Chandrayan-2 Mission

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Amber G.
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Re: Chandrayan-2 Mission

Postby Amber G. » 12 Jul 2019 09:29

Few comments:
Mort Walker wrote:..
...
It's not clear to me if Vikram communicates directly with ground control, or if it only communicates with the Chandrayaan-2 orbiter. I know weight is a concern, but I would think the designers would provide redundant communication paths to ground control; directly and via the orbiter.
....
I haven't been as excited since 1969 when watching Apollo 11, some 50 years ago.

Yes, I am also as excited as I was in 1969 watching Apollo 11..

And I remember people were able to "eavesdrop" on Moon lander communications and data transmission using a radio telescope , so I am fairly sure that one can, if one wants to, at least listen from the ground with Vikram or even Pragyan. The frequencies used can pass through earth's atmosphere, and one does not require too much power.
( Some people claim that they have beeb able to listen to direct communications from space suits - theoretically this IMO is possible as one easily can have such powerful antenna and one can pinpoint the location. Remember the position on moon's is some-what stationary so it is not too hard to point at the direction.

I don't know the details of how the actual data links for Vikram/prgyan are setup -- may be some one can give more details - but technically weight/power are not the criteria which are too important here.
(Radio telescopes are incredibly sensitive they can "listen", if one knows "where" , even very low-power signals)
***
Saw this:
SwamyG wrote:
It, Vikram, can communicate with IDSL near Bangalore, as well as the Orbiter.

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Re: Chandrayan-2 Mission

Postby Vivek K » 12 Jul 2019 10:29

Good luck to the mission scientists and engineers! This mission will prove several techs!

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Re: Chandrayan-2 Mission

Postby Mort Walker » 12 Jul 2019 17:44

Listening is easy if you have a large gain antenna, low noise amplifiers, and signal processing to filter noise from a coherent signal. Two way data communication is more difficult if you need the space vehicle to perform critical manoeuvers in a timely manner. The space vehicle will have to receive commands even though a high power transmission will be used.

The 15 minutes descent of Vikram to the moon surface will be the most difficult. This is an area near the lunar south pole which hasn’t been extensively surveyed before. Landing on the moon has had roughly a 50% success rate.

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Re: Chandrayan-2 Mission

Postby Singha » 12 Jul 2019 18:30

rather than all-or-nothing vikram lander, I would have preferred a 'swarm' concept in which 16 small and light plastic landers would be dropped off a MIRV bus and use tiny gas thruster or retro rockets to brake against lunar gravity before falling on the soil and releasing 'rat drones' which would crawl out and in turn release 'ant drones' .... using IOT concepts the backflow of data would be ant -> rat -> lander -> orbiter . the ants and rats would stop and charge on each lunar day, and move around furtively at night.

the MIRV bus would fly to a low level using its main braking engines before dropping off the warheads.

that way we would be sure atleast some would succeed. all we need is "cloud service availability" , individual machines go off and on all the time...opaque to user.

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Re: Chandrayan-2 Mission

Postby Vivek K » 12 Jul 2019 19:02

^^^^ too much Star Wars? Or did you just finish "Enders Game"?

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Re: Chandrayan-2 Mission

Postby Singha » 12 Jul 2019 19:09

just trying to increase Pk brother. a few months ago, a israeli lander crashed the lunar landing.

army of ants vs herd of elephants

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Re: Chandrayan-2 Mission

Postby Mort Walker » 12 Jul 2019 21:02

Let's try to concentrate on this mission Chandrayaan-2. It’s all set to go. The first big test will be trans lunar injection. Jai Bharat Mata, Jai Bhavani! Our prayers are with you Chandrayaan-2.

I’m hoping the news channels cover this like the GE or ICC World Cup, anything less will be disappointing.

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Re: Chandrayan-2 Mission

Postby SwamyG » 12 Jul 2019 21:19

Amber and other gurus, which part of the entire journey from lift off to landing the rover would be cause for concerns & celebrations? From a mission perspective, that is.

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Re: Chandrayan-2 Mission

Postby Amber G. » 12 Jul 2019 21:32

Two way data communication is more difficult if you need the space vehicle to perform critical manoeuvers in a timely manner. The space vehicle will have to receive commands even though a high power transmission will be used.

... Not to mention the finite speed of light and time delay makes it all but impossible to perform any critical maneuvers in "timely" fashion. Of course one needs highly fast computers and software on board.

... Also even other commands need to be coded (and digitally signed etc) so that they can't be spoofed by hackers with high power transmission. Interestingly even for Apollo 11, while all audio communication was not coded, data link was coded/encrypted (even though the computers were much lass powerful then).
...would have preferred a 'swarm' concept in which 16 small and light plastic landers would be dropped off a MIRV bus and use tiny gas thruster or retro rockets to brake against lunar gravity before falling on the soil and releasing 'rat drones' which would crawl out and in turn release 'ant drones' .... using IOT concepts the backflow of data would be ant -> rat -> lander -> orbiter . the ants and rats would stop and charge on each lunar day, and move around furtively at night.

This, perhaps could be more practical on Mars, but with no atmosphere on the moon, it won't be practical. In atmosphere, smaller objects has less terminal velocity. Physics favors an ant over an elephant if there is atmosphere but with retro rockets to brake in an airless world this will not be practical. :)

Using these kind of radio telescopes One can literally see a object just a few meters wide at the distance of the moon!


Found this Long Lost Indian Moon Probe Found by Earth-Based NASA Radar

Radar imagery acquired of India’s Chandrayaan-1 spacecraft as it flew over the moon's south pole on July 3, 2016. The imagery was acquired using NASA's 230-foot (70 meters) antenna at the Goldstone Deep Space Communications Complex in California. This is one of four detections of Chandrayaan-1 from that day. (Image credit: NASA/JPL-Caltech )
Image

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Re: Chandrayan-2 Mission

Postby Amber G. » 12 Jul 2019 21:39

SwamyG wrote:Amber and other gurus, which part of the entire journey from lift off to landing the rover would be cause for concerns & celebrations? From a mission perspective, that is.

For me the most critical part will be Vikram's soft landing on the moon. As there is no air, the inertial guidance based retro-rockets have to be extremely accurate. India has impressive and proven technology (used in MoM) here so I am quite hopeful.

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Re: Chandrayan-2 Mission

Postby Mort Walker » 12 Jul 2019 21:51

SwamyG wrote:Amber and other gurus, which part of the entire journey from lift off to landing the rover would be cause for concerns & celebrations? From a mission perspective, that is.


Just a novice here, but will give it a shot, but a good question and it needs actual dates and times.

1. Achieving earth orbit.
2. Successive raising of orbit in each step.
3. Trans lunar injection - that is timing Chandrayaan-2 to fire its thrusters precisely to send it to the moon when it is closest to earth.
4. Precise braking to enter lunar orbit. Important or Chandrayaan-2 is lost in space.
5. Entering and achieving lunar orbit. That means Chandrayaan-2 is now under the gravitational pull of the moon and not the earth. More importantly that it is placed at 100KM orbit. This will be done in a series of lowering steps of an elliptical orbit with correct apogee and perigee.
6. Separation of Vikram lander.
7. Lowering of Vikram lander to less than 50KM from moon surface.
8. The 15 scary minutes of braking Vikram, scanning the surface for determining the most suitable landing spot.
9. Actual landing that doesn’t crash of damage Vikram.
10. Deploying the Pragayan rover.

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Re: Chandrayan-2 Mission

Postby prasannasimha » 12 Jul 2019 22:56

Amber G. wrote:
SwamyG wrote:Amber and other gurus, which part of the entire journey from lift off to landing the rover would be cause for concerns & celebrations? From a mission perspective, that is.

For me the most critical part will be Vikram's soft landing on the moon. As there is no air, the inertial guidance based retro-rockets have to be extremely accurate. India has impressive and proven technology (used in MoM) here so I am quite hopeful.


The translunar injection - we have done it so we have the data etc and experience. What is the real challenge is the soft landing on the moon which we will be doing for the first time. this is something totally new for us in the actual microgravity of the moon all the more to see that the plume does not displace lunar top soil too much.

After that is done deployment of Pragyaan and its communication sequence being maintained and its ability to maintain data link.

While it is planned for one lunar day the hope is that it may be reactivated but that would then be cherry on the cake.

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Re: Chandrayan-2 Mission

Postby Vivek K » 12 Jul 2019 23:24

Could the orbiter try to locate Chandrayaan-1 and see if it answers back?

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Re: Chandrayan-2 Mission

Postby Amber G. » 13 Jul 2019 00:31


While it is planned for one lunar day the hope is that it may be reactivated but that would then be cherry on the cake.

Mars Rover is still operational. As of today Curiosity has been on Mars for 2463 sols (2530 total days) since landing in 2012 :).

The "mission life" for the orbiter chandrayaan II is said to be about a year. As we know Chandrayaan I is still in the same precise orbit..we do not need too much fuel for longer mission life.

For me, another fun thing would be to eavesdrop on Chandrayaan II optically as it carries LRA (a mirror which reflects laser) so may be some one with a nice laser would able to see Vikram/Pragyan location with it.

The LRA is the same design as the one carried aboard Israel’s Beresheet moon lander. ( Beresheet crashed during its touchdown attempt in April)

(The LRA is a mirrored device that reflects laser signals to help mission team members pinpoint where a lander is as well as precisely calculate the moon's distance from Earth ityadi)...

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Re: Chandrayan-2 Mission

Postby disha » 13 Jul 2019 00:39

Vivek K wrote:Could the orbiter try to locate Chandrayaan-1 and see if it answers back?


Vivek K wrote:Could the orbiter try to locate Chandrayaan-1 and see if it answers back?


Chandrayaan-1 is dead. That is why we lost it in first place!

No point in locating C-1 and trying to enliven it. It is a dead object.

---

Space endeavours are always risky. There are thousands of variables which can go wrong and each variable can throw new variables which when un-contained jeopardizes the entire mission.

For example, on the two solid rocket boosters, if there has been an error in casting and one of the boosters produces more thrust than the other, the rocket starts veering off. Of course the SITVC will come into play and correct the veer. However what happens if the veer is beyond the tolerance of SITVC margin? Notice the placement of the L110 nozzles, it is perpendicular to the S200 SRBs. This will help in counteracting an imbalance in the SRB thrust. Of course this has to be within certain tolerances.

In essence, using GSLV-MkIII for Chandrayaan will prove that ISRO has another versatile rocket in its pocket for GTO/Lunar/Man missions. This will make GSLV-MkIII very very cost competitive and partly its cost competitiveness is due to reusing and scaling up various technologies including the SRBs. Casting such large SRBs within very very narrow tolerances is very difficult. And ISRO (NASA/Arianne as well) has mastered it and is an area where we are at least a decade ahead of some other agencies.

Landing on moon is another challenge. This is the first time we are doing a soft landing and the retro rocket does kick up lot of moon dust. The nature of the moon dust is such that it is very very coarse and sharp, since moon does not have atmospheric forces to smoothen the particles, and this creates a "sand blasting" effect on the lander and its instruments.

Of course an appropriate location has to be found to land and for that the orbiter has to be injected precisely and all its instruments have to be functional and for the orbiter to be injected precisely the gravity pumping near Earth has to go flawlessly and for that GSLV Mk-III has to inject the payload into a very precise trajectory.

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Re: Chandrayan-2 Mission

Postby Vivek K » 13 Jul 2019 01:33

disha wrote:
Vivek K wrote:Could the orbiter try to locate Chandrayaan-1 and see if it answers back?


Chandrayaan-1 is dead. That is why we lost it in first place!

No point in locating C-1 and trying to enliven it. It is a dead object.

Well the idea came from posts in this thread of radar tracks of the first mission. Of course the current mission has its own schedule of activities and challenges.

But once the mission is accomplished. And the orbiter has life left it would be a challenge to raise a peep back from “One”. Not saying we want to bring it back to life. It is fantastic that “One” is still in lunar orbit.

But pushing that aside the current mission has its challenges. Having flown the path before to Lunar Capture, one would expect that Vikram’s mission will be the biggest challenge.

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Re: Chandrayan-2 Mission

Postby krishGo » 13 Jul 2019 04:46

There are a lot of variables in such a complex mission. Disha and others have already go over some of the aspects of could go wrong.

IMO these are the critical milestones in the mission

1. Ignition of C-25 & successful operation

While the ignition, successful operation of solid boosters & L110, their staging & payload fairing seperation are also critical, the cryo stage operation is the most important step in the launch. Why? It is the last step in the launch and ensures the probe is in the correct EPO (Earth Parking Orbit).

Something goes wrong here, the probe probably wont go much further or would do so at a great cost to lifetime of the probe. An example would be the Phobos Grunt mission. It was the first Russian interplanetary mission after the breakup of USSR. It was intended to travel to the Martian moon Phobos and return soil samples back to earth. The upper stage of the Proton rocket launching it failed, leaving it in a highly unstable LEO from which re entered the atmosphere and burnt up.

I would be waiting for the "C25 ignition successfull. Performance normal" announcement.

2. First orbit raising manouvre

This is where the onboard motors on Chandrayaan-2 will be first tested. Mind you, these engines have to take Chandrayaan-2 till the moon and stay in operation even after that. Although the onboard engines on our other missions have been quite reliable, this first firing will set the tone for the orbit rasing stage.

Beresheet, the recent commerical Israeli mission to the moon, had problems firing the onboard engines the first time. Their first orbit raising manouvre actually failed. Fortunately, they could salvage the situation and engines worked going forward. But they had change their orbit raising schedule & the orbits themselves due to this.

3. Traslunar Injection

After the last orbit rasing manouvre, Chandrayaan-2 will be hurtling towrds the moon. During TLI, the probe turns itself around, and fires all its motors to deccelerate and is captured by the moons gravity. If this doesn't go well, the probe misses the moon (and maybe no fuel to reattempt) or worse, crashes into it.

On the Japanese Akatsuki mission to Venus, its main onboard engines failed during the orbital insertion and the probe missed Venus and continued around the sun. They could salvage the mission when the they had another opportunity for orbital insertion in 2 years, and they used the Vernier engines (tiny engines to control pitch & yaw) on the probe to decelerate the probe & get captured into a highly elliptical orbit around Venus. Obviously, the the risks were different from a moon mission as here the engines were dormant for a long time during the journey to Venus, but its a good example of what happens if you miss and don't crash.

4. Vikram lander separation & soft landing

The most critical aspect and one where we lack prior experience. Especially the 15 or so minutes before touchdown are absolutely critical. Even if Vikram descends just a few meters too quicly, it will crash into the moon. The engines on the lander have to work flawlessly till the touchdown.

5. Latch opens & Pragyaan rover emerges

Once Vikram has landed & the dust has settled, lietrally and figuratively, the latch on the lander opens up and Pragyaan, will drive itself down to the lunar surface. Once down, the lander photographs the rover & the rover photographs the lander. Even though, Pragyaan has to operate for 14 earth days, at this point, I would consider the mission a full success.

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Re: Chandrayan-2 Mission

Postby Vivek K » 13 Jul 2019 10:19

Thank you for a great perspective! Great job of laying out the challenges faced by the mission!!

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Re: Chandrayan-2 Mission

Postby A Nandy » 13 Jul 2019 12:23

GSLV Mk III carrying Chandrayaan2 spacecraft, undergoing launch checks at launch pad in Sriharikota. Launch is scheduled at 2:51AM IST on July 15.

Image

Fat Boy! :D

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Re: Chandrayan-2 Mission

Postby SSridhar » 13 Jul 2019 12:54

disha wrote: . . . Of course the SITVC will come into play and correct the veer.

Correction. Not SITVC but flex nozzles with mechanical actuators.

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Re: Chandrayan-2 Mission

Postby prasannasimha » 13 Jul 2019 14:24

Lunar days are different from mars day so the battery which is discharged progressively can cause hibernation and later wake up. Problem is a Lunar day is 15 days and between extreme heat and cold so reawakening the rover is the challenge that all Lunar missions face unless there is an RTG

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Re: Chandrayan-2 Mission

Postby prasannasimha » 13 Jul 2019 18:26

Image

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Re: Chandrayan-2 Mission

Postby Mort Walker » 13 Jul 2019 19:36

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Re: Chandrayan-2 Mission

Postby Mort Walker » 13 Jul 2019 19:55

Indeed, the soft landing is the most difficult part as the moon has no atmosphere that you can't use parachutes or balloons to cushion a descent. Vikram's engines and thruster rockets to correct for yaw-pitch-roll all have to work in unison to get it right. On top of that, the moon's surface is rocky with lots of big and small craters. Hopefully the scanning goes well. Vikram has less than 2 minutes to make this decision. From ground control, sending messages back and forth to Vikram will take at least 3 seconds.

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Re: Chandrayan-2 Mission

Postby SSridhar » 13 Jul 2019 20:33

ISRO’s lunar touchdown has dry run on soil fetched from Tamil Nadu - Madhumathi D.S., The Hindu
Newly designed cars are tested for road-worthiness on terrain where they would be driven, while new aircraft are test-flown in the skies. But where on earth did the Chandrayaan-2 mission’s lander and rover, which will head for the moon on July 15, check out their legs and wheels?

More than a decade ago, even as the Chandrayaan-1 orbiter mission of 2008 was being readied, the Indian Space Research Organisation (ISRO) created a proto-Lunar Terrain Test Facility (LTTF) at its advanced satellite testing unit, ISITE, in Bengaluru. This, it did, by modifying a balloon research lab, about 30-40 m high, long and wide.

At the time, ISRO was grappling with the task of indigenously executing the cryogenic stage for its GSLV MkII rocket. Any thought of sending a moon lander was a distant dream of low priority. Equipping the LTTF and making it look and feel like being on the moon was the first challenge. It needed lunar ‘soil’ with almost all its features and texture, lunar temperatures, low gravity and the same amount of sunlight as on the moon.

Image

For recreating the terrain, an option was to import simulated lunar soil from the U.S. — at an exorbitant $150 a kg (the then prevailing price). The facility needed about 60-70 tonnes of soil.

ISITE’s parent, the U.R. Rao Satellite Centre, or URSC (it was called the ISRO Satellite Centre or ISAC at the time) did buy a small amount of simulated lunar soil from the U.S., but soon decided to find its own solution at a lower cost.

M. Annadurai, who as URSC Director oversaw activities related to the Chandrayaan-2 spacecraft until he retired in August 2018, recounts that geologists of various national agencies had found that a few sites near Salem in Tamil Nadu had the ‘anorthosite’ rock that somewhat matches lunar soil in composition and features. The URSC’s lunar soil simulation studies team zeroed in on Sithampoondi and Kunnamalai villages for the soil.

It turned out to be a ₹25 crore project: experts from the National Institute of Technology in Tiruchi, Periyar University in Salem, and the Indian Institute of Science, Bengaluru, joined in, working without any fee.

Professional crushers broke down the rocks and soil to the micro grain sizes sought by the ISRO-led team. Transporters moved the tonnes of this ‘lunar earth’ to ISITE, all free of charge, Dr. Annadurai recalls.


These challenges were not there when he led the first lunar orbiting-only mission, Chandrayaan-1, as its project director.

At the LTTF, the team spread the soil trucked in from Salem up to a height of about 2 metres. Studios were hired to illuminate the facility exactly as sunlight would play on the lunar terrain.

On the Moon, the metre-long rover, weighing 27 kg, must move for about 500 metres during its expected life of 14 Earth days (one lunar day). Rover tests began as early as in 2015. The ISRO team had to reckon with the weak lunar gravity, about 16.5% of Earth’s. The rover’s weight was artificially reduced using helium balloons.


Previous missions by other countries have suggested that the southern part of the Moon is mineral rich with the promise of water, which was first confirmed by the Chandrayaan-1 mission.

Lunar south pole


ISRO Chairman K. Sivan recently said the Indian lander Vikram would be the first ever spacecraft to land at the lunar south pole.

It has two site options, the craters Manzinus-C and Simpelius-N.

The sites were picked after scouring through a few thousand lunar images from Chandrayaan-1 and other missions.

For testing the lander, ISRO had a large test bed created at its new R&D campus at the Challakere Science City, some 400 km from Bengaluru. Vikram’s set of sensors, called the Hazard Detection and Avoidance (HDA) system, is a critical part of the mission.

In the actual descent to the Moon, the lander hovers for a few seconds over a site and the sensors must assess whether the spot is flat enough for the lander’s legs: whether it has rocks that might topple the lander, and whether the lander can be steady to release the rover within it. If the spot is not safe, it must quickly rise and shift to a neighbouring spot and again assess if it is suitable to land on, all in seconds.

Sometime in 2016, the URSC created several artificial ‘lunar’ craters at the Challakere site. Late that year the team put a test bed of lander sensors in a small ISRO plane and flew it over the craters to see if the sensors could read the terrain and find the right landing spot.

According to Dr. Annadurai, the success of the landing depends on the sensors’ correctly guiding the lander to a safe site; and the fuel in the lander lasting for duration of the whole exercise.

Other tests were conducted to clear the working of the lander’s propulsion system, its actuator and legs, and the rover’s movement.

In a joint paper presented at the International Academy of Astronautics symposium in June 2017, Dr. Annadurai and his co-authors wrote: “One of the key elements essential for safe landing is the Hazard Detection and Avoidance (HDA) system. [It] comprises of several sensors... [which] provide information like lander’s horizontal velocity, vertical velocity, height above moon’s surface, relative position of the lander with respect to moon’s surface, and hazard/safe zone around the landing site.

“The HDA system processes the inputs from various sensors, compares the data collected with the information already stored in the lander and provides the required inputs to the navigation and guidance system in real time to correct the trajectory at the end of rough braking to enable a safe and soft landing.”


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Re: Chandrayan-2 Mission

Postby Mort Walker » 13 Jul 2019 20:46

^^^Note that the Vikram lander weight includes Pragyan. Total payload is 3850 Kg according to ISRO.

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Re: Chandrayan-2 Mission

Postby SwamyG » 13 Jul 2019 21:03


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Re: Chandrayan-2 Mission

Postby SwamyG » 13 Jul 2019 21:05

Mort Walker wrote:
SwamyG wrote:Amber and other gurus, which part of the entire journey from lift off to landing the rover would be cause for concerns & celebrations? From a mission perspective, that is.


Just a novice here, but will give it a shot, but a good question and it needs actual dates and times.

1. Achieving earth orbit.
2. Successive raising of orbit in each step.
3. Trans lunar injection - that is timing Chandrayaan-2 to fire its thrusters precisely to send it to the moon when it is closest to earth.
4. Precise braking to enter lunar orbit. Important or Chandrayaan-2 is lost in space.
5. Entering and achieving lunar orbit. That means Chandrayaan-2 is now under the gravitational pull of the moon and not the earth. More importantly that it is placed at 100KM orbit. This will be done in a series of lowering steps of an elliptical orbit with correct apogee and perigee.
6. Separation of Vikram lander.
7. Lowering of Vikram lander to less than 50KM from moon surface.
8. The 15 scary minutes of braking Vikram, scanning the surface for determining the most suitable landing spot.
9. Actual landing that doesn’t crash of damage Vikram.
10. Deploying the Pragayan rover.

I see 10 reasons to celebrate :-)

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Re: Chandrayan-2 Mission

Postby SwamyG » 13 Jul 2019 21:09

thanks to all the gurus and Amber for answering my questions, and highlighting the critical areas / milestones. There is so much to cheer.

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Re: Chandrayan-2 Mission

Postby SSSalvi » 13 Jul 2019 22:03

Some Numbers , if anyone is interested.
Can't post the source link link because I have lost the link. :(


Launch Sequence .. Graphical Representation and Tabulated.

Image


Image



Orbit Raising Graphic:

Image



Moon Gravity Insertion and De-Orbiting to 100kmsX100Kms final Orbit from where Lunar activities will be carried out:

Image


Mission execution Time-Table:

Image
Last edited by SSSalvi on 13 Jul 2019 22:46, edited 5 times in total.

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Re: Chandrayan-2 Mission

Postby Mort Walker » 13 Jul 2019 22:13

SSSalviji,

Thank you so much!!! That information is exactly what we need here. I suggest it become the sticky at the top.

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Re: Chandrayan-2 Mission

Postby SwamyG » 13 Jul 2019 22:19

SSSalvi wrote:Some Numbers , if anyone is interested.
Can't post the source link link because I have lost the link. :(

It is all here in the launch kit: https://www.isro.gov.in/gslv-mk-iii-m1- ... kit-glance

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Re: Chandrayan-2 Mission

Postby SSSalvi » 13 Jul 2019 22:23

^^^
Thanks SwamyJI ( Sorry, I played around your personal property.. Your Name )

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Re: Chandrayan-2 Mission

Postby Mort Walker » 13 Jul 2019 22:30

Thanks SwamyG-ji!

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Re: Chandrayan-2 Mission

Postby Mort Walker » 13 Jul 2019 22:37

By 15 July 3:08 AM IST we should know that Chandrayaan-2 has successfully separated.

01 AUG 2019 - Translunar Injection
06 AUG 2019 - Lunar Orbit
03 SEP 2019 - Vikram Separation
06 SEP 2019 - Vikram Landing
Last edited by Mort Walker on 14 Jul 2019 01:24, edited 1 time in total.

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Re: Chandrayan-2 Mission

Postby Mort Walker » 13 Jul 2019 22:45

Here's the update page from ISRO:

Chandrayaan2 Latest Updates

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Re: Chandrayan-2 Mission

Postby Amber G. » 14 Jul 2019 00:29

Mort Walker wrote:Indeed, the soft landing is the most difficult part as the moon has no atmosphere that you can't use parachutes or balloons to cushion a descent. Vikram's engines and thruster rockets to correct for yaw-pitch-roll all have to work in unison to get it right. On top of that, the moon's surface is rocky with lots of big and small craters. Hopefully the scanning goes well. Vikram has less than 2 minutes to make this decision. From ground control, sending messages back and forth to Vikram will take at least 3 seconds.

Though there are many critical challenges but for me, this will be the most critical. We and others have done other parts before but we are doing the soft landing on moon for the first time.. and many others who have tried failed in soft landing.

To navigate and land softly ISRO and developed many sensors etc and we will see how good they are. All are developed by Indian sources over the years.
Specially -
- Very high resolution optical camera OHRC (Orbiter High-Resolution Camera" (OHRC).
- Ka-band Altimeter.
- Another optical devices LPDC ( Lander Position Detection Camera ) and LHDAC (Lander Hazard Detection and Avoidance Camera ).

Vikram will make vertical decent in the south pole region but before that ..
- Orbiter and Vikram Lander will enter the lunar orbit. The OHRC ( attached to the orbiter) that will image scan the landing site to find the exact descent point.
-Once landing site is finalized, Vikram will detach from the orbiter. After detaching, the lander will carry out manoeuvres (using the other sensors for feedback) and it will make use of rough braking.
- Then there will be a fine braking to stabilize and finally land softly at the descent point amid all the flying sharp moon dust.
- This will be a nail-biting 15 minutes even for cool/experienced operators.

****
Once successfully landed - Vikram Lander also has LRRA (Laser Retro-reflector Array'- given by NASA) - This instrument ( mirrors) will be used to reflect laser signals from the Orbiter (or Earth) to locate the position of the Vikram lander on the Moon with pin-point accuracy. In fact It will also be able to measure the distance between the Earth and the Moon accurately within a cm or so.

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Re: Chandrayan-2 Mission

Postby Mort Walker » 14 Jul 2019 01:30

Though there are many critical challenges but for me, this will be the most critical. We and others have done other parts before but we are doing the soft landing on moon for the first time.. and many others who have tried failed in soft landing.


Absolutely. Some 50 years ago, Neil Armstrong said before the lunar module separated, there is only a 50% chance of landing on the moon, but 90% chance of safely returning.

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Re: Chandrayan-2 Mission

Postby SwamyG » 14 Jul 2019 05:59

It looks like the rover, when it moves around, it will make two impressions on the surface 1) ISRO logo 2) Ashoka Chakra.

Dr. Sivan, says the 15 minutes will be terrifying moments.

Good interview....

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Re: Chandrayan-2 Mission

Postby g.sarkar » 14 Jul 2019 06:57

https://thediplomat.com/2019/07/indias- ... ic-impact/
India’s Chandrayaan 2 Moon Mission and Its Strategic Impact
The lunar mission comes amid a changing strategic context for outer space.
By Namrata Goswami, July 13, 2019
On July 20, 1969, Apollo 11 landed on the moon, and Neil Armstrong became the first man to walk on its surface. Next week, as we gear up to celebrate the 50th anniversary of that historic landing, there is another lunar mission that will be on its way to the moon. India’s Chandrayaan 2 moon mission is scheduled to be launched on July 15. The landing site is between Manzinus C and Simpelius N, about 70 degrees south of the equator, closest to the South Pole of the moon. The mission will consist of an orbiter, a lander called Vikram, and a rover known as Pragyan. The touchdown of the lander is scheduled for September 6 this year. While the motivations for the Chandrayaan 2 mission likely preceded the global dialogue on space resources that has animated the world this year, India is rebranding the mission within that emerging discussion on space resources, especially with a landing close to the lunar South Pole.
The South Pole appears to be among the most important areas for industrial exploitation, and China has already articulated lunar settlement plans nearby in its long-term space goals. Significantly, India will be attempting to land on an ancient high plane just 600 kilometers from the Lunar South Pole. According to the Indian Space Research Organization (ISRO), “the payloads will collect scientific information on lunar topography, mineralogy, elemental abundance, lunar exosphere and signatures of hydrogel and water ice.” India is attempting to land on an area where no nation has landed before, and once there aims to study the potential for helium-3 deposits on the lunar surface, worth trillions.
Consideration of helium-3 appears to have been a motivation or consideration of India’s lunar program from the start. As early as September of 2006, two years before the launch of Chandrayaan 1, then-ISRO Chairman Madhavan Nair stated that Chandrayaan 1 will search the moon’s surface for deposits of helium-3, which can be used to power future nuclear reactors. Speaking at the Bhabha Atomic Research Center in Mumbai, Nair stated, “The quantity of helium-3 is also very important as it will determine the economics before we exploit it.” According to K. Sivan, the present chairman of ISRO, “The countries which have the capacity to bring that source from the moon to Earth will dictate the process…I don’t want to be just a part of them, I want to lead them.” Helium-3 is abundant on the moon, compared to Earth, and would require difficult extraction processes, but once that technology is cracked, it could theoretically meet Earth’s energy demands, several decades over.
Chandrayaan 2 will be the first of a parade of lunar landers after China’s Chang’e 4 reignited international interest on the moon, and kindled a new attention among space-faring nations, aimed at resource exploitation. The timing of the Indian lunar landing is significant internationally. Chang’e 4 landing on January 3 on the far side of the moon established a new global context, a context I have termed the Chang’e era of long term space development and presence. It changed the focus of conversation from an Apollo-era focus on dramatic firsts in space to broader concerns over securing access to space-based resources such as lunar ice and metals. Chandrayaan 2 is the first mission to take place in this new global context. There is now a broad interest in space mining and accompanying legal frameworks. These are propelled by expectations that the size of the space economy will grow from its present $400 billion to exceed over $1 trillion by 2040.
.....
Gautam


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