This mission is an important step for ISRO as it will showcase its ability to dock two spacecraft in space.
India is gearing up for a major milestone in its space journey with the launch of the Space Docking Experiment (SpaDEX), planned for December 30, 2024. The mission will be carried out by the Indian Space Research Organisation (ISRO) using the Polar Satellite Launch Vehicle (PSLV-C60). The rocket is set to take off at 9:58 PM IST from the Satish Dhawan Space Centre in Sriharikota.
This mission is an important step for ISRO as it will showcase its ability to dock two spacecraft in space. This is a key technology for future space missions. The main goal is to design and test the systems needed for bringing two spacecraft together, docking them, and then separating them again.
Mission Summary and Goals
The SpaDEX mission will send two identical satellites into space, named Chaser (SDX01) and Target (SDX02) . Each satellite weighs about 220 kilograms .
The two satellites will be positioned in a circular orbit 470 km above Earth, at an angle of 55 degrees. The objectives of the mission are:
Showing accurate movements needed to bring the satellites close together and connect them.
Testing how electricity can be shared between two connected spacecraft.
functioning of the payload after the satellites separate, with the mission lasting up to two years.
Note : The term “payload” refers to the essential equipment or instruments carried by a spacecraft to perform its mission. It’s a critical part of the satellite, as it directly contributes to achieving the mission’s goals.
ISRO announced that the PSLV-C60 rocket has been fully assembled and moved to the First Launch Pad for final tests before the mission.
India’s Progress Toward a Space Station
The SpaDEX mission is an important step for India’s space exploration goals,” an ISRO official said. “It will make India the fourth country in the world to develop advanced docking technology.”
This technology is important for missions that need several launches to work together for a shared goal. It will be useful for tasks like repairing satellites, coordinating multiple spacecraft to fly in formation, and building complex structures in space, such as India’s planned space station, the Bharatiya Antariksh Station (BAS).
Creative Use of PSLV’s Fourth Stage : Apart from its docking goals, the mission will make use of the PSLV rocket’s used-up fourth stage, called POEM-4 (PSLV Orbital Experimental Module). Instead of letting it go to waste, this stage will be turned into a platform to carry out experiments in microgravity, helping scientists test and study various conditions in space.The mission will carry 24 payloads onboard, provided by various academic institutions and startups.
“PSLV’s Fourth Stage Transformed for Experiments”
The 4th stage of the PSLV rocket is the final part that helps place satellites into their orbits. Once its job is done, it usually becomes space junk, floating unused in orbit. However, ISRO has found a way to reuse it by turning it into a science platform called POEM. Now, instead of being wasted, it carries small experiments and tests in space, especially in microgravity. This makes better use of the rocket and reduces waste in space.
After placing satellites into their desired orbits, the PSLV’s 4th stage (PS4) remains in space with leftover fuel and onboard systems like batteries, solar panels, and communication equipment. ISRO modifies this stage to act as a platform for experiments. By attaching scientific instruments and sensors to it before launch, the stage can perform experiments in microgravity, test new technologies, or study space conditions. The fuel helps in minor adjustments, and its power systems keep the experiments running, turning the once-unused stage into a cost-effective space lab.
Mission Design and Implementation Strategy
The Chaser and Target will be released into orbit at the same time but as separate objects.
The PSLV rocket is very accurate, so it will make sure the satellites are placed in orbit with only a small difference in their speeds. This means the satellites will start off moving almost together, making it easier to control and manage their movements in space.
The Target satellite will use its onboard thrusters to slowly move away from the Chaser satellite, creating a distance of 10-20 kilometers between them. This phase is called the “Far Rendezvous” (a planned meeting or approach in space), where the satellites are far apart but still close enough to interact or prepare for the next steps in the mission.
The Chaser satellite will gradually move closer to the Target satellite in steps, reducing the distance between them to 5 kilometers, then 1.5 kilometers, then 500 meters, 225 meters, 15 meters, and finally 3 meters. At this final distance, the two satellites will connect, or “dock,” with each other. Once they are docked, the mission will test the transfer of power from one satellite to the other. After this test is complete, they will separate again to carry out other tasks with their payloads.
The Chaser satellite, is equipped with a powerful high-resolution camera. The Target satellite, is equipped with special tools to study Earth and space. It carries a multispectral sensor, which can capture detailed images in different light wavelengths. This helps monitor natural resources, track vegetation health, and study the environment. Additionally, it has a radiation monitor to measure space radiation, which will help scientists collect important data and build a database for future research.
Why SpaDEX Matters ?
The SpaDEX mission is more than just a technology test; it is an important step toward ISRO’s bigger plans. Learning how to dock spacecraft is essential for future goals like bringing back samples from the Moon, exploring other planets, and creating a long-term human presence in space.
India is working to join a small group of countries—the US, Russia, and China—that have successfully developed in-space docking technology. This mission highlights ISRO’s dedication to creating advanced space technology that is both effective and affordable.
For the first time, ISRO is sending a robotic arm into space to test how it can collect space debris. Along with this, India’s first astrobiology experiments (studies related to life in space and how living organisms survive in space conditions) created by students from RV College of Engineering in Bengaluru and Amity University in Mumbai, are also heading to space. These experiments are part of the 24 payloads that the POEM platform will carry.
Out of the 24 payloads, 14 come from ISRO’s Department of Space. One of these will focus on developing technologies to grow and sustain plants in space or on other planets. The remaining 10 payloads are from non-government organizations, including contributions from educational institutions.
A team of undergraduate students from RV College of Engineering (RVCE) has created India’s first microbiology experiment for space research. Developed by Team Antariksh, the project focuses on studying how gut bacteria behave in space conditions. According to GS Varshini, the 20-year-old mission manager, this research is important for understanding how space affects human health, as this specific gut bacterium plays a key role in maintaining overall well-being.
Their experiment will study how gut bacteria grow in microgravity. By adding prebiotics (nutrients that help bacteria grow), they will compare its growth in space with how it grows on Earth. This research is important for astronaut health, as it will help scientists understand how the human microbiome works in space. The findings could also be useful for managing waste in space, cleaning up pollutants (bioremediation), and creating new antibiotics for future space missions.
Debris Capture & CROPS Research
The CROPS (Compact Research Module for Orbital Plant Studies) payload is designed to help ISRO explore ways to grow and maintain plants in space in the future. This could be an important step for long-term space missions.
Along with this, a robotic arm is being sent to test how it can capture space debris. As part of the experiment, a small cube (called a debris cube) will be attached to the robotic arm with a tether (a rope, chain, or similar device used to attach or secure something).The cube will be released into space, and the robotic arm will try to retrieve it. This test could help develop technology to clean up space debris in the future.
Cowpea Seed Growth Experiment
The CROPS payload, created by VSSC, is designed as a step-by-step platform to help ISRO develop the ability to grow and support plants in space or other planets.
It is a fully automated system that will run a 5 to 7-day experiment to test if seeds can sprout and grow into small plants (up to the two-leaf stage) in microgravity.
The experiment will use eight cowpea seeds, which will grow inside a closed box with controlled temperature. Various conditions like oxygen (O2) and carbon dioxide (CO2) levels, humidity, temperature, and soil moisture will be monitored. Cameras will also capture images to track the plants’ growth. This research could help us understand how to grow food in space in the future.
Robotic Arm for Space Debris
Debris Capture Robotic Manipulator : Developed by VSSC, this experiment is designed to test how a robotic arm can capture space debris using a tether (a type of cord or cable that keeps objects connected). The robotic arm uses cameras and advanced motion prediction technology to locate and grab the debris, even as it moves in a space-like environment. It will also test a special tool called a parallel end-effector—this is like a robotic hand designed to grab and hold objects securely, making it easier to manipulate debris or other items in space.
If this experiment works successfully, the robotic arm could eventually be used for more complex tasks in space. For example, it could capture free-floating debris (objects drifting in space without being tethered) or even refuel spacecraft, whether they are tethered or floating freely. These abilities will be very useful in future POEM missions, helping clean up space junk and making space operations more efficient. This research is a step toward solving the growing problem of space debris and improving how we maintain and use spacecraft in orbit.
Spinach Growth Experiment in Space
In a unique experiment, Amity University, Mumbai, will study how plants react to microgravity using its Amity Plant Experimental Module in Space (APEMS) payload.
Amity University Vice-Chancellor, Santosh Kumar, explained that the experiment will use spinach (Spinacia oleracea) to study how plant cells (called callus, which are a mass of undifferentiated plant cells) grow and change under both space and Earth’s gravity. Sensors and cameras will monitor the growth and color of the callus, helping scientists understand how plants adapt to different gravity conditions. This research is important for figuring out how to grow plants during long space missions and could also benefit farming on Earth.
(The author of this article is a Defence, Aerospace & Political Analyst based in Bengaluru. He is also Director of ADD Engineering Components, India, Pvt. Ltd, a subsidiary of ADD Engineering GmbH, Germany. You can reach him at: girishlinganna@gmail.com)
(Disclaimer: The views expressed above are the author’s own and do not reflect those of DNA)
