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Indian Space Programme Discussion - Sept 2016

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Amber G.
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Re: Indian Space Programme Discussion - Sept 2016

Postby Amber G. » 23 Feb 2017 23:38

Gagan wrote:How do those nano sats stabilize themselves? Reaction wheels? Ion thrusters?
They can't be of much use of they are rotating around in all three axes I imagine

Believe it or not brf had discussed it before :) .. many years ago in physics dahaga - to answer/explain a strange utube video of strange behavior of a "spinning" top - I discussed this, and remarked that in early space flights to stabilize camera (so that they point in right direction) without gyro/thrusters.. Engineers learned again what Newton/Euler did about Moment of Inertial tensor. (See Note ** If you are interested in Physics part).

Basically this stabilization is achievable "passively" (that is without servo, reaction wheels or gas jets) by using earth's gravity gradient, (or some times even magnetic field gradient if parts are made of metal). The theory and practice is known and there are quite a few good sources for interested people.

For example: this 1964 article: http://techdigest.jhuapl.edu/views/pdfs/V03_N5_1964/V3_N5_1964_Fischell.pdf

Gyro-effect (that is providing some spin when nano's are released) is used, here too one has to not forget some graduate level physics choosing the right eigen vector of moment of Inertia tensor as one of early satellite with camera did. (see note ** below)

Note ** - I can not find physics dhaga where this was discussed nicely.. If you are interested in this check out "Dzhanibekov Effect" (Named after an soviet gaganaut who was first-one to bring it to popular press) or something like "Tennis racket theorem" in a physics book/wiki.

https://www.youtube.com/watch?v=4dqCQqI-Gis
Added later: Know what? Wiki has an entry, pretty good imo - https://en.wikipedia.org/wiki/Tennis_racket_theorem

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Re: Indian Space Programme Discussion - Sept 2016

Postby Snehashis » 24 Feb 2017 00:19

Varoon Shekhar wrote:http://www.isro.gov.in/annual-report-2016-2017-english

New annual report of ISRO, covering 2016, is out surprisingly early. In recent years, the annual report has been coming out as late as April and May.

Many gems as usual!



IRNSS 1H & IRNSS 1I to be launched this year along GSAT - 11, GSAT - 17 & GSAT - 20 in the communication segment.

Chandrayaan II and another Cartosat to be launched in the next FY.

Added later :


IRNSS-1H and IRNSS-1I are two ground spare satellites planned to be realised as part of the approved project. Both IRNSS 1H and 1I satellites will have a configuration similar to the current IRNSS spacecraft bus and Navigation payload.


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Re: Indian Space Programme Discussion - Sept 2016

Postby Amber G. » 24 Feb 2017 00:44

^^^First thanks for putting the news/link of the report and highlighting interesting parts.

I hope ISRO enables team Indus plants Tiranga on Moon on January 26, 2018, and hope they win the google lunar prize to boot.

Back in 2010 when the prize was announce, not many knew about Rahul Narayan (and he has said he had no interest about space in 2010, just running a startup) or his team Indus..or where ISRO will go in 7 years ... Now just seven years later this team is on their way of sending the rover to the moon!

Here is link to team Indus: http://lunar.xprize.org/teams/team-indus
TeamIndus' Mission is a celebration of all things great about India – the audacious goal, the young bright engineers, the can-do entrepreneurial spirit, partners who commit their resources, and the new breed of world-class entrepreneurs who have supported our mission – all of whom are united by a vision to deliver a best-in-class technology outcome entirely out of India.

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Re: Indian Space Programme Discussion - Sept 2016

Postby disha » 24 Feb 2017 01:58

Amber G. wrote:Disha - First there is no reason to get upset, and really this is NOT phD thesis, more like high-school physics.


Amber on a personal note., please if you do not know something., feel free to ask! Do not assume that others are mis-informed terming others as 'quite-inaccurate'. Also learn to do some research please before you term others 'quite inaccurate'.

Second., I do feel that there is a subtle goal shifting that happens when you bring your counter statements in.

For example, you were never aware that ISRO does passivate their last stages & now that has been established, you stop mentioning it and instead shift the goal with patronization's like "my post there was to give some perspective and challenge you". Point is, if you need to 'challenge' somebody - please take it to your maths or physics thread.

Also., when you mention that you are surprised that ISRO talks about passivation and degenerate orbit., your surprise does come across as an elitism towards ISRO that it can be so caring to take care of its own space junk unlike other 'more advanced' space agencies!

Having the personal issues out of the way the next posts describe the last stage "issues" including that of C37.

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Re: Indian Space Programme Discussion - Sept 2016

Postby JayS » 24 Feb 2017 02:18

Amber G. wrote:
Note ** - I can not find physics dhaga where this was discussed nicely.. If you are interested in this check out "Dzhanibekov Effect" (Named after an soviet gaganaut who was first-one to bring it to popular press) or something like "Tennis racket theorem" in a physics book/wiki.

https://www.youtube.com/watch?v=4dqCQqI-Gis
Added later: Know what? Wiki has an entry, pretty good imo - https://en.wikipedia.org/wiki/Tennis_racket_theorem


Interesting. I observed this while playing with my cellphone. I have habit of throwing it up in the air spinning and catching it. Didn't this one has a name to it too. I thought its simply similar to the inertia coupling effect.

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Re: Indian Space Programme Discussion - Sept 2016

Postby disha » 24 Feb 2017 02:50

On ISRO's C37 launch, I claimed that ISRO plans to study the last stage C37 for '10 orbits or so'.

I was watching the live launch and caught the post-launch interviews in passing. I was very happy for ISRO doing the study on the C-37 last stage.

Now please check out the video below (from 58 mins to 1:03 mins) (I had linked the video on my previous post as well):

https://www.youtube.com/watch?v=yPtFNJ2SSUw

ISRO's director K. Sivan (I think) clearly mentions that ISRO will study C37 last stage for 10 orbits (and leaves the stage passivation and degenerate orbit implied).

ISRO has been doing stage passivation since PSLV-C12/C-14 (2009) and is a standard practice on all PSLV launches since then. What ISRO does for stage passivation? It basically empties out the propellant tank (remember they are hypergolic propellants and will explode in extremes of space) so that any uncontrolled explosion does not create a debris field. Also removes any stored energy like draining the batteries.

ISRO has been doing extensive prediction analysis of space objects going back to at least 2 decades (IMHO). In fact by 2009/10 ISRO has one of the best space object reentry estimation. For example., ISRO predicted that the final stage of GSLV-F04 launched in 2007 will re-enter in 2010/2011 and it precisely did.*

Given this it can be assumed that ISRO has the tools of placing the last stage in a 'degenerate' orbit where the last stage can re-enter (and thus de-orbit) in a precise time.

Let us take ISRO's GSLV's GTO. ISRO places INSATs in GTO at 170 km x 35945 km orbit., the perigee 170km is low to be influenced by earth's atmosphere. Yes., there is a drag on the last stage by earth's atmosphere and the object ceases to be a space junk and burns up in earth's atmosphere within 2-3 years (or sooner).

In theory, space is a vacuum., but where does space begin and earth's atmosphere end? The karman line (100 km) is considered as the boundary between earth's atmosphere and space. However that is an arbitrary line., earth's atmosphere very gently merges into space (and that is the best way to describe it in english - from my limited intellect).

In fact - Karman line is so arbitrary that., at 120 km earth's atmosphere has a very noticeable effect. That is any object at 120km orbit loses velocity very fast and de-orbits (or re-enters) rapidly.

Earth's atmosphere is also affected by solar heat/radiation, pull of moon and sun etc and hence is not a perfect sphere. In fact one can safely assume that upto 500 km., earth's atmosphere has affects on orbiting bodies.

Hence pure theoretical equations will tell us that an object placed at say 170km orbit will be in space for several years or decades., but in reality - the object will re-enter within 2-3 years. In fact anything placed say around 500/550 km will have significant orbit decay - in fact without any external means to maintain orbit., the orbit decay happens in 15 years (at 500 km)**. It can happen even sooner or later., it depends upon the type of the body. A satellite with its solar array deployed will have larger decay rate compared to a streamlined body. Hence if you place a nano-sat with solar array deployed., you can safely assume that in 7-8 years it will re-enter earth's orbit.

Or if you launch sats., ensure that the last stage remains within 500/550 km and it will de-orbit. Putting it in a degenerate orbit, that is even by lowering the perigee to say 400 km hastens the decay by a significant factor.

So if you are a responsible space launcher like ISRO - what will you do? Basically passivate the stage and park it in a degenerate orbit. GSLV stages will burn up in <2 years and PSLV stages will burn up <10 years. You are basically helping Earth clean up the space junk easily by a little effort from your end using the already extra propellants.

*Anybody who gets surprised 'now' that ISRO does stage passivation is definitely uninformed :-D
** All numbers rounded off. Eschewing physics and equations and formulas.
Last edited by disha on 24 Feb 2017 21:00, edited 3 times in total.

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Re: Indian Space Programme Discussion - Sept 2016

Postby disha » 24 Feb 2017 03:09

Gagan wrote:How do those nano sats stabilize themselves? Reaction wheels? Ion thrusters?
They can't be of much use of they are rotating around in all three axes I imagine


Stabilizing small sats is daunting. On large satellites, one can place a boom or have reaction wheels or Ion thrusters. At the same time large sats have to contend with solar radiation pressure and atmospheric drag (however minuscule it is & depending on altitude) and hence active stabilization is required.

Small sats do not have the luxury of active stabilization. Not that it cannot be done, it is just complicated for the cost and life of the sat.

Using gravity gradient is a neat idea but implementing it on say a cube sat (where is the dumbbell?) becomes messy. Generally cubesats/nanosats use magnets and line them up to earth's magnet. The sat body itself can be used as a 'magnet' to dampen any oscillations. This area is very active and there is indeed lot of research going on.
Last edited by disha on 24 Feb 2017 21:01, edited 1 time in total.

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Re: Indian Space Programme Discussion - Sept 2016

Postby disha » 24 Feb 2017 03:58

If somebody has access to this article: "Design and operational practices for the passivation of spacecraft and launchers at the end of life
C Bonnal" - it will help. It is an article that compares ISRO's op practices and other space launch organizations.

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Re: Indian Space Programme Discussion - Sept 2016

Postby chetak » 25 Feb 2017 03:01

C25 Cryo Engine Test Firing

https://youtu.be/D-DikwGfe14



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Re: Indian Space Programme Discussion - Sept 2016

Postby Varoon Shekhar » 25 Feb 2017 23:03

^
Nice! Comparisons are very odious, particularly when made by a non-technical person :oops: , but you can't help notice the contrast between the huge success of this programme, and the never ending struggle with the Kaveri engine. Reports on the C-20/C-25 engine and stage, speak of 3 distinct engines being successfully developed and tested. All in a relatively shorter time span. Cryogenic engines are not jet engines, even a layperson knows the latter have to withstand more heat, usage and wear and tear, but still...

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Re: Indian Space Programme Discussion - Sept 2016

Postby vasu raya » 27 Feb 2017 00:06

http://www.newindianexpress.com/nation/2017/feb/26/record-breaking-pslv-mission-has-a-downside-ex-isro-chief-1575032.html

On February 15, a PSLV released a flock of over 100 nano- and micro-satellites of overseas customers for a fee. Of them, 88 satellites called "Doves" belonged to Planet, a San Francisco-based startup. All these tiny satellites, each smaller than a briefcase, were lobbed into a polar orbit 506 km above the Earth by the PSLV in a flawless mission.

"I am somewhat concerned because the region where so many of these objects have been placed is the same where our own Earth observation satellites are, or will be," Nair told this correspondent over the phone.

The nano-satellites, Nair pointed out, have a short useful life after which they become junk that will keep floating in space for years in the same orbit with chances of colliding with ISRO's operational satellites sharing the same space.

"The debris that these nano-satellites will leave after their brief existence in space are potential source of damage to us. Safety of our satellites is more important," Nair maintained.

He cautioned that ISRO should carefully weigh a few million dollars of commercial gain from launching foreign nano-satellites into 500-km orbits against the potential harm to the present and future Earth observation satellites close to their lanes.


While ISRO spokesman Deviprasad Karnik said his agency has "no comments" to offer to the concerns raised by the agency's former chairman, Planet spokesperson Rachel Holm dismissed any danger to ISRO's operating satellites as feared by Nair.

"At Planet, we designed our concept of operations with debris mitigation in mind," the company said in an email. "Our Doves fly at a self-cleaning orbit. After 3-5 years, gravity pulls our satellites down into Earth's atmosphere where they burn up completely."


if Bharat Karnad can elicit a response from IAF...

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Re: Indian Space Programme Discussion - Sept 2016

Postby Lilo » 27 Feb 2017 07:34

Long March 5 had its 1st successful flight in Nov 2016.its max payload to GTO is 14 tonne.
GSLV Mk3 is going to have its 1st flight in March 2017, its max payload to GTO is 4 tonne.

IMHO we should not be taken in by the psyops of Western MSM inflating us on the 104 sat launch and what not.They have their own game to play wrt to China.Indian space program is a mere prop for this.
After all words are free.Market access & real launch capability are not.We dont have either.West wont give it to us.
Infact West will actively throttle our actual capacity development in launch business as seen wrt Cryo & semiCryo engine sabotage.

ISRO is not successful yet .

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Re: Indian Space Programme Discussion - Sept 2016

Postby chetak » 27 Feb 2017 09:40

twitter

uncontaminated and unencumbered by sarkari "scientists" and sarkari "managers"

and consequently punching much above it's weight class.


ISRO--rare example of an Indian organization out performing the best in the world in its domain of expertise

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Re: Indian Space Programme Discussion - Sept 2016

Postby jamwal » 27 Feb 2017 17:37

http://www.spansen.com/2017/02/pslv-sta ... aunch.html

Image

PSLV Stage Separation ...... A Case For Launch Success
Mechanisms facilitating Stage separation & Satellite deployment with the PSLV.


Multiple engines, operating in succession, a.k.a Stages, propel the Rocket towards the point, where it could initiate satellite deployment. One amongst the gazillion ways in which a launch mission could fail, therefore, Stage Separation would constitute a critical vulnerability. Watching the on-board view of the Polar Satellite Launch Vehicle [PSLV] jettisoning the remnant of a Stage - Fuel Tank, Engine & Control System, helped underline the importance of this step. Staging & jettison achieve 2 broad objectives - One, Staging allows for the rocket to be propelled by an Engine optimised for that phase of the flight trajectory; Two, by unloading the dead-weight, it reduces the net mass needed to be accelerated upward.

Precedence tells us that missions have failed because Space Transportation Systems [STS] have experienced improper Stage separation. In 2015, Russia’s Progress 59 Unmanned Cargo Spacecraft mission ended in failure as it "experienced difficulties during separation from the third stage of its Soyuz booster rocket". Failure of its Stage 3 to function correctly is again attributed as the cause of the failure of its Progress 65 [aka MS-04] mission, last December, in 2016. The Japan Aerospace Exploration Agency's [JAXA] H-IIA F6 mission of November 29, 2003 ended in failure after one of its Solid Rocket Booster [SRB] failed to jettison. The PSLV's first ever launch, the PSLV-D1, launched in September 20, 1993 was, itself, unsuccessful due to separation & jettison issues.


However, after undertaking in-depth Failure Mode Evaluation & Criticality Analysis [FMECA], accompanied by numerical simulations, like 6DoF rigid body dynamic analysis, & physical testing [Ex: wind tunnel studies] for design improvement, the Indian Space Research Organisation [ISRO] had been able to overcome the issue. The PSLV hasn't, since, witnessed any setbacks, let alone one involving Stage separation.

Also read: Simulation Based Conceptual Design of Separation Mechanism

A typical Separation System involves 3 broad sequential steps:

Actuation - initiate the separation process
Release - physical separation
Separation Impulse - provide a kick, velocity to speed up the separation
The annotated photograph of the PSLV, below, lists out the various mechanisms ISRO has employed in order to achieve Actuation, Release & Separation impulse in its various stages.


Image

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Re: Indian Space Programme Discussion - Sept 2016

Postby SSSalvi » 27 Feb 2017 19:59

^
15 days after birth of the blog, and so much of inside info .. what a way to go!!

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Re: Indian Space Programme Discussion - Sept 2016

Postby sas » 27 Feb 2017 22:58

50th High Performance Motor Case (HPS3) for Third Stage of PSLV Realised

http://www.isro.gov.in/50th-high-performance-motor-case-hps3-third-stage-of-pslv-realised

Image

Image

Image

High Performance motor case (HPS3) is the improved version of PS3 motor case. An optimum design for this was evolved by selecting appropriate different profiles for both the domes, introducing dome reinforcements and adopting modified helical winding with wide band in multi axis filament winding machine. The motor case is designed for a maximum operating pressure of 60.8 bar using Aramid/Epoxy for the construction of shell. The motor case consists of helical hoop layers and Aramid fabric for dome reinforcements. Carbon/Aramid/Epoxy hybrid construction for the skirt extension to attach with the fourth stage of PSLV is designed for taking the structural tensile load of 460 kN and a compressive load of 215 kN. A design factor of 1.25 is applied over the flight loads. Aluminium alloy end fittings are provided for the assembly of igniter and nozzle on either side. After rocasin insulation lay-ups, 7500 kg of solid propellant is cast. The design was qualified by proof pressure test, structural qualification level load test, burst testing of the case, cyclic proof pressure test with bucket flange and motor level static firing.


The achieved HPS3 motor case weight is 285 kg and the demonstrated performance factor, which is the indicative of efficiency of design, is 14 km. Tests carried out have proven the adequacy of the design and fabrication technology. This high performance motor case was inducted from PSLV-C4 mission onwards and the performance of the case has been satisfactory.

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Re: Indian Space Programme Discussion - Sept 2016

Postby disha » 28 Feb 2017 01:21

^That is what was also called as 'Kevlar Motor' tested from PSLV-C4 onwards.

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Re: Indian Space Programme Discussion - Sept 2016

Postby disha » 28 Feb 2017 01:22



Glad to see such technical blogs coming on mainstream.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Indranil » 28 Feb 2017 02:34

Lilo wrote:Long March 5 had its 1st successful flight in Nov 2016.its max payload to GTO is 14 tonne.
GSLV Mk3 is going to have its 1st flight in March 2017, its max payload to GTO is 4 tonne.

IMHO we should not be taken in by the psyops of Western MSM inflating us on the 104 sat launch and what not.They have their own game to play wrt to China.Indian space program is a mere prop for this.
After all words are free.Market access & real launch capability are not.We dont have either.West wont give it to us.
Infact West will actively throttle our actual capacity development in launch business as seen wrt Cryo & semiCryo engine sabotage.

ISRO is not successful yet .


Can we give it to the Chinese that they lead us in payload capacity and we lead them in versatility and in cost per kg to orbit?

Frankly, your last line is ridiculous.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Bheeshma » 28 Feb 2017 02:43

Its the inferiority complex, ppl like chinese 50 cent-er's also have it a lot. ISRO has done well enough to make a name for itself.

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Re: Indian Space Programme Discussion - Sept 2016

Postby nukavarapu » 28 Feb 2017 02:45

Lilo -- Don't you thinks our priorities are vastly different from Chinese? Most of the space programs globally including Chinese have more HND factor rather than the humble notions that men and women at ISRO carry. Its not that we can't have the capability, its more about what is our priorities. And payload capacity or not, when did China sent a last successful mission to Mars? It surely did had make them realize that certain things won't change no matter how much money you throw at it and no matter how much 1 center drones you sponsor to hijack a forum. I personally don't think that we are lacking behind. But I do agree that our priorities are different. Also, let me ask a very dumb question, whats the commercial requirement of having a 14 Ton GTO launch capacity? I think it was always about supporting their man in the space aspirations, nothing more nothing less.

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Re: Indian Space Programme Discussion - Sept 2016

Postby disha » 28 Feb 2017 04:04

If payload capacity is the only measure., then yes Chinese are ahead (on paper) and Americans and Russians and ArianneSpace are so far ahead that even Chinese leave alone ISRO are a patch on the payload capacity.

However if launch reliability, versatility and costs are the measures then ISRO is way ahead., so far ahead that ISRO just obsoleted Vega.

Think it this way., the designers of HETE probe took a decade to research, design, build, test and launch the probe. The first one failed to launch., the pegasus rocket launcher had only 40% success rate (or so) and the small HETE (125 kg) had no other option but to book a launch on Pegasus. The consequences of it was that the scientific team behind HETE could not do research on gamma ray burst and fell behind by more than a decade. Seeing their colleagues from other nations march ahead with both data and scientific papers.

Those designers of HETE would have loved to have ISRO's PSLV around. Since ISRO's PSLV is not high on payload capacity., it is actually just right for several such sats to band together and go to space safely, reliably and at a much lower cost!

See my note on Vega just getting obsoleted. At this stage., no scientific team will want to risk their payloads at a higher cost on a less reliable system. China does not have one such, JAXA does not have one such rocket and the only nearest competitors Vega and Orbital Sciences Antares are 'less' reliable compared to PSLV and more costly. And of course some of them do not have even demonstrated the versatility of PSLV., so we can leave that topic there.

Payload capacity is the last of the measure. If payload capacity was the only measure., then not just PSLV., but even GSLV mkIII is obsolete. But PSLV was designed around 80s itself and it has emerged as the only hope for nano/micro to small to mid-size satellite launches! If this is not success then I really do not know what success is!

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Re: Indian Space Programme Discussion - Sept 2016

Postby disha » 28 Feb 2017 04:11

Also the comparisons with other space launches should go into the international space discussion thread., not here. Having said that one thing I do want to point out is LM5 is very much unproven., so are its sibling variants LM6 and LM7. Chinese launch system is now evolving around ISRO's strategy! But they are saddled with unproven launch systems for the next 2-3 decades. So the question naturally arises - who is ahead and who is behind? :-D

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Re: Indian Space Programme Discussion - Sept 2016

Postby disha » 28 Feb 2017 04:20

nukavarapu wrote:... whats the commercial requirement of having a 14 Ton GTO launch capacity? I think it was always about supporting their man in the space aspirations, nothing more nothing less.


The idea was that the GeoComm sat market will continue to grow and to defray the cost., a 14 ton GTO capacity will take two (or maybe three) sats (like what Arianne is doing). However., there is an upper limit to GeoSat market and with advent of nano EO sats - the entire geo sat based earth observation market is rapidly vanishing. Leaving only Comm applications.

For human space flight., one does not need 14 ton GTO capacity. That may be necessary for putting man on moon., but not in space. GLSV MKIII core alone can do it.

Hence a heavy lift rocket is a niche play unless it is versatile enough for other applications. For man on moon., one needs super heavy launch vehicles like Saturn V. Currently no nation has one operationally.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Lilo » 28 Feb 2017 05:40

space station ... military payloads(including payloads for impending weaponization of space) .. interplanetary probes(not the orbital insertion technology demonstration type) ... mars exploration & colonization .. moonshot & moonbase ... microgravity research ... Hubble telescope like basic astronomy & astrophysics research ...

All require reliable & cost effective & massive payload carrying rockets.

I don't get this 4 tonne to GTO is more than enough approach.Unless we want to keep on bragging about our sixth nation syndrome .

I don't want to hear that ISRO achieved this or that with a shoe string budget yay! kind of claims adnauseum. I think even folks at ISRO are tired to hear that .
Instead everyone must question why more budget is not alloted to ISRO for more bigger goals.Especially when we are going to be the 3rd largest economy in 15 years time.
It's not for H&D purpose that China is planning to raise a space station into orbit.
Has India been promised a piece of ISS real-estate to be smugly foregoing all the microgravity research in biotech & basic physics(nanotech) etc ? I don't think so.
Last edited by Lilo on 28 Feb 2017 06:05, edited 1 time in total.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Kashi » 28 Feb 2017 06:01

Lilo wrote:space station ... military payloads(including payloads for impending weaponization of space) .. interplanetary probes(not the orbital insertion technology demonstration type) ... mars exploration & colonization .. moonshot & moonbase ... microgravity research ... Hubble telescope like basic astronomy & astrophysics research ...

All require reliable & cost effective & massive payload carrying rockets.

I don't get this 4 tonne to GTO is more than enough approach.Unless we want to keep on bragging about our sixth nation syndrome .


Yes they are important and one gets there incrementally. It took us over two decades from the first successful PSLV launch to a state where we can launch 100 satellites without breaking a sweat.

Let us get GSLV MKIII working like a clockwork and there's no reason why we cannot follow the same template as PSLV- keep learning, keep refining, keep improving and keep increasing the payload.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Varoon Shekhar » 28 Feb 2017 08:29

Well said! Yes with GSLV MRk 3, India will be doing all those glamorous things, and also launching heavier comm says, and no doubt launching multiple comm sats commercially at some stage!

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Re: Indian Space Programme Discussion - Sept 2016

Postby asgkhan » 28 Feb 2017 09:25

http://www.thehansindia.com/posts/index ... ide/283768


"I am somewhat concerned because the region where so many of these objects have been placed is the same where our own Earth observation satellites are, or will be," Nair told this correspondent over the phone. The nano-satellites, Nair pointed out, have a short useful life after which they become junk that will keep floating in space for years in the same orbit with chances of colliding with ISRO's operational satellites sharing the same space.

"The debris that these nano-satellites will leave after their brief existence in space are potential source of damage to us. Safety of our satellites is more important," Nair maintained. He cautioned that ISRO should carefully weigh a few million dollars of commercial gain from launching foreign nano-satellites into 500-km orbits against the potential harm to the present and future Earth observation satellites close to their lanes.

He also noted that in case of a future collision between the debris from any of these nano-satellites and a working satellite belonging to another country, India will have to pay for the damages.

"Therefore, I do not know if we should do it," he said. Nair was referring to the Space Liability Convention that entered into force in 1972, under which launching countries "should bear international responsibility" for all space objects launched from their territory "regardless of to whom the space object belongs".

Nair said that in his view, short-lived nano-satellites, if launched, should be put in much lower orbits -- below the operational region of remote sensing satellites. Any junk formed in such low-earth orbits will descend to Earth due to atmospheric drag and pose no problem to the working satellites. "Also, this issue should be raised in the United Nations Committee on the Peaceful Uses of Outer Space in order to arrive at a designated corridor for small and nano-satellites."

ISRO is a member of Inter-Agency Space Debris Coordination Committee (IADC) which coordinates global efforts to reduce man-made and natural space debris by sharing research and identifying debris mitigation options. While ISRO spokesman Deviprasad Karnik said his agency has "no comments" to offer to the concerns raised by the agency's former chairman, Planet spokesperson Rachel Holm dismissed any danger to ISRO's operating satellites as feared by Nair.

"At Planet, we designed our concept of operations with debris mitigation in mind," the company said in an email. "Our Doves fly at a self-cleaning orbit. After 3-5 years, gravity pulls our satellites down into Earth's atmosphere where they burn up completely."
Nair's concerns have, however, been echoed by space debris experts in different forums.

At a recent International Astronautical Congress in Toronto, Hugh Lewis, a leading space debris expert from the University of Southampton, said that since 2005, CubeSats have been involved in more than 360,000 close encounters, "many of these in Sun-synchronous orbits that are popular with remote sensing and Earth science satellites".Lewis had warned that if CubeSats continue to be launched into long-lived orbits without any means of disposing them of, "they will contribute to the growing space debris hazard".

In 2014, the International Space Station had to move three times to avoid lethal chunks of space debris and, only a month ago, European Space Agency had reported that its Swarm-B satellite had a miraculous escape from space debris that came as close as 361 metres.

Experts predict that satellites – just like drones – are increasingly coming within reach of ordinary people. As the cost of getting them in orbit plummets, the risks of collisions in space "will grow," says a recent report from the US National Academy of Sciences.



On cue, the criticism has started.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Vivek K » 28 Feb 2017 10:26

No such concerns were raised when ASAT weapons were tested - time for India to test one itself. People like rogue nations more than docile one begging for everyone's approval.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Zynda » 28 Feb 2017 10:56

Actually, the concern about space debris was raised when China tested its ASAT weapon in surprise. The Chinese didn't give a damn and defended its ASAT move. I was under the impression that these satellites will be programmed to descend in to earth and burn up in the atmosphere during re-entry. If they are left afloat in space after their useful life, it is indeed dangerous and IMHO irresponsible on part of the org.

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Re: Indian Space Programme Discussion - Sept 2016

Postby disha » 28 Feb 2017 11:00

Goal posts are being shifted now to demand a particular payload capability. If it is not GeoSat., then it is about space station or military sats.

I think 1970s/80s outlook is being applied to future launch requirements.

The idea about sending in a massive space station itself in one go is ridiculous. It increases risk and it creates problems if some components fail. In fact space station is going through evolutionary approach., that is modules are added over time. This also ensures that once a core is established, several other modules can be added to it for different packages and different countries and different goals. Modularization also defrays cost.

Now a genuine question that needs to be asked is, what humans do in terms of scientific mission that cannot be done by automated instruments? Put it this way what is the need for humans in space? To colonize mars? To study long term affects of space on humans? Why should humans go to mars? To further pollute it?

Currently space station has been a big boondoggle for NASA and its partners. Yes, it allows one to thump their chest and say we have a permanent settlement in space! And to what purpose?

If NASA had said that we are going to moon to mine resources and bring asteroids to say moon, crash it there and get valuable gold/platinum/iridium/tungsten etc then yes there is a purpose and a clear goal.

Regarding spy sats., let the armed forces come up with requirements that require a payload and let ISRO see if it can meet the payload with existing requirements or require a new launch vehicle to be designed and tested. Remember GSLV was first planned in 80s and its realization took 3 decades.

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Re: Indian Space Programme Discussion - Sept 2016

Postby disha » 28 Feb 2017 11:14

Zynda wrote:Actually, the concern about space debris was raised when China tested its ASAT weapon in surprise. The Chinese didn't give a damn and defended its ASAT move. I was under the impression that these satellites will be programmed to descend in to earth and burn up in the atmosphere during re-entry. If they are left afloat in space after their useful life, it is indeed dangerous and IMHO irresponsible on part of the org.


25% of very long term space debris (above 500 km) is chinese contribution. Their space industry is very dirty and sooner than later they will be paying a steep price to it.

Please read my posts., anything @500 km orbit - the mean life can be estimated to be 5 yrs (easy to remember, 500km-5yrs)., of course the orbit lifetime increases exponentially., and beyond 800 km it is in several decades.

What chinese with their ASAT test did was create a debris field @800 km - very dirty.

ISRO/India does not have to do any ASAT test. Doing an ASAT test is easy., the dregs in Chinese military just wanted to do a hoo-ha about perceived capability and ruined the 800km+ orbit for all space faring nation including themselves.

There are better ways to prove capability., ISRO can launch a nano-sail satellite which goes and grabs a large object in >800km orbit., deploys the sail and uses solar radiation pressure to bring down to lower orbits, put itself into a degenerate orbit and destroy it by re-entry. Kind of space cleaning. It will prove several technologies in play including a benign ASAT tech.

In fact you can do it., create a nano sat with sail option and book a launch on ISRO. Test it out on few objects circling in LEO and then scale it to higher orbits.

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Re: Indian Space Programme Discussion - Sept 2016

Postby JTull » 28 Feb 2017 20:59

Govt seeks Isro help to identify water sources

Bengaluru: Faced with unprecedented water crisis and plummeting groundwater table across the state, the government has sought the support of the Indian Space Research Organization (Isro) to identify surface water sources through satellite mapping.
"We are exploring scientific methods to address the problem. Isro can help in identifying water sources which can be tapped to the maximum extent and used through efficient networking," rural development and panchayat raj minister HK Patil said on Monday.
The minister said he has already held talks with scientist Radhakrishna Pillai and soon will meet the Isro chairman.
According to a scientist, remote sensing satellites have sensitive devices to take high resolution images after identifying traces of underground source. It can also spot remote water resources like ponds and lakes and provide inputs to the government.
Rs 544 cr to tackle crisis: The government has earmarked Rs 544.71 crore to all zilla panchayats in the state to take measures to mitigate potable water problem during summer in their respective districts. The first instalment of Rs 179 crore was released on February 18.
Patil said the situation is bad in 500-600 villages and acute in 20 of the 176 taluks, especially in Vijayapura, Belagavi and Kalaburagi districts. A whopping 6,000-7,000 borewells, including 2,000 in Belagavi, have gone defunct in the state.

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Re: Indian Space Programme Discussion - Sept 2016

Postby JTull » 28 Feb 2017 21:01

Karnataka ropes in ISRO to find new lakes in & around Bengaluru

Only 478 lakes remain in the metropolitan region of Bengaluru, a city fabled to have had a thousand lakes once upon a time.

Given the city's natural gradient that supports water bodies, are there undiscovered lakes that are not known to government records? Perhaps.

With this conviction, the Karnataka Lake Conservation and Development Authority (KLCDA) will spend the next three months looking for new lakes in and around the city. It has roped in space agency Isro for this exercise.

“When a water body gets dry, water has to find its own course and form new bodies elsewhere,“ KLCDA chief executive G Vidya Sagar told ET.

The mission is a follow-up to an inventory of lakes the Environmental Management and Policy Research Institute (EMPRI) has put together. The database has identified all the keres, kattes and kuntes in the metropolitan region of Bengaluru using revenue maps, topo sheets, satellite images and field visits. It found 478 lakes.

“We are cross-checking the EMPRI data with Isro through GIS mapping to see if new lakes have been formed that are not shown in any reports or records,“ Sagar said. “The job will be done in 90-120 days.“

At least 82 lakes have disappeared in the past decade, according to EMPRI data. The lakes have been replaced by roads, parks, temples, residential layouts, graveyards or farmland. The Kasaba Yeshwantpur lake, for instance, now has a hospital in its place.“Almost all roads in Bengaluru are on lake beds,“ Sagar said.

Even EMPRI does not rule out the possibility of new water bodies that might have gone off the radar. “It's a new area of research. If drainages are disrupted and channelled into lowlying areas, water bodies can come up,“ EMPRI director general Ritu Kakkar said.

Water expert S Vishwanath was amused. “British engineers, as early as the 18th century , concluded that water had been harvested wherever possible. There are no new lakes,“ he said.

All new tanks in South Karnataka, he said, were formed by throwing a bund across the valley and not due to natural depression. “The EMPRI report is comprehensive enough. We need to start acting on saving the lakes that have been identified.“

The KLCDA, unlike its predecessor, Lake Development Authority, has statutory powers to protect, conserve, reclaim, restore and integrate development of lakes. “I'm thinking of the present and the future,“ Sagar said, on discovering new lakes.

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Re: Indian Space Programme Discussion - Sept 2016

Postby SSSalvi » 01 Mar 2017 03:07

INS-1A and INS-1B yet to achieve stability. :(

While ISRO has put out the first set of images taken by the Cartosat 2 series satellite, there has been no information about INS-1 A and INS 1-B since their launch even as data from some sites monitoring the satellites have indicated that the two have not stabilised despite over 10 days in space.
“Attempts are being made to stabilise the experimental nano satellites that were launched. The efforts are still on,’’ ISRO director for publicity D P Karnik said.


http://indianexpress.com/article/technology/science/isro-doves-happy-suspense-on-nano-twins-4547218/

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Re: Indian Space Programme Discussion - Sept 2016

Postby disha » 01 Mar 2017 03:29

^ Unfortunate but not surprised. This is the first time ISRO is standardizing on the nano sat bus.

Of course they could have done their calculations more thoroughly on this bus. It is not that they have lost communication to the nanosats., they are very much communicable but looks like they are still tumbling around uselessly.

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Re: Indian Space Programme Discussion - Sept 2016

Postby SSSalvi » 01 Mar 2017 03:40

^ Surprising .. They never had this problem in stabilizing the satellite.

Tumbling sats are difficult to communicate with because the commanding has to be done in the brief period when satellite antenna briefly points to the station.

They could be studying the tumbling pattern so that an appropriate 'communication chance' window can be known beforehand.

==========

There were 4 rocket launches in the month February 2017 which carried 112 satellites to space.

Image

104 out of these 112 were carried in a single flight, PSLV C37 !!!

( Image uses part of original post in Wikipedia )
Last edited by SSSalvi on 01 Mar 2017 03:54, edited 3 times in total.

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Re: Indian Space Programme Discussion - Sept 2016

Postby JTull » 01 Mar 2017 03:42

Any news on SCE-200 while they prep for the MkIII launch?

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Re: Indian Space Programme Discussion - Sept 2016

Postby Rishi Verma » 01 Mar 2017 18:03

Isro shocks Trump nominee for Director of National Intelligence post

If Americans were "shocked" then the Chinese must be electrocuted. Well done Isro.

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Re: Indian Space Programme Discussion - Sept 2016

Postby krishGo » 02 Mar 2017 03:19

disha wrote:
25% of very long term space debris (above 500 km) is chinese contribution. Their space industry is very dirty and sooner than later they will be paying a steep price to it.

Please read my posts., anything @500 km orbit - the mean life can be estimated to be 5 yrs (easy to remember, 500km-5yrs)., of course the orbit lifetime increases exponentially., and beyond 800 km it is in several decades.

What chinese with their ASAT test did was create a debris field @800 km - very dirty.

ISRO/India does not have to do any ASAT test. Doing an ASAT test is easy., the dregs in Chinese military just wanted to do a hoo-ha about perceived capability and ruined the 800km+ orbit for all space faring nation including themselves.

There are better ways to prove capability., ISRO can launch a nano-sail satellite which goes and grabs a large object in >800km orbit., deploys the sail and uses solar radiation pressure to bring down to lower orbits, put itself into a degenerate orbit and destroy it by re-entry. Kind of space cleaning. It will prove several technologies in play including a benign ASAT tech.

In fact you can do it., create a nano sat with sail option and book a launch on ISRO. Test it out on few objects circling in LEO and then scale it to higher orbits.


And the other important about the Chinese ASAT test was that they used kinetic kill to destroy the satellite. So instead of vaporizing the satellite, they basically broke into thousands of pieces on impact adding to space debris.

And like disha ji says the debris in the higher orbits will potentially stay there forever.


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