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Mahesh

09/04/24 05:58 AM IST

ISRO’s ‘zero orbital debris’ milestone & the space debris crisis

In News
  • The Indian Space Research Organisation (ISRO) has said its PSLV-C58/XPoSat mission has practically left zero debris in earth’s orbit.
About POEM
  • Developed by the Vikram Sarabhai Space Centre (VSSC) as an inexpensive space platform, POEM uses the spent fourth stage of a PSLV rocket as an orbital platform.
  • Used for the first time in the PSLV-C53 mission in June 2022, ISRO had POEM orbit the earth as a stabilised platform to perform in-orbit scientific experiments with various payloads
  • POEM is powered by solar panels mounted on the fuel tank of the rocket’s fourth stage and a lithium-ion (Li-ion) battery.
  • It has a dedicated navigation, guidance, and control (NGC) system to stabilise its altitude along with helium control thrusters.
  • The NGC system has four Sun sensors, a magnetometer, and gyroscopes, and talks to ISRO’s NavIC satellite constellation for navigation.
  • POEM also has a telecommand system to communicate with the ground station.
  • ISRO first demonstrated the reuse of the spent fourth stage of its rocket in its PSLV C-44 mission in 2019.
  • After satellites were injected in the target orbits, the fourth stage, carrying a student payload called Kalamsat-V2, was moved to a higher circular orbit of 443 km and stayed there, allowing the payload to make observations.
Achievement by POEM-3
  • ISRO launched the PSLV C-58 mission from the Satish Dhawan Space Centre in Sriharikota on January 1, 2024.
  • After deploying the XpoSat satellite in its desired orbit of 650 km, the fourth stage, now called POEM-3, was lowered to a 350-km high circular orbit.
  • The lower a satellite is in orbit around the earth, the more drag it experiences and the more energy it needs to expend to stay in orbit.
  • POEM-3 featured nine payloads: two each from VSSC and Bellatrix Aerospace Pvt Ltd, one each from the start-ups TakeMe2Space, Inspecity Space Labs Pvt Ltd., Dhruva Space, and from LBS Institute of Technology, KJ Somaiya Institute of Technology, and ISRO’s Physics Research Laboratory, Ahmedabad.
  • POEM-3 completed 400 orbits around the earth by its 25th day. The payloads were operationalised to perform their experiments during this time.
  • ARKA200, RUDRA, and LEAP-TD completed their respective experiments while the data from WeSAT, RSEM, and DEX were collected after every orbit for further analysis on the ground.
  • Two fuel cells from VSSC demonstrated their ability to generate power. By January 27, 2024, all of POEM-3’s payload objectives were completed.
  • POEM-3 prepared for its re-entry while ISRO tracked it with its Telemetry, Tracking and Command Network (ISTRAC) stations in Bengaluru, Lucknow, Mauritius, Sriharikota, Port Blair, Thiruvananthapuram, Brunei, and Biak (Indonesia) and the Multi-Object Tracking Radar (MOTR) at Sriharikota.
Significance
  • With the rise in the number of satellites in orbit around the earth, space debris has become a pressing issue.
  • Space debris in the low earth orbit (LEO) mainly comprises pieces of spacecraft, rockets, and defunct satellites, and the fragments of objects that have deteriorated explosively as a result of anti-satellite missile tests.
  • This debris often flies around at high speeds of up to 27,000 kilometres per hour. Due to their sheer volume and momentum, they pose a risk to several space assets.
  • The LEO extends from 100 km above the earth’s surface up to 2000 km above. It includes satellites tracking intelligence data, encrypted communication, and navigation.
  • According to ISRO’s Space Situational Assessment report 2022, the world placed 2,533 objects in space in 179 launches in 2022, up from 1860 objects in 135 launches in 2021.
  • Debris also exists, but in smaller volumes, in the geosynchronous orbit (GEO), which is 36,000 km above the earth’s surface.
  • Currently, there are 7,000 operational satellites orbiting the earth at different altitudes along with millions of pieces of space debris.
  • A major contributor to the rising number of satellites is American launch-services provider company Space X, which is currently also building a large constellation of 12,000 satellites to provide internet services worldwide.
  • The project, named Starlink, has deployed satellites in 550 km, 540-570 km, and 335-345 km orbits and is expected to be completed by 2027.
  • SpaceX has also applied for a second generation of Starlink satellites comprising 30,000 LEO satellites.
  • As more communication satellites/constellations are launched and more anti-satellite tests are conducted, more on-orbit breakup and collisions occur, producing smaller and smaller fragments in orbit.
  • The number of space objects (debris or functional equipment) greater than 10 cm in size in LEO is expected to be about 60,000 by 2030, per ISRO estimates.
  • Space debris also leads to two major risks – it creates unusable regions of the orbit due to excessive debris, and leads to the ‘Kessler syndrome’ – creation of more debris due to cascading collisions resulting from one collision.
Orbital debris program
  • NASA had instituted its Orbital Debris Program in 1979 to find ways to create less orbital debris and design equipment to track and remove existing debris.
  • Currently, the sixth U.S. Armed forces wing, called the Space Force, tracks space debris and collisions in LEO.
  • However, the agency has not implemented any technology to clean such debris yet; most such ideas are in the conceptual stage.
  • Similarly, the European Space Agency (ESA) has adopted a ‘Zero Debris charter,’ which includes multiple ways to mitigate space debris.
  • It has also called for zero space debris by 2030 and seeks that other agencies adopt it as well.
  • Japan also has a project, called the Commercial Removal of Debris Demonstration (CRD2), to tackle space junk
  • . The Japan Aerospace Exploration Agency (JAXA) has partnered with private space company Astroscale to assess debris in phase I of the programme.
  • In the second phase, JAXA will launch a satellite to approach the debris and rendezvous with it before capturing and removing it from orbit. Currently, JAXA is conducting tests of this craft.
  • India is working to mitigate space debris.
  • Apart from the POEM missions, ISRO has set up a Space Situational Awareness Control Centre to protect its high-value assets from close approaches and collisions with inactive satellites, pieces of orbiting objects, and even near-earth asteroids.
  • An Indian start-up named Manastu Space is working on technologies like in-space refuelling, de-orbiting of old satellites, and satellite life extension.
Source- The Hindu

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