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Chandrayaan-3 vs. Apollo 11: Time to Reach Moon

The Indian Space Research Organisation (ISRO) utilized its heaviest rocket, the Geosynchronous Satellite Launch Vehicle (GSLV)......Chandrayaan-3 vs. Apollo 11: Time to Reach Moon

The Indian Space Research Organisation (ISRO) utilized its heaviest rocket, the Geosynchronous Satellite Launch Vehicle (GSLV) Mark-III, to put the Chandrayaan-3 propulsion module, carrying the lander, into an elliptical orbit around the Earth.

Chandrayaan-3’s Journey to the Moon:

Orbit Raising Maneuvers:
  • Over the next two weeks, ISRO will conduct between five to six orbit raising maneuvers.
  • These maneuvers will be carried out using the onboard propulsion system.
  • With each burn of the propulsion system, the module will spiral outwards in increasingly elongated ellipses.
Achieving Escape Velocity:
  • The speed of the propulsion module will steadily increase during the orbit raising maneuvers.
  • This speed increase is necessary to reach the escape velocity required to break free from Earth’s gravity.
Lunar Transfer Trajectory (LTT):
  • Once the propulsion module reaches the escape velocity, it will enter a Lunar Transfer Trajectory (LTT).
  • This trajectory will set a course for Chandrayaan-3 towards the moon.
Translunar Injection:
  • The critical moment of Translunar Injection will occur on 1 August.
  • Translunar injection is when Chandrayaan-3 will leave Earth’s orbit and begin its journey towards the Moon.
Projected Landing Date:
  • The anticipated landing date on the lunar surface is projected to be around 23 August.
  • This landing will occur over three weeks after the Translunar Injection.
Final Steps:
  • After over 40 days from the launch and several orbital maneuvers, the lander will finally reach the surface of the Moon.
  • Once on the Moon, the lander will deploy the rover, commencing its exploration mission.

Why Chandrayaan-3 Takes Weeks to Reach the Moon?

The simple answer is because ISRO does not have a rocket powerful enough to put Chandrayaan-3 on a direct path to the Moon.Following are also reasons for delayed of Chandrayaan-3 Journey:

Difference in Trajectories:
  • Previous missions like China’s Chang’e 2 and Chang’e 3, the Soviet Union’s Luna-1, and Apollo-11 used direct trajectories called Translunar Injection (TLI).
  • Direct Translunar Injection involved a powerful engine burn to send the spacecraft directly towards the Moon, allowing them to reach the Moon relatively quickly within a few days.
ISRO’s Rocket Capability:
  • Chandrayaan-3 is following a different trajectory due to the lack of a rocket powerful enough for a direct path to the Moon.
  • ISRO’s current launch vehicles cannot execute a direct TLI like the Saturn V used in Apollo missions.
  • While the GSLV Mk-III is a capable launch vehicle, it does not have the same power and payload capacity as the Saturn V used in the Apollo missions.
  • As a result, a more gradual trajectory was chosen to optimize the mission within the constraints of the launch vehicle.
Earth Orbits and Engine Burns:
  • Chandrayaan-3 employs a series of Earth orbits and engine burns to gradually increase its speed and position for lunar insertion.
  • The spacecraft enters an initial Earth orbit and performs engine burns at specific times to transfer to a trajectory intersecting with the Moon’s orbit.
  • Multi-step approach used by the ISRO for the Chandrayaan and Mangalyaan missions requires more time but allows for the use of a relatively less powerful launch vehicles.
Lunar Insertion:
  • After the required Earth orbits and engine burns, another engine burn will be conducted to insert Chandrayaan-3 into lunar orbit.
  • This process takes more time compared to the direct TLI used in previous missions.
Saturn Rocket’s Slingshot Effect:
  • In contrast to Chandrayaan-3‘s method, the Apollo missions utilized a single six-minute-long burn of the Saturn rocket’s third stage for a slingshot-like effect to direct the spacecraft towards the Moon.

Despite the longer travel duration, Chandrayaan-3’s trajectory remains a feasible approach given ISRO’s current rocket capabilities. The mission aims to achieve lunar orbit and carry out its scientific objectives, contributing to further lunar exploration efforts.

Chandrayaan-3 vs. Apollo 11

Chandrayaan-3’s: Clever Gravity-Assisted Journey to the Moon:

Earth’s Elliptical Orbit and Perigee:
  • The module orbits the Earth in an elliptical path, with a point closest to the planet called the perigee and a farthest point called the apogee.
  • At perigee, the module is at its highest speed due to Earth’s stronger gravitational pull.
Utilizing Earth’s Gravity:
  • Each time the module reaches perigee, the onboard engine fires, increasing its speed even more, and pushing it into a higher, more elongated orbit.
Escape Velocity and Lunar Transfer Trajectory (LTT):
  • As the module continues its journey, it reaches the escape velocity to break free from Earth’s gravity.
  • The module’s orbit elongates, enabling it to set a course towards the moon.
Strategic Lunar Orbit Insertion:
  • The Chandrayaan-3 module’s entry into LTT is precisely timed to align with the moon’s position in its orbit.
  • A manoeuvre called lunar orbit insertion reduces the module’s velocity and allows the moon’s gravitational field to pull it into a stable lunar orbit.
Orbiting the Moon:
  • Once in lunar orbit, the module revolves around the moon in an elliptical path.
Lowering Altitude for Lunar Surface:
  • A series of manoeuvres progressively lower the module’s altitude to place it in a 100 km circular orbit around the moon.
Separation of Propulsion Module and Lander:
  • At this point, the propulsion module separates from the lander, which continues its journey towards the lunar surface.
Groundbreaking Soft-Landing:
  • If all goes as planned, around 23 August, Chandrayaan-3 will achieve a groundbreaking feat by becoming the first mission to successfully soft-land near the lunar south pole.

Chandrayaan-3’s innovative use of gravity and precise manoeuvres ensures a successful journey to the Moon and sets the stage for groundbreaking lunar exploration.

Chandrayaan-3 vs. Apollo 11: Time to Reach Moon,Chandrayaan-3 vs. Apollo 11: Time to Reach Moon

Read Also : Space Research Centres In India

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