Chandrayaan 3: Launch and Discussions

[Amber G.]

Here is support video for last post.

It shows how the 4 locations get sunlight one after another with timegap of one day between each.

The arrow from South Pole is the Sun direction.

<youtube>iTR-NBjjw-U</youtube>

Cool! Thanks.
See my post -- (Do you have ephemerides of CY3 - the most recent. TIA.

[SSSalvi]

For those who want to read about LUNA25 launch :

https://russianspaceweb.com/luna-glob-flight.html

[Amber G.]

Luna 25 (per their announcement) have completed a TCM burn around 13:00 UTC today. The spacecraft is approximately 262000 km from Earth.

[Amber G.]

Coming back to CY3!
Journey so far: For BRF quick reference:
Last edited August 14, 2023 by Amber G.

Earth Bound:

1 15 July 2023 — 41,762 km 173 km Success
2 17 July 2023 — 41,603 km 226 km Success
3 18 July 2023 — 51,400 km 228 km Success
4 20 July 2023 — 71,351 km 233 km Success
5 25 July 2023 — 127,603 km 236 km Success

Trans Lunar Injection:

31 July 2023 — 369,328 km 288 km Success

Lunar Bound

1 5 August 2023 -- 18,074 km 164 km Success (Orbit Time Approx. 21 h )
2 6 August 2023 — 4,313 km 170 km Success (Orbit Time Approx. 6.25 h)
3 9 August 2023 — 1,437 km 174 km Success (Orbit Time Approx 2.3 h )
4- 14 August 2023 - 151 km 179 km Success (Orbit Time Approx 2.07 h)
5 16 August 2023 -

?? August 2023 Lander Module Separation
?? August 2023 Lander Deorbit Burn I
?? August 2023 Lander Deorbit Burn II

23(?) August 2023 Vikram Landing.

Click images below to see animation:

Earth Bound: (Click the image to see video)



To the Moon: (Click the image to see video)


Around the Moon: (Click the image to see video)

[disha]

Given the proximity of the two sites, I hope this is not some Chinese-inspired plan to show up there first and somehow jam CY3 communications during the crucial landing phase. Not sure if it is feasible to even load any such equipment into a small lander/rover, but I can't help "thinking the unthinkable".

First of all Luna25 does not have a rover and second, the Chinese are trying to explore the far side of the moon and are the first to land a rover there and drive around. And also get back some samples and they reported presence of hydroxyl molecules (-OH) which they are theorizing has been deposited using Solar wind. This is significant, that is if this theory is correct, one can surmise that in future water or hydrogen & oxygen can be harvested from solar wind.

There is no point in having a CT on Cheenis trying to jam C3 using Russian Luna 25.

I do hope ISRO goes forward with a plan for moon and that includes C4 and C5 including a sample return from S. Pole (of moon) by C4 and a robotic observation station and science center via C5 at Moon's S. Pole. Nailing the landing of C3 is important in that respect.

I still believe that if ISRO/India is able to land within vicinity of a given crater of its choice, it makes it easier to do some more research.

[sanman]

First of all Luna25 does not have a rover and second, the Chinese are trying to explore the far side of the moon and are the first to land a rover there and drive around. And also get back some samples and they reported presence of hydroxyl molecules (-OH) which they are theorizing has been deposited using Solar wind. This is significant, that is if this theory is correct, one can surmise that in future water or hydrogen & oxygen can be harvested from solar wind.

Solar wind mainly consists of mostly protons and some alpha particles (Helium nuclei), so I don't think lot of hydroxyl molecules will come from that.
The main source of hydroxyl ions or water would be cometary impacts.
But there is also a cold gas "weather cycle" that seems to occur on the Moon, with small trace amounts of cold gases migrating across the lunar landscape, between the various cold traps which may contain water ice.

https://www.jpl.nasa.gov/images/pia1222 ... n-the-moon

There is no point in having a CT on Cheenis trying to jam C3 using Russian Luna 25.

I do hope ISRO goes forward with a plan for moon and that includes C4 and C5 including a sample return from S. Pole (of moon) by C4 and a robotic observation station and science center via C5 at Moon's S. Pole. Nailing the landing of C3 is important in that respect.

I still believe that if ISRO/India is able to land within vicinity of a given crater of its choice, it makes it easier to do some more research.

What I'd read is that the next mission to Moon is planned to be done jointly with Japan, thanks to previous joint talks between the 2 countries.
They would supply the launch vehicle and also the rover, while we would supply the lander.

[SriKumar]

Anyone know if the Doppler signal received from CY3 is generated by CY3 or is it generated from earth-bound radars and bounced off CY3?

[Amber G.]

Anyone know if the Doppler signal received from CY3 is generated by CY3 or is it generated from earth-bound radars and bounced off CY3?

They are generated by CY3.. and can be easily (relatively speaking if you are in the line of sight and have a good receiver/access to radio telescope). ISRO, I believe should get A+ in keeping all the relevant information in public.

[SSridhar]

There are quite a few theories about the water source on the lunar surface. The solar wind, meteorite and asteroid theories are three of them. Both meteorites and asteroids contain ice and their impacts could have left a lot of it at the permanently shadowed bottom part of the craters, especially in the South & even North poles of the moon. The solar wind theory comes from the reasoning that hydrogen atoms in the constant solar wind combine with oxygen on the lunar regolith to form water. The latest evidence, namely the 'glass beads' which were brought back to Earth by the Chinese Chang'e-5 confirms the 'solar wind' theory. The chemical composition of water within the glass beads suggests the solar wind theory. We should see what CY3 throws up like CY1 confirming water. The VIPER mission of NASA, the LUPEX mission of ISRO/JAXA and the planned Russo-Chinese mission are all going to delve deeper into this in the coming years.

[SSSalvi]

Anyone know if the Doppler signal received from CY3 is generated by CY3 or is it generated from earth-bound radars and bounced off CY3?

CY3 transmits its fixed frequency Telemetry channel.
The doppler is generated due to varying distances between Earth ( Receive antenna ) and CH3 Transmitter.
Under regular circumstances doppler does change but slowly.
Whenever sudden changes in speed ( like Apogee changing mechanical impulse ), occur , sudden doppler changes are seen and measuring that, one ( like AbmerG tutorial ) can calculate the change in attitude.

Added later: No, it ( amateur measurements mentioned earlier ) is not radar measurement. )
For that there is a separate fixed frequency beacon used exclusively by satellite operator in conjunction with Ranging equipment using Tx/Rx for accurate measurements )

[SSridhar]

For that there is a separate fixed frequency beacon used exclusively by satellite operator in conjunction with Ranging equipment using Tx/Rx for accurate measurements )

Also, laser-ranging through laser retro-reflectors affixed on spacecraft. Don't know if CY3 carries any.

[SSSalvi]

^^^
US payload aboard CH3 is LRR

[Ashokk]

https://twitter.com/isro/status/1690978432321269760

Chandrayaan-3 Mission:
Orbit circularisation phase commences

Precise maneuvre performed today has achieved a near-circular orbit of 150 km x 177 km

The next operation is planned for August 16, 2023, around 0830 Hrs. IST

On the ISRO website the size of the orbit is given as 151 km x 179 km, possibly after more detailed measurements.

[Ashokk]

Russia's moon craft starts processing first data - space agency

MOSCOW, Aug 13 (Reuters) - Russia on Sunday switched on the scientific instruments aboard its lunar lander and scientists began processing its first data as the space craft sped towards the moon in a bid to be first to find ice on the Earth's only natural satellite.

The Russian Luna-25 mission, the first since 1976, is racing against India, which launched its Chandrayaan-3 lunar lander last month, to complete a soft landing on the moon's south pole where scientists believe there are pockets of water ice.

[Amber G.]

On the ISRO website the size of the orbit is given as 151 km x 179 km, possibly after more detailed measurements.

Thanks. I have updated this in the <above post of the summary>

[Amber G.]

For that there is a separate fixed frequency beacon used exclusively by satellite operator in conjunction with Ranging equipment using Tx/Rx for accurate measurements )

Also, laser-ranging through laser retro-reflectors affixed on spacecraft. Don't know if CY3 carries any.

As pointed out in S^3 post, CY3 has a very nice LRA (developed by NASA). I wrote about this <here> earlier.

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.

[SSridhar]

Thanks, S^3 & AG on LRA. I am aware of that and was not referring to that. I was referring to ranging the CY3 itself as it orbits the moon now in order to precisely determine the orbit. Satellites in earth bound orbits are increasingly being ranged through lasers with retroreflctors on the body of the satellites. However, only one or two ground stations are capable of ranging those in lunar orbits.

[Amber G.]

Anyone know if the Doppler signal received from CY3 is generated by CY3 or is it generated from earth-bound radars and bounced off CY3?

Don't know how much interest is here, but FWIW, sharing it for BRF for those who may be interested:

Amateur Radio Astronomer's Guide to Tracking Chandrayaan 3 (or any such object Using Doppler Shift of Radio Signals

- Amateur radio astronomers have a unique opportunity to contribute to the study of spacecraft orbits, particularly those of Chandrayaan, by utilizing the Doppler shift technique on radio signals. This method involves monitoring the frequency shifts of the spacecraft's transmitted radio signals, allowing you to deduce its velocity and orbit. While your measurements may not match the precision of professional agencies like ISRO , they can still offer valuable insights and contribute to the broader scientific community. Besides it is fun.

Exploring Radio Doppler Shift:
The Doppler shift, in the context of radio signals, is a change in the frequency of the signal caused by the relative motion between the spacecraft and the observer (you). As Chandrayaan approaches or recedes from Earth (as it does when it orbits the moon), the transmitted radio signals experience a shift in frequency.

Required Equipment and Preparation:
To embark on the journey of tracking Chandrayaan's orbit through radio Doppler shift, you'll need:

Radio Telescope: Access to a radio telescope or radio receiver capable of detecting the frequency of the CY3's
(Many institutes in India (and US) like IITs', TIFR, have access to theses too)

Antenna System: A high-quality directional antenna system that can accurately pick up the spacecraft's signals.

Radio Spectrometer (optional): A device that can help analyze the spectral characteristics of the received signals, aiding in precise frequency measurement.

Software Tools: Utilize specialized tracking software or applications that predict Chandrayaan's passes and assist in Doppler shift calculations.

Steps to Observe and Measure:
Follow these steps to track Chandrayaan's orbit using radio Doppler shift:

Pass Prediction: Utilize tracking software or applications to determine when Chandrayaan will be visible from your location.

Antenna Alignment: Properly align your antenna system to the predicted position of Chandrayaan's pass.

Baseline Calibration: Before the spacecraft's pass, calibrate your equipment using known radio sources to establish a baseline frequency.

Signal Monitoring: During the spacecraft's pass, monitor and record the frequency of its transmitted radio signals.

Doppler Shift Calculation: Calculate the Doppler shift by comparing the observed frequency with the baseline frequency. This calculation reveals the spacecraft's velocity and motion.

Contributing to Scientific Knowledge:

While your measurements may exhibit some variability compared to ISRO data, your efforts provide valuable insights into the spacecraft's orbit. Discrepancies or deviations in your data, when compared to more accurate sources, could point to interesting phenomena that warrant further investigation.

Collaboration and Data Sharing:
To enhance the accuracy of your observations, consider collaborating with fellow radio astronomers or participating in collaborative projects. Sharing your data with professional researchers and space agencies can also contribute to a broader dataset for in-depth analysis.

Amateur radio astronomers possess the ability to actively engage in tracking the orbits of spacecraft like Chandrayaan through the analysis of radio Doppler shift. While your measurements may not match the precision of established agencies, your dedication to contributing valuable data furthers our comprehension of space dynamics and enriches the global pursuit of scientific knowledge.

Good Luck!
---
(CY3 transmission frequencies are not controlled by atomic clock type oscillators so original frequency is not known precisely - (ISRO can get that from various other ways and get accurate shift) - but with good software tools one can still get a lot of useful data - some calibration can be done, knowing the precise orbit (ISRO data) and your data)

----
(Note: CY3, is much easier to track as radio frequencies are known/stable etc.. Luna 25 OTOH is quite secretive ( Many of us (friends) tried but have not been able to listen to it - signals may be very weak and requires big antenna systems)

[Amber G.]

Space Research Institute showed first pictures taken by the Luna25 cameras during the flight to the Moon on August 13 - The article .

[Amber G.]

Meanwhile, Horizon has updated CY3 orbits... and also Sankar Viswanathan animation of the orbits..

[SSSalvi]

Space Research Institute showed first pictures taken by the Luna25 cameras during the flight to the Moon on August 13 - The article .

A quick translation of essential part of this:


They flew away from the Earth. We fly to the moon
August 14, 2023
Project news

The Space Research Institute of the Russian Academy of Sciences has completed an express analysis of telemetry and measurement data of scientific instruments aboard the Luna-25 automatic station, performed on August 13, 2023 in two sessions of the first inclusions at a distance of about 310 thousand km from the Earth. All instruments showed full operability and readiness for lunar exploration. Their analog and digital nodes and blocks worked perfectly.

The STS-L onboard television cameras received the first images from space, which will go down in the history of Russian cosmonautics. These images show the structural elements of the Luna-25 apparatus against the background of the Earth, from which we have already departed forever, and against the background of the Moon, to which we will soon arrive. The third picture shows the mission emblem and the onboard manipulator bucket.
The image was taken by the camera of the STS-L complex aboard the Luna-25 spacecraft on August 13, 2023 during the flight to the Moon from a distance of about 310,000 km from the Earth.

[Amber G.]

^^^ I noticed that 310,000 Km distance on August 13, with little curiosity.. ( Moon's distance from earth varies between 362,600 km and 405400 km).

[sanman]

[Amber G.]

A day before New Moon, (Moon is very close to the Sun( angular position) and thus not easily visible)... Local Time is 2:34 PM EDT (GMT -4). Moon is CY3 is 400,000 Km (400,360 Km) away moving about .7 Km/sec..

It is 1897 Km from the center of the Moon, Just 159.5 Km above the surface, Moving at 1.61 Km/sec (wrt to Moon)... Pretty close to the north pole of the moon.

Here are the orbits in XY, YZ and ZX plane... and a picture of the surface, if one looks out of the window of CY3..

X-Y Axis, North pole is is on the center of the moon... CY3 is the red dot. (Earth is toward red axis)


Y-Z Plane: (North pole is at top, CY3 is red dot.. Earth is far away (see red axis -- coming out of the screen towards you)


ZY Plane: (CY3's Earth orbit could be seen on the left..) (Earth's direction is 'below' (going away from the screen).. but orbital plane is tilted so you can see the CY3 orbit around earth part to little left)

Scene below: (Landing site is on the other pole_

[SSridhar]

Chandrayaan-3 vs. Luna-25: Are India and Russia racing to the moon's south pole? - Space.com

[ramana]

Chandrayaan-3 Mission:

Today’s successful firing, needed for a short duration, has put Chandrayaan-3 into an orbit of 153 km x 163 km, as intended.

With this, the lunar bound maneuvres are completed.

It’s time for preparations as the Propulsion Module and the Lander Module gear up for their separate journeys.

Separation of the Lander Module from the Propulsion Module is planned for August 17, 2023.

[SSSalvi]

^^^
17th? Have they planned for a change of touchdpoint?..
Too bad if it happens, just to be ahead of a mad dog?
World has respected Indian philosophy of slow but systematic planning.
Hope it is not poli compulsion.

BTW, in earlier translation of rus publicity material, it is said, that automated sequence.
The reason is that Rus has no international support for telemetry relay from the " other ", hemisphere ( geographically and politically).

[sajaym]

Too bad if it happens, just to be ahead of a mad dog?
World has respected Indian philosophy of slow but systematic planning.
Hope it is not poli compulsion.

I think people have not understood that this 'moon rush' is just the beginning of the creation of another exclusive club like the UNSC. If we miss this bus, the 'big boys' will create another 'Lunar Security Council' and we Indians will once again stand outside with a cow knocking on the door.

So yeah, better be ahead of all other mad dogs.

[Ashokk]

^^^
17th? Have they planned for a change of touchdpoint?..

From the slides shown by S Somnath at the IISC lecture, the lander and propulsion module separation was planned for the 17th, then the lander will go through two de-orbit steps on 18th & 20th with the final touchdown on 23rd.

[Ashokk]

[SSSalvi]

^^^
17th? Have they planned for a change of touchdpoint?..

From the slides shown by S Somnath at the IISC lecture, the lander and propulsion module separation was planned for the 17th, then the lander will go through two de-orbit steps on 18th & 20th with the final touchdown on 23rd.

Thanks for clarification.
So Lander will still be Orbiting in its own orbit.

[Ashokk]

Thanks for clarification.
So Lander will still be Orbiting in its own orbit.

Yes. Here's the screenshot of the relevant slide -

[Amber G.]

Journey so far: For BRF quick reference:
Last edited August 16, 2023 by Amber G.

Earth Bound:

1 15 July 2023 — 41,762 km 173 km Success
2 17 July 2023 — 41,603 km 226 km Success
3 18 July 2023 — 51,400 km 228 km Success
4 20 July 2023 — 71,351 km 233 km Success
5 25 July 2023 — 127,603 km 236 km Success

Trans Lunar Injection:

31 July 2023 — 369,328 km 288 km Success

Lunar Bound

1 5 August 2023 -- 18,074 km 164 km Success (Orbit Time Approx. 21 h )
2 6 August 2023 — 4,313 km 170 km Success (Orbit Time Approx. 6.25 h)
3 9 August 2023 — 1,437 km 174 km Success (Orbit Time Approx 2.3 h )
4- 14 August 2023 - 151 km 179 km Success (Orbit Time Approx 2.07 h) (ISRO Figures: 7434 sec)
5 16 August 2023 - 163 Km 153 Km Success - (Orbit Time 2.05 h)

17 August 2023 Lander Module Separation

?? August 2023 Lander Deorbit Burn I
?? August 2023 Lander Deorbit Burn II

23(?) August 2023 Vikram Landing.

Click images below to see animation:

Earth Bound: (Click the image to see video)



To the Moon: (Click the image to see video)


Around the Moon: (Click the image to see video)

[/quote]

[Amber G.]

^^^ The orbit times, measured by ammature radio astronomers who shared the data after 8/15 reduction (and timing across a few orbits was within a few seconds of ISRO's figures 7434 seconds (calculated from 150*177km orbit .


---

The reason is that Rus has no international support for telemetry relay from the " other ", hemisphere ( geographically and politically)

(Luna25 could still not be observed (by some of these astronomers who I follow, who have been trying by using sophisticated equipments ) for doppler shift..)

[Amber G.]

^^^
...
Too bad if it happens, just to be ahead of a mad dog?
World has respected Indian philosophy of slow but systematic planning.
Hope it is not poli compulsion.

I hope that too.

There have been some talk (and people ask) if CY3 could land before Luna 25 ...Technical answer is it can if they want... It is already in circular orbit and plenty of time .... but I hope they stick to the original well thought plan. Few years from now no one will remember Luna 25 (or when it landed on the Moon) but if Vikram's landing is perfect (or not perfect ), this will be remembered for a long time.

Meanwhile: Luna 25 is in Moon's orbit

[Ashokk]

As per the latest update from Roscosmos, Luna-25 has entered into lunar orbit.

https://www.roscosmos.ru/39629/
Translation:

The Luna-25 automatic station created at the Lavochkin Research and Production Association (part of Roscosmos State Corporation) has entered the orbit of the Moon's artificial satellite.

This was ensured by two activations of the automatic station's propulsion system. The first activation was performed at 11:57 Moscow time by the corrective braking engine and lasted 243 seconds, the second - by the soft landing engines and lasted 76 seconds.

For the first time in the modern history of Russia, an automatic station at 12:03 Moscow time was put into orbit of an artificial satellite of the Moon.

All systems of Luna-25 are functioning normally, communication with it is stable. Sessions of measuring the current navigation parameters are being conducted.

For the first time in the modern history of Russia the automatic station "Luna-25" was sent to the Earth's natural satellite. The mission is to work out the technology of soft landing, take and analyze the soil and conduct long-term scientific research, including the study of the upper layer of the surface regolith in the area of the Moon's South Pole, as well as the lunar exosphere.

In terms of landing, Luna-25 is fundamentally different from its predecessors: Soviet lunar stations landed in the equatorial zone, the new station should make a soft landing in the near-polar region with a significantly more complex terrain.

[Amber G.]

Meanwhile: ISRO has revealed a picture of some craters on the far-side of the Moon taken by the Lander Horizontal Velocity Camera (LVHC) on the Vikram Lander on #Chandrayaan3!

The picture was taken at an altitude of 4,400 km on 9th Aug.

[Amber G.]

FWIW: Was curious to see what -69.32 degree, 32.25 degree spot looks like on earth - did google map.. looks interesting and challenging even on earth!

[Amber G.]

...The reason is that Rus has no international support for telemetry relay from the " other ", hemisphere ( geographically and politically).

To add, a few comments:
Due to Ukraine, Russia is notably isolated internationally. European Space Agency stopped its involvement in the Luna-25 (26 etc too) missions. It also postponed the launch of the Rosalind Franklin rover from the ExoMars program, which aims to seek out traces of past or present life and will now launch no earlier than 2028.

ESA's PILOT-D navigation camera is no longer available to assist it's landing attempt.

India, OTOH, is being supported by ESA's "Estrack" network of deep space stations, helping to track, command and receive data from Chandrayaan-3. NASA is contributing the retroreflector for LRA (This will be a big help for future missions - if all other things fail, this could still survive - as it requires no battery so it will remain for a long time)

India is also planning a joint mission with Japan (LUPEX). Big news (for me - in Modi's recent visit to US, this was mentioned both by Biden and Modi) -- India has also signed up to the Artemis Accords.

[drnayar]

Too bad if it happens, just to be ahead of a mad dog?
World has respected Indian philosophy of slow but systematic planning.
Hope it is not poli compulsion.

I think people have not understood that this 'moon rush' is just the beginning of the creation of another exclusive club like the UNSC. If we miss this bus, the 'big boys' will create another 'Lunar Security Council' and we Indians will once again stand outside with a cow knocking on the door.

So yeah, better be ahead of all other mad dogs.

Indeed hope the C 3 puts an Indian flag on the "dark" side of the moon

OT but the chinese seems all ready to put their man in the moon on two rockets instead of one., one with the "astronauts" and the other with equipment ostensibly to overcome their shortcomings of not having a powerful enough "saturn" class heavy rocket