). They were aboard a SpaceX Crew-9 Dragon spacecraft carrying American Nick Haque and Russian cosmonaut Aleksandr Gorbunov. The mission began in June of the previous year, originally planned as an eight-day journey to test Boeing's Starliner during its first crewed flight. However, the Starliner was deemed unfit for return due to propulsion issues and subsequently returned empty. This unforeseen extension resulted in Williams and Wilmore spending 286 days in space, completing over 4,500 orbits and traveling more than 121 million statute miles. Now, they will undergo NASA's 45-day post-mission rehabilitation program to help them readjust to Earth's gravity after such a prolonged period in space. Their safe return not only marks the successful conclusion of their mission but also serves as an inspiring tale of human endurance and perseverance.
Upon their return, the astronauts were welcomed back to Earth in pleasant weather, with wind speeds of 2-3 knots and dolphins greeting them during their smooth landing at the designated spot. While their nine-month stay is remarkable, it is not the longest on record; that distinction belongs to a Russian astronaut who spent 662 days in space, although details of his experiences remain scarce. The lengthy duration of their stay will have both physiological and psychological impacts. For instance, bone density may decrease while their weight could increase, leading to muscle atrophy. These changes will complicate their adjustment to Earth, necessitating a rigorous rehabilitation program lasting 45 days to two months, supported by a team of experts and a variety of sensors. Damage incurred during their time in space can be categorised as either reversible—such as muscle atrophy and potential decreases in bone mass and height—or irreversible, like radiation exposure, which is significantly higher at an altitude of 400 km.
The complexities of rocket science contribute to the challenges faced by space scientists, whether in manned or unmanned missions. Rocket science encompasses intricate programs with numerous variables to consider, including propulsion, control, guidance, navigation, payload integration, and trajectory determination. The entire system is expected to meet Six Sigma standards, with redundancies built in to ensure that backup systems are available in case of failure. The unexpected extension of the astronauts stay illustrates that such exigencies are not routine and can present significant physical, physiological and psychological challenges, as well as logistical concerns regarding food supplies. Astronaut selection involves assessing candidates personality traits, stress tolerance and resilience to ensure they can withstand these challenges.
Rigorous training prepares astronauts for the demands of space travel, addressing both physiological and psychological aspects to make them more robust. Mission planning is crucial and must account for all potential exigencies. In this case, the initial challenge was successfully docking with the ISS, complicated by a propulsion system failure and helium leakage that delayed their return. SpaceX, in collaboration with NASA, effectively managed the challenge of sending a recovery vehicle, facilitating its safe return.
Upon their return, astronauts will face several physiological challenges, including vascular deconditioning that affects the hemodynamic system and equilibrium issues that may lead to disorientation and falls. Restoring hemodynamic stability is essential during the first 45 days to prevent syncope, while muscular atrophy is another concern, as any unused organ will undergo atrophy. Psychological adjustment to the circadian rhythm is also significant. These challenges underscore the importance of the rehabilitation period in restoring acclimatization to the terrestrial environment.
This experience provided valuable lessons for ISRO, highlighting the need to address various challenges, contingencies and crisis management in future missions. For human flights, whether involving a launcher or spacecraft modules like Dragon or Starliner, systems must be certified for human rating. This entails that most systems include triple redundancy and established procedures. The astronauts on this mission are not newcomers; each has completed three flights. The Dragon spacecraft has previously carried supplies, while a Soyuz spacecraft that could have been used remained parked, perhaps deemed unnecessary for this mission. The ISS can accommodate six astronauts, and supplies are stored for longer periods to prepare for emergencies.
The astronauts conducted about 200 experiments and completed 62 extravehicular activities for maintenance. Their landing was meticulously planned, with the tracking network—including the Tracking and Data Relay Satellite System (TDRSS) and ground networks—functioning precisely. The descent engine operated gradually, ensuring a safe return to a suitable environment. However, one concern is that acceleration can create issues in the blood and brain. When Gaganyaan launches, ISRO should leverage the experiences of NASA, Russian space agencies, and other allies to enhance its mission planning.
ISRO has programmes aimed at fostering interest in space among schoolchildren and college students aspiring to join ISRO or DRDO, both of which are heavily involved in space work. The Indian Institute of Space Science and Technology (IIST) in Thiruvananthapuram plays a significant role in this, offering numerous programs and establishing cells in various educational institutions. ISRO invites students to witness launches, significantly stimulating interest in space exploration and technology, suggesting a bright future for the field in the country.
To further this interest, the Prime Minister has invited Sunita Williams to visit India once she recovers. We hope she accepts the invitation, returns to her country of origin, and inspires the next generation of scientists eager to excel in space research and exploration.
(The author is an
advocate by profession)