Samudrayaan mission: How oceans make going to space look easy

Days after Elon Musk’s SpaceX nailed the breathtaking capture of a 200-ton Super Heavy rocket, the dream of sending humans to Mars inches closer to reality.
While Mars has yet to welcome its first human visitors, its soil is already home to a fleet of rovers. These robotic explorers have peeled back layers of Martian mystery, not just studying the planet’s surface but probing its air, its poles, and the secrets buried deep beneath.
We have similar data on the Moon, thanks to the daring Apollo missions that first sent humans to our celestial neighbour in the 1970s. Now, the US, Russia, China, and India are all eyeing new human expeditions to the lunar surface. Yet despite our growing expertise in sending astronauts to the International Space Station — an impressive 400 kilometers above Earth — we, oddly, know little about one of our own planet’s most fascinating realms: the deep ocean.
The vast, pitch-black seafloor remains an enigma. For centuries, humans have tried to unlock its secrets, often failing in the face of unforgiving natural forces.
But India is ready to take that plunge, literally. The nation is preparing to launch Samudrayaan, a bold mission to explore the ocean’s frigid depths, where sunlight vanishes, temperatures plummet, and the crushing pressure makes human survival seem unthinkable.
The mission aims to send the submersible Matsya-6000 to a staggering depth of 6,000 meters below sea level. But don’t be fooled — this journey is far from straightforward. Engineers are facing challenges that make space travel look routine in comparison.

India’s Samudrayaan mission will plunge into the depths of the ocean. (Photo: NIOT)

Ocean depths are classified by light penetration, which stops at around 100-150 meters. Beyond that, there’s total darkness.
And while space may be a vacuum, the ocean depths present their own dangers — pressure so intense it could crush ordinary vessels like a tin can.
When it comes to exploring the deep sea, one of the greatest challenges is communication or rather, the lack of it.
Unlike space missions, where electromagnetic waves can zip across vast distances in seconds, the ocean is an entirely different story. In space, radio signals can be relayed through satellites, allowing astronauts to stay in near-constant contact with mission control.
But underwater, it’s a whole new ballgame. Here, sound is the only reliable medium for communication because electromagnetic waves can’t penetrate water.

Juno spacecraft communicates with Earth from orbit around Jupiter. (Photo: Nasa)

This reliance on sound presents its own set of issues. Sound waves travel much more slowly than radio waves, meaning commands sent to submersibles like Samudrayaan take precious time to reach their destination.
Once the signal arrives, the reply faces the same slow crawl back. For Samudrayaan’s pilots, that means an eight-second delay for any communication—an eternity in mission-critical moments.
To navigate these depths, sonar—a technology based on sound navigation and ranging—becomes the go-to tool for mapping and understanding the ocean floor. But even sonar has its limits, adding to the complexity of exploring this dark, silent world.
Space may be a near-perfect vacuum, but the ocean’s depths are a crushing world of extreme pressure. Astronauts in space don pressurized suits to keep their bodily fluids from boiling away due to the absence of external pressure. But in the deep sea, it’s the opposite problem: the deeper you go, the more intense the pressure becomes as water piles up, ton by ton, above you.
At extreme depths like the Mariana Trench, pressure can reach over 1,000 times the pressure at sea level, equivalent to having several tons of weight pressing on every square inch of your body.
For India’s Samudrayaan mission, which plans to dive 6,000 meters into the ocean, the challenge is just as daunting. The pilots will face a pressure 596 times that of Earth’s atmosphere, which is like having the weight of 1,848 elephants pressing down on their vessel.

Diving into the ocean presents numerous challenges. (Photo: Getty)

This enormous pressure makes deep-sea exploration as perilous as space travel, if not more. Submersibles like Matsya-6000 must be engineered with materials strong enough to resist being crushed. Regular steel won’t cut it in these depths, as the corrosive seawater would eat it away. Instead, high-strength materials like titanium, combined with special coatings, are needed to build a sub that can withstand the forces at work.
“Pressure increases as we go down into the ocean, making thicker materials necessary. Seawater is corrosive, so we can’t use steel. Titanium with proper coating is crucial. There’s no light, so we also need illumination. Everything must be encapsulated to ensure the systems not only survive but perform their tasks,” explained Dr. S. Ramesh, Scientist-in-Charge of the Deep Sea Mission.
Without these technological safeguards, the risks of structural collapse are all too real, making deep-sea missions an engineering marvel—one that rivals even the feats of space exploration.
For centuries, ocean exploration has fascinated humanity, with early expeditions mapping sea routes that ultimately paved the way for global trade. However, delving into the depths beneath the surface is a far more complex challenge, one that demands advanced technology—and significant funding.
While countries worldwide regularly conduct ship-based surveys, there is a glaring lack of high-resolution data about the deep sea.

India’s deep-sea submersible Matsya-6000 at NIOT. (Photo: Sibu Tripathi)

India’s Deep Ocean Mission (DOM), with a five-year budget of Rs 4,077 crore, aims to fill these gaps. Yet, as the National Institute of Ocean Technology (NIOT) works to develop the necessary equipment and infrastructure, the costs are expected to rise, underscoring the financial hurdles of exploring Earth’s final frontier.
India’s aerospace sector is riding high on the wave of Chandrayaan-3’s success, with the space sector now opening up to private players. However, when it comes to deep-sea exploration, the scene remains more traditional—largely dominated by government agencies, with private industry yet to dive in.
As India gears up for ambitious underwater missions like Samudrayaan, scientists are increasingly vocal about the need for an indigenous industry that can cater to the growing demands of ocean exploration.
At present, the National Institute of Ocean Technology (NIOT), which is at the helm of developing Samudrayaan, is heavily reliant on imports for critical components. This dependence not only drives up costs but also slows down development.

There is a glaring lack of high-resolution data about the deep sea. (Photo: AFP)

“An India-based industry would drastically reduce operational expenses, speed up development, and ensure quicker turnaround times,” explains Professor Balaji Ramakrishnan.
Despite the staggering challenges, the NIOT team is pushing forward, collaborating with global experts to ensure India’s place in deep-sea exploration. The countdown is already on for the first wet test of Matsya-6000, before it plunges to depths of 6,000 meters below sea level in the coming years.