Chandrayan-2 Mission

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Re: Chandrayan-2 Mission

Postby prasannasimha » 25 Jul 2019 23:23

Even there only 94%

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Re: Chandrayan-2 Mission

Postby Amber G. » 25 Jul 2019 23:25

Indranil wrote:Let me answer my own question :P

There are roughly 13 lunar days in a lunar year and there is no place (not even at its poles) which is in perpetual darkness. Much like the earth, at most, there may be places that could be in darkness for 6 earth-months.

Not to nit-pick but there are roughly 12 ( about 12.4) lunar days in a lunar year. The sidereal period of Moon (from a star rise to a star rise) is about 27.3 days while the "day" (synodic period - or from "sun rise to sun rise" is 29.5 days.

On Earth the axis is tilted (about 23 degrees) so you have about 6 month day/lights at the pole.. If Earth's axis was not tilted, places like Antartica (which is much higher elevation) may have eternal day-light.

Hope this helps.

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Re: Chandrayan-2 Mission

Postby Indranil » 25 Jul 2019 23:30

Did not think about aberrations on the surface. Good point.

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Re: Chandrayan-2 Mission

Postby Amber G. » 26 Jul 2019 00:08

Just checked - Wiki has a fairly good article about "Peaks of Eternal Light", so some more details, if one is interested, could be gathered from there , or links given there).

Moon's tilt is near zero but not not zero - it is about 1.5 degree. So at the high peaks one may have 100% (or near 100%) "day" in "summer" - except for things like eclipses / shadow from other peaks etc while in "winter" at some of these peaks one (per wiki) gets "day" for about 70-90%..

Here is a nice photo, of the peaks I was talking about, which has "eternal light" (in surrounding darkness).


Nice original question BTW to get some nice discussion.


Image

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Re: Chandrayan-2 Mission

Postby krishGo » 26 Jul 2019 02:32

Mort Walker wrote:Chandrayaan 2 Raising Schedule:

24 JUL 19: 14:00-15:30 241.5 x 45,162 Km
26 JUL 19: 01:00-02:00 262.9 x 54,848
29 JUL 19: 14:30-15:30 281.6 x 71,341
02 AUG 19: 14:00-15:00 262.1 x 89,743
06 AUG 19: 14:30-15:30 233.2 x 143,953

Translunar Insertion
14 AUG 19: 03:00-04:00 278.4 x 412,505 Km
Lunar orbit by 20 AUG 19


https://www.isro.gov.in/update/24-jul-2019/chandrayaan-2-updatemission-plan-of-chandrayaan-2-spacecraft


Chandrayaan2 update: Second earth bound maneuver completed successfully

Second earth bound orbit raising maneuver for Chandryaan-2 spacecraft has been performed successfully today (July 26, 2019) at 0108 hrs (IST) as planned, using the onboard propulsion system for a firing duration of 883 seconds. The orbit achieved is 251 x 54829 km.

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Re: Chandrayan-2 Mission

Postby Indranil » 26 Jul 2019 03:02

1. Is ISRO focusing on larger LAM engines?
2. I thought GiSAT was going to be PAM-G based. But it has been dropped for LAM. Any thoughts on LAM versus PAM-G?

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Re: Chandrayan-2 Mission

Postby Mort Walker » 26 Jul 2019 03:03

Seems a little short. I would have thought they would have exceeded the desired apogee. Maybe that’s what they revised it to.

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Re: Chandrayan-2 Mission

Postby krishGo » 26 Jul 2019 03:42

Indranil wrote:1. Is ISRO focusing on larger LAM engines?
2. I thought GiSAT was going to be PAM-G based. But it has been dropped for LAM. Any thoughts on LAM versus PAM-G?


1. More thrust isn't that big of a concern for onboard engines. Efficiency is much more important factor. ISRO has been working on ion propulsion for quite some time now with the EPS (Electric Propulsion System). It is a replacement for LAM with much lesser thrust, but very high specific impulse hence needing only around quarter of the fuel mass. This means all the mass saved can be used for useful payload like transponders. The drawback is that GTO to GEO transfers will take much longer, from less than a week to almost 6 months because of the low thrust.

I believe EPS was tested on South Aisa sat. How widely ISRO wants to use it is an open question.

There have been some deep space missions which have used ion propulsion. SMART-1 used it to get to the moon in a very similar way to Chandrayaan2 but took a LOT longer. Basically, for deep space / interplanetary missions, most of the work needs to be done by the launch vehicle or through gravity assists. Bigger onboard engines themselves would lead to marginal gains.

2. PAM-G and LAM were always thought as two different things. PAM-G is thug that was supposed to impart a certain delta-V needed to get to some orbit at a particular position (perigee) (as a one time thing). LAM also does this but not as a onetime thing and it & its propellant tanks are part of the satellite itself. PAM-G is more like the 4th stage of a rocket.

As far I know, PAM-G was for a very specific mission. It was supposed to act as the 4th stage of GSLV (GSLV-C) to launch the Russian GLONASS satellites. There was some kind of an agreement where ISRO would launch a couple of GLONASS ssatellites for Russia. The whole agreement got canned and looks like so too did the PAM-G.

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Re: Chandrayan-2 Mission

Postby UlanBatori » 26 Jul 2019 07:10

The fatwa says that using an ion rocket (continuous low thrust) for orbit transfer, requires twice the delta-v of a "Hohmann Transfer" which is very short burns only at perigee. But an ion rocket can have specific impulse of 10,000 seconds vs. 450 for the cryo LH2-LOX, or <300 for solid thrusters. And an ion rocket may take 6 months to get from LEO to GEO.

If I were doing a deep space mission, the ion rocket appears unbeatable because it requires so little mass flow and can be solar-driven at least until the rocket gets out of the inner solar system.

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Re: Chandrayan-2 Mission

Postby SSSalvi » 26 Jul 2019 09:35

SSSalvi wrote:
Indranil wrote:I can see the pictures.

Ssalvi ji, are there parts of the moon in perpetual darkness?


No ( At least to my knowledge. There could be some very small portion which is not illuminated anytime .. but not sure ).

What is shown as bright area is mostly what is facing Earth..
Other side is not seen because when it is lit we are in Amavasya period .. so the illuminated portion ( i.e. Backside of moon as far as Earth is concerned ) is away from Earth


I was talking of general area on surface.
There will surely be some deep craters around the poles where the bottoms could never have been illuminated.

Imagine light coming from about 30 deg elevation on a Cup and saucer. ( 30 deg to take care of Ecliptic and liberation inclinations ).
Saucer bottom will be illuminated but the cup bottom will not. Unless you are using a special shallow cup ... I came across one such cup in Iran!!

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Re: Chandrayan-2 Mission

Postby juvva » 26 Jul 2019 10:30

Mort Walker wrote:Seems a little short. I would have thought they would have exceeded the desired apogee. Maybe that’s what they revised it to.


One of the advantages of this strategy ( achieving TLI thru multiple orbit raising burns) , is that they have an opportunity to characterize the LAM in actual conditions, this will help better accuracy in further orbit raising burns, and even more importantly in the critical LOI burn.

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Re: Chandrayan-2 Mission

Postby Indranil » 26 Jul 2019 10:45

UlanBatori wrote:The fatwa says that using an ion rocket (continuous low thrust) for orbit transfer, requires twice the delta-v of a "Hohmann Transfer" which is very short burns only at perigee. But an ion rocket can have specific impulse of 10,000 seconds vs. 450 for the cryo LH2-LOX, or <300 for solid thrusters. And an ion rocket may take 6 months to get from LEO to GEO.

If I were doing a deep space mission, the ion rocket appears unbeatable because it requires so little mass flow and can be solar-driven at least until the rocket gets out of the inner solar system.

Exactly my thoughts. For missions where a Hoffman transfer is the "best" option, switching to the new engines deviced for the chandrayaan lander may not be a bad idea. It is throttable and restrartable and would provide 800 N instead of the current 440 N LAM rocket.

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Re: Chandrayan-2 Mission

Postby prasannasimha » 26 Jul 2019 11:40

Ion engines can be used for say GTO to GSO or GEO transfer. They would provide significant weight penalty advantge. Howrver thete are dtill a lot of issues with ion engines that have to be smoothened out. Thats why they are not still widely used and only a few missions have acruslly used it. The Rissiam house keeping electric propulsion are Hall effect thrusters. India alsi has some Hsll effect thrusters

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Re: Chandrayan-2 Mission

Postby UlanBatori » 26 Jul 2019 18:03

800N ion rocket is way too large: the killer problem with ion rockets is the mass per unit thrust. Too many electrical windings etc I suppose. Even a 1N ion rocket is "large".
Read this devastating phrase on Wikidevata:
though experimental versions have achieved 100 kilowatts (130 hp), 5 newtons (1.1 lbf).

But 1 Newton for several months builds up to a huge impulse. Also, the idea of propulsive efficiency suggests that for higher-speed missions, the best efficiency comes with faster exhaust speeds, though I am not quite sure how that applies in vacuum. For example, it is not a good idea to put a turbojet engine on a Mark -3 Go-Cart.
In environs of the Earth's orbit around the Sun (such as for NEO resource extraction missions), eventually, solar sails will do far better. No propellant needed at all.

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Re: Chandrayan-2 Mission

Postby Vivek K » 26 Jul 2019 22:56

Admins - can we please the ion propulsion discussion to the Indian Space thread and leave this one with details relevant to the Chandrayan -2 mission only?

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Re: Chandrayan-2 Mission

Postby prasannasimha » 26 Jul 2019 23:26

Yes this thread is being sidelined. Please shift ion engine discussions toi ISRO thread

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Re: Chandrayan-2 Mission

Postby Indranil » 27 Jul 2019 09:36

UB ji

The 800N rocket is hypergolic fuel based.

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Re: Chandrayan-2 Mission

Postby UlanBatori » 27 Jul 2019 14:18

Gee! The Thought Polis are out in force, time to exit to caves. Might as well tell us to shut brain off and use narrow-vision blinders. Back to watching Republic TV blabber, thanks very much. The Moon looks soooooo pretty, no?

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Re: Chandrayan-2 Mission

Postby pankajs » 27 Jul 2019 19:37


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Re: Chandrayan-2 Mission

Postby prasannasimha » 27 Jul 2019 20:40

UlanBatori wrote:Gee! The Thought Polis are out in force, time to exit to caves. Might as well tell us to shut brain off and use narrow-vision blinders. Back to watching Republic TV blabber, thanks very much. The Moon looks soooooo pretty, no?

No one has policed anything = just discuss this in another appropriate thread suddenly becomes thought police.

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Re: Chandrayan-2 Mission

Postby Kakarat » 27 Jul 2019 21:27

Created our Youtube channel by the name Spacelaunch. IN and will be starting a website by the name spacelaunch.in shortly

Our First Video
GSLV MKIII M1 Chandrayaan 2 Launch


This is the SD version, will be releasing another properly edited HD version within a week to 10 days
Watch it in 720P and good sound

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Re: Chandrayan-2 Mission

Postby UlanBatori » 27 Jul 2019 21:37

prasannasimha wrote:
UlanBatori wrote:Gee! The Thought Polis are out in force, time to exit to caves. Might as well tell us to shut brain off and use narrow-vision blinders. Back to watching Republic TV blabber, thanks very much. The Moon looks soooooo pretty, no?

No one has policed anything = just discuss this in another appropriate thread suddenly becomes thought police.

Hello:

OK, sorry i left without any trouble, but now I do have to make a brief comment on this gratuitous pissiks-dhaga-type rudeness:
Ion engines / continuous thrusters are relevant to lunar missions because they are the smart way to get to the Moon and GEO for unmanned missions where there is no hurry. Some of the complex maneuvers that Haridasji cited, are because the burns are not really bursts at the perigee, but longer burns of an engine using smaller thrust. Extending this gives the continuous-thrust trajectories, and I gave the simple theoretical answer on how to calculate the mission parameters for continuous thrust.

Look at recent ESA missions to GEO for instance. The overall mass ratio of the mission can be improved, so larger and more useful payloads can be carried on smaller rockets. This is of interest to people who think ahead about what the Chandrayaan missions imply for the Indian Space program, not just parrot what is in some manual. It will become deeply interesting as China builds up a Moon base.

If you calculate the payload of Chandrayaan-2, it is almost exactly at the limit for what the GSLV-3 can carry. To carry larger loads, such as for a sample-return mission, should one wait for a much bigger rocket, or become smarter and use continuous-thrust trajectories? You cannot allow anyone a but of space to even mention such a speculation in the context of the present mission?

Just curious: Is the culture inside ISRO still really that bad? Many years ago I was told that no one in India had any interest in hydrogen propulsion, since ISRO was interested in saalid raackit onlee, so go away to some other "appropriate" country to learn about hydrogen. Looks like the same culture has persisted. Eventually the cryogenic engines appear to have been developed after trying very hard to shoot the nation in the musharraf with the Nambi Narayanan case, idiot politicians and polis etc.

If I want to go post chest-thumping about ion engines, I will do so, thank you very much: no need for bullies to push me there. I have not tried to derail any thread, or tried to bully anyone: I simply answered a question. Ordering me to go elsewhere to an "appropriate thread" because you are ignorant of the significance of many things outside of some memorized manuals, is completely uncalled-for. I know this is a sort-of tradition of the Military Forum where some appear to believe they are conquering herrows to give military orders. Sad.

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Re: Chandrayan-2 Mission

Postby Indranil » 28 Jul 2019 07:42

UB ji,

With highest respect, that was uncalled for. I agree with your grievance, but this kind of vehemence is below you (IMHO). Without being pedantic, may I appeal to make your vinayam as exemplary as your vidya.

1. The above moderation was not directed at you. And only a fool would stop the discussion on ISRO's choices in rocket design in the past, present and future. But, this is a more generic discussion, and its best place is the Indian Space Program: News & Discussion thread. Let's cool down and continue the discussion there.

2. An open forum like ours needs danda-dharis. It is an imbalance in power. But, what to do?

Let's all cool down and let better senses prevail.

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Re: Chandrayan-2 Mission

Postby prasannasimha » 28 Jul 2019 09:58

.UB if you think tha ISRO is simply hatching eggs - you are wrong and they are doing work on ion thrusters and that you do not know about it is your problem.They have developed working Hall thrusters that are being deployed FYI and work is going on wrt other ion thrusters and electric propulsion development is very much on the cards. Do you know that they have plans for interplanetary transfer and even to GEO using ion thrusters in the future ? The reason for use of each propulsion method and the advantage and disadvantages are different. If you want to circularize a GTO orbit to GSO it can be done and can take upwards to 3-6 months and will use less fuel but more time .. Please do not assume that others also do not know about it There are enough papers on low thrust trajectory optimization including interplanetary transfers by ISRO. One cannot help if you are not aware of it but do not jump to denigrate an organization and other people by your ignorance of the fact.

You may hear many rumors about cryogenic engines etc etc and they are what they are - rumors and not the truth. Problem was that we did not have cryogenic technology at hand at the time and they had to keep it at second priority while trying to make the program move ahead. Yes there were some ego battles between groups but that was just that while the key decision makers ahd to decide what was achievable at that point of time and prioritized that.Was PSLV then a mistake ? . Just think - if that was the case - why did they develop GSLV Mark2 ?
So please do not assume that everyone else is dumb.
The reason for asking to shift to another thread is precisely for the reason that Chandrayaan does not have ion thrusters and this thread is for Chandrayaan related stuff. You are welcome to post there was also was told. Yes there is some moderation in every thread = like it or not - that is the forum rules as with rules about anything in life. It is expected that everyone stick within those parameters and if you don't -sorry but it will not be allowed to derail the thread.
Lets be clear -in a moderated group - there will be moderation to keep discussions within focus and prevent it from rambling.
**Moderate note There will be no irrelevant discussions in this thread. Please move non Chandrayaan related discussions to the main ISRO thread. This thread needs to be focussed on collating information about a specific mission Chandrayaan-2.
Irrelevant posts will be deleted. Persist and bans will be enforced. **

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Re: Chandrayan-2 Mission

Postby SSSalvi » 28 Jul 2019 10:15

There WILL always be better options which the experts may not have opted for.

But for that there may be some other blockades .. like lack of technology for other feeder equipment equipment, cost/expertise to go in for the new tech etc.
It is also possible that after putting in so much of effort in some proven technology they may find that adopting new tech is not appropriate to meet at least the CURRENT GOALs.

It is also possible that those guys may be on the way for the technology suggested .. is it mandatory to make everything known to public?

Coming to the culture of ISRO, ... This seems to be the only organisation where the heads of deptts are raised only from the internal juniors - unlike other places where the outsiders are deputed to head.
Is there any organisation where the director of center sits with you on ground at midnight when you are working alone and says ' ok, let's trace that blue wire. Yahan J1-12 mein connected hai, tumhare rack mein J15-32 mein anee chahiyen' ? ( A factual instance )
I mean the seniors are raised from bottom and they know EXACTLY what is happening at ground level and with increased vision they can guide the bottom level on right path.
The junior on the other hand knows that you can't fool your senior by showing some flashy presentation.
------
added later:
( I had started writing this post prior to the post above .. but it tells a similar thing )

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Re: Chandrayan-2 Mission

Postby Ashokk » 28 Jul 2019 12:55

PM Modi Watches Live Telecast Of Chandrayaan-2

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Re: Chandrayan-2 Mission

Postby Ashokk » 28 Jul 2019 18:27

Chandrayaan-2 may orbit Moon for 2 years
BENGALURU: The orbiter on Chandrayaan-2, which Indian Space Research Organisation (Isro) initially said would go around Moon for one year, will be able to have a lifespan of at least two years if everything goes as per Isro’s current estimations.

At least five people associated with the Rs 978-crore mission told TOI that it’s life may be extended by an additional year as per the current status of things, which is a significant bonus from the one-year lifespan that Isro chairman K Sivan had said it would have on June 12.
“Chandrayaan-1 was planned for a longer life than it had but a problem with the power converters led to a curtailed lifespan, which has been corrected for Chandrayaan-2. And, going by the amount of fuel that will remain in the orbiter after all the manoeuvres, we will have Chandrayaan-2 orbiting for at least two years,” a source working with the mission team, said.

The orbiter was packed with 1,697kg of propellant at the time of the launch, and it has already expended about 130kg of it for the two manoeuvres Isro conducted on July 24 and 26. As on Saturday (July 27), the orbiter had more than 1,500kg of propellant remaining.
A scientist said that a better-than-textbook launch has given the agency an advantage of about 40-odd-kg of fuel. Besides, another scientist said: “Even as per the initial plan we had, additional fuel was budgeted keeping in mind some emergencies. But going by present estimates and calculations, we will have more fuel than it is needed to orbit for a year.”

Sivan had earlier said that all the manoeuvres until the separation of Vikram, the lander, will be fuelled by the propellants on the orbiter. This means that there are nine more manoeuvres before the separation, during which many more kilograms of fuel will be used up.
According to Isro’s present estimation, at the end of all Earth-bound and lunar-bound manoeuvres, the orbiter should be left with at least 290.2kg of fuel when it is in the 100kmX100km orbit around Moon (see graphic).
“This will be more than enough for it to go around Moon for two years as there will be no more big manoeuvres required,” the first scientist said. Another scientist said that the only manoeuvres after reaching the desired lunar orbit, if at all, would be minor ones.

“But, given that Moon’s gravity is not uniform unlike Earth, the orbiter needs to be kept in the correct orbit, which will require periodic intervention. If left unattended, the closest point to Moon could become very narrow. These manoeuvres will use up some fuel,” the scientist explained.
All the scientists emphasised that they could only confirm the exact number of additional days the orbiter could have around Moon once the lunarcraft is settled into an orbit there. “Chandrayaan-2 is expected to be inserted into the lunar orbit on August 20, and we can assess how long it would last once it is there and we know exactly how much fuel is left,” one of them said.

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Re: Chandrayan-2 Mission

Postby prasannasimha » 28 Jul 2019 21:14

Third earth bound maneuver for Chandrayaan 2
29.07.2019

14:30 - 15:30 IST

268 x 71558 Kms

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Re: Chandrayan-2 Mission

Postby disha » 29 Jul 2019 10:25

I do not understand the derision and the rona-dhona posters do here.

At this rate, I am not so sure that this thread will survive the 12 minutes of hell Chandrayan 2 will go through. Look at the south pole. It is pockmarked with craters. The equatorial sea of tranquility on moon seems to be a very tranquil plain of "smooth surface" where Apollo 11 had to its own scary moments prior to landing.

Look at Change'4 lander image https://phys.org/news/2019-07-image-change-lander.html. The place looks as smooth as baby's bottom. And what did it find?

The researchers expected to find a wealth of excavated mantle material on the flat floor of the SPA basin, since the originating impact would have penetrated well into and past the lunar crust. Instead, they found mere traces of olivine, the primary component of the Earth's upper mantle.


At the same time, they did successfully execute multiple missions and were the first to land at the far side of moon.

Look at the audacity of the C-II mission. It follows up on C-I., C-1 found water on moon through its impact probe and kicked open a door on new science to be carried out at Moon's south pole. Everybody is now targeting moon's south pole now.

C-II landing at south pole will be major achievement. It will be actually a miracle if it lands and even bigger miracle if it is able to do successful science. Sending in rover will be even bigger and finding water will be hitting jackpot. All on 2 solid rocket boosters, a well tested and very reliable hypergolic engine and a newly introduced cryo upperstage.

Completing a stated mission reliability and economically is the outcome one should wish for. Where does all this new fangled SatyaNasa'isms come in? How do they help?

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Re: Chandrayan-2 Mission

Postby Indranil » 29 Jul 2019 11:35

Has everybody had their say, or is there more left? :x

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Re: Chandrayan-2 Mission

Postby ravikr » 29 Jul 2019 16:02

UPDATE

July 29, 2019

Third earth bound orbit raising maneuver for Chandryaan-2 spacecraft has been performed successfully today (July 29, 2019) at 1512 hrs (IST) as planned, using the onboard propulsion system for a firing duration of 989 seconds. The orbit achieved is 276 x 71792 km.
All spacecraft parameters are normal.
The fourth orbit raising maneuver is scheduled on August 2, 2019, between 1400 – 1500 hrs (IST).
https://www.isro.gov.in/chandrayaan2-latest-updates

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Re: Chandrayan-2 Mission

Postby prasannasimha » 29 Jul 2019 22:10

Enough fuel saved with the preliminary launch injection is such that Chandrayaan's life may be extended by a year (to two years) if all subsequent burns are nominal

At the end of all Earth-bound and lunar-bound manoeuvres, the orbiter should be left with at least 290.2kg of fuel when it is in the 100kmX100km orbit around Moon

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Re: Chandrayan-2 Mission

Postby Mort Walker » 29 Jul 2019 22:51

I would have been happy with Chandrayaan 2 mission if it only had an orbiter with sensors and cameras that did a 10Km x 10Km orbit around the moon.

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Re: Chandrayan-2 Mission

Postby RonyKJ » 29 Jul 2019 23:56

10km circular orbit around moon would not be sustainable for long due to the variation in moon's gravity. The orbit would soon become distorted and huge amounts of fuel would be needed to correct it. This was attempted during Apollo 15/16 by releasing a sub-satellite called PFS1 and PFS2
https://science.nasa.gov/science-news/science-at-nasa/2006/06nov_loworbit

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Re: Chandrayan-2 Mission

Postby Mort Walker » 30 Jul 2019 09:25

^^^Any low orbit which allows for detailed remote sensing would be a good mission. Maybe another impactor too. Landing on the moon will be tough, let's hope it goes well come Sep. 7.

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Re: Chandrayan-2 Mission

Postby Cybaru » 30 Jul 2019 09:37

Why 10 km by 10 km? What is achieved by it? What does staying at 100km by 100km miss out on? Aren't the sensors good enough at the moment to create excellent maps?

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Re: Chandrayan-2 Mission

Postby prasannasimha » 30 Jul 2019 10:07

The moons gravity is fairly distorted due to its internal mass distribution ( due to the mechanism of its birth being gouged out die to Earth's collision with a Mars sized object , asteroid impacts and Lava flows.

Please look up about "Mascons" and "Frozen orbits"

The lower you go the more the distortion so skimming low is not easy and will sharply increase station keeping and reduce life time.
Most instruments can acquire enough information and for ground data the lander and Pragyaan will give data for evaluation and calibration.

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Re: Chandrayan-2 Mission

Postby Mort Walker » 30 Jul 2019 18:29

Cybaru wrote:Why 10 km by 10 km? What is achieved by it? What does staying at 100km by 100km miss out on? Aren't the sensors good enough at the moment to create excellent maps?


Detailed mapping and remote sensing. Even a 100x100 is unstable, but uses less fuel.

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Re: Chandrayan-2 Mission

Postby sanjaykumar » 30 Jul 2019 19:18

What would the orbital velocity have to be for a 10 km orbit?

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Re: Chandrayan-2 Mission

Postby disha » 31 Jul 2019 02:02

Simple - orbital velocity formula is v = SQRT(G*M/R)., where R is radius of orbit, which will be avg. radius of moon + height above moon

Plugging in the numbers, for G, M and R for 10 Km at moon orbit, I think it will be around 70 Km/sec. Raising it to 100 km will be @22 Km/Sec. (I might have eaten a zero here or there :mrgreen: so please do not quote me or correct me on the numbers calculated :( ...)


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