Chandrayaan 3: Launch and Discussions

[SivaR]

So I 'm sorry, but I feel I must digress into a small personal peeve of mine in regards to this mission.

I wanted our PROPER TRICOLOUR FLAG to be PROPERLY VISIBLE on this mission.

I beg to differ , the Indian flag is clearly visible on the rear side of the rover when it landed from Vikram. In fact , it looks like a Monitor screen with white background light having both Lion symbol and Indian flag below it. It is the white part, rest of the rover is fully wrapped in Heat Shield.

[Amber G.]

One thing I was thinking about...

Star Agustya (अगस्त्य ) (also known as α Carinae, or Canopus), is quite prominent ..as one looks .. high and very bright. (Possible it could be seen if you are in shade or block the sun even in the day time - as apart from sun/earth/ Venus , it is the brightest in the Lunar sky as seen from Vikram)

I am thinking of Lobbying to name some important point / crater after Agustya... Agustya is a great rishi too. - The star is named after Agustya as he travelled to South India and was one of the first person to describe this star (as the time of Agustya rishi - the star was not visible from norther parts of India).

[Shwetank]

ISRO Chief, S. Somnath (Lord of the moon!) talks about ancient Sanskrit texts (Surya Siddhanta, etc) which describes concepts which are today accepted worldwide and form the basis of modern science.

FWIW: The reason of my learning Sanskrit well was to read Surya Siddhanta in original (English Translation - especially many British scholars do not translate the text well - misses many important points.... (I know enough sanskrit to read math texts - and also Prakrit to read lot of Jain (Brahamagupts etc) texts.. (Many in math dhaga may have noticed that point.. ..

Amberji, have you compiled these translations somewhere? What were some main differences that western scholars missed? Can continue in math thread

[Amber G.]

While I was listening to PM Modi's speech (Youtube link is here in many of the posts), I was happy that he asked newer generation to study scientific texts like Surya Sidhanta - *and* modern scientific data and how these can be brought into modern scientific language. So just for fun, here is a challenge:

In Surya Sidhant we are given a few different figures of length of Lunar month : (I am giving approximate values in modern (commonly know) units (All in days); (There figures are given, how many cycles it will make in a whole yuga etc.)

1 - 29.53059 days
2 - 27.32158 days
3 - 27.32166 days
4 - 27.55455 days
5 - 27.21222 days

These are the *average( length of different cycles* (all in days) for 'full rotation' to calculate the exact position (naxtra) of the Moon, if you knew a position at one time... or to help you make a panchng of a particular year.

Challenge Q: What these different cycles represent? Why they are (slightly but noticeably) different from each other?
(If you know the answer, wait for a day or so before explaining -- if you did not know the answer before , and figured it out, please do comment)

(These values are pretty close to modern values, BTW)

[Cain Marko]

Even though I can't understand half of Dishaji and AmberGs posts on math, space and medicine, I propose....

Can we just appoint AmberG as BRs Bill Nye, the Science Guy ( or should it be, gal?).

AmberG, is BR's Scienceji. There. That's proper desi and even rhymes. Screw Bill Nye.

Hey CainJi, thanks. But what about me, that is what desi name you propose?

Sir, aap toh sabko disha dikhane mein jutey ho - Disha dikhane waley ko Dishajihi upyukta naam hai!

[Najunamar]

Dishaji can be called Desika like the great Nigamantha desika! One who shows the true disha!

[rahulm]

Somnath discusses many aspects inc. Gaganyaan timelines. LVM3 is now human rated.

From ~ 19.00 he discussed Atmanirbharta in space tech. Indigenous content: 1) Launchers = 80%, Satellites and sensors: 50% (all space qualified chips are imported), 3) ground equipment for space comms and remote sensing = mostly imported.

He states Atmanirbharta effort are paying off and expects an uptick in indigenous content for 2 and 3 in the future.

[sudarshan]

While I was listening to PM Modi's speech (Youtube link is here in many of the posts), I was happy that he asked newer generation to study scientific texts like Surya Sidhanta - *and* modern scientific data and how these can be brought into modern scientific language. So just for fun, here is a challenge:

In Surya Sidhant we are given a few different figures of length of Lunar month : (I am giving approximate values in modern (commonly know) units (All in days); (There figures are given, how many cycles it will make in a whole yuga etc.)

1 - 29.53059 days
2 - 27.32158 days
3 - 27.32166 days
4 - 27.55455 days
5 - 27.21222 days

These are the *average( length of different cycles* (all in days) for 'full rotation' to calculate the exact position (naxtra) of the Moon, if you knew a position at one time... or to help you make a panchng of a particular year.

Challenge Q: What these different cycles represent? Why they are (slightly but noticeably) different from each other?
(If you know the answer, wait for a day or so before explaining -- if you did not know the answer before , and figured it out, please do comment)

(These values are pretty close to modern values, BTW)

I think I know two of these five, will wait a day or so.

[Najunamar]

I have only seen the synodic and sidereal months, the others are OHT for me...

[vijayk]

Why are we not seeing any pictures from the rover? Is there something technically wrong?

[sanman]

Why are we not seeing any pictures from the rover? Is there something technically wrong?

As ISRO Chairman Somnath mentioned in his speech to Modi, the low bandwidth/speed of transmission means that it takes a long time for images to be transmitted back and processed for release. That seems to be the limiting factor in getting images out to the public.

Perhaps future ISRO missions there should include upgraded communications relay back to Earth.

[williams]

Why are we not seeing any pictures from the rover? Is there something technically wrong?

As ISRO Chairman Somnath mentioned in his speech to Modi, the low bandwidth/speed of transmission means that it takes a long time for images to be transmitted back and processed for release. That seems to be the limiting factor in getting images out to the public.

Perhaps future ISRO missions there should include upgraded communications relay back to Earth.

I am guessing we may need to upgrade our DSN to achieve better bandwidth.

[SSSalvi]

Why no pic?
Yesterday we saw lander facing sun for charging.
Certain protocols and SOPs have to be followed.
Only after that science can start.
We must give them time. One thing is sure, they don't hide facts.. if there is a problem they will accept and tell.

DSN speeds are always low for deep space missions. It could be more for moon, but currently sun is behind moon so communication windows may be smaller.

[Amber G.]

^^^ And apart from other things.. CH2 (which is getting those pictures from Vikram) is not in the light of sight 100% of the time.. (Remember it is in orbit with a period of 2.1 Hours) to communicate..

Just for perspective .. in many of other missions ... a long time elapsed before those stunning pictures were available to aam janta. (For may High resolution pictures from Apollo mission, they have to wait till the photographic film was returned to earth and developed )
(Apart from that, there is probably encryption for that data which not for all eyes)

---
Also how much transparency this program has ...
A trip to the Moon in Doppler!

--- Picture or not..
Chandrayaan-3 Mission:

Of the 3⃣ mission objectives,

Demonstration of a Safe and Soft Landing on the Lunar Surface is accomplished

Demonstration of Rover roving on the moon is accomplished

Conducting in-situ scientific experiments is underway. All payloads are performing normally.

[RCase]

Picture is worth 100 words.

Attempting with real simulation

Salvi ji, Amber ji and others - thank you for your responses to my questions. Hoping that I have understood you guys properly and am taking the liberty of using a simplistic metaphor by using earthly props that an aam abdul will be able to relate to. For those of you who are gurus at this, you can give this post a skip.

Here is my take at a pic is worth a 100 words... - no math, trig, astronomy etc required.


I am using a picture of a merry-go-round to visualize this. A person sitting on the merry go round horse/bench (moon), watching the center column (earth). Even though you are sitting on the horse, your body is turned to always be facing the center column. No matter what, you are always facing the column like the near face of the moon always facing the earth (tidal locking).

1. If the sun is in the background and you are on the horse in the foreground, the center pole is darker (not lit by the sunlight). However you can see the background lit up by the sun (lunar day on the near side of the moon). For the person on the earth facing you, it is night on earth, as he cannot see the sun and can see the horse (moon) lit up by the sun.

2. When the horse is on the other side of the merry go round, the sun is to your back (remember, your focus is always on the center column). The center pole is lit up by the sun (day time on earth), but only your backside is getting the sunlight (lunar night on the near side of the moon).

3. If you see people, cars (nakshatras, other planets) etc. passing by on the outside, say from east to west; that is exactly what you would see the stars do. Similar situation with the sun. However, from your view point, the center pole never moves in any direction. It is always in the same spot, although you get to see its different facets (continents, oceans etc.) and that is why there is no earth rise and set in the traditional way we are used to seeing things in the sky on the earth.

4. This should also give you an idea about the eclipses from the moon's perspective.

5. You can also visualize if the column is also rotating about its axis (one rotation every earth day) and if it is faster than the rotation of the horse (one rotation in 28 earth days), the pictures on the column would go by and you get to see them again and again.

6. This also gives you a clue of why we see the moon rise and set. If you are on the center column and can imagine 'standing' on the column (i.e. parallel to the rotating base) , you will be approaching the horse (moon) low on the horizon and passing by it overhead and fading away in the back into the horizon to give the moon rise and moon set.

This is my very simplistic way of visualizing this to explain away things.

[Amber G.]

^^^ Cool!

[putnanja]

Picture is worth 100 words.

Attempting with real simulation

Salvi ji, Amber ji and others - thank you for your responses to my questions. Hoping that I have understood you guys properly and am taking the liberty of using a simplistic metaphor by using earthly props that an aam abdul will be able to relate to. For those of you who are gurus at this, you can give this post a skip.

Here is my take at a pic is worth a 100 words... - no math, trig, astronomy etc required.
....

Very clear explanation RCase!

[SSSalvi]

^^^
Very appropriate visualization rcase ji.
Admire your imagination of finding a suitable anology.
This can always be used for orbit understanding.

[sanman]

I beg to differ , the Indian flag is clearly visible on the rear side of the rover when it landed from Vikram. In fact , it looks like a Monitor screen with white background light having both Lion symbol and Indian flag below it. It is the white part, rest of the rover is fully wrapped in Heat Shield.

Alright, fair enough, I stand corrected on the rover part. But we could've had the tricolour displayed in the camera foreground of the lander/propulsionmodule stack while it flew to the Moon. Remember that all this video footage is kept for posterity.

[Amber G.]

^^^ Cool!

Added later: BTW, one can explain the different values of the length of the 'lunar month' i mentioned in my post with similar analogy..

[sanman]

According to people quoting people quoting other people, Team ISRO have tried taking pics using both lander and rover. One of the problems with taking pics from the rover is that the partial shadowing of the rover is causing optical effects. So turning the rover toward better angles is required, but they're concerned that such turning could result in loss of solar power to the rover, which only has a small battery unit that cannot sustain it for long without solar power. So they've decided to continue carrying out scientific measurements of soil first to gather useful scientific data, before later performing any maneuvers to help picture-taking.

I personally would love to see picture of our lander with Earth in the background.
"Earthrise" would be especially cool.

[RCase]

I am just using my intuition to figure out the difference between the 29+ days and the 27+ days. I am not sure of the actual astronomical terms for these lunar months. This is just my guess.

If we were to go back to the merry go round analogy, for the moon to start from a point and do a complete rotation and come back to the same point is probably the 27+ day period. For e.g. the horse in the foreground doing a complete circle and coming back to the same point in the foreground.

However, the earth is also rotating. So while the moon does a full rotation and comes back to the foreground point, the corresponding point on the earth (facet on the column) has probably moved forward and the moon will take a few more days to catch up to the exact facet at the start. This I presume is the 29+ day period.

The minor value changes in the 27+day period may be due to the elliptical nature of the orbits, rather than circular simplistic assumptions in this analogy.

[RCase]

I personally would love to see picture of our lander with Earth in the background.
"Earthrise" would be especially cool.

I don't think that will be possible in this mission of 14 days. In the current period of 14 days of Day on moon will correspond to night side on earth. So Vikram/ Pragyan will not be seeing an earth rise during these 14 days. If the lander/ rover can work beyond the 14th day (lunar night) and can send back pictures, then it might be possible to see an earth rise. I am sure there are gurus out here who can correct me if I am wrong.

[sanman]

I don't think that will be possible in this mission of 14 days. In the current period of 14 days of Day on moon will correspond to night side on earth. So Vikram/ Pragyan will not be seeing an earth rise during these 14 days. If the lander/ rover can work beyond the 14th day (lunar night) and can send back pictures, then it might be possible to see an earth rise. I am sure there are gurus out here who can correct me if I am wrong.

Even while being in the Moon's Southern Polar region, VIkram is still on the Near Side of the Moon which faces Earth. I think that's the main criteria for being able to see Earth in the lunar sky. As for which phase we'll get to see Earth in, that doesn't matter to me as much.

Here's a free online simulator which can render a view of the Earth from the Moon's surface, just by entering the lat/long coordinates:

https://www.fourmilab.ch/cgi-bin/Earth/action?opt=-m

[juvva]

According to people quoting people quoting other people, Team ISRO have tried taking pics using both lander and rover. One of the problems with taking pics from the rover is that the partial shadowing of the rover is causing optical effects. So turning the rover toward better angles is required, but they're concerned that such turning could result in loss of solar power to the rover, which only has a small battery unit that cannot sustain it for long without solar power. So they've decided to continue carrying out scientific measurements of soil first to gather useful scientific data, before later performing any maneuvers to help picture-taking.

I personally would love to see picture of our lander with Earth in the background.
"Earthrise" would be especially cool.

but
the lander must be having multiple cameras and (persumably ) no power issues.
how come we see only one or two pics and short videos from only one camera ?

[SSSalvi]

Ye to kaam karna chalu kiya !!!

https://twitter.com/isro/status/1695725102166671448

https://twitter.com/isro/status/1695725 ... 48/photo/1

[SSSalvi]

Interesting stuff:
https://twitter.com/rocketgyan/status/1 ... 2190497089
https://twitter.com/rocketgyan/status/1 ... 2190497089

[arvin]

^^^
SSSalvi Sir, About RHU I dont think the news is credible.
If it indeed carried one, the CH3PM needs to have the distinctive radiator fins. None of it was visible.
DAE would have been involved from the very begining and safety measures would have different. Such things can't be done hush hush due to radiation concerns if launch fails.

[Amber G.]

Here's a free online simulator which can render a view of the Earth from the Moon's surface, just by entering the lat/long coordinates:

https://www.fourmilab.ch/cgi-bin/Earth/action?opt=-m

Thanks. Simulator is nice..though one does not need a simulator ... to see (or not see) 'earthrise .. (BTW, there are JPL/Horizon or many other such tools give beautiful *and* *almost realistic views'. But math is quite simple to deduct how things will look.. also most skymap type apps (like steller sky) on you iPhone, one can set the location not only any place on earth but on moon too)

So Vikram/ Pragyan will not be seeing an earth rise during these 14 days.

"Earthrise" would be especially cool.

It has been mentioned here a few times.. but mentioning again --- from Vikram/Pragyan - There will not be any 'earthrise' -- in near future (that is next few hundred/thousand years)

-- Earth hangs suspended, nearly fixed in the sky, at about 20 degrees (+-5) above the horizon.
-- During the lunar day (at present), Earth is not as bright as it appears during the lunar night. However, just as we can see the Moon in the daytime, we can now also observe Earth from Moon . After 14 days, during the lunar night, Earth will become more prominent in the sky. Around that time, it will reach its 'full' phase, likely on September 14th. It's worth noting that cameras are unlikely to function due to lack of power and the extreme cold during this period.
-- Every 29.5 days cycle it becomes 'full' and 'new'earth' . In a cycle of approximately 29.5 days, Earth becomes 'full' and 'new,' similar to the Moon's phases. In August..., Earth will experience a 'super newearth', ( Amavasya). During this time, it will appear larger due to its proximity (Earth's closest point) to the Moon, which is near perigee in its orbit. This is an interesting detail that seems to have been overlooked. On Earth, it will manifest not just as a full moon, but as a 'super full moon.'

--- Regarding the part of Earth visible from Vikram: If the Moon is visible from point X on Earth, then point X will also be visible from Vikram. Whether it appears on the illuminated or dark side of Earth will depend on whether it is currently daytime or nighttime at that specific point on Earth (a cycle of 24 hours)."

----

--- Nerdy science tidbit: (Which every student of astronomy ought to know

-- Earthrise / Earthset can be seen from CH3PM (of CH2) .. cycle of every 2.1 hour.. probably photographed thousands of times)
-- On the surface of the moon - only places where earth rises or sets -- are northern or southern pole areas higher than 85 degrees in lattitude.. or small areas near the boundary of near/far side (due to 'liberation')


---

[Najunamar]

Quick question: All Apollo missions mention the sub-surface temperature on the moon as relatively stable compared to the surface temp which can go between extremes (lunar days and nights), but they also hypothesized that temp will rise as you go deeper. Is the temp profile decreasing-increasing during lunar days and monotonically increasing with depth during lunar nights?

[Amber G.]

I don't think that will be possible in this mission of 14 days. In the current period of 14 days of Day on moon will correspond to night side on earth. So Vikram/ Pragyan will not be seeing an earth rise during these 14 days. If the lander/ rover can work beyond the 14th day (lunar night) and can send back pictures, then it might be possible to see an earth rise. I am sure there are gurus out here who can correct me if I am wrong.

See my above pos (or posts) t.. to be clear - these 14 days is one lunar day.. and 14 days/nights on earth.
Day/Night side on earth are not 'fixed' (every place has day and night in a cycle of 24 hours). From Pragyan (or any point on near side of earth).. there are no 'earthrise'.. (Earth just hangs at a fixed point as seen from moon's surface... there are phases of the earth (1 month cycle) and earth spins (so you can see all part of earth in 24 hour period)...

Just like on earth - we can see moon in night ( around full moon time) or moon in the day ( around amavasya) - (Granted that moon is difficult to 'see' in day time)... From Moon (if you are on near side) one can see earth all the time... in lunar night it is easier to see because there is no sun to outshine the earth).. (Of course, a 'full earth' is much brighter than other phases , but will be visible almost all the time)

[SriKumar]

In Surya Sidhant we are given a few different figures of length of Lunar month : (I am giving approximate values in modern (commonly know) units (All in days); (There figures are given, how many cycles it will make in a whole yuga etc.)
1 - 29.53059 days
2 - 27.32158 days
3 - 27.32166 days
4 - 27.55455 days
5 - 27.21222 days

These are the *average( length of different cycles* (all in days) for 'full rotation' to calculate the exact position (naxtra) of the Moon, if you knew a position at one time... or to help you make a panchng of a particular year.

Essentially all of them measure the time for a full revolution in time units of earth days (a very awkward unit to measure a 'year', fraught with a lot of significant digits). I think two of the above would be the time for moon to go around earth, two of them would be to measure earth's revolution around the sun, and the last one I am not sure. The two measures for each category would relate to different reference points: as in the difference between tropical year (ecliptic crossing as the reference point?) vs. sidereal year (distant stars as the reference point).

[SriKumar]

Ye to kaam karna chalu kiya !!!
https://twitter.com/isro/status/1695725 ... 48/photo/1

Why would the temperature increase above the lunar surface relative to the surface. The heat on moon surface is entirely due to the solar radiation absorbed by the moon surface. I guess the above-the-surface measurements are being done not in shade, and are catching the sunlight directly (typical temperature measurements are done in shade on earth but on the moon it may be OK since there is no air or clouds to mess up the measurements).

[Amber G.]

^^^ (posting from above)ISRO:

Here are the first observations from the ChaSTE payload onboard Vikram Lander.

ChaSTE (Chandra's Surface Thermophysical Experiment) measures the temperature profile of the lunar topsoil around the pole, to understand the thermal behaviour of the moon's surface. It has a temperature probe equipped with a controlled penetration mechanism capable of reaching a depth of 10 cm beneath the surface. The probe is fitted with 10 individual temperature sensors.

The presented graph illustrates the temperature variations of the lunar surface/near-surface at various depths, as recorded during the probe's penetration. This is the first such profile for the lunar south pole. Detailed observations are underway.

[Amber G.]

Meanwhile:
Japan's lunar lander which will be launching tomorrow (28 August) at 5:56am (IST).

The lander named SLIM(Smart Lander for Investigating Moon) will demonstrate high precision pinpoint landing for future missions like LUPEX.

[sudarshan]

Ye to kaam karna chalu kiya !!!
https://twitter.com/isro/status/1695725 ... 48/photo/1

Why would the temperature increase above the lunar surface relative to the surface. The heat on moon surface is entirely due to the solar radiation absorbed by the moon surface. I guess the above-the-surface measurements are being done not in shade, and are catching the sunlight directly (typical temperature measurements are done in shade on earth but on the moon it may be OK since there is no air or clouds to mess up the measurements).

EDIT: I WAS READING THE CHART WITH WRONG UNITS, SO THE BELOW IS PROBABLY IRRELEVANT, EVEN IF THERE MAY BE SOME TRUTH TO IT.

My guess - we say the moon has no atmosphere, but there is actually a little bit of "air" close to the surface, at very low pressures. So the same phenomenon that we see on earth, where temperature drops gently with altitude, is also seen on the moon, except that on the earth the slope of temperature with altitude is much gentler, whereas on the moon that whole phenomenon plays out essentially within meters of the surface. "Outer space" on earth is like a hundred kilometers (or a thousand - depending on whom you ask) from the surface, whereas for the moon, it would be like a meter to 10 meters from the surface.

Again, the above is just speculation on my part.

[juvva]

Ye to kaam karna chalu kiya !!!
https://twitter.com/isro/status/1695725 ... 48/photo/1

Why would the temperature increase above the lunar surface relative to the surface. The heat on moon surface is entirely due to the solar radiation absorbed by the moon surface. I guess the above-the-surface measurements are being done not in shade, and are catching the sunlight directly (typical temperature measurements are done in shade on earth but on the moon it may be OK since there is no air or clouds to mess up the measurements).

since it is early in the morning ( at shiv shakti ) , the ground may be still retaining the cold of the night...

[Amber G.]

^^^
SSSalvi Sir, About RHU I dont think the news is credible.
If it indeed carried one, the CH3PM needs to have the distinctive radiator fins. None of it was visible.
DAE would have been involved from the very begining and safety measures would have different. Such things can't be done hush hush due to radiation concerns if launch fails.

FWIW: (I do not have any information in this particular case) Radiation concerns associated with a small (1W) Pu-238 RTG unit are manageable with proper containment and handling procedures..IMO, it will not be 'hush' 'hush'..if it wasn't public and all clearance have been takes.. I don't know the guidelines or procedures in India... but for purely technical point of view..In the context of space missions, the primary concern is preventing the release of radioactive material into Earth's atmosphere. This could occur during launch failures or reentry accidents. Contingency plans and safety measures are in place to minimize the potential impact in such scenarios...( these are designed with robust containment systems to prevent the release of radioactive materials. ityadi)..Alpha particles emitted by Pu-238 can be harmful if they come into direct contact with living tissue (internal tissues) - if you inhale etc... But alpha particles have limited penetration, and they can be easily stopped by materials like tissue paper or even human skin....the risk of external alpha radiation exposure is minimal as long as the RTG casing remains intact.

[juvva]

^^not sure if some international body like iaea needs to be informed and kept in loop.

[Amber G.]

^^^ Not a lawyer, but from what I know - There are guidelines but nothing legally binding codes ... guidelines are proper shielding...informing public/shareholders ..and following procedures commonly agreed by NASA/ESA/ISRO etc.. (For sats, there is also re entry safety procedures/protocols but CH3 is not going to return back..)

----

Its morning - still temperatures on the surface is more than 50C...