In a milestone achievement marking its centenary mission, the Indian Space Research Organisation (ISRO) had successfully launched the NVS-02 satellite aboard the GSLV-F15 rocket. The launch represents a significant advancement for India’s Navigation with Indian Constellation (NavIC) system, a homegrown satellite navigation network serving both civilian and defense purposes. However, the space organisation announced that NVS-02 is currently facing a technical hurdle.
The satellite, intended to bolster India’s navigation capabilities, encountered a problem during the critical “orbit raising maneuvers,” the process of moving it from its initial launch orbit to its designated operational slot. Although it is not known how long the technical challenges may continue, it is to be noted that such things are not unusual in space missions.
While communication with the satellite has been established and its solar panels are functioning, the valves responsible for activating its thrusters—the engines that enable orbital adjustments—have failed to open. This has left the satellite stranded in its transfer orbit, raising concerns about its future functionality and the gravity of the situation. Satellites are rarely placed directly into their final operational orbits after launch. Instead, they are typically injected into a transfer orbit, often an elliptical path around Earth. From this transfer orbit, a series of carefully planned maneuvers are executed to propel the satellite to its designated orbital slot.
“For navigation satellites like NVS-02, the target is often a geostationary orbit. A geostationary orbit is a special type of orbit where the satellite appears stationary relative to a point on Earth’s equator. This is achieved by placing the satellite at a specific altitude (approximately 35,786 kilometers) and ensuring its orbital period matches Earth’s rotation period (approximately 24 hours). This allows the satellite to provide continuous coverage over a specific region, crucial for navigation and communication services,” remarked space expert Girish Linganna.
Linganna pointed out that the process of reaching geostationary orbit from a transfer orbit involves several steps such as the launch vehicle; in this case, the GSLV-F15 rocket carries the satellite into space and releases it into a preliminary orbit. This orbit, known as the Geosynchronous Transfer Orbit (GTO) for NVS-02, is designed to be close to the intended path but not the final destination. Then there is the orbit -raising maneuvers which are one of the most critical phase.
“The satellite uses its onboard thrusters to gradually increase its altitude and adjust its orbital inclination (the angle of the orbit relative to Earth’s equator). These maneuvers require precise timing and controlled bursts of thrust. Each burn of the thrusters changes the satellite’s orbital parameters, pushing it closer to its target geostationary slot. As the satellite’s altitude increases, its elliptical orbit is gradually circularized. This ensures a stable and consistent distance from Earth, essential for maintaining a geostationary position. Once the satellite reaches its designated geostationary slot, it is not the end of the story. Due to gravitational influences from the Earth, Moon, and Sun, the satellite tends to drift out of its assigned position. Therefore, small, periodic thruster firings are required for station keeping, ensuring the satellite remains in its designated slot and continues to provide uninterrupted service,” said Linganna.
Space experts point out that NVS-02’s current predicament stems from a failure of the valves that control the flow of oxidizer to its thrusters.
Thrusters require a propellant (fuel) and an oxidizer to generate thrust. Without the oxidizer reaching the thrusters, the satellite cannot perform the necessary orbit-raising maneuvers. This effectively leaves the satellite stranded in its transfer orbit, unable to reach its designated geostationary position. ISRO has confirmed that the satellite’s other systems, including its solar panels and communication links, are functioning correctly. This is a positive sign, indicating that the core functionality of the satellite is intact. However, the inability to perform orbit-raising maneuvers poses a significant challenge.
The primary objective of NVS-02 was to augment India’s NavIC constellation, providing precise navigation and timing services. The current issue could delay or even prevent the satellite from becoming operational, impacting the overall capabilities of the NavIC system. NVS-02 is part of a series of second-generation navigation satellites designed to replace older satellites in the NavIC constellation. A failure to achieve its operational orbit would reduce the system’s redundancy and resilience, making it more vulnerable to disruptions.
Developing and launching a satellite is a costly endeavor. A significant malfunction like this could lead to financial losses and necessitate further investment in replacement satellites. “While setbacks are common in space exploration, this particular issue could raise questions about the reliability of certain components and the robustness of the orbit-raising system. A thorough investigation will be crucial to identify the root cause of the valve malfunction and prevent similar issues in future missions,” pointed out Linganna.
“ISRO engineers are undoubtedly working tirelessly to find a solution to NVS-02’s predicament. Experts point out that there could be alternative steps which the scientists could explore in order to rectify the satellites. Engineers might explore alternative strategies to maneuver the satellite using the available resources. This could involve using the limited functionality of the thrusters (if any) or exploring unconventional methods to adjust the orbit. Satellites often have redundant systems for critical components. If NVS-02 has a backup system for the thruster valves, engineers might be able to activate it remotely. ISRO likely has contingency plans for such scenarios. These plans might involve accelerating the launch of other planned navigation satellites to compensate for the potential loss of NVS-02,” observed Linganna.
Experts say that the current technical challenge with NVS-02, while significant, should be viewed within the broader context of space exploration’s inherent risks and learning opportunities. Rather than indicating failure, such incidents provide valuable data and insights that contribute to the advancement of space technology. These experiences often lead to improved systems and more robust mission protocols.
“As ISRO prepares for future launches, including the next GSLV mission, continued support from both the public and government sectors remains essential. Enhanced funding for research, development, and infrastructure will not only help address current technical challenges but also strengthen India’s position in the global space sector. The ongoing development of NavIC and satellite technologies positions India to play an increasingly significant role in international space exploration and commerce. The mission’s outcomes underscore the dynamic nature of space exploration, where each challenge presents an opportunity for technological advancement and innovation,” remarked Srimathy Kesan, founder and CEO of Space Kidz India.
