Isro's SpaDeX: India successfully conducts historic space-docking test

The Indian Space Research Organisation (ISRO) has successfully conducted its first-ever space docking, connecting two small spacecraft in orbit. This technology is crucial for India's future ambitions of building a space station and achieving manned lunar missions. The mission, named SpaDeX, was launched on December 30 from the Satish Dhawan Space Centre in Sriharikota, southern India. The two spacecraft were launched by a single rocket and separated in space.

The docking process was originally scheduled for January 7 but was rescheduled multiple times. On Thursday morning, ISRO announced that they had made history, becoming the fourth country in the world to master this technology, following the United States, Russia, and China. Indian Prime Minister Narendra Modi witnessed the scientists' tests at ISRO's office in Bangalore.

Prime Minister Modi subsequently posted on social media platform X, stating, "This is an important step for India's ambitious space missions in the future." Federal Science Minister Jitendra Singh also expressed his relief that the docking had "finally" succeeded. The two spacecraft on SpaDeX (short for Space Docking Experiment) are named SDX01 or "Chaser" and SDX02 or "Target". Each spacecraft weighs about 220 kg, and since their launch, they have been operating in space at carefully chosen speeds.

"They were launched together into space, but upon separation, they were given different speeds to establish a distance of 10-20 kilometers between them," Mira Mitra, a former NASA scientist and co-founder of Delhi-based space education company Stem and Space, told the BBC. "During the docking process, scientists maneuvered them to reduce the distance so that they could connect," she added. The docking was initially planned for January 7, but ISRO later postponed it by two days, saying they needed to conduct "more tests through simulations" before the actual docking. The second time, they stated that there was a glitch when attempting to bring the satellites closer, but added that the spacecraft were safe.

On Sunday, ISRO said that scientists had successfully reduced the distance between the "Chaser" and the "Target" first to 15 meters and then to 3 meters. They stated that after a test run, the spacecraft were "moved back to a safe distance," and they were analyzing the data. S. Somanath, who was the head of ISRO at the time of the SpaDeX (Space Docking Experiment) launch and had been monitoring its progress until his retirement a few days prior, had described the docking as "a very complex process" that required extreme precision and coordination.

First, the two spacecraft had to be in the same orbit so that the "Chaser" could begin approaching the "Target." On Thursday morning, scientists first gradually reduced the speed of the two spacecraft, bringing them closer and closer until they were only 3 meters apart. Then, their connectors were latched together. Next, the two spacecraft were perfectly screwed together, forming an airtight passage for the safe transfer of materials or personnel, thus completing the space docking. An ISRO official told the BBC that in the next two to three days, the mission would conduct one of what is considered its most important experiments—it will transfer power from the "Chaser" to the "Target."

Ms. Mitra said that this is to demonstrate that a spacecraft can be sent to service another spacecraft in space. The experiment will also demonstrate "the undocking and separation of the two satellites." Ms. Mitra stated that the mission will also test India's inter-satellite communication capabilities, as the spacecraft must communicate with ground stations and with each other during docking and undocking so that they know each other's position and speed. The spacecraft also carry scientific instruments and cameras, which will then be deployed. Over the next two years, they will measure radiation in space and monitor natural resources on Earth.

ISRO, known for its economical space missions, also utilized a part of the rocket that sent SpaDeX into space—a part that would normally become space debris—to conduct some important experiments in orbit for three months. PSLV Orbital Experimental Module (POEM) is carrying 24 payloads and has already successfully conducted two experiments. The first experiment demonstrated seed germination. Last week, ISRO posted a video on X stating that "cowpea sprouts showed their first leaf in space under microgravity." Microgravity is the near weightless condition experienced on spacecraft.

Scientists say this is good news because it means that future astronauts can produce food on long-duration missions. The second experiment involves a robotic arm, which Ms. Mitra said is one of the most important payloads of the rocket. A video on ISRO's X account showed the robotic arm moving to grab a piece of space debris. Ms. Mitra said that this arm will play a "key role in the construction of space stations, as it can be used to capture and place objects." She added that it will also come in handy for "Chandrayaan-4" (India's next lunar mission), which aims to collect and bring back lunar soil samples.