Chandrayaan 2, India's second moon mission, is expected to complete its final orbit-lowering manoeuvre around the moon this evening. The lunar-bound manoeuvre is planned for 6-7 pm on 1 September by firing the spacecraft's onboard propulsion system. This fourth and final manoeuvre will move Chandrayaan 2 from its current 126 x 168 km (nearest x farthest distance) elliptical orbit to an almost-circular orbit of 114 x 128 km.

The Chandrayaan 2 composite has carried out three successful in-orbit manoeuvres since it entered lunar orbit — all to lower its altitude for separation of the Vikram lander and the landing itself. If successful, the final manoeuvre today will put the spacecraft on a circular path that passes over the lunar poles at a distance of roughly 100 km from the surface. Entering this circular orbit is the mission's final milestone before the Vikram lander separates from the orbiter to make its planned soft-landing on the moon's surface on 7 September at 1.55 am IST.

Chandrayaan 2 composite orbiting the moon before the lander's separation. Image: ISRO

The 100 x 100 km circular orbit will be close enough for the Vikram lander, currently bound to the orbiter in a 'composite', to separate. The separation and landing sequences are planned for 2 September and 7 September at 1.40 am, respectively. Between these two key milestones, the first maps of the landing site will be created (planned for 3 and 4 September) by the Vikram lander to ensure the landing site is safe, as previously thought, to make a soft-landing.

This is a crucial step in the mission since ISRO's mission engineers won't be operating the spacecraft remotely from the control centre. The orbiter will also be surveilling its year-long home for the first time, ensuring that no damage was caused to its instruments on the journey so far and conducting a thorough examination of the Vikram lander's landing site at the moon's South Polar region.

Chandrayaan 2 is expected to make its long-awaited powered descent and landing on 7 September at 1.40 am IST in a landing sequence that the ISRO Chief describes as '15 minutes of terror'.

While subsequent events in the mission won't be streamed live, you can catch live updates on the mission on our dedicated Chandrayaan 2 domain, our Twitter page, ISRO's website, or Twitter page.