Take a look at the essential concepts, terms, quotes, or phenomena every day and brush up on your knowledge. Here’s your knowledge nugget on the significance of Shubhanshu Shukla’s return from space.(Relevance: UPSC has asked questions on space missions, and considering the significance of the Axiom-4 mission, it becomes an important topic for your exam. Knowing the important facts related to Shubhanshu Shukl, only the second Indian to go the space, and the significance for India, will be helpful for your upcoming exams.)Why in the news?After spending 18 days on the International Space Station and orbiting around the Earth 288 times, Indian astronaut Group Captain Shubhanshu Shukla and his three colleagues on the Axiom-4 mission splashed down in the Pacific Ocean on Tuesday (15th July) after a 20-hour journey from the International Space Station.This mission not only strengthens India’s foray into human spaceflight but also showcases its growing contribution to space research through a series of significant experiments led by Shukla aboard the International Space Station (ISS).Key Takeaways:During his time in space, Shukla conducted and completed all seven microgravity experiments and other scheduled scientific tasks. These included research on the Indian strain of Tardigrades, Myogenesis, Sprouting of methi and moong seeds, Cyanobacteria, Microalgae, Crop seeds, and the Voyager Display.1. Study of space microalgae: Among the most crucial of Shukla’s experiments was the study of space microalgae to examine their ability to generate food, oxygen, and biofuels. The resilience of microalgae in microgravity is considered key to sustaining human life during extended space missions. Additionally, through centrifugation of cyanobacteria, Shukla compared two strains to understand the impact of microgravity on their growth and biochemical activity.2. Myogenesis study: Shukla conducted microscopic observations and sample collection for the Myogenesis study, aiming to understand muscle cell behaviour in space. The results are expected to benefit not just future Moon or Mars missions but also medical treatments for muscle-wasting diseases and age-related immobility on Earth.Story continues below this ad3. Sprouting of methi and moong seeds: As part of the Sprouts project, he observed how methi and moong seeds germinate in space. subjected the sprouts to -80 degree Celsius temperatures to study the impact of microgravity on seed development. Upon return to Earth, he will cultivate the seeds, and multiple generations will be observed for any changes in genetics, microbial ecosystems, and nutritional profiles, aiming to identify plants with desirable traits for sustainable farming in space. Group Captain Shubhanshu Shukla enjoying a stunning panoramic view of the Earth from the 7 windowed Cupola Module of International Space Station (ISS), on Saturday. (@ISROSpaceflight X/ANI Photo)4. Studies on astronaut health and safety: Shukla and his crewmates participated in several collaborative studies to assess astronaut health and safety. These included measuring radiation exposure with the Rad Nano Dosimeter, studying mental and cardiac health during prolonged spaceflight, observing heat transfer and the human body’s adaptability to microgravity and conducting neuromuscular electrical stimulation sessions to explore ways to combat muscle loss in space.5. Muscle atrophy: He also investigated muscle atrophy using the Life Sciences Glovebox facility and contributed to sustainable space agriculture by irrigating crop seeds under microgravity conditions. Tardigrades have long fascinated scientists as they can withstand extreme conditions. Wikimedia Commons (File Photo)6. Research on the Indian strain of Tardigrades: Tardigrades, also known as “water bears”, are robust aquatic animals that have been around for roughly 600 million years, 400 million years before dinosaurs walked the planet. The study on the Indian strain of Tardigrades was part of Shukla’s experiments. The primary objective of the experiment was to identify the genes that are responsible for making these animals resilient.Story continues below this adReason for the study of TardigradesThese micro-animals were discovered in 1773 by German zoologist Johann August Ephraim Goeze. They have been part of intensive research because tardigrades are remarkably resilient creatures, known to survive in the harshest of conditions. Water bears have been known to withstand temperatures as low as minus 272.95 degrees Celsius or as high as 150 degrees Celsius; endure ultraviolet radiation of space and pressures of 40,000 kilopascals (equivalent to what can be experienced at a depth of 4 km under the ocean’s surface); and live after being stored in a freezer for 30 years7. Study on cyanobacteria: Through centrifugation of cyanobacteria, Shukla compared two strains to understand the impact of microgravity on their growth and biochemical activity. The findings could support the development of sustainable systems for carbon and nitrogen recycling in space and highlight cyanobacteria’s potential as a superfood for long-duration missions.8. Voyager Display: This experiment focused on the interaction between humans and electronic displays in microgravity. The experiment also checked if using screens in space makes astronauts feel more stressed or tired. The experiment was designed by IISc, Bengaluru.9. Seed resilience trials: It involved seed resilience trials, testing rice, cowpea, sesame, brinjal, and tomato seeds that have been exposed to microgravity. The objective is to assess the impact of space conditions on these seeds, to advance space agriculture, and develop climate-resilient plant varieties suitable for cultivation on Earth and beyond a microgravity environment.10. About Axiom-4 mission: The mission was launched on 25th June, 2025, after much delay and anticipation. It carried four astronauts into space along with Shukla: Peggy Whitson from America as commander of the mission, Slawosz Uznanski-Wisniewski from Poland, and Tibor Kapu of Hungary. The crew travelled to the ISS on a SpaceX Dragon spacecraft using the Falcon 9 rocket. The mission is operated and managed by Axiom Space, a private US space companyStory continues below this ad01Why is splashdown preferred?When a spacecraft re-enters the Earth’s atmosphere, it experiences deceleration due to friction. At this time, the speed comes down to about 25-30 km per hour, which is safe for a splashdown in the ocean.The low viscosity and high density of water provide a much greater cushion. The other reason is the availability of vast open spaces, which, in the case of landing on the ground, would require precise definition. Also, in the ocean, there is no danger of hitting something else, even if the spacecraft is dragged a bit off-course by air or water currents.02Why do astronauts need Reconditioning?Astronauts need reconditioning after coming back to Earth in order to deal with the symptoms they experience. The reconditioning process includes training the astronauts to start listening to their inner ear again, helping with motion control, and taking care of conditions they face when they are standing. It also deals with their perception of the movement of their own bodies, strength, and endurance. In addition, it looks at the astronauts performing skilled activities.03What is microgravity?According to NASA, "Microgravity is the condition in which people or objects appear to be weightless. The effects of microgravity can be seen when astronauts and objects float in space. Microgravity can be experienced in other ways, as well. “Micro-” means “very small,” so microgravity refers to the condition where gravity seems to be very small." It is not same as zero-gravity.BEYOND THE NUGGET: SpaDeX Mission1. The SpaceX Dragon spacecraft docked with the International Space Station (ISS), which involves an intricate procedure as ISS orbits Earth at an altitude of more than 400 km, and the procedure takes place while both the space station and the approaching vehicle are travelling at speeds of around 27,000 km/h. In January, India became the fourth country to successfully dock two satellites in space with the launch of the SpaDeX (Space Docking Experiment) satellites.2. The SpaDeX mission was lifted off from the Satish Dhawan Space Centre in Sriharikota on December 30 by PSLV-C60 and successfully placed two satellites in the desired lower earth orbit (below 2000 Km). Two small satellites, the SDX01 Chaser and SDX02 Target, injected in a 475-km circular orbit after the launch, have successfully demonstrated docking.3. Docking is a process by which two fast-moving spacecraft are brought to the same orbit, brought closer to each other manually or autonomously, and finally joined together. This capability is necessary for carrying out missions that require heavy spacecraft that a single launch vehicle may not be capable of lifting off with.4. This technology will be required for setting up the Bharatiya Antariksh Station. The first module is planned to be launched in 2028. It is supposed to have five modules, which are expected to be launched separately and brought together in space.Story continues below this ad5. Docking capability will also be required for the next lunar mission, Chandrayaan-4, which aims to bring back samples from the Moon. This mission will see five key modules sent into orbit in two separate launches.Post read questionConsider the following statements:1. When a spacecraft re-enters the Earth’s atmosphere, it experiences acceleration due to friction.2. Rakesh Sharma was the first Indian to go to the International Space Station (ISS).3. Tardigrades are robust terrestrial animals that have been around for roughly 600 million years.Which of the following statements is/are incorrect?(a) 1 and 2 only(b) 2 and 3 only(c) 1 and 3 only(d) 1, 2, and 3Story continues below this adAnswer key(d)(Source: Simpler, safer: Why spacecraft prefer splashdowns over landing on ground, Methi sprouting to microalgae: 7 experiments Shubhanshu Shukla conducted in space, Knowledge Nugget: Axiom-4 mission — What you must know for UPSC Exam, What’s next for Shubhanshu Shukla, other astronauts on return from space mission, Knowledge nugget of the day: SpaDeX Mission)Subscribe to our UPSC newsletter. 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