International Defense Security & Technology Your trusted Source for News, Research and Analysis
Related Articles
In an era where space exploration is becoming increasingly commercialized, the need for cost-efficient, reusable space technologies is more pressing than ever. The Indian Space Research Organisation (ISRO) is rising to the occasion with a series of highly successful Reusable Launch Vehicle Landing Experiments (RLV LEX), culminating in the most recent achievement, the RLV LEX-03 mission. This program not only marks a significant milestone for India’s space program but also positions ISRO among the leading global space agencies developing cutting-edge reusable launch technology.
The Push Toward Reusable Launch Vehicles (RLVs)
Reusable Launch Vehicles (RLVs) are at the forefront of space innovation, enabling cost-effective missions by allowing components like the first stage of a rocket to be recovered and reused. Reusable rockets have emerged as a revolutionary solution to the high cost of space access. Traditionally, rockets were single-use, with each flight requiring the construction of a new vehicle. This approach made space access incredibly expensive, with launch costs reaching tens of millions of dollars per mission. The cost of rockets was predominantly concentrated in the first stage, which would burn up upon reentry into the atmosphere.
Traditional expendable rockets jettison their stages after use, but RLVs like the Pushpak vehicle return intact for refurbishment and relaunch, significantly reducing launch costs and making space exploration more sustainable. Reusable rockets are designed to be launched, landed, and launched again multiple times. Unlike traditional expendable rockets, which are used only once and then discarded, reusable rockets aim to recover and refurbish their components for future missions. This approach significantly reduces the cost per launch, making space access more affordable and sustainable.
What is the RLV LEX-03 Mission?
The RLV LEX-03 mission, conducted on June 23, 2024, is the third and final test in a series aimed at demonstrating autonomous landing capabilities for ISRO’s reusable launch vehicles. In this mission, the winged vehicle, named Pushpak, was released from a Chinook helicopter at an altitude of 4.5 km by the Indian Air Force (IAF). The Pushpak vehicle autonomously executed cross-range correction maneuvers, approached the runway, and performed a precise horizontal landing at the centerline of the runway in Chitradurga, Karnataka. It confirmed that ISRO had the necessary skills to develop an RLV. Earlier ISRO’s LEX-01 mission on April 2, 2023, and LEX-02 mission on March 22, 2024, had also been executed flawlessly.
Unlike its predecessors, the LEX-03 mission was executed under more challenging conditions, including a greater cross-range distance of 500 meters compared to LEX-02’s 150 metres and severe wind conditions, demonstrating the robustness of ISRO’s advanced guidance algorithms.The high-speed landing, which exceeded 320 km/h, was successfully controlled using brake parachutes and landing gear brakes, eventually slowing the vehicle to around 100 km/h.
“As this vehicle has a low lift-to-drag ratio, it had to land at a speed of over 320 km/h. In comparison, commercial planes usually land at around 260 km/h and fighter jets typically land at about 280 km/h. A low lift-to-drag ratio means an aircraft or object generates a relatively smaller lift compared to the drag it experiences, resulting in less efficient flight performance and increased fuel consumption. Drag is the force that resists an object’s motion through air or fluid, slowing it down and requiring energy to overcome,” explained space expert Girish Linganna.
Technological Advancements Demonstrated in RLV LEX-03
The RLV LEX-03 mission marked a significant technological leap in autonomous flight capabilities. The Pushpak vehicle demonstrated its ability to autonomously correct its trajectory during descent, handling real-time corrections for cross-range and downrange deviations. This feat ensured the vehicle’s precision landing, even under challenging release conditions and severe wind speeds, showcasing a high level of technological maturity in real-time guidance and control systems.
“This mission successfully simulated the approach and high-speed landing conditions of an RLV returning from space. With the RLV-LEX-02, Isro has revalidated its indigenously developed technologies in areas such as navigation, control systems, landing gear, and deceleration systems, which are essential for performing a high-speed autonomous landing of a space-returning vehicle,” Isro said.
ISRO noted that this mission tested and confirmed an advanced guidance algorithm that corrects errors in both forward and sideways directions. This system is crucial for future missions where vehicles re-enter Earth’s atmosphere from orbit.
Another notable advancement in this mission was the use of multi-sensor fusion. The Pushpak vehicle employed a variety of sensors, including inertial sensors, radar altimeters, and flush air data systems. These systems worked in tandem to provide the vehicle with the data needed for accurate guidance, even at high speeds and during rapid descent. This integration of multiple sensing technologies ensured that the vehicle remained on course and executed its landing with pinpoint precision, a critical capability for future orbital re-entry missions.
A core achievement of the RLV LEX-03 mission was its focus on reusability. The Pushpak vehicle reused key components and systems from the LEX-02 mission without any modifications, demonstrating ISRO’s success in designing durable, reusable technologies. This aspect of the mission highlights the potential for significant cost savings in future space missions, as reusable systems drastically reduce the need for new hardware with each launch.
The mission also successfully simulated the high-speed landing interface that a space-returning vehicle would encounter. By replicating these conditions, the Pushpak vehicle was able to demonstrate its ability to autonomously handle the aerodynamic forces and environmental disturbances that are typical during re-entry. This testing of high-speed landing scenarios is crucial for validating ISRO’s advanced algorithms and ensuring that future reusable launch vehicles can safely return to Earth after orbital missions.
Global Landscape of RLV Technology
ISRO is not the only space agency pioneering RLV technology. SpaceX in the USA has set the benchmark with its Falcon 9, boasting over 220 launches, 178 landings, and 155 reflights as of May 2023. For instance, in the United States, the Space Shuttle is one of the most famous reusable spacecraft programmes, that operated from 1981 to 2011 and X-37B is an unmanned, reusable space plane operated by the US Air Force. Similarly, Blue Origin has achieved success with its New Shepard, which performs suborbital flights. Other agencies like JAXA (Japan) and the European Space Agency (ESA) are also actively researching RLV systems to reduce space access costs.
When comparing ISRO’s RLV-TD to its global counterparts, it’s important to note that it serves primarily as a small-scale technology demonstrator, while other programs, such as the Space Shuttle, represent full-scale operational systems. The RLV-TD is primarily focused on demonstrating technologies for future reusable vehicles, whereas other programs are or were operational launch systems. In terms of design, RLV-TD features a winged body configuration akin to that of the Space Shuttle and X-37B, setting it apart from vertical landing systems like SpaceX’s Falcon 9.
While RLV-TD is still in its early testing phases, other programs are either operational or in more advanced stages of development. Additionally, similar to the X-37B, the RLV-TD is engineered for autonomous operation, distinguishing it from crewed systems like the Space Shuttle. This focus on autonomy and technological demonstration underscores ISRO’s commitment to pioneering innovations in reusable launch vehicle technology.
ISRO’s RLV program stands out due to its focus on autonomous landing technologies and multi-sensor guidance systems, which set the stage for more efficient, reliable, and affordable space missions.
Significance of ISRO’s RLV LEX-03 Mission
The success of the RLV LEX-03 mission is a pivotal moment for India’s space program, paving the way for fully reusable launch vehicles that could drastically cut costs associated with space missions. By validating its autonomous landing technology under harsh conditions, ISRO has demonstrated the feasibility of future Orbital Re-entry Missions, where vehicles would need to autonomously land after re-entering Earth’s atmosphere at high speeds.
The autonomous landing demonstrated in the LEX-03 mission simulates critical components of re-entry, particularly longitudinal and lateral error corrections, which are essential for safe, controlled landings of space-returning vehicles. This breakthrough sets the stage for ISRO to develop vehicles that can be launched multiple times without discarding expensive components, a key factor in making space exploration more economically viable.
Collaborative Efforts and Future Outlook
The success of ISRO’s RLV program is a result of collaborative efforts involving various ISRO centers, the Indian Air Force (IAF), and a range of research and development establishments like the Aeronautical Development Establishment (ADE), Aerial Delivery Research and Development Establishment (ADRDE), and several academic institutions.
ISRO’s push towards reusable launch vehicles is part of a broader vision to make space more accessible and affordable. Future orbital re-entry missions will benefit from the technologies demonstrated in the RLV LEX series, moving ISRO closer to fully operational reusable launch vehicles.
After the success of the LEX programme, ISRO’s ‘Reusable Launch Vehicle-Technology Demonstrator’ (RLV-TD) project is set to advance by testing an unmanned Orbital Re-entry Vehicle (ORV). This new vehicle will be about 1.6 times larger than Pushpak. It will be launched into a 400-km orbit within the next two years using a modified geosynchronous satellite launch vehicle (GSLV).
The ORV mission will carry out several experiments in space. These tests are designed to evaluate a heat shield that protects against high temperatures during re-entry into Earth’s atmosphere, as well as a foldable landing gear system.
The implications for India’s space industry are enormous. With reusable technology, ISRO can offer more competitive pricing for satellite launches, bolstering India’s position in the global space market. Additionally, it will enhance India’s ability to conduct long-term space missions, including potential crewed missions, with greater frequency and lower costs.
Conclusion
ISRO’s RLV LEX-03 mission marks a critical step forward in the development of reusable launch vehicle technology. By demonstrating autonomous landing under challenging conditions and validating the reusability of key systems, ISRO has showcased its readiness for the next phase of space exploration.
While ISRO’s RLV-TD programme is not as advanced as some other countries’ reusable spacecraft programmes, it represents a significant step for India in developing this technology. The programme aims to reduce launch costs and increase access to space, which aligns with global trends in the space industry.
With continued success in this domain, India is poised to become a leader in affordable and efficient space missions, contributing to the global push towards a more sustainable space future.
