What makes the launch of Agnibaan SorTeD by Agnikul Cosmos unique?

Come March 22, 2024, and history will be made when Chennai based space start up ‘Agnikul Cosmos Private Limited’ will launch its rocket, named Agnibaan Sub-Orbital Technology Demonstrator (Agnibaan SOrTeD), from the private launchpad at the Satish Dhawan Space Centre, Sriharikota Andhra Pradesh. The launch marks an important milestone by being a vehicle that is flying with the world’s first single piece 3D printed semi-cryogenic rocket engine and launching from India’s first private launchpad, ALP-01 located at SDSC SHAR. The inaugural flight of Agnibaan SOrTeD, Mission-01, serves as a test f light, gathering crucial flight data and ensuring optimal functioning of systems for Agnikul’s orbital launch vehicle, the ‘Agnibaan’. 

Semi-cryogenic engine Agnibaan SOrTeD is India’s first ever vehicle equipped with a semicryogenic engine, the Agnilet, a subcooled liquid oxygen based propulsion system developed indigenously. It will also has the first ever ethernet based avionics architecture and fully in-house developed autopilot software from India.  Agnikul had inaugurated a launch pad within ISRO’s Sriharikota spaceport, replete with a control room exclusively for its use. 

“This event is also a landmark in India’s space exploration history, signifying the first launch site operated by the private sector in the country. The construction of this facility signifies the growing involvement of private companies in India’s space sector and highlights the collaborative efforts between ISRO and private firm,” remarked space experts Girish Linganna. 

Interestingly Agnikul Cosmos is a space startup located in Chennai that originated from the incubation program at IIT-Madras. In December 2020, Agnikul Cosmos established in 2017 by Srinath Ravichandran, Moin SPM and Satya Chakravarti became the inaugural company in India to enter into an agreement with the ISRO as part of the IN-SPACe initiative. This agreement granted Agnikul Cosmos access to the expertise and facilities of ISRO to construct their rocket, Agnibaan. 

“The company is currently developing a technique that allows the rocket to be launched from a specialized platform mounted on the rear of a truck. This approach enhances flexibility and mobility in comparison to conventional launch systems,” remarked Linganna. 

The distinct feature of Agnibaan SOrTeD lies in its propulsion system, which operates on a combination of commercially sourced aviation turbine fuel (kerosene) and medical-grade liquid oxygen. This cutting-edge approach to rocket propulsion marks a considerable advancement in the field of space technology. 

The Agnibaan rocket has 3 stages, which stands 18 meters tall and is 1.3 meters in diameter. It has the capability to carry a 100-kg payload up to a height of 700 km with a lift of mass of 14,000 Kgs. The rocket uses liquid oxygen (LOX), stored in a tank at very low temperatures, and kerosene, which is kept at normal, room temperature. Agnibaan’s first flight will be suborbital, not entering space, lifting off from Satish Dhawan Space Centre, Sriharikota. It will ascend vertically to 10 km, then descend, landing in the Bay of Bengal, 30 km from its launch site. 

The primary section of the rocket, also known as the first stage, is propelled by a group of seven Agnite engines. These engines generate a thrust of 25kN each when operating at sea level. The entire combustion area is manufactured as a single component using 3D printing technology.The second stage of the rocket is driven by the identical Agnite engine as the first stage. As for the third stage, it is an additional stage that is not always necessary and is positioned within the payload fairing. This fairing has enough space to accommodate either a single or multiple small satellites. The rocket engines employ batteries and electric motors to operate the fuel pumps. To ensure the safe export and transportation of the rocket, it is designed without any explosives or pyrotechnics. Instead, pneumatic systems are utilized for the separation of stages. 

“Agnikul Cosmos is setting a new milestone for Indian private companies by using a semi-cryogenic engine in its rocket something even ISRO has not done yet. ISRO conducted its first test of a semi-cryogenic engine on a test bed on July 3 last year, but it has not yet flown one. This move by Agnikul Cosmos showcases its innovative spirit and dedication to advancing India’s space technology capabilities. A semi-cryogenic engine is a type of rocket engine that uses a combination of liquid oxygen (LOx) as the oxidizer and a refined form of kerosene, such as RP-1, as fuel. In contrast, a cryogenic engine uses both fuel and oxidizer in their liquid states at extremely low temperatures—typically liquid hydrogen (LH2) as the fuel and liquid oxygen as the oxidizer. The main difference is that semi-cryogenic engines use a fuel that is storable at higher temperatures compared to cryogenic engines, which makes handling and storage simpler while still offering high performance,” explained Linganna. 

This expert says that cryogenic engines offer higher efficiency and thrust with cleaner emissions than semi-cryogenic engines due to the use of liquid hydrogen. They excel in space, but require complex handling due to extremely low storage temperatures. 

In additon to that the Agnikul launch is set to mark a global milestone with its indigenously produced unique, single-piece 3-D-printed engine. This innovative vehicle boasts a plug-and-play engine system, which can be tailored to meet the specific requirements of each mission. A plug-and-play engine design is like using interchangeable parts for a rocket, making it easy to swap out, or upgrade, for different missions, saving time and money, while offering flexibility. 

“3-D printing creates engines by stacking material in precise layers from a computer design, enabling rapid production of complex, lightweight parts. This method is more efficient, using only necessary materials and allows for intricate structures that traditional cutting methods cannot achieve, leading to innovative and cost-effective engine designs,” pointed out Linganna. 

The Agnibaan SOrTeD rocket will launch vertically instead of using the traditional guide rails and will follow a specific trajectory. As it ascends, it will carry out a sequence of precise manoeuvres. This approach demonstrates the sophisticated technology and skill behind Agnikul Cosmos’s initial sub-orbital launch. Sub-orbital flights are space missions that go high enough to enter space, but do not circle Earth. They go up, cross the edge of space, and then come straight back down without orbiting the planet. They do not have the velocity necessary to stay in orbit around Earth.