Space Debris

Article Title: Space Debris


Science & Technology Current Affairs Analysis

Why is in news? "Another milestone": ISRO rocket accomplishes zero orbital debris mission

ISRO on 8th April, 2024 said its Polar Satellite Launch Vehicle (PSLV) has accomplished zero orbital debris mission, and described it "another milestone". This was achieved on March 21, when the PSLV Orbital Experimental Module-3 (POEM-3) met its "fiery end" through a re-entry into the Earth's atmosphere.

About POEM-3:

It was launched on January 1, 2024 POEM-3 utilized the spent PS4 stage of the PSLV-C58 vehicle, which initially launched XPoSat.

It is a three-axis-altitude controlled platform with power generation and tele-command & telemetry capabilities, for supporting Payloads.

The XPoSat mission aimed to leave no debris in space, demonstrating ISRO’s commitment to responsible space practices.

The stage was deorbited from 650 km to 350 km, which facilitated its early re-entry, and was passivated to remove residual propellants to minimise any accidental break-up risks.

Upon deployment into its orbit at 650 km, POEM-3 was maneuvered to a 350 km circular orbit to minimize orbit decay time after the experiment’s completion.

After completing 400 orbits, POEM-3 re-entered Earth’s atmosphere after 73 days in space.

POEM-3 was configured with a total of nine different experimental payloads to carry out technology demonstrations and scientific experiments on the newly developed indigenous systems.

Out of these, six payloads were delivered by Non-Government Entities (NGEs) through Indian National Space Promotion and Authorization Centre (IN' SPACe).

Through the POEM, which serves as a very cost-effective platform for carrying out short-duration space-borne experiments, ISRO has opened up new vistas for academia, startups, and NGEs to experiment with their new payloads.

This novel opportunity has been effectively utilised by numerous startups, universities, and NGEs for carrying out experiments in space, which included electric thrusters, satellite dispensers, and star-tracking.

POEM also incorporates new features such as total avionics in single-chain configuration, industrial-grade components in avionics packages including Mission Management Computer, standard interfaces for electric power, telemetry & telecommand, and new in-orbit navigation algorithms making use of rate-gyro, sun sensor, and magnetometer.


With the rise in the number of satellites in orbit around the earth, space debris has become a pressing issue.

POEM-3's controlled re-entry into Earth's atmosphere effectively mitigated the risk of space debris by ensuring the safe disposal of the fourth stage of the PSLV rocket.

The experiments conducted on POEM-3 showcased advancements in areas such as power generation, navigation, and scientific research in the space environment.

By re-entering Earth's atmosphere, POEM-3 minimized the accumulation of space debris in low Earth orbit, contributing to the preservation of the space environment.

ISRO's meticulous tracking of POEM-3 during its re-entry phase ensured the safety of terrestrial assets and populations by monitoring the trajectory of the descending module.

By effectively disposing of spent rocket stages and conducting controlled re-entries, ISRO's initiatives help mitigate the risks associated with space debris collisions and orbital congestion.

The insights gained from POEM-3's mission outcomes are valuable for international space agencies and organizations engaged in similar endeavours.

Space debris:

It is also known as space junk, refers to any non-functional or discarded human-made objects in space, including defunct satellites, spent rocket stages, fragments from previous collisions, and paint flecks.

These objects of space debris remain in various orbits around Earth and pose potential threats to operational satellites and space missions.

Current Status of Space Debris:

As per ESA's Space Environment Report 2022, over 30,000 pieces of space debris have been recorded and are being tracked on a regular basis by space surveillance networks.

It is estimated that there are approximately 200,000 pieces of micro debris ranging in size from 1 to 10 cm, with millions more smaller than 1 cm.

There were approximately 6,718 active satellites orbiting the Earth in 2022, an increase of nearly 2,000 satellites in just one year.

According to NASA, the number of satellites orbiting Earth is expected to reach 60,000 by 2030, up from the current 9,000, and the amount of untracked debris is a cause for concern.