New Delhi: Chandrayaan-2, India’s second mission to the Moon, took off from Sriharikota at 2.43 pm Monday after a week’s delay.
Chandrayaan-2 was initially scheduled to be launched on 15 July but was called off with less than an hour to go due to a technical snag in the launch vehicle system.
Described as ISRO’s most complex mission so far, Chandrayaan-2 is expected to land an orbiter on the Moon and build on its predecessor’s startling discovery of water on the Earth’s satellite.
Its vehicle is the GSLV Mk-III, India’s most powerful rocket.
Chandrayaan-2 consists of three spacecraft: The Chandrayaan-2 orbiter, the Vikram lander (named after Vikram Sarabhai, the father of India’s space programme), and the Pragyaan rover.
The mission aims to explore the region near the Moon’s south pole, where the lander will tentatively touchdown on 6 or 7 September.
A long journey ahead
While the GSLV employed in the mission is India’s most powerful, it doesn’t compare very well to some of the big rockets from around the world.
Unlike NASA’s Saturn V, or even the Falcon 9 of the private company SpaceX, which delivers payloads to the International Space Station, the GSLV Mk-III is still not powerful enough to drop the spacecraft directly onto a path to the Moon.
Instead, the rocket’s fourth stage, into which the orbiter and the lander (which contains the rover within it) are stacked on each other, will inject Chandrayaan-2 into the Earth’s orbit at an altitude of 182 km.
The spacecraft will then perform a series of orbit-raising manoeuvres around the Earth. With each orbit, it will use the planet’s gravity to gain some more altitude, finally escaping the Earth’s gravitational pull in its sixth orbit, 17 days from now.
The whole spacecraft will then fly towards the Moon, taking five days to complete the journey. For nearly a month after that, the orbiter will perform lunar manoeuvres: It will first reorient itself near the Moon and fire its engines again to act as a brake. The craft will then enter into a lunar orbit by performing orbit lowering manoeuvres. It will subsequently settle into its home, in a circular orbit 100 km over the Moon’s surface.
On 2 or 3 September, the lander will separate from the orbiter and perform a controlled descent towards the landing site.
Also read: ISRO Chandrayaan-2 mission: Limited to symbolic national pride or is there a scientific gain?
The south polar region
A successful landing will make India the fourth country to perform a landing on the Moon. Upon landing, the rover will be deployed through a ramp on to the lunar south pole region.
The south polar region is unexplored so far. This is the region where Chandrayaan-1 discovered water ice in 2008 when it crashed an impactor onto the surface and studied the debris thrown up.
The pole has one of the largest craters in the solar system, called the Aitken basin. It is thought that the impact that created the crater was so intense that a part of the lunar rock melted, bringing material from the mantle to the top.
As a result, the geology of the south pole region is very different from that of the rest of the Moon.
The region is dotted by large craters. Owing to the angle of the Sun, several shadowed parts of these craters have never seen sunlight at all. These act as pristine fossils of the early solar system, giving us information about the formation of the Earth-Moon system, as well as the Sun and its planets.
The payloads will also study the mineral mapping of the surface, the composition of gases near the Moon, surface and sub-surface geology, as well as moonquakes.
Also read: Why Chandrayaan-2 is ISRO’s ‘most complex mission’ so far
Reaching out
With this mission, ISRO is also seeking to shed its reputation of being closed and disconnected.
Much like during the launch of the Mars Orbiter Mission, the globally-celebrated project that saw India reach the Red Planet on its maiden attempt, ISRO has once again become active on social media.
It has also launched an official YouTube channel, where ISRO has posted explainer videos.
Additionally, members of the public were invited to apply for an opportunity to view the launch from the new Launch View Gallery at Sriharikota, which can house 5,000 attendees.
Congratulations ISRO. Safe landing.