Chandrayaan 3: Launch and Discussions

[SSSalvi]

The next Lunar bound orbit maneuver is scheduled for August 6, 2023, between 22:30 and 23:30 Hrs. IST.

[Amber G.]

Just for general info:

Showing the significance of orbit attained.

Ground path that the orbit takes while the CH3 is orbitting.

Notice the Landing sight 'L' and the South pole 'P'

( Note: This is based on Planned orbit ... not on the achieved orbit. Will update when available including . How the sunlight illumination plays role in deciding the 14 days life of Lander. )

<Image>

The primary landing site (from what I know - actual site we will know in 2-3 weeks is in the vicinity of the lunar South Pole region, located at 69.37 degrees south latitude and 32.35 degrees east longitude - No previous Moon mission has landed (softly) at a lower latitude... Thought I will put a map or the region..

CY2 has detailed map of the area - the above one is The scene above was captured from an LROC Quickmap fly-around of the site, image width is about 150 kilometers across the center. CY2 orbiter is still in orbit collecting science data.

Train your telescopes here (Image from earth - this does not change with time):

[Amber G.]

One of the CY3' Vikram/Pragyan pay load interesting to me is LRA ( Laser Retroreflector Array), supplied by NASA. This is passive instrument (requires no batteries etc), weighs only about 20 gms (about 3 gm on the moon ). LRA consists of eight tiny retroreflectors affixed to a hemispherical platform attached to the Vikram. The device, when struck by laser light, reflects the light back to its source to reveal its location - precise location! The device, I think is too small to be used by lasers from earth (at least now) but from PM (or other space-crafts) can be use it to locate it exactly even if everything else is not working.

LRAs can be used as precision landmarks for guidance and navigation during the lunar day or night. In the future, by placing a few LRAs around a specific site they can guide arriving robotic or human-carrying landers to a safe, pinpoint landing.

Other payloads: ChaSTE, ILSA, Langmuir Probe, APXS, LIBS etc have been talked about but I have not heard much about LRA so posting it here.

[SSSalvi]

Landing location ( within 2 3 kms margin) is mentioned in mission document published by ISRO

[Amber G.]

Increasing Orbit:

To increase the orbit's size (altitude), a spacecraft typically fires its thrusters at apogee. This is because when the spacecraft is at apogee, it is moving slower in its orbit, and applying thrust at this point increases its kinetic energy. This results in a higher perigee and apogee, effectively raising the orbit's altitude.

Dumb question: I thought that the use of the engine at higher speeds generates a greater change in mechanical energy and a hence higher orbit (Oberth effect), than its use at lower speeds. So would it not be more efficient to fire the engines at the perigee (highest velocity) than at the apogee or am I missing something?

Allow me to answer it in little more details - some insights physics wise ...

It depends on what you want to do...

To be clear let us be sure if we are talking about sats on earth's orbit or sending a probe to some other planet (or moon).. and perigee/apogee/speed wrt to what object (frame of reference)>

Let us make things simple and just consider a spacecraft and Earth (any planet).. in Earth's orbit

- Here to raise altitude - or increase the average distance from the center of the planet - from an elliptical orbit, typical firing is done at apogee. For details see for example "Hohmann transfer orbit' (in wiki or any standard text book).
-- Typically, if you want to put an orbit in Geosynchronous orbit, you achieve an elliptical orbit initially , whose apogee is far but semimajor axis (arithmetic mean of perigee and apogee) is much less. A burn at apogee (or near apogee) puts into higher (bigger semimajor axis - near circular orbit).

---Even in when a PSLV / Or GSLV case , at the time of just before the second stage (or third stage), the orbit is ellipse, the perigee is close to center of the earth/inside the earth, as earth is not a point but a sphere .. and rocket will hit the surface before it reaches perigee. The second stage is fired at apogee (at highest point)..

(Side note - there are more complex maneuvers which are more fuel efficient but they are more complex, takes more time to achieve the required orbit and need more calculations to make it perfect - see Bi-elliptic transfer for example)
(The subject matter, to be honest, is quite complex, one does need good math background to understand *everything* Most 'explanations' given for popular consumptions are sometimes quite misleading/false).

---
When another planet is involved, say the Moon, and take CY3's case:

- The final orbit of CY3, wrt to earth: (See <this picture posted by me before for example , the final orbit of CY3 is a circular orbit (Just like our Moon .. with some *small* wiggles (those 'orbits' going around moon ...the *last* LOI burn was done at the *apogee* (wrt to earth!) which almost doubled the 'altitude' (from earth).. now equal to the Moon's orbit.

(Thanks to ISRO's magic/calculations - the moon's position *assisted* in reducing the burn).

- The orbit (wrt to moon) decreased, by this burn. This burn was done at the *perigee* (wrt to the moon)

---

Oberth effect, you talked about, (also called gravity assist, sling shot etc).. is taking the advantage of moon's position.. (It does require very complex computations to be precise). By carefully timing, one can reduce amount of fuel needed to make CY3 to 'capture by the moon' or *speed* it up to, say shoot it to Mars.. (with less fuel than you will ordinary need if there was no moon).

Hope this helps.

[Ashokk]

Hope this helps.

Thanks.

[Amber G.]

iirc the apollo lunar missions used to execute a loi burn on the far side of the moon, but it looks like chandrayan_x missions execute the burn in radio visibility of earth.
why the difference?

FWIW: In the days before we had access to fast computers/software to do precise calculations, and magicians in ISRO to take advantage of these, all probes were in same (or nearly - with small up-down perturbations) plane as moon's orbit around earth. (Which is tilted about 28 deg - at present - from earth's equatorial plane and about 7 degrees wrt to Moon's equator, and around 5 degrees wrt to ecliptic).

So this meant, LOI have to be done around the 'other side of the moon'.

(Not only that, it was hard to achieve 'polar' orbit around the moon. One needs fuel (and access to fast computers to time the burbn to change inclination) All orbits were near equatorial orbits wrt to the moon)
(CY3 - as s^3 said - orbit plane is such that CY3, is quite far enough on z-axis to not be eclipsed by the moon. This is, more to do with conserving the fuel than make the LOI burn be visible from earth. Not that I am complaining -- I was getting live data from radio telescopes from Canada (where the moon was visible etc). But computes *on board* of CY3 are good enough to do all that burn without help from Earth-bound computers and could easily do that at anytime - visible from earth or not.

(For Apollo 11 and other crafts - one of the tens situation were these burn as they have to be done behind the moon, Human beings were behind the controls. Still, if anything was not right, the instructions were to skip the burn - and the spacecraft will return to earth - as carefully planned. Apollo 13 did take advantage of this).

[Ashokk]

Tapan Misra speaking on Chandrayaan 3, on board instruments, discovery of water on the moon etc.

[Amber G.]

Very first pictures of the Moon captured by #CY3 as it draws closer to its destination as the world looks at us with awe and envy. (Click the image to see the video)


The ISRO Video is here:

[SSSalvi]

^^^
Thrilling to see going from light to darkness. To remind its purpose... Tamaso maa... Jyotirgamaya.
Let there be no darkness
Make the things bright.. unveil the hidden region

BTW, publication of 1st image by Boss.. not chief.

[disha]

The ISRO Video is here:

Or this link: https://twitter.com/i/status/1688221675157118978

[Anant]

Awesome!

[Anant]

To the experts on here, I love reading all your posts. Please keep them coming. I'm a biochemist but love all sciences. Amber G, how I wish I had instructors like you when I was in university! Good luck to a safe soft landing. Might have to get some jilebi.

[Ashokk]

https://twitter.com/isro/status/1688248504458846208

Chandrayaan-3 Mission:
The spacecraft successfully underwent a planned orbit reduction maneuver. The retrofiring of engines brought it closer to the Moon's surface, now to 170 km x 4313 km.

The next operation to further reduce the orbit is scheduled for August 9, 2023, between 13:00 and 14:00 Hrs. IST.

[Amber G.]

CY3 underwent a planned orbit reduction maneuver successfully. Orbit now is 170 km x 4313 km . Next orbit correction is scheduled for August 9, 2023, 1 pm to 2pm per ISRO

Using this method this means
The time period of this orbit is about 2.1 Hours. If you have a calculator (or can do simple math on pen and paper )It might be fun to calculate speed (v), delta-v etc for each maneuver and see how close your values are with those supplied by ISRO or other sources ...(If you have 'r' (distance from the moon) and 'v' (speed wrt to moon, direction does not matter, just the magnitude), you can calculate everything else).

[sanman]

View from Chandrayaan-3 entering lunar orbit:

[Amber G.]

Latest update from ISRO:

Dance of Chandrayaan: A Lunar Symphony"

In the realm of starry dreams, Chandrayaan soared,
With engines aflame, its mission restored.
A dance with the Moon, a celestial embrace,
A voyage of wonder, through time and space.

Orbit maneuver deftly planned and precise,
Engines retrofired, like whispers in the night.
Closer to Luna's heart, it gently drew near,
170 km x 4313 km, its path now clear.

A cosmic waltz, a ballet in the sky,
Chandrayaan's journey, oh so high.
On August 9th, with eager hearts aglow,
Another step closer, as the hours flow.

Guided by science, a cosmic ballet's tune,
Chandrayaan's orbit, a celestial monsoon.
Closer it drew, with engines that hummed,
A lunar waltz played, as the universe thrummed.

On August 23rd, another chapter shall unfold,
As Chandrayaan's saga continues, bold and untold.
Vikram poised to land, with grace untold,
Softly touching lunar soil, a story to be told.

Pragyan, swift and nimble, shall play its part,
'Midst craters and shadows, a dance to start.
A triumph of science, human spirit and might,
In the realm of the Moon, a beacon of light.

May Rakshaks rejoice, with joy and glee,
As Chandrayaan fulfills its destiny.

- Author anonymous brfoldie - all rights reserved.
Had to add this image

[ramana]

Chandrayaan-3 Mission:
The spacecraft successfully underwent a planned orbit reduction maneuver. The retrofiring of engines brought it closer to the Moon's surface, now to 170 km x 4313 km.

The next operation to further reduce the orbit is scheduled for August 9, 2023, between 13:00 and 14:00 Hrs

#Space #CY3

[Amber G.]

Chandrayaan-3 Mission:
The spacecraft successfully underwent a planned orbit reduction maneuver. The retrofiring of engines brought it closer to the Moon's surface, now to 170 km x 4313 km.

The next operation to further reduce the orbit is scheduled for August 9, 2023, between 13:00 and 14:00 Hrs. IST.

And the radio telescopes all over the world noticed it. The SNR is low (as position of the moon is not ideal for this telescope) but you can clearly see the burn ~2023-08-06 17:37 UTC w/ Doppler bend...




(ISRO has tweeted about it and brfites have already written poems about it ... (See <above post>)

[Amber G.]

JUST FOR FUN - Ignore if not interested in boring math.....

I wish, ISRO, (or somebody who has data), put the ephemerides in form, we all (at least those who know elliptical orbits and do calculations - or have software to draw orbits) can use .. to know exactly what's going on...

(Sankar V have not updated the app with the latest data as yet.. so for those who want to calculate.. here is my attempt to put ephemerides in the old-fashioned (Keplerian) way....

(These are NOT official numbers, (or from any one source) from fuzzy data given by ISRO (and seeing some radio Telescope data etc).. the numbers are approximate but good enough to do any calculation)

EPOC Time: August 5, 2023, 13:58:58 UTC
Reference system Moon:
Post LOI orbit:
SMA = 10856.3 Km
ECC = 0.82
INC = 89.2
RAAN = 268.2
AOP = 289
TA = 356

(For those whose knowledge about Keplerian orbital elements is rusty, the acronyms stand for the following:


SMA: Semi-Major Axis
Ecc: Eccentricity
Inc: Inclination
RAAN: Right Ascension of Ascending Node
AOP: Argument of Periapsis
TA: True Anomaly
Here's a brief explanation of each term:

Semi-Major Axis (SMA): The average distance between the center of the primary body (e.g., a planet) and the orbiting object (e.g., a satellite) in an elliptical orbit. (See my old post, it is simply average of Perigee and Apogee - (ISRO gives altitude so you have to add Moon's radius)

Eccentricity (Ecc): A measure of how elliptical an orbit is. An eccentricity of 0 indicates a perfect circle, while higher values indicate more elongated orbits. ( Geometric mean of perigee and apogee is semi minor axis)

Inclination (Inc): The angle between the orbital plane and a reference plane - (Moon's equator) for polar orbits it is 90 deg.

Right Ascension of Ascending Node (RAAN): The angle measured along the celestial equator from vernal equinox to the ascending node of the orbit.

Argument of Periapsis (AOP): The angle measured in the orbital plane from the ascending node to the periapsis.
True Anomaly (TA): The angle measured in the orbital plane from the periapsis to the current position of the orbiting object.

These orbital elements are used to fully define the shape and orientation of an orbit in celestial mechanics. They are particularly important in the study of satellites, planets, and other celestial bodies' orbits around a central body..

---
After the first orbit correction, we have perigee = 1737.4+170, Apogee = 1737.4+4313 so SMA = 3979 Km
(Calculation of ECC is left as an exercise - INC is not going to change
(Okay SMA = 3979 Km, ECC = 0.52 - If my calculations are right )

[suryag]

Gurus, Chandrayaan1(according to wiki) took 23 days to reach 100x100 orbit, mass 1380kg, Chandrayaan2 took 41 days, mass 3850 kg, chandrayaan 3 with similar mass is taking 10 days less ? whats the science behind this ?

[sajaym]

https://www.ndtv.com/world-news/russia- ... google.com

Is this news true? The russkies supposedly also planning a lander to the moon's South pole.

Luna-25 will launch on a Soyuz-2 Fregat booster and will be the first lander to arrive on the South Pole of the moon, Roscosmos has said.

[SSSalvi]

^^^ suryag post :

Done some extensive search...

CH1:launched on a PSLV . 256 x 22,866 km x 17.8 deg > i 37,000 km> 73,000 km > 387,000 km.

Chandrayaan 2 was launched on(GSLV) Mark III. (170 x 40400 km altitude) [ There is an interesting side show: Instead of shutting off last stage at intended Launch altitude, ISRO let the engine burn till depletion. Due to this the craft attained 6000 kms extra coverage in altitude and so planned 1st orbit raising was not necessary !! ].
2nd ( and which answers your question ) sideshow : Original launch was on 14 July, which had to be postponed to 22 July due technical glitch. original 17 days orbit raising ( if launch was on 14 July ), extended to 23 days due to this launch on 22nd.

Final orbit raising time is dependent on Moon position. If you are fully confident then you may not dwell more on each orbit raise and reduce the Launch to LOI and LOI to final Lunar orbit period extensively.

[Ashokk]

https://www.ndtv.com/world-news/russia- ... google.com

Is this news true? The russkies supposedly also planning a lander to the moon's South pole.

Luna-25 will launch on a Soyuz-2 Fregat booster and will be the first lander to arrive on the South Pole of the moon, Roscosmos has said.

Yes, launch scheduled for 11th, they plan to land on moon's South pole on the 21st.

[Amber G.]

^^^ This is *long* planned and *well-known*.
Initial mission plans were for a lander and orbiter, and impact penetrators deployment. At present , In its current form, Luna 25 is a lander only. (Primary mission - proving out the landing technology just like India). Plans are to carry 30 kg of scientific instruments, a robotic arm for soil samples and possible drilling
The launch is currently scheduled to occur on 10-11 August 2023 on a Soyuz-2.1b rocket with Fregat upper stage, from Vostochny Cosmodrome. (It is the first time since 1976 that they are sending a lander).

There is a Japanese space craft too (SLIM) .. Around August 26 .. (LOI time to be yet announced)

(SLIM is going to orbit around the Moon. SLIM stands for "Small Lunar In Situ Mass Spectrometer." It is a small, CubeSat-sized spacecraft that is being developed by NASA's Jet Propulsion Laboratory (JPL). The main goal of the SLIM mission is to study the composition of the lunar regolith)



--- Chandrayaan3 is not alone... apart from Luna25, SLIM and CY1 and CY2 orbiter following well known objects are there too - (Partial list)
Chang'e 4: China's Chang'e 4 lunar lander and rover(first spacecraft to soft-land on the far side of the Moon in January 2019) The lander is still in orbit around the Moon, while the rover has been exploring the surface for over two years.

Lunar Reconnaissance Orbiter (LRO): NASA's LRO has been orbiting the Moon since 2009. The LRO is used to map the Moon's surface, study its geology, and search for potential landing sites for future missions.

Gravity Recovery and Interior Laboratory (GRAIL): NASA's GRAIL mission was launched in 2011 and orbited the Moon for two years. The GRAIL mission used two spacecraft to measure the Moon's gravity field, which helped scientists to learn more about its interior structure.

Deep Space Climate Observatory (DSCOVR): NASA's DSCOVR spacecraft is currently in a halo orbit around the Moon. The DSCOVR mission is used to monitor the Sun and Earth's atmosphere.

Lunar Gateway: The Lunar Gateway is a planned space station that will orbit the Moon. The Lunar Gateway will be used as a staging ground for future missions to the Moon and beyond.

Just a few - CY3 will not be lonely..

[Amber G.]

Remembering the night of September 7, 2019

"Echoes of the Past, Dreams of Tomorrow"

In Luna's embrace, Chandrayaan Three,
May your descent be gentle, a moonlit spree.
With Pragyan's wheels swift, with Vikram's delight,
Exploring lunar landscapes before arrival of night.

September Seventh, Twenty-Nineteen's night,
A fateful collision with boulder's might.
Vikram two's courage, an upside-down fate,
Human spirit resilient, it continues to resonate.

Here lies the site, where history did unfold,
A chapter of bravery, a story of bold.
As we gaze at the stars, with hope anew,
Chandrayaan Three, we entrust in you.



In moon's tranquil orbit, where mysteries reside,
May your journey be smooth, with the universe as your guide.
Soft landings, swift rovings, aspirations anew,
Chandrayaan Three, the world watches you.

-Author Anonymous Brfoldie .

[Ashokk]

Lowering Chandrayaan-3 from 100 km orbit very critical phase: ISRO chief

"Up to 100 km we do not see any difficulty. The issues are only in estimation of the position of the lander accurately from earth. This measurement is a very critical measurement, we call it the orbit determination process. If it is correct, the rest of the process can be done," Somanath told PTI.

"We are able to bring it down very correctly this time. The orbit changes are happening as planned. There is no deviation. So, it shows excellent results and we are hoping that all will be fine," the ISRO chairman said.

[suryag]

Thanks SSS sir, so a whole bunch of calculations, I am very proud of those ISRO scientists who got the slingshot correct with CY1(does indeed mean a serious amount of calculations were done, no one's going to share with you that methodology although you will find bits and pieces across)

[SSSalvi]

Current Orbit around Moon with updated Status: As on 8Aug 9:30 IST

[Amber G.]

Continuing ..
Looks like JPL has not updated the data -- but using data from other sources (radio telescope doppler data..

(These are NOT official numbers, (or from any one source) from fuzzy data given by ISRO (and seeing some radio Telescope data etc).. the numbers are approximate but good enough to do any calculation)

EPOC Time: August 5, 2023, 13:58:58 UTC
Reference system Moon:
Post LOI orbit:
SMA = 10856.3 Km
ECC = 0.82
INC = 89.2
RAAN = 268.2
AOP = 289
TA = 356
<< For details of what these symbol means see my last post..

---
After the first orbit correction, we have perigee = 1737.4+170, Apogee = 1737.4+4313 so SMA = 3979 Km
(Calculation of ECC is left as an exercise - INC is not going to change
(Okay SMA = 3979 Km, ECC = 0.52 - If my calculations are right )



Eg after 2nd LOI data. Two perilunes were visible. The data supports ISRO's figures *nicely*


Basic parameters as I put in my last message and here .. a = 3975.4km, T = 22489s (6.25 Hours orbit time) are consistent with statements of ISRO 170x4313km orbit.

So the elements are ( Calculated from this - They are not official but mathematically quite accurate)

Epoch = '07 Aug 2023 12:32:38.000';

SMA = 3975.38
ECC = 0.52
INC = 89.28
RAAN = 268.59
AOP = 288.82
TA = 0.56
< Orbit from this >


S^3 -- did not see your post (just posted 2 minutes ago..) .. (Has JPL updated the data ?)

[SSSalvi]

Horizons updated
Apolune : 6.053490647869025E+03 kms
SMA : 3.980368646406959E+03 Kms

Hats off to Amberg,s back of the table napkin calculator

[Amber G.]

^^^ Great! Also, Sankar V. Has updated his site too! (just last few minutes) Enjoy!

[SSSalvi]

Latest tweeter post by ISRO:

The retrofiring of engines brought it closer to the Moon's surface, now to 170 km x 4313 km.

[Amber G.]

Horizons updated
Apolune : 6.053490647869025E+03 kms
SMA : 3.980368646406959E+03 Kms

Hats off to Amberg,s back of the table napkin calculator

Thanks!
ISRO's Tweet, and values I posted are pretty close.
Apolune: Horizon: 6053.49, ISRO: ≈ 6040 (I just took only 3-4 significant figures only to calculate this)
SMA: Horizon: 3980.3 , ISRO ~ 3979 , Mine (deduced from Doppler data) ~ 3975.4 (All calculations done by hand/calculator).
(This is not surprising - but noteworthy that the values can be gotten by aam-abdul with access to a decent radio telescope)..

Any way, As I post, Using Horizon data/Sankar V. animation has been updated (Browsers may give some trouble, Chrome works better than others, I think): For BRF Archives:

August 8, 2023 9:40 AM (Local time in Ohio = EDT = - GMT-4),
CY3: Distance from Earth 382,572 Km, moving at 2.4 Km/sec
(Wrt to Moon: 1933 Km (Just 196 Km above the surface) moving at 1.96 Km/Sec is CY3.
(Nearly polar orbit (Inc = 89.2 Deg), Orbit period = 6.25 Hours..

Orbit looking in 3D, and projections on XY, YZ and ZX planes..

(Three D view)


Z-X Plane.



Z-Y Plane


X-Y Plane



(Lunar poles and star background is added to get the orientation right.

( You are free to use these images but please acknowledge BRF/poster/Sankaranarayanan Viswanathan/Horizon if you use these images)

[disha]

A friend of friend of friend of mine who is a great prof. at IISc forwarded me this:

ISRO Chairman S. Somnath detailing failure of C2 and improvements in C3.

PS: Skip forward to 32:00 mins into the video to start of technical details of C2 failure. Move to 50:00 mins to see the software mitigations. And 54:00 for engine changes.



Above video has lot of details. Lots and lots of details that will take several days for the posters here to unspool and discuss. The above is a keeper.

And this was my analysis of C2 failure. Prior to the talk, my post few days back.

For the moment lets assume that In C2, the velocity must have been a derived value. Based on various calculations on the rocket burn time, the initial rate of approach etc. Keep this as derived_velocity attribute.

The lander was given a specific target, and as it approached the target, its parameters were to approach it at a specific velocity and angle. Keep this as intended_target attribute.

Now from here there are two paths that open up:

1. As the lander descends, it needs to know how much burn it has to do to reach the intended target.

2. And approach the intended target at the correct velocity

For item #1, it has to increase the burn and that will increase the velocity. However it has to reach that particular spot and the increased velocity is not desirable since

3. It will overshoot the intended_target AND

4. The derived_velocity of approach will be very high and over the margin.

That means that the braking rockets need to fire to bring the lander under the velocity limit. However doing the same will mean the thrusters have to fire more to approach the intended_target.

This back & forth firing increased the attitude deviations which led to a circular lock in to more thruster firing. Think of it as locked into a thrust/counterthrust "outward" loop. That is the errors now build up leading to more errors (attitude deviations) and this overwhelms the computing unit while the lander runs out of fuel. Thus a crash land.

The changes in C3 is now significant. First of all, the algorithm is "opened up". Instead of going to a particular target, it gets a set of targets and parameters, all achievable. This set of targets are identified by the excellent survey carried out by C2.

Second, with the laser doppler velocimeter, at any point the lander knows its true velocity. So now the algorithm, just has to calculate what targets are reachable given its current velocity and approach one of the priority and as it reaches it, fire the reverse thruster and hover over the target and land.

Also the central thruster which was added to clear the moon dust away is eliminated. And does not compete for its share of fuel.

In nutshell, the algorithm locked in and tried to manage its "approach" parameters instead of "given the approach parameters", which target can be achieved.

[Ashokk]

Lots of information in the slides shown by S Somnath at the IISC lecture.
Some important dates -
The next orbit reductions will happen on 9th, 14th & 16th Aug, followed by lander and propulsion module separation on 17th. Then the lander will go through two de-orbit steps on 18th & 20th with the final touchdown on 23rd.

[disha]

^That and the detailed failure analysis of C2 by the chairman himself and mitigations done in C3.

I was surprised that they did not do a montecarlo simulation of C2 landing. If they had done that, they could have come up with potential failure outcome. Thankfully it was done in C3*

My analysis of C2 failure based on meagre information holds very well!

* ISRO needs to hire more data and software engineers.

[Ashokk]

https://twitter.com/isro/status/1689192034916265984

Chandrayaan-3 Mission:
Even closer to the moon’s surface.

Chandrayaan-3's orbit is reduced to 174 km x 1437 km following a manuevre performed today.

The next operation is scheduled for August 14, 2023, between 11:30 and 12:30 Hrs. IST

[Ashokk]

Slide showing the different phases during landing -

[Amber G.]

Chandrayaan-3 Mission:
Even closer to the moon’s surface.

Chandrayaan-3's orbit is reduced to 174 km x 1437 km following a manuevre performed today.

The next operation is scheduled for August 14, 2023, between 11:30 and 12:30 Hrs. IST

The 3rd LOI burn has occurred ~07:30 UTC per looking at doppler (!)... measured orbital period of 11492 secs vs about 11503 secs ..
success of the burn is visible to all..