Russia’s attempt at landing its spacecraft on the far side of the moon failed and all eyes are now on India’s Chandrayaan 3 which is set to create history by accomplishing the feat. On Sunday, ISRO announced that the lander module of Chandrayaan-3, the third lunar mission of India, is expected to touch down on the surface of the Moon around 6.04 pm on Tuesday, August 23.
Chandrayaan-3 Mission:
🇮🇳Chandrayaan-3 is set to land on the moon 🌖on August 23, 2023, around 18:04 Hrs. IST.
Thanks for the wishes and positivity!
Let’s continue experiencing the journey together
as the action unfolds LIVE at:
ISRO Website https://t.co/osrHMk7MZL
YouTube… pic.twitter.com/zyu1sdVpoE— ISRO (@isro) August 20, 2023
Not just Indians, but all those across the world who are passionate about human odysseys into space will be glued to their television sets or digitals screens to watch the live telecast of the landing event that will begin at 5.20 pm (Indian Standard Time) on Wednesday (August 23).
Chandrayaan-3 Mission🚀
Witness the cosmic climax as #Chandrayaan3 is set to land on the moon on 23 August 2023, around 18:04 IST.@isro pic.twitter.com/ho0wHQj3kw
— PIB India (@PIB_India) August 21, 2023
Now you may wonder why is the Chandrayaan 3 waiting for 23rd August when it has completed all the steps of lowering its orbit around the moon for a safe and successful landing.
Remember, the Russian spacecraft crash-landed on Saturday, 19th August while attempting to land on the moon’s surface. Powered by powerful rockets, it had arrived in the Lunar orbit in a matter of 5 days since its launch from the Earth and was all set to land on the 10th day. Meanwhile, ISRO’s Chandrayaan had taken 21 days to enter the Lunar orbit.
Why did the Chandrayaan not attempt landing even though it has arrived earlier?
Simple. It is the lunar night phase on the moon until a sunrise greets it on 23rd August. The Luna 25 had electronic equipment that runs on solar power. It also had an onboard generator. The Luna 25 battery that could last a year could keep the Luna 25’s essential electronics from freezing in the frigid moon temperatures of near minus 100 on a moon night and still keep them working without a worry about how little sunlight was available on the moon.
In stark contrast, Chandrayaan 3, built and launched on a far lower budget but with a huge amount of research and passion, has battery enough only for a day – that will be used on the day of landing say reports (https://www.tv9marathi.com/national/why-chandrayaan-3-have-to-wait-till-23-august-for-soft-landing-on-moon-and-how-russias-luna-25-can-land-in-night-time-1004886.html).
Therefore, ISRO had to be very careful about choosing the day for the soft landing plan. 23rd August will be the day of sunrise on the moon and the lunar day will last 14 Earth days. The lander and rover are designed to operate for one lunar daylight period (about 14 Earth days).
According to Earth Sky (https://earthsky.org/space/how-often-can-you-see-sunrises-and-sunsets-from-the-moon/), the sunrise on the moon comes suddenly. On Earth, we are used to the eastern horizon developing a warm glow before the sunrise and the twilight turning the western horizon red as the sun sets in the evening. Due to the scattering effect of light due to our planet’s atmosphere – when we watch a sunrise or sunset, we can see colored light in the sky.
The moon, meanwhile doesn’t have an atmosphere, so there are neither morning glows nor any twilight colours. The sky in the distance is dark and black, not blue; and if you were watching a sunrise on the moon, you would see stars rise in the sun’s vicinity and cross the sky with the sun throughout the lunar day.
That makes the sunrise and sunset appear and happen suddenly, abruptly. The moment the sun sets, the sky goes pitch dark as midnight, and there is no residual lingering light or colour.
While Earth’s spin on its axis gives us a day of 24 hours, there are about 29 earthly days from one lunar noon to the next.
The Hindu calendar that calculates its month on a lunar calendar, therefore, has a fortnight of roughly 14+ days as there would be about two weeks between each lunar sunrise and sunset, from any given spot on the moon’s globe.
The moon too spins on its axis but slow enough to keep its one face aimed in our direction. ha is why we see only a single spot on the moon.
Here’s a video below from Kurdistan Planetarium in the UK that shows the sun rising as seen from the moon’s surface and setting two weeks later.
This video by the Kurdistan Planetarium shows sunrise & sunset on the Moon from 22/5/2010 to 6/6/2010 pic.twitter.com/NMblO1TXvR
— Spaceguy²⁴ (@spaceguy_24) April 27, 2023
If Chandrayaan, by any chance, misses the landing opportunity now and the next few days, it may have to wait till September for the next window to open up.
Now you know why Chandrayaan-2 chose 23rd August to attempt the soft landing step.
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