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What did he do last time? Do not recall the details.
He started heckling / hollering at the ISRO spokesman who came to face the press immediately following the CY-2 landing failure, claiming that ISRO Chairman Sivan himself should have come instead.
sanman ji,
he displayed the typical hubris and the arrogant sense of entitlement of the runditeevee journalists, most of whom were dynastic hires from the families of those who illegally helped prop up this third grade channel using govt resources and pilfered DD equipment + content
they should have continued to kept this ignorant guttersnipe away from all ISRO media proceedings
SriKumar wrote: ↑15 Jul 2023 04:27
7 LVMs launched and all 7 seccussful. Cryogenic ignition working well. Next stop: Aug 23rd.
I hope they control the TV cameras in Mission Control better this time.....and keep Pallav Bagla (NDTV) out of the press conference post-landing, after what he did the last time.
What did he do last time? Do not recall the details.
ISRO
Scientists at the Indian Space Research Organisation have performed the first orbit raising manoeuvre of the Chandrayaan-3 spacecraft on Saturday, the space agency said. The health of the spacecraft was "normal", ISRO said in a social media post. Chandrayaan-3 is now in an orbit, which when closest to Earth is at 173 km and farthest from Earth is at 41,762 km, the space agency said. "
Atmavik wrote: ↑16 Jul 2023 00:53
Is the orbit raising done by firing the CUS ?
No, the Chandrayaan-3 payload stack (propulsion module + lander) has already separated from CUS (you may have seen that at the end of the onboard camera video posted upthread). So all of these burns are being done by the propulsion module portion of the stack.
Just 4 more such maneuvers to go, and then we can do TLI burn to head out for the Moon!
Last edited by sanman on 16 Jul 2023 06:21, edited 1 time in total.
Just wanted to clarify something, as per my understanding:
ISRO personnel, including the current ISRO chairman, have given their explanation of what went wrong with the Chandrayaan-2 lander. They said that as the lander descended, the attitude deviations ("errors") began accumulating faster than expected, necessitating larger sharper corrections by the thrusters. At the same time, there was a bug in the software that manifested itself due to these larger sharper corrections being required. This software bug was not allowing for larger corrections by the thrusters beyond a certain amount. Had the attitude errors/corrections been smaller in size, then the software bug would not have been encountered - but because they were large enough, that software flaw then came into play. Therefore the lander was unable to properly perform the required attitude corrections on the way down, causing the resulting crash. ISRO personnel refer to this problem as "dispersion" handling, meaning that those attitude errors/deviations were larger (ie. had a larger dispersion) than anticipated, which the software was unable to handle. That has now been corrected, along with other improvements and upgrades made to this Chandrayaan-3 lander.
They said that as the lander descended, the attitude deviations ("errors") began accumulating faster than expected, necessitating larger sharper corrections by the thrusters. At the same time, there was a bug in the software that manifested itself due to these larger sharper corrections being required. This software bug was not allowing for larger corrections by the thrusters beyond a certain amount.
.....refer to this problem as "dispersion" handling, meaning that those attitude errors/deviations were larger (ie. had a larger dispersion) than anticipated, which the software was unable to handle. That has now been corrected, along with other improvements and upgrades made to this Chandrayaan-3 lander.[/b]
The primary cause was the braking rocket(s) slowing the lander more than was necessary. The reasons for this have not been discussed in the S.Somnath interview video linked by you or the one by rahulm. This is a bit curious since (I believe) these are the same rockets that are used to perform orbital raising maneuvers (not 100% sure but I think so) and behavior should be known. So now the craft had to move faster to the designated landing spot, but this was prevented by software limits placed on the control systems preventing it from doing so. This as far as I can tell is not a software bug- it was a feature. (Did Somnath use the term bug- I think not. I think these limits were deiiberate, meant as a safeguard to prevent extreme maneuvers and speeds by the lander). I these limits are now increased significantly thereby giving the lander more freedom in how it wants to adjust its speed (and orientation). I did not understand what errors accumulated that was seen as a problem (this was not discussed). Altitude and speed deviations from the planned path in new missions are only to be expected. So not sure why this was a problem.
Other changes made for this mission was to get a better landing site, a larger landing site, a priori knowledge of the landing terrain (thanks to CY 2 orbiter taking hi-res pictures)- this was not available in the first mission and the landing site was being determine during it flight. Also, more fuel will allow it to hover around for a better landing site. All of these directly give the lander more freedom to pick a spot. Hope that the final spot it picks has no boulders.
SriKumar wrote: ↑16 Jul 2023 05:11
The primary cause was the braking rocket(s) slowing the lander more than was necessary. The reasons for this have not been discussed in the S.Somnath interview video linked by you or the one by rahulm. This is a bit curious since (I believe) these are the same rockets that are used to perform orbital raising maneuvers (not 100% sure but I think so) and behavior should be known. So now the craft had to move faster to the designated landing spot, but this was prevented by software limits placed on the control systems preventing it from doing so. This as far as I can tell is not a software bug- it was a feature. (Did Somnath use the term bug- I think not. I think these limits were deiiberate, meant as a safeguard to prevent extreme maneuvers and speeds by the lander). I these limits are now increased significantly thereby giving the lander more freedom in how it wants to adjust its speed (and orientation). I did not understand what errors accumulated that was seen as a problem (this was not discussed). Altitude and speed deviations from the planned path in new missions are only to be expected. So not sure why this was a problem.
Other changes made for this mission was to get a better landing site, a larger landing site, a priori knowledge of the landing terrain (thanks to CY 2 orbiter taking hi-res pictures)- this was not available in the first mission and the landing site was being determine during it flight. Also, more fuel will allow it to hover around for a better landing site. All of these directly give the lander more freedom to pick a spot. Hope that the final spot it picks has no boulders.
Remember that there were 5 of those 800N engines -- the 5th one had been added at the last minute, out of concern that 4 might not be enough.
So, in retrospect, it's not that surprising that some over-braking may have been happening.
Just returned from my units annual weekend exercise.
Congratulations to ISRO and Bharat on the 1st step of CY3's ultimate objective on a Lunar soft landing (Vikram) and then Rover (Pragyan) deployment.
Dilbu-ullah has saved the day, once again.
The first post launch parameter to check will be the injection orbit after separation from CUS25 - marking it here as 170 +/- 3.5 kms x 36,500 +/- 500 kms and inclination 21.3 deg from the Brochure.
I haven't found the actual injection orbit and inclination achieved. I Will look for it and post if I find it.
Edited later: @ 53:24 Somnath reiterates 170 x 36,500 kms intended orbit and confirms injection into "precise orbit" which means injection was within specifications. Lovely.
^Excellent! They are very very very good chants ("first stage naarmal", "performaance naarmal") which someone can download from twitter, and get the .wav file (or any sound file) for ringtones. This can also be incorporated into Dilbu'saar's meditation routine, for example "May Lord Venkatesha grant this launch the following: "first stage naarmal", "performaance naarmal").
^Excellent! They are very very very good chants ("first stage naarmal", "performaance naarmal") which someone can download from twitter, and get the .wav file (or any sound file) for ringtones. This can also be incorporated into Dilbu'saar's meditation routine, for example "May Lord Venkatesha grant this launch the following: "first stage naarmal", "performaance naarmal").
We need Kerbal Space Program: Naarmal Edition
Or better yet, make our own competing product: Naarmal Space Program
ISRO twitter is getting 2.5 M views and ISRO link on C3 launch got 8+ million views! But their launch production quality is way below pathetic. Exactly inverse to their technical capabilities.
2nd orbit raising maneovure done.
Perigee at 220 km and will remain there for next three orbit maneovure.
Now ISRO will raise the apogee to ~143000 km and the perigee may come to ~275 km. Any inclination trimming is carried out at the apogee in that highly elliptical orbit, C3 will be slingshot at perigee burn to 400000 km for the trans-lunar injection.
ISRO twitter is getting 2.5 M views and ISRO link on C3 launch got 8+ million views! But their launch production quality is way below pathetic. Exactly inverse to their technical capabilities.
I too used to whine for this, arguing that more PR from ISRO would also even garner them more budgetary support.
Like all other fanboys, I was hungry for more visual footage, more eye-candy.
But then I saw how ISRO was falling into inflating its mission achievements, pumping the numbers with gaudy posters emphasizing payloads launched over # of launches, etc.
Chandrayaan-2 was preceded by much PR fanfare, only to see hopes dashed with disappointment from the landing failure.
The humbling from our failure made me realize we shouldn't get too carried away with the PR hype.
We Indians like to preen. Even the DD announcer lady was speaking of India's "prestigious Chandrayaan mission" - we always seem to be hankering for prestige. That isn't the best formula for success.
Besides, the more popular appeal takes over, then the more it attracts politicians who then come to apply their own pressures on ISRO, impacting its decision-making and priorities, etc.
ISRO needs to focus on its actual serious work, rather than tooting its own horn, "outreach", etc.
I like S Somnath, and his sober frank plain-speaking talk. He calls a crash a crash, not a "hard landing".
I feel his sober unassuming unpretentious attitude will lead ISRO to more success.
Last edited by sanman on 17 Jul 2023 01:23, edited 3 times in total.
sanman wrote: ↑16 Jul 2023 23:02
Lord Venkatesha grant this launch the following: "first stage naarmal", "performaance naarmal").
... He did not say 'Parfamans Naarmal'. (everything but this). I would also have liked to hear: Cryo ignition kanfarmed, and cryo stage naarmal.
On a different note, whoever made the twitter video is also following the call-outs by the ISRO mission control closely. I am trying hard to hear the Mission Control callouts over the voices of the 2 DD commentators taking about the weight of the first stage, altitude, velocity etc......pratham charan ab prajwalith hui hai aur apni bhayaanak dahaadh se chaaron aur kampann utpann kar raha hai and then the English version follows with similar poetic inanities (aasmaan ko cheerte hue .....). Any one with an ear to the ISRO or DD- please request them to consider providing a feed with just mission control callouts only.
FWIW:
(From a friend's simulation using ISRO/NASA/Horizon data for CY III)
Today at the time of this posting: July 16 2023, 18:22 (EDT = GMT-4)
Chandrayaan 3 Now (Earth's XY Plane):
And if you turn your camera towards earth (from CYIII) You will see:
On July 25, 2023, at 4:57 EDT (GMT -4) EBN# 4 will execute..
And CYIII will be last time so near to earth looking at:
Earth surface a mere 935 Km away - (Moon still ~ 390,000 Km away), Speed will increase to 10 km/sec)... and TLI will be on July 31st..
WION has produced a Gold mine interview with M Sankaran, ISRO Satellite Centre Director
This is an AI generated summary. There may be inaccuracies.
00:00:00 - 00:15:00
In an exclusive interview with M. Sankaran, the Director of India's ISRO Satellite Centre, he discusses the complexities of the Chandrayaan-3 mission and the importance of landing at the Moon's South Pole. Sankaran explains the step-by-step process of the lunar landing, from testing systems to reducing velocity and maintaining orientation. He also highlights the challenges of the limited sunlight and darkness cycles on the Moon and the significance of landing in the permanently shadowed zones of the South Pole, which could potentially contain frozen water and provide insights into the Moon's evolution. In terms of modifications from Chandrayaan-2, Sankaran mentions the addition of redundancy, increased fuel capacity, improved software, and a direct velocity measurement sensor in the Lander.
00:00:00 In this section, Dr. Shankaran, the director of India's ISRO Satellite Center, explains the complexities of landing the Chandrayaan 3 spacecraft on the moon. He mentions that many systems will be tested for the first time during this process. They plan to be in a 100km orbit for about four or five days to test the equipment and sensors. The orbit will then reduce to 100km by 30km, and accurate determination of the orbit is crucial. The descent will be initiated by firing four throttle level 800 Newton engines to reduce the velocity and bring the Lander towards the moon's surface. The entire landing process is divided into four segments, with the first segment focusing on reducing velocity and maintaining the correct orientation of the Lander. At around 7.3km altitude, the altimeters will start giving output to determine the craft's height from the moon's surface. The software will make necessary corrections to target reaching a height of 800 meters above the lunar surface.
00:05:00 In this section, M. Sankaran, the Director of the ISRO Satellite Centre, explains the process of lunar landing in the Chandrayaan-2 mission. He describes the fine braking phase, where the Lander's velocity is reduced to zero using velocity measurement cameras, allowing it to hover over the targeted landing area. Once the location is confirmed, the Lander enters the final phase, where it slightly increases velocity to start descending towards the lunar surface. The Lander is designed to touch down with a velocity of about one meter per second. Sankaran also discusses the design life of the Lander and Rover, which is 14 days, as they rely on solar energy. The mission was designed for a single lunar day, but if it survives beyond the 14 days, it will be considered lucky. He goes on to explain the hardware testing done to ensure the success of the lunar landing.
00:10:00 In this section, M. Sankaran, the Director of the ISRO Satellite Centre, discusses the various tests and simulations conducted to ensure the functionality and reliability of the Chandrayaan-2 mission. These tests included simulating the lunar module's gravity and mass, characterizing the lander legs to withstand impact loads, and performing software level tests to account for different conditions. He also explains the scientific experiments that will be carried out on the moon, such as studying lunar soil composition, detecting moon quakes, and capturing images with the lander's cameras. In terms of the rover's operation, it will be connected to the lander through radio communication and is expected to travel approximately one kilometer within the limited 13-day timeframe. The challenge of lunar dust settling on the solar panels has been accounted for with design considerations and power generation adjustments. The initial landing date is set for August 23rd, with a backup opportunity on August 26th in case of any malfunctions or delays.
[Edit from 8:51h He describes the tests in detail that the AI summariser has not captured. Briefly,
1) Cold tests, Lander flown by helicopter simulating lunar features in the Chitradurga facility with terminal phase velocity, to test sensors, electronics and software
2) Integrated hot test: they hung the leader from a tower crane at Sriharikota and fired the engines and thrusters to test all sensors, electronics and software
]
00:15:00 In this section, M. Sankaran, the Director of India's ISRO Satellite Centre, explains the reasons for the waiting period between landing opportunities and the significance of landing at the South Pole of the Moon. He mentions that if the initial landing attempts fail, the next opportunity would only come after a month due to the limited sunlight and darkness cycles on the Moon. However, landing in a different spot would be challenging as the orbit track of the orbiter would not be identical. Landing at the South Pole is scientifically important because it has permanently shadowed zones that could potentially contain frozen water and evidence of the Moon's evolution. When talking about the modifications made from Chandrayaan 2 to Chandrayaan 3, Sankaran highlights the addition of redundancy and increased fuel capacity in the Lander, as well as the inclusion of a direct velocity measurement sensor and more robust software.
here is CHANDRAYAAN-3 OBSERVATION DATA. not sure what we can make out of it but looks like ScottTilley is constantly updating the data in the location both Doppler and CADU.
ramana wrote: ↑17 Jul 2023 07:31
RahulM, I saw a ppt of 11 changes between CY-2 and -3 and one of them is less instruments due to using CY-2 as the relay.
They said that as the lander descended, the attitude deviations ("errors") began accumulating faster than expected, necessitating larger sharper corrections by the thrusters. At the same time, there was a bug in the software that manifested itself due to these larger sharper corrections being required. This software bug was not allowing for larger corrections by the thrusters beyond a certain amount.
.....refer to this problem as "dispersion" handling, meaning that those attitude errors/deviations were larger (ie. had a larger dispersion) than anticipated, which the software was unable to handle. That has now been corrected, along with other improvements and upgrades made to this Chandrayaan-3 lander.
If I remember correctly the problem explained that time was ( Trying to explain in my language ):
1. Large deviations were not expected
2. So after ( suppose it is a 16 bit processor ) FFFF Hex, the value (say ) was 10000 Hex.
3. Since the processor was not programmed to handle beyond FFFF ( because deviation beyond that was not expected ) the system interpreted it as 0000 ( ignored the carry 1. ) and thought that more power needs to be pumped, and fired the engines more while it was expected to reduce the power.
(everything but this). I would also have liked to hear: Cryo ignition kanfarmed, and cryo stage naarmal.
