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by prasannasimha
18 Sep 2019 09:28
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

^ It was done by US for the one if the Mars landers. I think spirit and opportunity but was given up subsequently
by prasannasimha
16 Sep 2019 12:37
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

The main mission whichis the orbiter is still going on and data as usual will be released in two tranches. First release is for ISRO and Indian researcherd. After 6 months data is released for any scientific use after registration with ISRO. Both MOM and ASTROSAT data are beingreleased in that forma...
by prasannasimha
15 Sep 2019 22:57
Forum: Military Issues & History Forum
Topic: Naval Tejas Mk1/Mk2: News & Discussion - 23 February 2019
Replies: 284
Views: 76714

Re: Naval Tejas Mk1/Mk2: News & Discussion - 23 February 2019

The arrestor cable is meant to be able to resist and is not a single fiber but a rope with multiple strands. Not easy to break. Suspension bridges are "suspended' using these.The breaking forces etc are well known.
by prasannasimha
15 Sep 2019 12:06
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

They will not release detailed images as this will give an idea of our 2 point discrimination capability. May be a later degraded image. The orbiter is working very well. Why would we want to hide any enhanced camera capability? This is being used on the moon to enhance the knowledge of humanity......
by prasannasimha
15 Sep 2019 10:58
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

Vikram’s quiet because it can’t talk! But Isro? What to write when there is no further info. They are trying to communicate and its not connecting. Everyone knows that. They will not release detailed images as this will give an idea of our 2 point discrimination capability. May be a later degraded ...
by prasannasimha
12 Sep 2019 00:55
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

I think somewhere now the Chandrayaan Orbiter would have made a pass over the putative crash site . Leet us hope we get some more useful data about it. I do not think we will get images from the orbiter wrt the lander so easily as it may give an idea about our two point discrimination capability or ...
by prasannasimha
12 Sep 2019 00:51
Forum: Military Issues & History Forum
Topic: INS Arihant: News & Discussion
Replies: 359
Views: 98314

Re: INS Arihant: News & Discussion

^Nothing that is released would be Inadvertent- it would have been done on purpose
by prasannasimha
11 Sep 2019 23:03
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

I am still trying to understand how the lander is intact. For this to happen, it had to slow down considerably from the time of the anomaly. That can only happen if the lander is right side up for most of the rest of the descent. I am more interested in the final moments now. One of the possibiliti...
by prasannasimha
10 Sep 2019 23:28
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

The small thrusters are 25 N ones From the paper that ramana gave link to: Chandrayaan-2 Lander will employ a clustered configuration of four 800N engines along with 50N attitude control thrusters placed at the bottom of spacecraft, to decelerate the spacecraft for braking and soft landing on lunar...
by prasannasimha
10 Sep 2019 14:24
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

^ 6 degrees of freedom. Pitch yaw and roll are the other 3. 3 DOF is only for a point object.
by prasannasimha
10 Sep 2019 13:32
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

Image
by prasannasimha
10 Sep 2019 08:46
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

The plane sune wavd is the carrier wave. The modulated wave pic is tge data transmission occuring. No terrestrial telescope has the resolution to even image Apollo landing sites and can only be imaged by LRO and now Chandrayaan. This is dictated by optics. Our largest telescope does not have the two...
by prasannasimha
10 Sep 2019 00:23
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

UlanBatori wrote:@JayS : Yes, but what happened to all the 100m-hover and the pattern-matching? Pls read the aiaa paper sections I posted above, thanks.

It probably was at too high a velocity to be able to decelerate to hover
by prasannasimha
10 Sep 2019 00:23
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

The small thrusters are 25 N ones
by prasannasimha
10 Sep 2019 00:22
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

Everything occurred with the somersault that it did.That is the crux to the whole problem. Why it happened for starters is one issue. After it occurred the correction was automatically attempted and probably worked but the time needed to land after full correction to decelerate to final requirements...
by prasannasimha
10 Sep 2019 00:08
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

Paper says that CY-1 (not CY-2) was forced to raise orbit from 100km to 200km to reduce heating. Is this radiant heat from lunar day? Wow! I thought it only reached 200C which should cause radiant heating only like an average day in Sriharikota summer, hain? Doesn't the orbiter rotate to distribute...
by prasannasimha
04 Sep 2019 00:38
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

There will be a whole host of system checks before Pragyaan can start its roll out. Remember that Vikram is virtually taking a powered descent and will be virtually dropped from a height of 5 meters and crash to the moon to avoid having a rocket plume distorting the landing site. It will be having c...
by prasannasimha
03 Sep 2019 01:16
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

There will be no real time transmissions till the Lander actually lands and the rover panel/slide is opened. We will probably be getting telemetry data. DrSivan told about one cause of Beresheets failure - human interference caused issues and muddled up things so they will allow the Lander to do the...
by prasannasimha
02 Sep 2019 18:16
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

Excellent! What would be the challenge of detaching the Vikram lander from the main orbiter, vis-a-vis more or less the same operation on the moon impact probe( MIP) onboard Chandrayaan-1? Is it just a question of more bolts to be sheared, or not even that? Vikram must not collide with the Orbiter ...
by prasannasimha
02 Sep 2019 15:20
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

Amber G, ISRO is known for what it has achieved. So are the isotopes the only way to get power? I understand the power source has to be light in weight. So I am not wondering why we not have a giant battery pack. Battery has to be recharged and where and how will the recharging happen = from Solar ...
by prasannasimha
02 Sep 2019 15:13
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

The radioisotope thermoelectric generator was never designed for CY2. Typical source would be Pu238. Why wasn’t it used I don’t know, perhaps the implantation would change the design and make the GSLV-III payload heavier. Or cost would go up beyond what was sanctioned in the budget. From what I kno...
by prasannasimha
02 Sep 2019 00:05
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

After separation why wait for Sep 7th? Is not the orbital position to commence the soft landing not achieved earlier than 7th? My layman's brain thinks the lander carrying the rover would complete more than on revolution in 4 earth days.... I know I am missing something very basic. This has been di...
by prasannasimha
31 Aug 2019 00:36
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

S^3 In such planetary travel/orbits 1km off is important no? Perigee/apogee distance and minor variation here is not important. What's important is the orientation (inclination of the orbit) and phase (= timing -- where CY2 is at one particular point in the orbit relative to ground) so that final V...
by prasannasimha
30 Aug 2019 22:51
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

ramana wrote:AmberG, Thanks for the explanation .
Its the corkscrew path to get there.
That accounts for the minor 1km variation in orbits achieved.

S^3 In such planetary travel/orbits 1km off is important no?

Not really corkscrew. they are ellipses that are marked in space time to get a corkscrew
by prasannasimha
27 Aug 2019 00:34
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

The US Navy has run into problems with touch screens in some of their naval ships and they are now rethinking of going back to push button type. They had a ship collision recently because the jing bang touch screens failed to respond.
by prasannasimha
27 Aug 2019 00:29
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

Not everything in military and space engineering is the latest or most efficient but often most reliable or time tested.For eg the processors for both space missions and military are slower than the fastest chips available(in fact many times slower) but things like radiation hardening etc etc are mo...
by prasannasimha
25 Aug 2019 19:57
Forum: Military Issues & History Forum
Topic: Indian Space Program: News & Discussion - Sept 2016
Replies: 3967
Views: 828440

Re: Indian Space Program: News & Discussion - Sept 2016

It was this - Cheaper and lighter: 'Made in Gujarat' spacesuits to be used in Gaganyaan. The countdown to India’s ambitious manned spaceflight mission Gaganyaan has begun and Isro scientists are at breakneck speeds to achieve the mission’s December 2021 deadline. India’s indigenously developed astr...
by prasannasimha
24 Aug 2019 17:14
Forum: Military Issues & History Forum
Topic: India Border Watch: Security and Operations
Replies: 3390
Views: 541871

Re: India Border Watch: Security and Operations

Nag has been used before as per baba
by prasannasimha
24 Aug 2019 17:10
Forum: Military Issues & History Forum
Topic: Indian Space Program: News & Discussion - Sept 2016
Replies: 3967
Views: 828440

Re: Indian Space Program: News & Discussion - Sept 2016

Varoon Shekhar wrote:I remember reading that a spacesuit was already made several years ago. Maybe they want more, or to try a different kind?

Technically it is a flight suit and not a space suit for EVCA.
More than that Russian collaboration is required for various training procedures etc.
by prasannasimha
24 Aug 2019 17:09
Forum: Military Issues & History Forum
Topic: Indian Space Program: News & Discussion - Sept 2016
Replies: 3967
Views: 828440

Re: Indian Space Program: News & Discussion - Sept 2016

Tenders for SC120 (from IPRC) continue to flow. This jingo is very happy! If you see the budgetary allocation of semicryo engine there are two budgetary allocations of interest = one is the semicryo itself and the other is for clustering of semicryo engine. Other interesting allocations are for spa...
by prasannasimha
23 Aug 2019 23:25
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

There are Doppler Inertial navigation systems and star sensors that are used for navigation
by prasannasimha
23 Aug 2019 23:20
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

From the calculations that I made (and I may be wrong about it) the Orbiter high resolution camera is 11,25,00,000‬ pixels from my calculation = 21.45 Megapixel camera and resolution of 0,32 meters Terrain mapping camera From ISRO website TMC 2 is a miniature version of the Terrain Mapping Camera us...
by prasannasimha
23 Aug 2019 07:55
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

Orbital inclination changes are typically done at the ascending or descending nodes or at intersection of current and desired orbit
by prasannasimha
23 Aug 2019 07:53
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

Varoon Shekhar wrote:Is that correct, about the recent pictures coming from the Vikram lander? The lander is not described as having an optical camera. It has 3 other type paylods. Do they mean the Orbiter?

The images are from the orbiter
by prasannasimha
23 Aug 2019 07:47
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

Varoon Shekhar wrote:Is that correct, about the recent pictures coming from the Vikram lander? The lander is not described as having an optical camera. It has 3 other type paylods. Do they mean the Orbiter?

No it is from the orbiter
by prasannasimha
22 Aug 2019 23:56
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

To get to the Lunar Transfer Trajectory, Chandrayaan-2 gradually increased the apogee using Oberth Effect via LAM firing at the perigee. I understand that. Now, couple of questions: But once around the orbit of the moon, to decrease the apogee and get to a more circular orbit, does the LAM fire at ...
by prasannasimha
20 Aug 2019 21:49
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

Talked to an actual space engineer and the three body problem and involvement of Lagrangian points are not used except for actual missions to Lagrangian points. The ellipse assumption is enough for modeling for lunar missions
by prasannasimha
20 Aug 2019 21:47
Forum: Military Issues & History Forum
Topic: Chandrayan-2 Mission
Replies: 1986
Views: 214849

Re: Chandrayan-2 Mission

Mort Walker wrote:
juvva wrote:114 km x 18072 km -achieved
vs
118 km x 18078 km -planned

WOW !!!!!


Most excellent!!!!

That's a sigma of 4.505 for apogee
by prasannasimha
18 Aug 2019 19:39
Forum: Military Issues & History Forum
Topic: Indian Space Program: News & Discussion - Sept 2016
Replies: 3967
Views: 828440

Re: Indian Space Program: News & Discussion - Sept 2016

sivab wrote:SCE-200 is a staged combustion engine.

Yes indeed I was referring to a full(LOX LH2 staged combustion engine that requires full engine firing. . In a semicryo you can hot test certain portions for eg till preburner.
by prasannasimha
17 Aug 2019 15:44
Forum: Military Issues & History Forum
Topic: Indian Space Program: News & Discussion - Sept 2016
Replies: 3967
Views: 828440

Re: Indian Space Program: News & Discussion - Sept 2016

One advantage of nonstaged combustion is portions of engine can be separately tested before full firing

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