India is set to take a huge step toward a debris-free space with plans to launch at least two key missions this year. These missions aim to dock, refuel, repair, relocate, deorbit, and extend the life of satellites that have reached the end of their operational lifespan.
ISRO Chairman and Secretary, Department of Space, S Somanath said the space agency is developing new technologies for space debris management.(PTI Photo/Manvender Vashist Lav)
ISRO chairman S Somanath said on Friday that the space agency will launch the SPADEX mission next month. This mission will test low-impact cooperative docking technology, allowing communication between satellites. After this, a propulsive device can be attached to deorbit satellites safely.
Additionally, the agency will test the ISRO Servicer Mission, which will use a tethered debris capture technique where a robotic arm on the upper stage will grab a satellite in motion. This mission will demonstrate capabilities in on-orbit servicing, life extension, and inspection.
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Speaking at the Chanakya Defence Dialogue 2024 on ‘Space Situational Awareness – Monitoring and Protecting National Interests,’ Somanath said, “Many of these problems (space debris management), don’t yet have a cost-effective solution, but that doesn’t mean we will shy away from developing new technologies.”
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ISRO’s upcomg missions: SPADEX and ISRO Servicer Mission(Chanakya Defence Dialogue 2024) What is tethered space debris capture?
Tethered space debris capture is a proposed method for removing space debris using a long, strong tether (rope-like) attached to a satellite.
The tether is deployed to capture a piece of debris, and then the combined mass of the satellite and debris is de-orbited, causing both to burn up in the Earth’s atmosphere, explains Manish Purohit, a former ISRO scientist and founder of Nimbus Education.
In one aspect of its mission, the ISRO Servicer Mission will operate on the PS4 Orbital Platform and perform several on-orbit operations while tethered to it, Purohit told HT.com.
Recently, ISRO has published two patents related to spacecraft capturing mechanisms for on-orbit satellite servicing, he added.
What are the challenges of tethered space debris capture?
Purohit adds that the technology has several challenges to overcome:
• Precise targeting: Accurately targeting and capturing small pieces of debris is challenging due to their high speed and unpredictable orbits.
• Tether deployment and control: Deploying and controlling a long tether in space is complex and requires precise engineering. The initial phase of extending the tether is critical. Any irregularities, such as snags or vibrations, can lead to system instability. Additionally, maintaining optimal tension in the tether is essential. Too much tension can damage it, while too little can cause slack, leading to oscillations and entanglement.
• De-orbiting: Safely and efficiently de-orbiting the captured debris poses a significant challenge.
How severe is space debris threat?
Space debris includes everything from inactive satellites to errant fragments of broken equipment. Today, 18,897 pieces of trackable space junk orbit Earth, according to Jonathan McDowell, a Harvard astronomer.
Recently, a Chinese rocket collided with debris, adding significantly to the junk cloud.
National Aeronautics and Space Administration (NASA) reported that earlier events, including the 2007 destruction of China’s Fengyun-1C satellite and a 2009 U.S.-Russian collision, added nearly 70 per cent more debris. In 2021, a Russian anti-satellite missile test created 1,500 new fragments, some of which have since decayed.
Anti-satellite tests by the US in 2008 and India in 2019 also contributed to the growing clutter.
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India’s aims for zero-debris space missions by 2030
India aims to achieve space missions with ‘zero debris’ by 2030 with its Debris Free Space Missions (DFSM) initiative. Starting in 2025, all Indian space missions, whether governmental or private, will adopt a “zero debris” approach.
Earlier this year, ISRO successfully re-entered a spent rocket from the XPoSat mission, which fell in the Pacific Ocean. ISRO also lowered the orbit of PSLV-37’s spent upper stage, ensuring it re-entered Earth’s atmosphere on October 6.
The space agency is now exploring mid-orbit debris capture technology, advancing India’s sustainable space exploration.