The Indian Space Research Organisation (ISRO) has been lending its technical knowhow and sharing its experience to build a vibrant space ecology. The Indian startup Agnikul Cosmos’s recent suborbital mission, Agnibaan suborbital technological demonstrator (SOrTeD) is one instance of this support. This mission demonstrates how dedicated ISRO is in supporting and fostering private startups in the Indian space sector.
On Thursday (May 30), Agnikul Cosmos made history by successfully launching a sub-orbital, single-stage technology demonstrator rocket. This rocket was launched from Agnikul’s own launchpad, which they built at ISRO’s Sriharikota launch facility with the help of ISRO, the national space agency, and IN-SPACe, which oversees and supports space activities in India.
3D-Printed Engine for space
The single-stage rocket, Agnibaan SOrTeD, was powered by Agnikul Cosmos’s unique Agnilet engine. This engine is special because it is the world’s first 3D-printed, one-piece, 6 kiloNewton (kN) semi-cryogenic engine. Additionally, it was the first time a test rocket in India used a semi-cryogenic engine. The engine does not have any parts that move or connect. There is no welding or fusing involved. While using 3D printing for space hardware is not new, no one has ever used a completely 3D-printed engine before.
3D printing can make things more efficient, lower costs, and reduce the chances of mistakes. In engines with many moving parts, each joint, or wire could cause problems. Agnibaan’s engine, called Agnilet, was developed entirely by Agnikul’s own team. Agnibaan used India’s first semi-cryogenic engine, which runs on sub-cooled liquid oxygen (LOx) and aviation turbine fuel (ATF). These liquid propellants are safer and reusable compared to solid ones.
“Semi-cryogenic engines boost payload capacity, lower launch costs and enhance the reliability and performance of launch vehicles. ISRO is currently working on a semi-cryogenic engine called the SCE-200, which will be used in its GSLV Mk-III rocket,” says Girish Linganna, Aerospace and Defence analyst.
Liquid fuel propulsion helps make vehicles reusable because it allows for precise control of the engine, making it easier to start and stop multiple times. This control means the vehicle can be safely landed and refurbished for future flights. Additionally, liquid fuel engines can be inspected and repaired more easily compared to solid fuel engines, enhancing their reusability.
The rocket is also equipped with four carbon composite fins for passive control. Passive control refers to a method of stabilizing and guiding a rocket without using active mechanisms, such as thrusters, or moving parts. Instead, it relies on fixed components, such as fins, or aerodynamic surfaces, to maintain the rocket’s stability and direction during flight.
Planned Vertical Path
Unlike traditional sounding rockets that launch using guide rails, Agnibaan SOrTeD followed a planned vertical path. This allowed it to carry out specific flight manoeuvres to test important technologies needed for the company’s future orbital flights. Traditional sounding rockets that launch using guide rails are rockets that are typically guided by a set of rails during the initial phase of their launch. These rails help stabilize, and direct, the rocket until it reaches a speed where its fins and other control mechanisms can take over to guide its flight path.
The tests included Angikul’s proprietary autopilot, navigation and guidance systems. They also assessed whether the launch pad was ready for more ambitious missions in future. For commercial launches, the rocket’s first stage can be powered by four to seven engines, with an optional, smaller stage available, if needed. Many potential customers from various industries were eagerly awaiting the successful test of Agnibaan.
In December 2020, AgniKul made history as the first Indian space tech startup to sign an agreement with ISRO, gaining access to the national space agency’s expertise and resources.
ISRO’s Optimal Launch Site
While Agnikul uses many of ISRO’s facilities, having its own launch pad allows Agnikul to schedule launches whenever it wants. The company aims to launch 35-40 Agnibaan rockets each year.
According to Linganna, for the Agnibaan mission, SDSC-SHAR/ISRO played a key role in finding the right site for the sub-orbital flight and helped set up both the launch pad and the control centre. “They established a reliable network to ensure smooth data and communication flow between the launch pad, the control centre and the ISRO control centre. SHAR also developed thorough safety plans and procedures to make sure all operations were safe and efficient,” he adds.
They handled the necessary launch clearances and Notices to Airmen (NOTAMs) for all launch attempts and provided extensive range systems, such as tracking, timing, real-time data processing and master control operations. Additionally, SHAR provided historical wind data for flight planning and real-time atmospheric data to help decide the launch timing, along with important logistics support for system setup and launch activities.
Confirms Engine Test Success
After its first test in early-2021, the engine was confirmed at the Vikram Sarabhai Space Centre (VSSC) /ISRO in Thiruvananthapuram. The engine uses liquid oxygen (LOx) and kerosene or ATF as fuel in all its stages. VSSC/ISRO offered their expertise and helped conduct a 15-second hot test—in which the engine was fired and run for 15 seconds to check its performance and ensure it operated correctly under real conditions—of the semi-cryogenic engine. A 15-second hot test of a semi-cryogenic engine helps engineers verify that all components are working as expected before the engine is used in actual launch.
They also carried out acoustic tests for the rocket’s inter-tank structure at CSIR-NAL’s advanced acoustic testing facility, meaning they used advanced sound equipment to simulate and measure the noise and vibrations that the rocket’s inter-tank structure would experience during launch. This helps ensure that the structure can withstand the intense acoustic environment of a rocket launch.
VSSC thoroughly verified and validated the mission design. It also provided a complete flight termination system—a safety feature that can destroy a rocket if it goes off course, preventing accidents and ensuring public safety during launches—which included pyro charges, batteries, telecommand decoders and tracking transponders to ensure the mission’s safety. A flight termination system typically includes such devices as pyrotechnic charges to destroy the rocket, batteries to power the system, telecommand decoders to receive remote commands and tracking transponders to monitor the rocket’s position.
Pyro Charges: These are small explosive devices used to safely destroy or separate parts of the rocket if needed, often as part of the safety system.
Batteries: These provide the necessary power to the rocket’s systems, including the safety mechanisms and communication devices.
Telecommand Decoders: These devices receive remote commands from ground control and decode them to execute specific actions on the rocket.
Tracking Transponders: These are used to track the rocket’s position by sending signals back to ground control, helping monitor its flight path.
VSSC/ISRO provided on-site assistance with assembly, integration, wiring and final pyro operations—tasks involving small explosive devices used in rockets, such as for separation stages or activating safety measures—during the launch campaign, including the pre-countdown and countdown phases. Pyro operations ensure the rocket functions correctly and safely during launch.
Launch and Tracking Systems
According to Linganna, “ISTRAC/ISRO supported the launch by providing telemetry and tracking services through an agreement with the startup. The teams held detailed discussions to finalize important systems, such as the onboard telemetry setup—the system installed on a spacecraft to collect and transmit data about the spacecraft’s performance and condition back to Earth—and the network of ground stations for tracking. The onboard telemetry setup includes such information as the spacecraft’s position, speed, temperature and other vital statistics.
ISTRAC assisted with the launch using its two ground stations in Sriharikota. They provided integration, testing and real-time tracking services. They also created and used vehicle data acquisition software to manage and display real-time data for the control centre. On launch day, ISTRAC’s ground stations gave real-time support and confirmed the launch as successful.”
Support For STARTUPS
ISRO’s broad support for missions by Indian startups highlights the cooperative environment available to them in the Indian space sector. ISRO not only guarantees its support, but also encourages private companies to participate in space activities, fostering a dynamic space ecosystem in the country.