ISRO is set to launch its Chandrayaan 3 Moon lander on Friday, July 14 at 2:35 PM IST. Its lander will attempt a soft touchdown on Luna as India’s second such try, as the lander on the 2019 Chandrayaan 2 mission unfortunately crashed during its final descent phase. A graceful touchdown would make India only the fourth country to achieve a lunar landing, following the US, the USSR, and China. I’m thrilled that I’ll be at Sriharikota to watch Chandrayaan 3 blast off for the Moon in person.
According to ISRO, the solar panels on both the Chandrayaan 3 lander and rover are mounted nearly 90° relative to the Moon’s surface. Since the landing site is at ~69°S, the Sun won’t rise higher than ~21° in the sky throughout the mission length of one lunar day. The sideways-facing solar panels thus maximize generated power.
Since the Chandrayaan 2 orbiter is operating successfully with its host of Moon-studying science instruments, and one observing the Sun in fact, the orbiter module of Chandrayaan 3 is primarily tasked with getting the lander to and around the Moon post-launch, and after the landing relay communications between Earth and the lander as an enhanced option. Having said that, the orbiter will host one Earth-observing experiment called SHAPE, which is a near-infrared spectro-polarimeter made to observe the full Earth disc from Luna to get a sense of what signatures of habitable Earth-like exoplanets might look like.
For testing Chandrayaan landers and rovers, ISRO developed a lunar soil simulant called LSS-ISAC-1. To make the simulant, ISRO sourced naturally occurring lunar-like anorthosite rock fragments from the Sittampundi Anorthosite Complex in southern India. This aided the simulant’s fidelity. The bulk chemistry, mineralogy, and physical & mechanical properties of the final LSS-ISAC-1 simulant are similar to Apollo 16 highland soil samples. This partly due to Chandrayaan 2’s target landing site having been a lunar highland too, as is also the case with Chandrayaan 3.
ISRO and NASA signed an agreement in February 2022 to use the latter’s Deep Space Network (DSN) to support communications for Chandrayaan 3. ESA will also provide backup mission communications via their Estrack network. ISRO uses its own Indian Deep Space Network as a primary means for communicating with its planetary spacecraft but partners with other space agencies like is the case here for backup and secondary options. India’s Chandrayaan 1 orbiter had DSN support too.