Chandrayan-2 Mission

The Military Issues & History Forum is a venue to discuss issues relating to the military aspects of the Indian Armed Forces, whether the past, present or future. We request members to kindly stay within the mandate of this forum and keep their exchanges of views, on a civilised level, however vehemently any disagreement may be felt. All feedback regarding forum usage may be sent to the moderators using the Feedback Form or by clicking the Report Post Icon in any objectionable post for proper action. Please note that the views expressed by the Members and Moderators on these discussion boards are that of the individuals only and do not reflect the official policy or view of the Bharat-Rakshak.com Website. Copyright Violation is strictly prohibited and may result in revocation of your posting rights - please read the FAQ for full details. Users must also abide by the Forum Guidelines at all times.
prasannasimha
Forum Moderator
Posts: 1170
Joined: 15 Aug 2016 00:22

Re: Chandrayan-2 Mission

Postby prasannasimha » 31 Oct 2019 19:39


prasannasimha
Forum Moderator
Posts: 1170
Joined: 15 Aug 2016 00:22

Re: Chandrayan-2 Mission

Postby prasannasimha » 31 Oct 2019 19:40

Just not making the orbiter will not cut it as to reach the moon the orbiter will be the system that will do the multiple orbiter elevation etc and then and only then can it detach and lander can land.

Amber G.
BRF Oldie
Posts: 6721
Joined: 17 Dec 2002 12:31
Location: Ohio, USA

Re: Chandrayan-2 Mission

Postby Amber G. » 31 Oct 2019 22:23


Thanks for posting this. So now all the payloads on the orbiter are returning awesome results!

The CHACE-2(neutral mass spectrometer-based) payload aboard the CY2 orbiter has detected Argon-40 from an altitude of approximately 100 km.

(For details see the ISRO's link given above.

Here's the schematic of the origin and dynamics of Argon-40 in lunar exosphere:
Image

Also:
CHACE-2 can detect constituents in the lunar neutral exosphere... it has detected 40Ar in the lunar exosphere from an altitude of ~100 km, capturing the day-night variations of concentration. 40Ar being a condensable gas at the temperatures and pressures that prevail on the lunar surface, condenses during lunar night. After lunar dawn, the 40Ar starts getting released to the lunar exosphere (blue shaded region in figure).


Image

Variation of Argon-40 observed during one orbit of Chandrayaan-2 during dayside and nightside of the Moon. The observed partial pressure has to be refined for the background and other effects to infer the density of lunar exospheric argon. The observations when Chandrayaan-2 was on the nightside is indicated by the black solid rectangle at the top of the panel and the two vertical dashed lines. Being in a polar orbit, Chandrayaan-2 enters the dayside of the Moon crossing the north pole, traverses through the dayside and enters the nightside after crossing the southpole.


Also, (see my earlier post) just a few days ago ..ISRO released several images gathered by Dual-Frequency Synthetic Aperture Radar of the moon that show different types of craters... Exciting times for science.

suryag
Forum Moderator
Posts: 3415
Joined: 11 Jan 2009 00:14

Re: Chandrayan-2 Mission

Postby suryag » 01 Nov 2019 01:12

AmberG ji what is the significance of this discovery ?

somdev
BRFite -Trainee
Posts: 60
Joined: 17 Sep 2019 00:34

Re: Chandrayan-2 Mission

Postby somdev » 01 Nov 2019 04:32

Lunar poles are the coldest region in the entire solar system and hence Argon is probably in a frozen state. Argon released elsewhere in the moon could migrate to the poles which acts as argon trap. The Apollo mission samples had traces of Argon

UlanBatori
BRF Oldie
Posts: 13033
Joined: 11 Aug 2016 06:14

Re: Chandrayan-2 Mission

Postby UlanBatori » 01 Nov 2019 04:38

coldest region in the entire solar system

Pretty broad statement, somdevji. Neptune / Pluto poles are probably not very warm either. Other planets also have moons as well, and some that are locked-in. Freezing point of argon is only -189 C which is relatively warm so u are right that any argon should be found in frozen form.

Amber G.
BRF Oldie
Posts: 6721
Joined: 17 Dec 2002 12:31
Location: Ohio, USA

Re: Chandrayan-2 Mission

Postby Amber G. » 01 Nov 2019 06:37

suryag wrote:AmberG ji what is the significance of this discovery ?

Here are some of the things which I think makes it all exciting ..
- All payloads on CY2 seem to be working perfectly. This is a good news. (They have not found issues like heat shielding etc which shortened the life of CY1's electronics).
- Virtually all of the payloads are state of the art -among the best.
- Most important is *huge* collection of data in coming years.. we will have best detailed maps - in many wavelengths of the moon for further landings and exploration. This includes radar maps (seeing under ground) and most detailed mineralogical map of the entire moon.
- More information about ice/water on moon.
- Study of solar flares to some extent (to help gather data of it's effect on our own communication/GPS sats) (We may have more, obviously with Aditya-1 or more earth-orbiting sats in the future - but this may be more useful as lot of such data from NASA etc are classified/not_shared at present)..
- Most important part are discoveries which are not expected at present but we will find in coming years as CY-2 may last a long time.

****
Also these are dual technologies - these multi-spectrum eyes in the sky will be *VERY* helpful in monitoring our friends...and those extremely accurate inertial guidance system can be used for pin-point surgical strikes.


- Of course we have learnt a lot from Vikram-1 crash landing too.. next time it will be better.

****

Amber G.
BRF Oldie
Posts: 6721
Joined: 17 Dec 2002 12:31
Location: Ohio, USA

Re: Chandrayan-2 Mission

Postby Amber G. » 01 Nov 2019 07:03

somdev wrote:Lunar poles are the coldest region in the entire solar system and hence Argon is probably in a frozen state. Argon released elsewhere in the moon could migrate to the poles which acts as argon trap. The Apollo mission samples had traces of Argon

Argon on earth's pressure freezes around -190 C, and becomes liquid around -185 C..but at moon's atmospheric pressure things are a little different.. but see my note#1 anyway)



Bur this is sort of academic.. as ISRO's article says there are about 10^4-10^6 molecules / cm3 .. this makes it less than 1 TRILLIONth abundance than say that of earth anyway... (Argon on Moon is sort of generated by radioactivity of K40 in the crust so there is always some supply while some molecules leaves moon -as it has relatively low escape velocity)..

BTW Moon's poles are NOT the coldest regions .. at south pole the average temperature is about -13 C .(warmer than our Antartica :) ). Even at night -and in craters- it is ( about -175C) much above Argon's freezing point.

Note#1 : Even at earth's pressure, Argon will NOT become liquid let alone a solid .

Slightly OT but if you are interested in phase diagram of Argon..(To see at what pressure the phases change) here it is:
Image

UlanBatori
BRF Oldie
Posts: 13033
Joined: 11 Aug 2016 06:14

Re: Chandrayan-2 Mission

Postby UlanBatori » 01 Nov 2019 07:51

Somdevji:

I think material that is buried at a depth, even in a place with 1/6 the surface G of Earth, will be at significant pressure, due to the weight of stuff above it. This is why crude oil, when opened to atmospheric pressure using a drilling core, shoots up above the surface.

For instance if material has a density of 2650kg/m^3 (SiO2), than at a depth of 1m and 1/6G, the pressure will be 2650 x 1 x 9.8/6 = 4328 N/m^2. In the middle school textbooks the formula is given as h * d * g.

At 10m, the pressure will be 43280 N/m^2, which is about 44% of Earth atmospheric pressure. 10m below the lunar S. Pole, it will be nearly quite as cold as the surface since there is little conducted heat to warm it up and little internal heating from the Moon's center.

Any substance delivered during the course of an impact, is likely to have penetrated to quite some depth (of course the collision would have generated much heat). But if ice could have been delivered by impact, so could other frozen substances. If it went 50 meters deep and the crater collapsed on it, it would be at more than twice atmospheric pressure.

All very rough calculations: Moon material is not all SiO2 so my density is only correct maybe to 1 decimal place, and Moon's gravity is not **EXACTLY** 1/6 of Earth's, but that is the best I can do from mental calculations. Ppl with textbooks and charts can derive these to several decimal places (great!), but assuming that argon, water ice is lying in pools on the surface is perhaps not very realistic even to zeroth order, sorry.

Amber G.
BRF Oldie
Posts: 6721
Joined: 17 Dec 2002 12:31
Location: Ohio, USA

Re: Chandrayan-2 Mission

Postby Amber G. » 01 Nov 2019 09:22

somdev wrote:. The Apollo mission samples had traces of Argon

Apollo 17 actually found Argon in Lunar exosphere too. Studying Nobel gases in Lunar exosphere is was one of *very* interesting and important activity by other missions.. done mainly by CY-2 type neutral mass spectrometers. Chandrayaan-1 also accumulated lot of useful data (shared in scientific community). In fact He, Ne and Ar all are there and how these noble gases are distributed around the moon's exosphere and how its concentration is distributed with respect to time (local lunar day/night) and position tells us lot about lot of things...

If there is interest, I may post something here (or in physics dhaga) but it may be too technical.

Amber G.
BRF Oldie
Posts: 6721
Joined: 17 Dec 2002 12:31
Location: Ohio, USA

Re: Chandrayan-2 Mission

Postby Amber G. » 01 Nov 2019 10:31

^^^ Added later..
Amber G. wrote:
suryag wrote:AmberG ji what is the significance of this discovery ?

If you are wondering about the significance of Argon (vs how good CY2's NMS is) specifically see the above post.
As said, NMS used to study noble gases for Moon's exosphere is quite significant. For example He, Ne, Ar all are found (and considered significant discoveries when found) on Moon's *very* thin atmosphere. They studied this starting with Apollo through CY1 (and many/most other lunar orbiters). As these gases are inert - their movement are less effected by chemical properties... Among other things, it helps us understand Solar wind (which contributes to He ions).. distribution of radioactive sources on the surface .. etc..))..For example Apollo 17 found that night time concentration of He was much higher (10x or more) than daytime .. resulting into some more understanding of some phenomena.

Just to give an example: CY-1 (and other orbiters ) data revealed that Ar density peaked when the spacecraft was overflying the 45° longitude (near western maria region) -- after making adjustments for night/day densities ..that correlated with high potassium deposit (and some other rare earth metals) etc in those regions..!!!!

chetonzz
BRFite -Trainee
Posts: 16
Joined: 18 Mar 2019 11:11

Re: Chandrayan-2 Mission

Postby chetonzz » 01 Nov 2019 13:27

i was looking at this video...

https://www.youtube.com/watch?v=gGzdgpeZ67I&t=140s

is it possible that, the "fatal Pirouette" part of the video could be the reason behind 'vikram lander' crash?
Image


Image

Image

Image

Image

in HD images of Lander from ISRO website, there is no LEM RCS system like thrusters [4 sets of (4 = 2 horizontal+ 2 vertical)]...
thus the absence of counter-torque?

Image
Image


ramana
Forum Moderator
Posts: 53474
Joined: 01 Jan 1970 05:30

Re: Chandrayan-2 Mission

Postby ramana » 05 Nov 2019 01:20

That "piroutte" was what we were discussing early on.
The thrusters were not at different planes to provide recovery moment once the lander started rolling.

Sad they introduce new terms when nomenclature already exists.

Let's wait for ISRO report.

Also the author is wrong in his nomenclature.
A pirouette is dance maneuver where the ballet dancers spins in vertical axis and moves horizontally.
This would be falt spin in aero terms.
What the Vikram lander encountered was a tumble that is spin along lateral axis.

Varoon Shekhar
BRFite
Posts: 1884
Joined: 03 Jan 2010 23:26

Re: Chandrayan-2 Mission

Postby Varoon Shekhar » 13 Nov 2019 21:06

https://www.isro.gov.in/update/13-nov-2 ... al-results

Terrain Mapping Camera-2 (TMC-2) is a follow-on of the TMC on-board Chandrayaan-1. TMC-2 provides images (0.4μm to 0.85μm) at 5m spatial resolution & stereo triplets (fore, nadir and aft views) from a 100 km orbit for preparing Digital Elevation model (DEM) of the complete lunar surface.

The triplet images from TMC-2 when processed into Digital Elevation Models, enable mapping of surface landform morphologies. These include

Amber G.
BRF Oldie
Posts: 6721
Joined: 17 Dec 2002 12:31
Location: Ohio, USA

Re: Chandrayan-2 Mission

Postby Amber G. » 13 Nov 2019 21:32

^^^ Pictures from above:
(Topographic Mapping Using TMC-2 of Chandrayaan-2: Initial Results
Terrain Mapping Camera-2 (TMC-2) is a follow-on of the TMC on-board Chandrayaan-1. TMC-2 provides images (0.4μm to 0.85μm) at 5m spatial resolution & stereo triplets (fore, nadir and aft views) from a 100 km orbit for preparing Digital Elevation model (DEM) of the complete lunar surface.

The triplet images from TMC-2 when processed into Digital Elevation Models, enable mapping of surface landform morphologies. )

Image
Image
Image

suryag
Forum Moderator
Posts: 3415
Joined: 11 Jan 2009 00:14

Re: Chandrayan-2 Mission

Postby suryag » 14 Nov 2019 01:35

No word yet on the lander ?

Ashokk
BRFite
Posts: 501
Joined: 11 Aug 2016 06:14

Re: Chandrayan-2 Mission

Postby Ashokk » 14 Nov 2019 03:34

Chandrayaan-3: Second bid to land on Moon by November 2020
BENGALURU: The Indian Space Research Organisation (Isro), which failed to land a probe on Moon in its first attempt in September 2019 (Chandrayaan-2), has begun work on Chandrayaan-3 with a deadline of November 2020, sources said.
Isro has formed multiple committees — an overall panel and three sub-committees — and held at least four high-level meetings since October. The new mission will include only a lander and rover, as the Chandrayaan-2 orbiter is functioning well. On Tuesday, the overview committee met with the agenda of reviewing the configuration of Chandrayaan-3. It also looked into the recommendations of various sub-committees on propulsion, sensors, overall engineering, navigation and guidance.
Work is in full flow, said a scientist. So far Isro has looked at 10 specific aspects of the mission, including landing site selection, absolute navigation and local navigation. Sources quoted an office order issued on October 5 as having instructed: “It is essential to carry out detailed analysis on the changes for improving the lander system considering the recommendations of both the expert committee (formed to look into Chandrayaan-2) and the recommendations which could not be implemented due to advanced stage of Chandrayaan-2 flight preparation.”
Another scientist said among the top priority for the new mission is “strengthening the legs of the lander”, so that it allows landing even with a high velocity. Sources said that Isro will be building a new lander and a rover. No final decision has been taken on the number of payloads on the lander.
A source said Isro teams are looking at having a detachable module that will carry fuel. “Tentatively called the propulsion module, it will help in taking the landing module — which will have the rover sitting inside the lander — to the lunar orbit,” the source said. In Chandrayaan-2, fuel carried on the orbiter was used for all the manoeuvres performed post launch and until the separation of the landing module. Here, the propulsion module will aid this process. Isro is also looking at reducing the number of manoeuvres around Earth and also during the transit to the lunar orbit. “Instead of six manoeuvres, we may have just three or four,” a source said.

Varoon Shekhar
BRFite
Posts: 1884
Joined: 03 Jan 2010 23:26

Re: Chandrayan-2 Mission

Postby Varoon Shekhar » 14 Nov 2019 03:51

^
Excellent news! Nice to see them being so confident and decisive, as well. particularly with regard to the deadline! So no orbiter this time, they will probably attach a LAM to the lander/rover combine, to perform the necessary orbital manoeuvers.

Indranil
Forum Moderator
Posts: 7761
Joined: 02 Apr 2010 01:21

Re: Chandrayan-2 Mission

Postby Indranil » 14 Nov 2019 04:39

Heartening. This fuel module is an interesting take. What has been revealed is that the lander module was designed to handle a certain amount of deviation. Increasing this tolerance would have increased fuel capacity. So this fuel module is to allow more flexibility.

Will it be launched using GSLV2?

arvin
BRFite
Posts: 249
Joined: 17 Aug 2016 21:26

Re: Chandrayan-2 Mission

Postby arvin » 14 Nov 2019 07:38

Good to see things moving fast. My guess is the new propulsion module would be a bare bones cy2 orbiter structure with only feul and thrusters. Our own fregat space tug. Isro would need to qualify the landing algorithm for re- use before the actual CY 3 mission in 2023 with JAXA.

Amber G.
BRF Oldie
Posts: 6721
Joined: 17 Dec 2002 12:31
Location: Ohio, USA

Re: Chandrayan-2 Mission

Postby Amber G. » 19 Nov 2019 03:27


ashbhee
BRFite -Trainee
Posts: 97
Joined: 15 Aug 2016 07:05

Re: Chandrayan-2 Mission

Postby ashbhee » 19 Nov 2019 04:33

arvin wrote:
ashbhee wrote:I think this is what ISRO should do.
They should not wait for 3 or 4 years to launch Chandrayaan - 3.
Just launch lander only mission, Virkarm - 2. It should be a replica of Vikram - 1 plus any changes that needs to be done for the landing mechanism.
Since it is a repeat mission, it can be done quickly and cheaply. Since it is much lighter mission it can be launched using PSLV or even the new SSLV.


PSLV fourth stage PS4 can only deliver till parking orbit. It is restartable, but wont have the feul for the 5 gravity assist maneovres to send the lander only config to moon capture orbit. Something like fregat would be required which we dont have.
Chandra yaan 2 was a closely coupled design in which lander piggy backed on the orbiter.
Lander only has feul to do the coarse and fine breaking after its drop from 100 km orbit.


When I said, "Just launch lander only mission, Virkarm - 2", I did not mean just send the lander without a navigation module to reach moon.
It looks like ISRO is thinking the same lines.
https://timesofindia.indiatimes.com/ind ... 047390.cms

somdev
BRFite -Trainee
Posts: 60
Joined: 17 Sep 2019 00:34

Re: Chandrayan-2 Mission

Postby somdev » 21 Nov 2019 03:18

So it was a hard landing for Vikram lander 500 meters from the planned landing site!

https://timesofindia.indiatimes.com/ind ... 148391.cms

ramana
Forum Moderator
Posts: 53474
Joined: 01 Jan 1970 05:30

Re: Chandrayan-2 Mission

Postby ramana » 21 Nov 2019 04:13

So how does this happen?
The control system expected the lander to be at higher speed for start of fine braking?

Gerard
Forum Moderator
Posts: 7650
Joined: 15 Nov 1999 12:31

Re: Chandrayan-2 Mission

Postby Gerard » 21 Nov 2019 07:14


disha
BR Mainsite Crew
Posts: 7221
Joined: 03 Dec 2006 04:17
Location: gaganaviharin

Re: Chandrayan-2 Mission

Postby disha » 21 Nov 2019 10:08

From TOI.

It appears that the reduction in velocity during the fine descent period was higher than the designed parameters. This might have thrown the software into tizzy and hence the crash landing.

My speculation, the lander has to go from point A to point B, but the braking is higher and the software realizes that it can only go to say A.5. Now it cannot add thrust! But it is designed to go to point B. And the software goes into an irrecoverable loop where all it has control on is varying braking thrust when it actually needs a 'boosting' thrust!

somdev
BRFite -Trainee
Posts: 60
Joined: 17 Sep 2019 00:34

Re: Chandrayan-2 Mission

Postby somdev » 21 Nov 2019 20:58

The control software is most probably written in ADA. In ADA operations may be implemented as subprograms using conventional sequential control structures. Unless there was something fundamentally wrong in logic the Ada execution is mostly flawless.

Indranil
Forum Moderator
Posts: 7761
Joined: 02 Apr 2010 01:21

Re: Chandrayan-2 Mission

Postby Indranil » 22 Nov 2019 01:15

disha wrote:It appears that the reduction in velocity during the fine descent period was higher than the designed parameters. This might have thrown the software into tizzy and hence the crash landing.

Yes, S. Somanath had hinted at this in the podcast I had linked before. It was not a bug or glitch. The parameters of the craft were outside the design parameters of the software. He had said that the spacecraft is designed for tolerances around ideal values. Tolerances can be increased, but that comes at the price of added fuel.

He had said that there is no reason to not make the whole report public as soon as it is ready. Let's see.

disha
BR Mainsite Crew
Posts: 7221
Joined: 03 Dec 2006 04:17
Location: gaganaviharin

Re: Chandrayan-2 Mission

Postby disha » 22 Nov 2019 01:38

Indranil wrote:Yes, S. Somanath had hinted at this in the podcast I had linked before. It was not a bug or glitch. The parameters of the craft were outside the design parameters of the software. He had said that the spacecraft is designed for tolerances around ideal values. Tolerances can be increased, but that comes at the price of added fuel.

He had said that there is no reason to not make the whole report public as soon as it is ready. Let's see.


I do not think I ever said it as a software bug or a glitch. My first post on this subject did say that the control software might have been presented parameters out of its design bounds. My thinking at that time was Vikram could not get a lock on the safe spot to land and that might have presented unbound parameters.

Now we know that the more than anticipated reduction in fine descent created this situation. And throwing software in tizzy is what I mean by control laws not able to gain control over the situation due to out-of-control events. :)

IMPORTANT: What Vikram attempted was far far far more complex than landing a craft in a region which is as smooth as a baby's bottom (comparatively and figuratively).

I am also *not* in favor of revealing the whole report in public. First of all the DDMs will not understand a difference between control and law and go into #Blow2ISRO mode. Second it will reveal the antecedents of the software. Since what is the difference between landing Vikram on a remote spot and a 'dharmo' on another remote spot? Other than former being more complicated.

disha
BR Mainsite Crew
Posts: 7221
Joined: 03 Dec 2006 04:17
Location: gaganaviharin

Re: Chandrayan-2 Mission

Postby disha » 22 Nov 2019 01:42

somdev wrote:The control software is most probably written in ADA. In ADA operations may be implemented as subprograms using conventional sequential control structures. Unless there was something fundamentally wrong in logic the Ada execution is mostly flawless.


It has nothing to do with Ada or even anything fundamentally wrong.

Think of it as this way, the control law needs to supply more fuel to the thrusters so that it can add more thrust to reach point B instead of point A.5. However there is not enough fuel in the craft! So what can it more do? And this is just one of the parameter we are speculating on. In reality, Vikram had to deal with 100s of parameters in realtime.

Indranil
Forum Moderator
Posts: 7761
Joined: 02 Apr 2010 01:21

Re: Chandrayan-2 Mission

Postby Indranil » 22 Nov 2019 01:49

Disha,

I understood what you said. I am supporting you. :D

chetak
BRF Oldie
Posts: 20509
Joined: 16 May 2008 12:00

Re: Chandrayan-2 Mission

Postby chetak » 24 Nov 2019 10:32

Finally, an official response on how #Chandrayaan2 lander #Vikram lost control. See attachments: Left: My story that "extra brakes may have sent it out of control", Right: Govt reply in Lok Sabha saying the same.


Read Full Report Here:

Extra braking caused Vikram to deviate: Govt in LS


Image


Image

chetak
BRF Oldie
Posts: 20509
Joined: 16 May 2008 12:00

Re: Chandrayan-2 Mission

Postby chetak » 24 Nov 2019 10:42

Chandrayaan-3 plans indicate failures in Chandrayaan-2


Chandrayaan-3 plans indicate failures in Chandrayaan-2

Chethan Kumar
Nov 19, 2019,

The Vikram lander made an unsuccessful effort to soft-land on the lunar surface

BENGALURU: The changes the Indian Space Research Organisation (Isro) is making in the proposed Chandrayaan-3 mission are indicative of the things that may have gone wrong with Chandrayaan-2 that failed to soft-land a probe on Moon in September 2019.

From a new guidance algorithm to improved communication systems on the lander, the overview committee that met last Tuesday (November 12) has pointed to multiple recommendations made by the failure analysis committee (FAC) looking into Chandrayaan-2 failure.

As part of the final discussions at the meeting the committee accepted the “Propulsion+Landing Module” configuration for Chandrayaan-3, and said: “Guidance algorithm to be finalised considering all recommendations of FAC and also after detailed simulations.”

The TOI was the first to report that Chandrayaan-3 mission is likely to have this — lander & rover (landing module) and propulsion module— configuration on November 14.

Software & Algorithm Glitch?

Sources indicated that one of the main reasons that the FAC found for Chandrayaan-2’s failure in soft-landing Vikram (the lander) was a glitch in the software and the algorithm that saw the lander lose orientation just metres away from the lunar surface. They said that the velocity of the lander was higher than expected and that it may have had attitude errors.

The overview committee, last week noted: “...Also, after detailed simulations LDV (laser doppler velocity) sensor for the direct measurement of velocities (all three axes) must be incorporated.

“The LDV sensor was developed even for Chandrayaan-2, but since it did not perform well in ground tests, it was not included,” a source said.

LDV sensors will be useful as they will help directly measure the velocity from the height of about 20km, sources added and said Bengaluru-based LEOS lab under Isro has developed the sensor.

Direct Velocity Measurement

Among other things, Isro is looking to improve the data transfer capability on the lander for the new mission, which will help transfer lunar surface images from the lander imager camera right from the beginning of the powered descent — likely to be from about 30km from the lunar surface.

“The camera was taking images even on Chandrayaan-2, but we didn’t have the capability to transfer real time, this time, the committee feels that we need this to get the right orientation,” another source said.

The committee has noted: “...Data rate, telemetry and orientation to be appropriately arrived at based on the descent trajectory.”

Power & Communication

Also, Chandrayaan-3 is expected to have solar cells on four sides of the lander— its predecessor had it only on three sides— to improve performance.

“Feasibility of populating solar cells on the fourth side vertical panel where Rover is accommodated to be studied to avoid power issues if landing happens with large attitude error resulting in absence of Sun in the plane,” the committee has said.

The panel, which will meet again later this year, has also tasked sub-committees to look at establishing margins for different touchdown conditions. “Strengthening of lander legs to be considered… power and communication between lander and ground to be ensured post landing irrespective of lander orientation,” the panel has noted.

Sources added that this may mean that the space agency will add more antennas on the lander to keep communication alive even if the lander does not land on the legs.

Vayutuvan
BRF Oldie
Posts: 10249
Joined: 20 Jun 2011 04:36

Re: Chandrayan-2 Mission

Postby Vayutuvan » 25 Nov 2019 00:26

Indranil wrote:The parameters of the craft were outside the design parameters of the software. He had said that the spacecraft is designed for tolerances around ideal values. Tolerances can be increased, but that comes at the price of added fuel.


I said this almost immediately after the hard landing.

Gerard
Forum Moderator
Posts: 7650
Joined: 15 Nov 1999 12:31

Re: Chandrayan-2 Mission

Postby Gerard » 03 Dec 2019 06:24


SaiK
BRF Oldie
Posts: 36392
Joined: 29 Oct 2003 12:31
Location: NowHere

Re: Chandrayan-2 Mission

Postby SaiK » 03 Dec 2019 06:56

I don't want C3 going to launch pad, w/ complete testing on Earth.

NRao
BRF Oldie
Posts: 16403
Joined: 01 Jan 1970 05:30
Location: Illini Nation

Re: Chandrayan-2 Mission

Postby NRao » 03 Dec 2019 11:06

NASA Finds India’s Vikram Moon Lander Crash Site, With Amateur’s Help

NASA has found pieces of Vikram, a small spacecraft that India attempted to land on the moon in September. They did it with the help of an engineer from India who scoured the lunar surface in his spare time.

Vikram was part of India’s Chandrayaan-2 mission to the moon, which launched in July. If the spacecraft had reached the surface in one piece on Sept. 7, India would have been only the fourth country to successfully put a lander on the moon. But less than two miles above the surface, Vikram veered from the planned descent trajectory and fell out of radio contact.

India’s space agency said the next day that it had located the lander. But it never published any images of the hard landing site taken by the mission’s accompanying orbiter, which remains in operation and is carrying out a scientific mission that will last for years.

A NASA spacecraft, the Lunar Reconnaissance Orbiter, has passed over the mission’s intended landing site, on a high plain near the south pole, several times since September. But initial analyses of the images did not reveal an obvious impact scar comparable to the Beresheet lander launched by Israel this year, which crashed in April. NASA scientists noted that the spacecraft might have been hidden in the shadows.

A lot of people were looking, including Shanmuga Subramanian, an Indian computer programmer and mechanical engineer.

“The crash landing of Vikram rekindled an interest in the moon not only for me and others also,” he wrote in an email. “I think even if Vikram had landed and sent some images, we would have never had such interest. For the first few days I was scanning the images randomly and there were lot of false positives.”

After reviewing the last known velocity and position of Vikram, Mr. Shanmuga shifted where he was looking. He noticed a white speck on the lunar surface that was about two-thirds of a mile from where Vikram was supposed to have set down. That speck was not visible in an earlier image. He wondered if the crash might have buried the lander in the lunar soil.

Mr. Shanmuga reported what he had found to NASA and scientists working with the Lunar Reconnaissance Orbiter’s camera, who confirmed his finding and scoured the surrounding area. Comparing images taken before Vikram’s landing attempt and those taken on Nov. 11, they were able to identify the impact point about 2,500 feet to the southeast of the planned touchdown site, and a spray of debris emanating outward.

The pieces of debris were not much bigger than the minimum of what the camera could make out. The resolution of the camera was about 1.3 meters per pixel; the three largest pieces of debris were about two pixels by two pixels in size and cast a one-pixel shadow, NASA said.

sanjaykumar
BRF Oldie
Posts: 4106
Joined: 16 Oct 2005 05:51

Re: Chandrayan-2 Mission

Postby sanjaykumar » 03 Dec 2019 11:10

Actually the Indian found Vikram with nasa’s help. That should be obvious.

sanjaykumar
BRF Oldie
Posts: 4106
Joined: 16 Oct 2005 05:51

Re: Chandrayan-2 Mission

Postby sanjaykumar » 03 Dec 2019 11:11

Even to the NYT.


Return to “Military Issues & History Forum”

Who is online

Users browsing this forum: Bart S, navneeet, sanjayc and 56 guests