PSLV C-37 rocket body re-enters the earth’s atmosphere: ISRO

Background:

The Indian Space Research Organisation (ISRO) announced that the upper stage of the Polar Satellite Launch Vehicle (PSLV) C-37 re-entered the Earth’s atmosphere in October 2024. This mission, launched in February 2017, was notable for deploying a record 104 satellites into space, including Cartosat-2D and 103 co-passenger satellites. After completing the mission, the upper stage (PS4) of the rocket was left in orbit.

Key Details:

1.     Re-entry and Monitoring:

o    ISRO’s System for Safe and Sustainable Space Operations Management (IS4OM) had been monitoring the orbital decay of the PSLV-C37’s upper stage since September.

o    On October 6, 2024, the orbit decayed to 134x148 km, and re-entry into Earth’s atmosphere was predicted for October 6, 15:49 UTC. The impact point was identified as the North Atlantic Ocean.

2.     Mission Overview:

o    PSLV-C37 was launched on February 15, 2017, and made history by launching 104 satellites in one mission.

o    After deploying the satellites, the upper stage of the PSLV-C37 was left in an orbit of 470x494 km.

o    The satellite payloads included notable satellites like INS-1A, INS-1B, Al-Farabi 1, and BGUSAT.

3.     Debris Mitigation:

o    ISRO emphasized that the re-entry of the rocket body complied with international debris mitigation guidelines, ensuring responsible post-mission management of the orbital life of debris.

o    Specifically, the guidelines from the Inter-Agency Space Debris Coordination Committee recommend limiting the post-mission life of debris in Low Earth Orbit (LEO) to 25 years or less.

4.     Tracking by International Agencies:

o    The rocket body’s orbit was tracked by U.S. Space Command (USSPACECOM) under NORAD ID 42052.

o    The decay and re-entry were closely monitored to ensure the impact would occur in an uninhabited area, as is standard for space debris management.

Significance:

1.     Historical Importance:

o    PSLV-C37 marked a significant milestone for ISRO as it successfully launched the highest number of satellites on a single mission, showcasing India’s growing capability in space exploration.

2.     Space Debris Management:

o    The careful tracking and planned re-entry of the PSLV-C37 upper stage reflect ISRO’s commitment to space debris mitigation, a critical aspect of sustainable space exploration.

o    This aligns with international efforts to manage space debris, reducing potential hazards to future missions and operational satellites.

3.     International Collaboration:

o    The monitoring of the PSLV-C37 upper stage by USSPACECOM highlights the importance of international cooperation in tracking space objects and ensuring safe re-entries of space debris.

Conclusion:

The re-entry of the PSLV-C37 upper stage is a well-managed event, demonstrating ISRO’s adherence to international debris management standards. The original mission, which set a world record for satellite launches, remains a pivotal achievement in India's space program, and the responsible re-entry of its debris reinforces India's role in sustainable space operations.

MCQs for Practice

1. Which of the following statements is/are correct regarding the PSLV-C37 mission?

1.     PSLV-C37 created history by launching the highest number of satellites in a single mission.

2.     The upper stage of PSLV-C37 was placed in geosynchronous orbit after the launch.

3.     The mission's payload included Cartosat-2D as the primary satellite.

Options: a) 1 and 3 only
b) 2 and 3 only
c) 1 and 2 only
d) 1, 2, and 3

Answer: a) 1 and 3 only

Explanation:
The PSLV-C37 created history by launching 104 satellites in a single mission, and Cartosat-2D was the primary satellite. The upper stage of the PSLV-C37 was left in Low Earth Orbit (LEO), not in geosynchronous orbit.

2. Consider the following statements regarding the re-entry of the PSLV-C37 upper stage:

1.     The re-entry of the PSLV-C37 upper stage complied with international debris mitigation guidelines.

2.     The impact point of the re-entry was over a populated region.

3.     The guidelines for debris mitigation aim to limit the post-mission life of objects in Low Earth Orbit (LEO) to 25 years.

Options: a) 1 and 3 only
b) 2 and 3 only
c) 1 and 2 only
d) 1, 2, and 3

Answer: a) 1 and 3 only

Explanation:
The re-entry of the PSLV-C37 upper stage was compliant with international debris mitigation guidelines, which recommend limiting the post-mission life of objects in LEO to 25 years. The impact point was in the North Atlantic Ocean, not over a populated region.

3. Which of the following statements best explains the concept of "orbital decay"?

a) It refers to the gradual increase in altitude of an object in orbit around the Earth.
b) It refers to the process by which an object’s orbit around the Earth decreases due to atmospheric drag and other forces, eventually leading to re-entry.
c) It refers to the process by which a satellite's orbit stabilizes at a constant altitude.
d) It refers to the increase in speed of an object as it approaches the Earth's atmosphere.

Answer: b) It refers to the process by which an object’s orbit around the Earth decreases due to atmospheric drag and other forces, eventually leading to re-entry.

Explanation:
Orbital decay is the process by which a satellite or object's orbit slowly decreases due to atmospheric drag and other forces, leading to eventual re-entry into the Earth's atmosphere.

4. Which of the following is true about the guidelines of the Inter-Agency Space Debris Coordination Committee (IADC)?

a) The IADC recommends that satellites in geosynchronous orbit should have a post-mission life of 25 years.
b) The IADC guidelines apply only to military satellites.
c) The IADC recommends limiting the post-mission life of objects in Low Earth Orbit (LEO) to 25 years.
d) The IADC mandates the use of reusable rockets to mitigate space debris.

Answer: c) The IADC recommends limiting the post-mission life of objects in Low Earth Orbit (LEO) to 25 years.

Explanation:
The Inter-Agency Space Debris Coordination Committee (IADC) guidelines recommend that objects in Low Earth Orbit (LEO) should have a post-mission life of 25 years or less to mitigate space debris. These guidelines apply to all satellites, not just military ones.

5. Which of the following accurately describes the purpose of the PSLV's upper stage (PS4) in a satellite launch?

a) It is used for carrying payloads into space but has no further function after deployment.
b) It helps in adjusting the satellite's position after launch and remains in space indefinitely.
c) It is responsible for injecting satellites into their designated orbits and is eventually left in space after the mission.
d) It is used for the recovery of satellites from orbit once their mission is complete.

Answer: c) It is responsible for injecting satellites into their designated orbits and is eventually left in space after the mission.

Explanation:
The upper stage (PS4) of the PSLV is used to inject satellites into their designated orbits and is usually left in orbit after the mission is complete. Its re-entry into Earth's atmosphere is later monitored to comply with space debris management guidelines.