Apollo-11 reached the moon in four days, so why is Chandrayaan-2 taking 48 days

Highlights:

1. Chandrayaan-2 will reach the moon in 48 days.
2. Apollo-11 reached the moon on the fourth day of its launch.
3. Recently, Chandrayaan-2 released pictures of the Earth.
4. The first time astronauts went to the moon from Apollo 11

The Indian Space Research Organization's ambitious moon mission Chandrayaan-2 will take 48 days to reach the moon, while Apollo-11, launched five decades ago, took just four days. So why chandrayaan 2 is taking so long to reach the moon?

Luna-2 of erstwhile Soviet Russia, launched on year 1959, took only 34 hours to reach the moon. While 10 years after that, Apollo-11, launched in 1969, took four days, six hours and 45 minutes. For the first time in this mission, humans were sent to the lunar surface.

Read also: Scientists claim: Newton's law of gravity is 'wrong', now Einstein's turn

So why is Chandrayaan-2 taking more than a month? The answer lies in the construction of the rocket, the amount of fuel and the speed of the Chandrayaan. Let's get to know. 

In space, high-speed and straight trajectories (the path the vehicle travels) are required to cover long distances. NASA used a super heavy-lift launcher Saturn-V rocket for Apollo-11 mission. This rocket was capable of traveling at over 39,000 km per hour.

The rocket's powerful engine brought the Apollo-11 3.8 million km away to the moon in just four days. However, for the Apollo mission in 1969, NASA then had to spend $25 billion (currently $300 billion).

India's Bahubali rocket was capable of lifting so much weight

India does not have a rocket as powerful as NASA, which can take Chandrayaan-2 directly to the moon. This is why ISRO chose an alternate way to take advantage of Earth's gravity, which would help take Chandrayaan-2 towards the Moon.

The GSLV Mk-III, popularly known as Bahubali Rocket, has a carrying capacity of only four tonnes whereas Chandrayaan weighs 3.8 tonnes. This rocket could leave Chandrayaan only up to geosynchronous transfer orbit. Currently Chandrayaan's propulsion system is pushing it towards its goal. During Earth's final orbit, the acceleration of Chandrayaan-2 will increase so much that it can reach the Moon's orbit.

A spacecraft needs a minimum velocity of 11 km per second to travel to the moon. Out of that, 10.3 kmph is being provided by the remaining portion of the vehicle while the remaining 700 meters per second is provided by the propulsion system of Chandrayaan 2.

Chandrayaan-2, because of its small engine, cannot be run continuously, so it is being run in a short time to maintain the speed. If ISRO had a powerful engine like Saturn-V, then Chandrayaan-2 could reach the moon in a short time.