Chandrayaan 3: Launch and Discussions

[Amber G.]

So, is there any one out with the answers? How good is your math?

Assuming it is now: September 4, 2023 6:30 AM (IST) (= 2023/09/04 01:00 UTC)
Q1 - What is the elevation of Sun at Vikram Now?
Q2 - When will sun set ? ( Date, Time in Hours, Minutes)
Q3 - When will be the first rays of sun will hit Vikram ?
Q4 - When will the elevation reach 6 degree?
Q5 - When will be the next 'noon' (Highest elevation of the Sun in the vicinity)?
Q6 - When will be the next dawn (or noon) in October?
Q7 - What is the length of the "day" (Noon in September to Noon in October.

And a 3 more (or less) challenging questions:
Q8 Where and when can one see Brightest star Sirius and second brightest star Canopus (There position on a given date or time of their rise or setting)
Q9 - How long does it take for these stars to make a full cycle (time it takes that it repeats it's position in the sky.
Q10 - What planets are visible in the night sky ?

Even simpler questions: In Hours (and minutes)
A ) Time elapsed between sunrise at Shiv Shaki in September & October ?
B ) Time elapsed between noon at Shiv Shaki in September & October ?
C) Time it takes for Earth to go through all the naxtras when you look from Shiv Shakti point

Just wanted to see... how much is the interest here..

[sanman]

Chandrayaan-3 Landing Site imaged by NASA's Lunar Reconnaissance Orbiter:

http://lroc.sese.asu.edu/posts/1314

[Amber G.]

^^^
Chandrayaan-3 lander is in the center of the image, its dark shadow is visible against the bright halo surrounding the vehicle. The image is 1738 meters wide, M1447750764LR [NASA/GSFC/Arizona State University].

[bala]

There are many Lunar Reconnaissance Orbiters. I am wondering whether other nation's landers are caught on such photos of the moon surface. The Indian Chandrayaan-2 orbiter caught the CY-3 lander and now Nasa's Lunar Reconnaissance Orbiter too. What about Apollo series, Russian Luna and of course China's Chang-e.

[disha]

Thanks Sanman'ji for beating me to posting the above. Will post my thoughts over the weekend.

The following are path breaking findings by Vikram/Pragyaan (C3)

1. The lunar regolith is a very good insulator.

Just 5 CM (or say 2 inches) of lunar regolith can insulate from scorching outside temperature to nice habitable (~20s) temperature.

2. Sulphur and Oxygen.

Use sulphur and lunar regolith itself to create sulphur concrete and lay it over prefabricated buckyballs and tunnels. And insulate it with lunar regolith. Use sulphur+Oxygen as rocket fuel!

[sudarshan]

If we're talking about a moon base which is air-conditioned by some kind of machine (heat engine during the lunar night, cooler during the day):

It would need some kind of power generation unit. Thermodynamic efficiency (based on the 2nd law of TD) is given by:

Efficiency=1-Tc/Th

where Tc is the cold side (heat rejection side) temperature, while Th is the hot side (heat generation side) temperature.

On the earth, heat rejection is dominated by convection to the atmosphere, at roughly 300 K. On the moon, I'm guessing that heat rejection would be dominated by radiation to outer space. So Tc would be a lot lower on the moon, than on the earth. Does this mean that engines would be way more efficient on the moon?

Does it depend on whether the engine is operating during the lunar day (and receiving heat from the sun, which it would need to reject in addition to its own generated waste heat), or during the lunar night? Or would the engine need to be shaded from the sun during the lunar day?

[Amber G.]

There are many Lunar Reconnaissance Orbiters. I am wondering whether other nation's landers are caught on such photos of the moon surface. The Indian Chandrayaan-2 orbiter caught the CY-3 lander and now Nasa's Lunar Reconnaissance Orbiter too. What about Apollo series, Russian Luna and of course China's Chang-e.

Some well-known orbiters with good cameras (Not a complete list - just some of my favorites):

NASA's Lunar Reconnaissance Orbiter (LRO): As you mentioned LRO is one of the most well-known lunar orbiters with excellent imaging capabilities. It has captured high-resolution images of the Moon's surface, including the Apollo landing sites. (A good database, many universities host detailed pictures available to all. (I often use it, when I have to look at any interesting spot - as the map/images are easy to see/search)

ISRO Chandrayaan-2 Orbiterr: As you mentioned, Chandrayaan-2's orbiter has also captured images of the Moon's surface, including the Vikram lander. Most detailed high resolution pictures. (Not as widely distributed/accessible as NASA)

Apollo Missions: The Apollo missions, especially Apollo 15, 16, and 17, carried Hasselblad cameras that captured images of the Moon's surface during astronaut activities. These historic photographs are valuable records of the lunar landscape.. (In those days, camera's with film were the only cameras captured high resolution pictures -- I have vast collection of these photos)

Russian Luna Missions: The Soviet Luna missions, such as Luna 9 and Luna 13, included cameras that transmitted images of the Moon's surface back to Earth. images are not high-resolution..., they were the first efforts.

China's Chang'e Missions: China's Chang'e series of lunar missions, including Chang'e-1, Chang'e-2, and Chang'e-3, have all carried cameras to capture images of the Moon's surface. ( Chang'e-3 included a rover with a camera that provided stunning lunar imagery) .. very few images are available to people like me.

[sanman]

Japan has just launched its own "sniper" Moon mission which will have its SLIM lander targeting a very precise spot on the Moon, arriving there after 4 months time.

Does anybody know what's so special about that particular spot, that it's being targeted so specifically and so precisely?

[Amber G.]

^^^ One of the primary objective of SLIM is to technically demonstrate pin-point landing. They chose a place and they want to land within 100 meters (remarkable/ unprecedented) of the determined spot.

[Amber G.]

Breaking News: (Just now)

[Amber G.]

Here is an image of the Chandrayaan-3 Lander taken by the Dual-frequency Synthetic Aperture Radar (DFSAR) instrument onboard the Chandrayaan-2 Orbiter on September 6, 2023.

[Amber G.]

From Nature: News Explainer
In just two weeks, the Indian mission has made some surprising discoveries about the composition of the Moon

Four things Chandrayaan-3 has taught us about the lunar south pole

The Indian Space Research Organisation’s (ISRO) Moon lander Vikram and robotic rover Pragyan have now been told to go to sleep. ISRO hopes to awaken them at lunar dawn on 22 September.

But in their two-week sojourn around the Moon’s south pole, they provided insights that have planetary scientists abuzz. Here are some of the first remarkable findings.

A thin soup of ions and electrons swirls near the lunar pole

A probe onboard Vikram made the first measurements of the density and temperature of Moon’s ionosphere. ISRO reports a “relatively sparse” mix of ions and electrons in the 100-kilometre-thick layer of electrically charged plasma that surrounds the Moon’s surface near the south pole.

Initial measurements of the plasma indicate a density of about 5 million to 30 million electrons per cubic metre. And the density seems to vary as the lunar day progresses, an ISRO scientist analysing the Chandrayaan-3 mission's data told Nature. The peak density of a similar layer in Earth’s upper atmosphere is one million electrons per cubic centimetre.

The density of the ionosphere would affect lunar communication and navigation systems if humans were to inhabit the Moon — the higher the electron density, the longer radio signals take to travel through the ionosphere. The sparse plasma means that potential delays would be “minimal”, the scientist says, and would not pose a problem for transmission.

Temperature variations with depth
Understanding lunar soil, including its temperature and conductivity, will be important when considering settlement on the Moon. The soil “is an important in situ resource for construction”, says Anil Bhardwaj, director of ISRO’s Physical Research Laboratory in Ahmedabad.

The lander is fitted with a temperature probe containing 10 sensors and able to reach 10 centimetres below the surface of the Moon. Its preliminary data show that during the day, the temperature 8 cm down is around 60 ºC lower than at the surface.

Planetary scientist Paul Hayne at the University of Colorado Boulder, says that a steep decline in temperature is expected during the lunar daytime, because the heat does not conduct downward from the warm sunlit surface. “This is similar to the effect one experiences when visiting a beach on a hot day — dig down just a few centimetres and the sand is much cooler,” he says.

Measurements so far have found that the temperature at the surface is significantly warmer than recorded by NASA’s 2009 Lunar Reconnaissance Orbiter, adds Hayne.

The temperatures “are far too warm for water ice to be stable”, says Hayne, explaining that water converts from solid to gas at a very low temperature in the vacuum of space — at about −160 ºC. Chandrayaan-3’s data indicate temperatures warmer than −10 ºC at all depths sampled. Further down "we expect temperatures to flatten out at close to the average surface temperature of about −80 ºC,” says Hayne.

A suspected moonquake
Among many vibrations recorded by the lander’s seismograph, one in particular caught the attention of scientists. The instrument “seems to have recorded a very small seismic event that decayed to background in about 4 seconds”, says planetary geochemist Marc Norman at the Australian National University in Canberra. ISRO scientists suspect it was a small moonquake or the impact of a tiny meteorite.

Such perturbations are expected on the Moon. “Small impacts and local tectonic adjustments related to tidal forces are common on the Moon, but we really need a global seismic network on the Moon and longer-term observations to understand the significance of any particular event,” says Norman.

Sulfur confirmed
Testing by the rover unambiguously confirms the presence of sulfur in the lunar surface near the south pole, ISRO reports. It also found aluminium, silicon, calcium and iron, among other elements.

“Sulfur, being volatile, is not generally expected,” explains Bhardwaj. Confirmation of its presence is really important, say scientists. Sulfur is a key element of molten rock, and researchers think that the primitive Moon was covered with a thick layer of hot molten rock, which crystallized to form the Moon’s surface. Measurements of sulfur concentrations can provide insight into that process, says the ISRO scientist. However, it’s also possible that the sulfur came from asteroids that bombard the Moon’s surface. The ISRO scientist says they hope to add their findings to those of the US Apollo missions to better understand the Moon’s geochemistry.

[sanman]

[Amber G.]

Remembering my favorite कहीं दूर जब दिन ढल जाए...
(Speeded up the day/night/day at the Vikram's place)
Enjoy:

(You can see Earth, planets, stars, and sun.. Sun set, as I posted here before on Sept 4, now waiting for the dawn)

See how the earth remains at almost the same place when stars and planets move in the background..

Click the image to see the animation..


(I know, the shadow of the Vikram does not move -- may be when time allows, it will be fun to do that.. and redo this with Mukesh's voice in the background)..

Added later: (Unlike some of my previous animations - this animation is not that mathematically accurate - produced with the help of an ordinary but popular app. Many using JPL/Horizon data are mathematically much more correct - I almost did not share it, keeping it here to to see comments. It does give some idea - how low the sun is, but directions and timing are not that accurate..For expert eyes, azimuth of earth , apparent size and brightness) are some of the things easily noticed.

[juvva]

^ lunar eclipse at 0:35 s ??

[nitzter]

^ lunar eclipse at 0:35 s ??

Solar Eclipse brother.

When we have a lunar eclipse, moon dwellers would have a solar eclipse...

[juvva]

wouldn't the apparent size of earth be greater than the apparent size of sun as seen from moon?

[Amber G.]

^^^ No eclipse. And yes, apparent size of earth, and azimuth are not mathematically correct ..( Earth should be above the rocks in the left - see the drawing I posted before).. apart of static shadow of Vikram etc.. (I edited /added few more comments in the original post - please read)..

The next solar eclipse Vikram will see is on October 28...(It will be dark for a few minutes even in the 'day'..)

[Mort Walker]

Although Sulfur was detected in lunar rock/dust samples collected by the Apollo mission, CY-3 detected in-situ on the moon surface. This was groundbreaking.

[ramana]

https://www.nature.com/articles/d41586-023-02852-7


An authoritative piece on how our moon mission has unravelled important scientific findings.

[chetak]

ISRO creates another World record - Highest viewed live stream event on YouTube


ISRO Chandrayaan 3: 8.06M you tube views

[Ashokk]

Chandrayaan-3: New lunar soil knowledge, other takeaways expected; Isro waits to hear from Vikram & Pragyan

BENGALURU: As Isro burns the midnight oil on Earth, waiting to hear again from Chandrayaan-3 lander (Vikram) and rover (Pragyan), principal investigators of instruments on the two have begun sifting through data for new findings.
Among many things the global scientific community is expected to learn from Vikram and Pragyan’s work before they went to sleep is new knowledge about the lunar soil, which will be useful for future missions, including ambitious projects aiming to send humans back to Moon.
“It would have been easy if there was a way we could know if they would wake up, but we have to wait and see how systems behave after Sunrise,” Isro chairman S Somanath said.
With Sunrise on Moon expected early Wednesday, the Sun elevation angle will be at 0° early in the day and reach a maximum of around 13° angle by the end of the day.
“The optimal Sun elevation angle for systems to work would be 6° to 9°. But the temperature has to rise above a certain threshold. For the wake up, we need power generation and temperature on the elements on Vikram and Pragyan to meet certain criteria. We should know something by September 21 or 22. If they wake up, it’ll wake up during this time,” M Sankaran, director, UR Rao Satellite Centre, the Chandrayaan-3 lead centre, told TOI.

Multiple Isro scientists TOI spoke with reiterated that Vikram and Pragyan waking would be a bonus and that the data the two have sent when they were awake is expected to give new information given that all earlier in situ experiments were carried out in the equatorial region of the Moon.
“Lot of data has been collected but outcomes will take several months, even a couple of years. There is anticipation that our data would lead to some new things. And if systems wake up again, there’ll be more data, which is good,” Sankaran added.
Physical Research Laboratory (PRL) director Anil Bharadwaj said teams were looking into datasets from instruments studying the surface, seismicity, temperature, elements, profile of temperature beneath the surface, regolith (topsoil) properties such as how fluffy, loose or grainy it is.
“There are many parametres being studied. Our observations have the potential to give new information about the topsoil. We can very clearly see rover movement paths being created, images of the vicinity of the landing site and rover movement site show grooves of the rover are about a centimetre, the lander legs going inside, suggesting loose soil. Soil will become compact as one goes deeper,” he said.
“...That part we need to understand. How much is topsoil (regolith) and where it gets compact. There are previous conjectures about the features, how they are able to retain signatures despite having loose soil. There’s information built into observations that are carried out, we have to look at multiple parametres, no one thing will tell us these things. These studies will be carried out,” he added.
As reported earlier by TOI, Chandrayaan-3 instruments have measured the temperature — which varies in the range of -10°Celsius to 60°Celsius, depending on the depth — and confirmed the presence of Sulphur, which indicates a volcanic past.
Isro Space Application Centre (SAC) director Nilesh M Desai said: “One of the things we had targeted while planning the mission was whether frozen ice could be found on crater rims. To know more we need to study the rover data. It depends on where the rover has moved, what kind of data it has found when it was close to a crater.”

[Piyal.g]

Remembering my favorite कहीं दूर जब दिन ढल जाए...
(Speeded up the day/night/day at the Vikram's place)
Enjoy:

(You can see Earth, planets, stars, and sun.. Sun set, as I posted here before on Sept 4, now waiting for the dawn)

See how the earth remains at almost the same place when stars and planets move in the background..

Click the image to see the animation..


(I know, the shadow of the Vikram does not move -- may be when time allows, it will be fun to do that.. and redo this with Mukesh's voice in the background)..

Added later: (Unlike some of my previous animations - this animation is not that mathematically accurate - produced with the help of an ordinary but popular app. Many using JPL/Horizon data are mathematically much more correct - I almost did not share it, keeping it here to to see comments. It does give some idea - how low the sun is, but directions and timing are not that accurate..For expert eyes, azimuth of earth , apparent size and brightness) are some of the things easily noticed.

great piece of art.......

[SSSalvi]

2mro, 21st ... 6 deg Sun Elevation at Landing site!!!
Time to wakeup if possible.
Waiting, fingers crossed... Will it ??? Will it not???

[Rakesh]

Chandrayaan-3: Sunrise on Shiv Shakti point today, ISRO preps to wake up Vikram
https://www.indiatoday.in/science/chand ... 2023-09-20
20 September 2023

In Short:

* The lunar duo have been in sleep mode.

* The sunrise is a crucial moment for the mission.

* With sunlight, their operational conditions are expected to improve.

[Amber G.]

^^^
Some thoughts / updates/ comments:

While Isro and many here keep their fingers crossed for signals from the silent Vikram lander and Pragyan rover on the Moon, scientists have been meticulous studying of the data collected thus far. This investigation promises to unveil insights into lunar mysteries and support next CY missions.

One of the most anticipated revelations pertains to the lunar soil, as Vikram and Pragyan's instruments were hard at work before they went dormant. This newfound knowledge about the composition and properties of lunar regolith could prove invaluable for future lunar missions.

The wait for sunrise on the Moon. The optimal conditions for the lander and rover's systems to reawaken require the Sun to reach an elevation angle of 6° to 9°. This threshold is necessary for power generation and to raise the temperature of key components. “It would have been easy if there was a way we could know if they would wake up, but we have to wait and see how systems behave after Sunrise,”-- chairman S Somanath said.

Sunrise on Moon was expected early Wednesday, (per calculations I have posted ) the Sun elevation angle will be at 0° early in the day and reach a maximum of around 13° angle by the end of the day. The temperature has to rise above a certain threshold. For the wake up, we need power generation and temperature on the elements on Vikram and Pragyan to meet certain criteria.. We should know soon .Per Sankaran, “If it wakes up, it’ll wake up during this time,” (The window for this awakening stretches from September 21 to 22) All watching for signs of life.

The potential reactivation of Vikram and Pragyan would be a significant bonus. Data transmitted during their active phases is expected to offer fresh insights, particularly as previous experiments were focused on the Moon's equatorial region.
An array of parameters is under scrutiny, including surface properties, seismicity, temperature variations, and regolith characteristics, such as its density and texture. These observations could reveal more about the Moon's topsoil and its deeper layers, shedding light on how it compacts and retains signatures.

Notably, Chandrayaan-3 instruments have already detected temperature fluctuations ranging from -10°C to 60°C, along with the presence of sulfur on the lunar surface

We are now eagerly exploring whether frozen ice exists on crater rims, a critical element for understanding the Moon's resources. The rover's movements and data near craters hold the key to this mystery.

Stay tuned for updates!

[suryag]

AmberG garu is it Wed(IST ?) are there comm stations(accessible online) that are looking for awake signal from CY-3

[Amber G.]

Syryag: On earth, sunrise can "last" a few minutes - Since Sun's diameter is about half a degree - it takes about a few minutes from top point of the sun to bottom point of sun to be above horizon. This time (about 2 minutes at equator) can last several minutes at higher lattitude as sun's path remains low on horizon.

On moon, things are much slower (about 30x slower) - and especially at 70 degree lattitude the sun's angle changes slowly -- and it takes hours from sunrise to sun to reach, say 6 degree above horizon... They say for solar batteries to start getting power, sun has to be about 6-9 degrees ... how long will it take for electronics to sufficiently warm up is still a guess -- We will know soon. As Sankaran said --- we will know within a day.

(Added later: As I post, the elevation of Sun is about 4 degree at Shakti point. ( Sept 20, 2023 17:30 UTC). Tomorrow around the same time it will be about 8 degrees .. 48 hours from now it will be about 12 degrees ... so the time can not be pinpointed up to the minute).

[Avid]

AmberG garu is it Wed(IST ?) are there comm stations(accessible online) that are looking for awake signal from CY-3

The solar panel is oriented to receive the light at the next sunrise expected on September 22, 2023.
The receiver is kept on.

From: https://x.com/isro/status/1698010732128764164?s=20

[Amber G.]

^^^ Just for perspective --- Just on earth -- especially at higher lattitude -- it may take about an hour (or more) before you start getting full sunlight (or stop calling it morning)... on Moon this may take day or two before sun's elevation reaches 6-9 degrees.

Some points:
- Since there is no air, morning sun is quite bright (unlike earth).. but shadows are long, sun is low so average temperature rises slowly. (Solar panels if oriented in right direction may be efficient)
- Surise has already happened but we might have to wait for hours (or a day or so)..

I think it is looking good...


(The brighter object on the left (of sun) is Venus, BTW)

[Amber G.]

It is September 21, 2023 (UTC- 00) -- All quiet.

Probably it is programmed so that when it wakes up and gets command from ISRO it may start sending back its radio transmission...

[SriKumar]

They said Pragyan (or Vikram) was tested for cold temperatures. I assume it must have been soaked in liquid nitrogen or something colder. Both have to survive.

[juvva]

They said Pragyan (or Vikram) was tested for cold temperatures. I assume it must have been soaked in liquid nitrogen or something colder. Both have to survive.

not the flight model, for sure.

[juvva]

is this real time? if so which orbiter ?

It is September 21, 2023 (UTC- 00) -- All quiet.

Probably it is programmed so that when it wakes up and gets command from ISRO it may start sending back its radio transmission...

[Amber G.]

^^^ Not an actual realtime photo but mathematically accurate... (Sun's position is accurate over a landscape from moon's map - at the specified time)

[Amber G.]

They said Pragyan (or Vikram) was tested for cold temperatures. I assume it must have been soaked in liquid nitrogen or something colder. Both have to survive.

Who said that? (From what I know, the electronics are not hardened - practical way is to use hardened electronic components, insulate with a small RHU. ISRO says, that they were power downed orderly (put in a sleep mode) with batteries fully charged to increase the probability that when temperature rises, electronics may come back to life (or may be partially functional )... we will know soon...

Meanwhile Saw this headline:

[juvva]

what is this trace ? (ground trace ?)

no one was concerned about the deviation during landing or post landing.

[Amber G.]

Meanwhile, Yadavji , (Senior Samajwadi Party Leader (I.N.D.I.A) says:

Scientists (ISRO) should not send ugly photos of Moon, It hurts those who consider the Moon a symbol of Beauty

[Amber G.]

Using KG Trigonometry suns elevation is about 9 degrees -- within 24 hours it is going to be 13 degrees .. some more hours of warmth needed I think ...

In lunar slumber deep, Chandrayaan3 lay,
Through cold and quiet night, it found its way.
Hoping Vikram and Pragyan would arise,
After this lengthy, chilling lunar guise.

With kindergarten trigonometry's grace,
I calculate sun's ascent on Shiv Shakti's face,
At zero hours, just nine degrees it kissed,
In twenty-four, thirteen, the sun persist.

A few more hours of warmth we shall see,
Before we beckon Vikram, make it free,
When it awakens, let the world rejoice,
In lunar dreams, we find our hopeful voice.

[drnayar]

Meanwhile, Yadavji , (Senior Samajwadi Party Leader (I.N.D.I.A) says:

Scientists (ISRO) should not send ugly photos of Moon, It hurts those who consider the Moon a symbol of Beauty

beauty is in the eye of the beholder., those who love the work, are patriotic , there is nothing more beautiful than seeing their baby on chandrama