Chandrayaan-2 now in final Earth orbit

Mission all set for moon transfer

Gearing up for an edgy jump to the lunar orbit, the Chandrayaan-2 moon mission has now reached its fifth and final orbit within the Earth-bound phase. The fifth orbit-raising maneouvre was successfully completed on Tuesday afternoon. 

Confirming this in a tweet, the Indian Space Research Organisation (Isro) informed that the maneouvre was carried out at 3.04 pm. To undertake this critical operation, the Mission's onboard propulsion system was fired for a duration of 1,041 seconds (about 17 minutes).

The Mission, integrating an Orbiter, Lander and Rover, has now been placed in a 276 x 1,42,975 km (nearest x furthest Earth-bound altitude). After the fourth orbit, Chandrayaan-2 had reached 277 x 89,472 kms. All the parameters of the spacecraft are now normal, according to Isro. 

India's most ambitious moon mission is now all set for the critical Trans Lunar Insertion (TLI), scheduled between 3 pm and 4 pm on August 14. Simply put, this maneouvre of thrusts on the spacecraft will place it on a moon-bound trajectory. 

The TLI phase is expected to take about a week, and Chandrayaan-2 is expected to be ready for insertion into the lunar orbit on August 20. This will come almost a month after its launch from the Satish Dhawan Space Centre in Sriharikota on July 22. 

Soon in focus: Orbiter

Once the Mission enters the lunar orbit, all eyes will be on the Orbiter. It is designed to first disengage the Lander onto the lunar surface and then stay in a 100 x 100km orbit for over a year. During its orbital motion, the Orbiter will capture hi-resolution imagery of the lunar surface.

To do this, it is equipped with TMC 2, a Terrain Mapping Camera that can map the lunar surface with a high spatial resolution of 5 m and a swath of 20 km. “The data collected by TMC 2 will give us clues about the Moon's evolution and help us prepare 3D maps of the lunar surface,” says Isro. 

The Chandrayaan-2 Large Area Soft X-ray Spectrometer (CLASS) onboard the Orbiter will measure the Moon's X-ray Fluorescence (XRF) spectra to examine the presence of major elements such as Magnesium, Aluminium, Silicon, Calcium, Titanium, Iron, and Sodium.

Another device, the Orbiter High-Resolution Camera (OHRC) will focus on the Lander, Vikram's landing site. This is critical to ensure that the intended soft-landing is also safe, without any craters or boulders. The image and data will have to be analysed before the Lander separates from the Orbiter. 

OHRC's images will be captured over the course of two orbits, covering an area of 12 km x 3 km with a ground resolution of 0.32 m. The performance of these cameras will determine the success of the soft-landing planned on September 7.

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