Vikram is expected to touch down on the lunar surface on September 7, around 1:45 am. Vikram and Pragyan would operate for 14 Earth days which is equivalent to one Moon Day.
By Ajey Lele
Chandrayaan 2 Landing: India Space research Organization’s (ISRO) second mission to Moon called Chandrayaan 2 is having flawless travel. The mission got space-borne on 22 July 2019. On 02 September 2019, from the ‘mothership’ Orbiter, the Vikram lander (with Pragyan rover in its belly) has got separated and have begun their journey towards the surface of Moon, for a soft landing on the 07 September 2019. Vikram is expected to touch down on the lunar surface on September 7, around 1:45 am. Four hours after that around 0600 am the Pragyan rover would get down on the Moon surface and start moving to study the Moon’s surface. With this, the Chandrayaan-2 mission actually begins. Vikram and Pragyan would operate for 14 Earth days which is equivalent to one Moon Day. While Orbiter has already started partially functioning and taking some images. The Orbiter, weighing 2,379 kg and with the power of 1000W has eight important sensors on-board which is expected to gather various observations during a period of next one year.
Where will Chandrayaan 2’s Vikram module land?
ISRO has already decided on the landing zone for Vikram on the 7th September landing. Vikram is expected to land between two craters called Manzinus C and Simpelius N at a latitude of around 70.9 degrees South and 22.7 degrees East. Just in case, if Vikram finds it difficult to make an approach to this landing site, then it can look for an alternative site which is 67.7 degrees South and 18.4 degrees West. However, one of the most important sensor on-board of Orbiter from the Vikram’s point of view is the Orbiter High-Resolution Camera (OHRC). This sensor would be providing high-resolution images of the landing site for ensuring the Vikram’s safe touchdown. Already Vikram must have got some inputs about the possibility of any craters or boulders around the landing site. A Digital Elevation Model (DEM) of the landing site would be generated based on the OHRC data. This would assist Vikram for landing on the D-day. OHRC’s images will be captured over the course of two orbits, covering an area of 12 km x 3 km. The ground resolution of the OHRC’s imagery is 0.32 m.
The travel-time for Chandrayaan-2 from the launch date to the soft landing is going to be 48 days in total. It is a very long journey and by 02 September Chandrayaan-2 has successfully completed 42 to 43 days of journey. For Vikram and Pragyan, this journey was not a major challenge (in a relative sense) because they were safely placed inside the womb of the orbiter. The Orbiter was required to take care of its own health because it’s travel towards the Moon was full of atmospheric resistance which was a worry for aerodynamics. The spacecraft must have experienced various external forces including gravitational force (since everything with a mass exerts this force), forces brought in by solar winds and forces occurring due to the change in the velocity of the spacecraft.
Now, Vikram is on its own, however, luckily at a location where the only vacuum is there and atmospheric drag matters less. Still, the journey towards the final destination is going to be challenging. Vikram has four legs and possibly may not find a totally flat location to land. But, it has an adequate mechanism to project any vibrations while landing, like the presence of shock absorbers. Vikram may kick up the lunar dust after the soft-landing. Possibly, this is why the Pragyan would make exit from Vikram to travel on Moon, only four hours after the soft-landing, so that by that time, the kicked up dust would have got settled down.
Vikram and Pragyan would get energy from the solar source. On the surface of the Moon, Pragyan which is a six-legged robot would be travelling some distance (maximum of 500 meters). Every minute is going to be a test in this journey since the surface of the Moon is uneven and rocky. The life of this system is going to be one Moon day (14 earth days) hence, the sunlight would always be available for charging their solar batteries. It is expected that the system may function beyond one Moon day. However, all that will depend on the life of the solar source. It should get re-energized after a gap in one night.
So far the travel of Vikram and Pragyan has been nice and safe. Now on the 7th September, it has to succeed with the soft-landing on the Moon’s surface to make every Indian proud. Let us wish best of luck to Vikram and Pragyan.
(The author is Senior Fellow, IDSA, New Delhi. Views expressed are personal.)