Indian Space Program: News & Discussion - Sept 2016

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

Postby Vips » 21 Dec 2018 18:59

Year of many new beginnings for Indian space sector.

The year 2018 could be termed as one of several new beginnings for the Indian space agency: the political sanction for a manned Gaganyaan mission, operationlisation of the heaviest rocket, steps to licence out lithium ion battery technology, introduction of new technologies in rockets and satellites and the decision to go ahead with the Indian Data Relay Satellite System (IDRSS), among others.

As the year ended, the IAF got its own eye in the sky to exponentially enhance its capabilities.

The Indian Space Research Organisation (ISRO) also carried out a sort of 'Swachh Bharat' mission - clearing the backlog of satellite launches.

"The year involved hectic activities with several rocket and satellite launch missions. We completed the NAVIC satellite constellation (a regional satellite navigation system similar to GPS) and launched communication satellites like GSAT 29, GSAT 11, GSAT 6A and GSAT 7A. Further, our heaviest rocket, GSLV Mk III, became operational," ISRO Chairman K. Sivan told IANS.

Interestingly Sivan is one of the new beginnings for ISRO as he assumed office in 2018.

"The major boost was the Gaganyaan announcement by the Prime Minister Narendra Modi. It was a major target announcement. Necessary infrastructure is being augmented," Sivan said.

"During 2018, almost all the technological issues relating to Chandrayaan-2 were sorted out. All the scientific instruments are ready," S. Somanath, Director, Vikram Sarabhai Space Centre (VSSC) told IANS.

"With the challenge of realising a human space mission in 2022 an energised ISRO is working hard towards various goals for realising the mission and others," Somanath added.

One of the critical projects was the IDRSS.

"There will be two IDRSS satellites of which one is targeted to be flown next year," Sivan said.

The IDRSS satellites will be placed in geostationary orbit, enabling satellite to satellite communication and reducing the dependence on the ground stations. This communication is crucial for a manned space mission as there cannot be a risk of being without a connection and data relay.

The year 2018 also saw sanctions for infrastructure augmentation -- connected and non-connected with the proposed manned mission.

"Approval for a fully electric-propelled satellite has been obtained. Similarly, sanction for additional satellites for the NAVIC system has been obtained. The next version of the reusable launch vehicle has also been sanctioned and augmentation of various infrastructural facilities are happening," Somanath said.

He said approvals for 30 more Polar Satellite Launch Vehicles (PSLVs) have also been obtained to be flown over the years.

Over 100 industries have shown interest in ISRO's lithium ion cell technology and 14 companies had been shortlisted. "ISRO has transferred the technology to BHEL for production of space-grade lithium ion batteries for its needs during the year," Somanath added.

The year also saw ISRO crossing the milestone of lifting and putting into orbit over 250 foreign satellites bringing the total to 269 foreign satellites.

"There is increased demand for satellites from strategic sectors. About six/seven satellites are planned to be built," a senior official told IANS, preferring anonymity.

The GSAT-7 and GSAT-7A are the two dedicated military communication satellites while all other earth observation and communication satellites launched earlier were of dual use -- civilian and defence.

Looking forward into 2019, ISRO will also be busy with the Rs 800 crore Chandrayaan-2, India's second moon mission slated in January; flying its new Small Satellite Launch Vehicle (SSLV) rocket.

Somanath said ISRO's new rocket to launch small satellites is being built and will be flown next year. It will be 37-metres tall and weigh 120 tonne. The rocket will be able to to carry satellites weighing 500-700 kg.

Somanath said in 2019, about eight PSLV, two GSLV Mk II and two GSLV Mk III, two SSLV and one test GSLV Mk III for Gaganyaan project will be flown.

"A total of over 32 missions -- satellites and rockets -- have been planned for 2019," Sivan said.

The one jarring note in ISRO's success symphony in 2018 was the loss of the GSAT-6A satellite couple of days after it was launched in March. The satellite stopped communicating with the ground stations owing to the failure of its power systems.

The GSAT-6A was supposed to compliment GSAT-6 launched in 2015, to help provide technologies for point-to-point communication.

Highlights of 2018:

* Prime Minister Narendra Modi announces manned mission in 2022

* Space crew escape module tested as part of manned space mission

* Tested technologies for manned space mission

* India's heaviest communication satellite, GSAT-11, orbited after being recalled from Kourou spaceport for checks

* Increasing production of solid fuel boosters for rockets

* Operationalised of heaviest rocket, GSLV Mk III

* Decision to licence out lithium ion battery technology

* Launched 100th satellite

* Kerala sanctions Rs 50 lakh compensation to former ISRO scientist Nambi Narayanan for his sufferings and ignominy after his wrongful arrest in the ISRO spy case.

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

Postby Haridas » 21 Dec 2018 21:48

^^^ very gratifying, dhoti/loongi dancing time it is.

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

Postby arun » 22 Dec 2018 10:23

Vips wrote:Year of many new beginnings for Indian space sector.

.......... Looking forward into 2019, ISRO will also be busy with the Rs 800 crore Chandrayaan-2, India's second moon mission slated in January; flying its new Small Satellite Launch Vehicle (SSLV) rocket.

Somanath said ISRO's new rocket to launch small satellites is being built and will be flown next year. It will be 37-metres tall and weigh 120 tonne. The rocket will be able to to carry satellites weighing 500-700 kg. .....................



Design for Small Satellite Launch Vehicle ready

Image

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

Postby Varoon Shekhar » 22 Dec 2018 13:46

Any issue with the perigee raising of GSAT-7A?

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

Postby arun » 22 Dec 2018 14:18

^^^ Seems all is fine. Why do you ask?


Clicky:

Dec 20, 2018
The first orbit raising manoeuver of GSAT-7A satellite has been successfully carried out today (20th December) by firing the Liquid Apogee Motor (LAM) engine of the satellite at 0916 Hrs IST for a duration of 3895 seconds.
The Orbital parameters after this Apogee Motor firing are:
• Apogee (Farthest point from Earth) x Perigee (Nearest point from earth): 38,905 km x 11,693 km
• Inclination: 5.75 deg
• Orbital period: 15.59 hours

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

Postby Varoon Shekhar » 22 Dec 2018 15:07

Thanks. Someone on another forum seemed quite concerned that there has been no further perigee raising after this one. I suppose ISRO is not announcing every manoeuvre as it's happening. We'll learn of the changes in the days ahead.

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

Postby wasu » 22 Dec 2018 15:11

ISRO is not bothered to announce every orbit raising maneuver now a days. For the previous launch, they put out a press release after all 3 steps were done. So, they probably will do the same here.

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

Postby Singha » 22 Dec 2018 15:46

Can the new slv replace most of current pslv missions.
Pslv at some 400ish tons is very heavy for what it does

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

Postby Haridas » 22 Dec 2018 22:56

^^ iirc many pslv launches comprise 700 kg main payload and few copassangers to SSO. those missions can be taken over by SSV. Most EOS fall in that cat.

Given that SSV can be assembled horizontally, I am looking forward to its launch from ports other than Sriharikota. Perhaps from Trivendrum. To avoid loss due to dogleg.

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

Postby wasu » 22 Dec 2018 23:41

https://www.thehindu.com/news/national/ ... 10147.ece#!

..In addition to the third launch pad at Sriharikota, ISRO is also scouting for a new location near Gujarat for the SSLV...
...“We have evaluated several locations. The first two SSLV launches will take place from Sriharikota. After that they will move to the new location,” the official said.

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

Postby prasannasimha » 22 Dec 2018 23:42

* The SSLV is going to be launched from a small spaceport in Gujarath which will not need any dog leg at all

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

Postby Singha » 23 Dec 2018 07:37

Game changer and maturity dividend. Waiting for its launch

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

Postby srin » 23 Dec 2018 08:52

Interesting that Gujarat has come up and not say, Kulasekharapattinam that has been in news as possible second location. I read somewhere (and the physics of it still escapes me) that polar launches are more efficient from high latitudes.

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

Postby Singha » 23 Dec 2018 09:22

Plus friendly state govt who can control fake ngos and other bif forces may play its part

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

Postby disha » 23 Dec 2018 09:48

srin wrote:Interesting that Gujarat has come up and not say, Kulasekharapattinam that has been in news as possible second location. I read somewhere (and the physics of it still escapes me) that polar launches are more efficient from high latitudes.


The additional kick from earths’ rotation is most at equator which helps geo sats. Polar sats do not need the additional ‘horizontal’ kick.

If you launch from Kulasekharapattinam, how will you track it say 1200 kms downstream (south)!

We already have a tracking at Thiruvananthapuram wbich is ‘1200 kms’ downstream from (say) Porbundar?

Industries can come up in Kutch (that district is larger than state of kerala) & can become hub for space tourism.

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

Postby Haridas » 23 Dec 2018 09:54

..
Last edited by Haridas on 23 Dec 2018 09:56, edited 2 times in total.

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

Postby Haridas » 23 Dec 2018 09:55

srin wrote:Interesting that Gujarat has come up and not say, Kulasekharapattinam that has been in news as possible second location. I read somewhere (and the physics of it still escapes me) that polar launches are more efficient from high latitudes.

polar orbit launch is not much sensitive to latitude. Sun synchronous polar orbit need slight offset, for which slight benifit can be had by intermediate latitude. In both cases not much effect on payload delta.

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

Postby prasannasimha » 23 Dec 2018 17:23

Kukashekaraptnam is being planned for other polar launches. The Gujarat site is planned for primarily SSLV launches

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

Postby JTull » 23 Dec 2018 17:40

arun wrote:^^^ Seems all is fine. Why do you ask?


Clicky:

Dec 20, 2018
The first orbit raising manoeuver of GSAT-7A satellite has been successfully carried out today (20th December) by firing the Liquid Apogee Motor (LAM) engine of the satellite at 0916 Hrs IST for a duration of 3895 seconds.
The Orbital parameters after this Apogee Motor firing are:
• Apogee (Farthest point from Earth) x Perigee (Nearest point from earth): 38,905 km x 11,693 km
• Inclination: 5.75 deg
• Orbital period: 15.59 hours


15.59 hours? Wasn't this supposed to be super synchronous orbit.

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

Postby prasannasimha » 23 Dec 2018 18:24

The orbital period of a supersynchronous orbit is not a 24 hour period.

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

Postby prasannasimha » 23 Dec 2018 19:41

https://acadpubl.eu/jsi/2018-118-16-17/articles/16/77.pdf

Article on IDRSS satellite system that we are launching

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

Postby PratikDas » 24 Dec 2018 00:30

prasannasimha wrote:https://acadpubl.eu/jsi/2018-118-16-17/articles/16/77.pdf

Article on IDRSS satellite system that we are launching

Thank you for sharing this informative paper. I don't understand why they're aiming so low at 400 kbps for Human Space Program (HSP) video.

Image

To put the 400 kbps number in context, a 240p video on YouTube is about 300 kbps and that's for non-real time video. Real-time videos aren't compressed as tightly as non-real time, so you can easily expect YouTube 240p quality or even worse from our astronauts when their feeds aren't within the field of view for ground stations and must be relayed through IDRSS. We should be aiming higher.

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

Postby prasannasimha » 24 Dec 2018 08:27

Thr video will be of least interest other than for PR. Its the telemetry data and voice transmission they will be worried about. Any higher speed video transmissions will be when they are ovuserhead. I watched Apollo and even for ISS video transmission is selective. IDSS is to reduce download to nonIndian ground stations . These has far reaching repercussions wrt many things. Just as a sample when we did MOM we needed ship based telemetry. We often have periods of loss of lelemetry during some launches. Others need not be mentioned

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

Postby Amber G. » 24 Dec 2018 11:12

JTull wrote:
<snip>

• Apogee (Farthest point from Earth) x Perigee (Nearest point from earth): 38,905 km x 11,693 km
• Inclination: 5.75 deg
• Orbital period: 15.59 hours


15.59 hours? Wasn't this supposed to be super synchronous orbit.

As I said here

Basically:

1. Time period of Geostationary (or Geosynchronous orbit) is about 24 hours -- actually 23 Hours 56 minute == time it takes earth to spin around its axis.

2. Geostationary orbit is circle with 0 inclination. (Time period = 23 hours 56 minutes)

3. Geosynchronous orbit has the same time period (23 Hours 56 minutes) but orbit can be (slightly) elliptical and inclination is (slightly) >0 (a few degrees).

3. Super Synchronous orbit is sort of transfer orbit, where Perigee, apogee and inclination is such that one uses the optimal (minimum or most cost effective) amount of fuel to put the orbit in GST. Typically (for rockets launched at India's latitude) they are what you see above. (One can calculate those fairly easy from basic principles).

4. In *all* the cases the time period is (see my note in here:

T≈ (3.14)*10^(-7)*sqrt(a^3).

Where T is measured in seconds and a in meters and a is average = (perigee + apogee)/2
(If you do simple math - the numbers will agree - Basically the time-period will be same as circular orbit of (perigee+apogee)/2 radius -- which, in the above case is about 20,000 Km = 20,000,000 meter for super-synchronous orbit - actually 26,000 Km if you measure the distance from center of the earth)

(For Geostationary sats a is about 42000 Km (about 36000 Km from surface of the earth))

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

Postby arun » 24 Dec 2018 15:32

arun wrote:^^^ Seems all is fine. Why do you ask?


Clicky:

Dec 20, 2018
The first orbit raising manoeuver of GSAT-7A satellite has been successfully carried out today (20th December) by firing the Liquid Apogee Motor (LAM) engine of the satellite at 0916 Hrs IST for a duration of 3895 seconds.
The Orbital parameters after this Apogee Motor firing are:
• Apogee (Farthest point from Earth) x Perigee (Nearest point from earth): 38,905 km x 11,693 km
• Inclination: 5.75 deg
• Orbital period: 15.59 hours



All appears well. Three further orbit maneuvering operations carried out and the GSAT 7A is almost home:

Dec 24, 2018

Latest update on GSAT-7A

After the launch of GSAT-7A on December 19, 2018, four orbit maneuvering operations have been performed successfully on GSAT-7A satellite using onboard Propulsion system. At present, the satellite is placed in an orbit with a perigee (nearest point to earth) of 35,800 km and Apogee (nearest point to earth) of 36,092 km with 0.2 deg inclination which is very close to the its final orbit.

Clicky

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

Postby Singha » 24 Dec 2018 18:03

haunting video of mk3 launch in 2017


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

Postby Amber G. » 24 Dec 2018 23:45

To add a few more points for those who are interested in GST Basics:
Amber G. wrote:
As I said here

Basically:

1. Time period of Geostationary (or Geosynchronous orbit) is about 24 hours -- actually 23 Hours 56 minute == time it takes earth to spin around its axis.

2. Geostationary orbit is circle with 0 inclination. (Time period = 23 hours 56 minutes)

3. Geosynchronous orbit has the same time period (23 Hours 56 minutes) but orbit can be (slightly) elliptical and inclination is (slightly) >0 (a few degrees).

3. Super Synchronous orbit is sort of transfer orbit, where Perigee, apogee and inclination is such that one uses the optimal (minimum or most cost effective) amount of fuel to put the orbit in GST. Typically (for rockets launched at India's latitude) they are what you see above. (One can calculate those fairly easy from basic principles).

4. In *all* the cases the time period is (see my note in here:

T≈ (3.14)*10^(-7)*sqrt(a^3).

Where T is measured in seconds and a in meters and a is average = (perigee + apogee)/2
(If you do simple math - the numbers will agree - Basically the time-period will be same as circular orbit of (perigee+apogee)/2 radius -- which, in the above case is about 20,000 Km = 20,000,000 meter for super-synchronous orbit - actually 26,000 Km if you measure the distance from center of the earth)

(For Geostationary sats a is about 42000 Km (about 36000 Km from surface of the earth))


The formula: T≈ (3.14)*10^(-7)*sqrt(a^3). (or more accurately (3.14710317)*(10^(-7) sqrt(a^3)) gives

For ideal Geostationary orbit:

when T= day (sidereal) = 23Hours 56 Minutes 4.1 second = 86164.1 sec.

We get "radius" = 42164. 2 Km (From center of earth)
subtraction radius of earth at equator (6378.137 Km) we get "height" = 35786.0 km for the orbit.
(And inclination = 0)
---
If it is not a perfect orbit than a small inclination will make the sat appear as periodically going north and south..
if the orbit is elliptical (but average height is still the same) then it will periodically go a little east and west ... (combining the above two) it appears as making a figure 8.

If orbital period is not exactly a sidereal day (the average height has changed), the satellite will drift and will not remain on the same longitude.
---
Now in "ideal" case, once a desired orbit is achieved, it will remain in that orbit without any additional fuel for ever.

But in earth's case -
- Earth is not a perfect sphere (flattened at the poles)
- Sun and Moon (and lesser extents other planets) are there to gravitationally influence.
- (Other factors are MUCH smaller)

So if you don't do any thing - orbit perturbs or precesses with a cycle time period is about 53 Years. so
- Each year it will drift (longitude wise) about 7 degrees so within a few years it may not remain over India.
- Each year inclination will also change (about 0.85 degree in the first year). Within 26.5 Years this may change about 15 degrees).
- The "T" ( also the "average" height) does not decay that fast over a few years. (The orbits may last for centuries)

So "orbit correction" is not one time (or just initial time period) thing. Although there are more corrections in the beginning but one must have enough fuel to periodically ( few times a year) correct the orbit to make it near the perfect orbit. So sat mush have enough fuel.

Hope this information is useful in understanding.
(Most of the math is UG physics except for precession cycle which requires a little more physics in case one wants to check out more details from a text book :)

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

Postby PratikDas » 25 Dec 2018 01:39

prasannasimha wrote:Thr video will be of least interest other than for PR. Its the telemetry data and voice transmission they will be worried about. Any higher speed video transmissions will be when they are ovuserhead. I watched Apollo and even for ISS video transmission is selective. IDSS is to reduce download to nonIndian ground stations . These has far reaching repercussions wrt many things. Just as a sample when we did MOM we needed ship based telemetry. We often have periods of loss of lelemetry during some launches. Others need not be mentioned

Excuses. If video is only for PR then is anyone waiting for PR from 1969? Answer that question first.

If it is only good for PR then PR like it’s 2019, or else don’t bother.

They should be aiming higher.

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

Postby Amber G. » 25 Dec 2018 04:00

srin wrote:Interesting that Gujarat has come up and not say, Kulasekharapattinam that has been in news as possible second location. I read somewhere (and the physics of it still escapes me) that polar launches are more efficient from high latitudes.

There was some discussion and interest so I put a message about "physics" some months ago but it went in a bit-bucket. So let me put some points about "physics" of polar/GSO/SSO orbits to understand some basic points.

First, before I do that let me just point out that for GSO or SSO you need a precise orbit with much more restrictions while for a polar orbit there is more freedom. Actually having a inclination = 90 is not a strict requirement, any thing close or high enough is okay for practical purpose. India (or its points of interests, enemies etc) does not have places with high latitude. So, if inclination of sat orbit is, say 80 degrees (or even less), it can cover all of India easily - as far as spy capabilities are concerned. (Many people call "polar orbits" even when the inclination is significantly smaller than 90 degrees)

Second - For perfect GSO orbits, as I covered, Inclination of the orbit has to be zero and T= 1 sidereal day. You need some fuel to be used few times a year to keep the orbit close to perfect otherwise it will drift quite a few degrees every year. (The precession cycle is about 53 year)

Third - For Sun synchronous orbit, one uses a high inclination ( about - 82 degrees) and T about 100 minutes (or little less) (This corresponds - if you use formula from my above post to a altitude of about 600-800 Km). All is chosen mathematically correct so that precession cycle is exactly 1 year. This keeps the sat synchronous to the Sun and the satellite can remain that way for a long time without additional fuel. Advantage here is that the sat will visit a particular position on earth around the same local time.

***
Now Physics (or basic principals) to select the launch site:

There may be more critical points to be considered such as infra-structure available at the launch site. How friendly the administration and people are. Is the launch site in India ?.. etc...

But let us consider only a few physics points here..:). Again I am just listing the points, you have to do the math to consider total impact.

-1) - "Higher" the launch point is, better it is. This is because you need less delta-V to attain the orbit. (Higher == distance from center of earth). A point on equator is higher than pole. Top of a mountain is higher etc.
- 2) - You need some less populated are in the direction of the launch. If something goes wrong and rocket falls etc.
(This is why Florida in US or Bay of Bengal shores in India is nicer if you are launching in East direction.
-3) If there is a choice, use "East" direction. This is because Earths rotation (about 0.5 Km/sec at equator) adds to the velocity.
4) If Using East direction - select a place closer to Equator. If using West direction select a place closer to the Pole.

***
So, for GSO or most other orbits - Things are quite clear. Places near equator are "higher", Earth's rotational velocity is higher there TOO. So select a place closer to equator. ( with non-populated are on the eastern side.)

If you HAVE to achieve a true polar orbit. Selecting a pole (South pole is better because it is "higher") requires no "compensating" to counter earth's rotational eastward speed. OTOH going near equator you are "higher". But if you calculate effect due to going "higher" ( about 22 Km= (6378- 6356) Km) is quite small. So is the effect of slight "westward" pointing to counter earth speed (Remember your pythagorus theorem for a right angle triangle where sides are 0.5 and 8 -- the third side is not that much more than 8 ). In all There is little practical difference.

For Sun Synchronous orbit things are a little complicated. Since orbit is retrograde (or inclination > 90 degrees or negative degrees) going away from equator helps a little (but not too much help). But not too much closer to pole either. One has to do the math. But even here the effect is quite small. IOW the advantages of closer to equator is no longer that important. Optimal value (I have not calculated) is probably mid latitude but advantage is rather small - other factors are going to weigh more.

In short, Gujarat or other areas for SSO (or polar) orbits may be attractive if there are other reasons to select it. Those sites will not be attractive (vs existing sites) for other normal (non-retrograde) orbits.

Hope this is helpful.

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

Postby srin » 25 Dec 2018 07:09

^^^ That makes a lot of sense, AmberG. Much appreciated. I didn’t get the full picture of the factors and trade offs before.

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

Postby Rakesh » 25 Dec 2018 07:17

Amber G, wow :shock: I am dazzled dude!

Nice to have folks like you here. You guys elevate BRF to a whole other level.

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

Postby Amber G. » 25 Dec 2018 08:23

prasannasimha wrote:Kukashekaraptnam is being planned for other polar launches. The Gujarat site is planned for primarily SSLV launches

Where is this site (Latitude/Longitude) ? (I can't seem to locate the site on google map)
(What is the range of possible Launch azimuth angles here? (Range of directions where where non-populated allow the launch without doing a dogleg)

At present do we have other than these sites:

Vikram Sarabhai Space Centre, Thiruvananthapuram (thumba) (8.5°N 76.9°E )
India Satish Dhawan Space Centre (Sriharikota) (13.7 °N 80.2°E)
India Abdul Kalam Island, Balasore (20.8°N 87.1°E)

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

Postby SSridhar » 25 Dec 2018 08:46

Kulasekharapatnam, 8.3989° N, 78.0524° E
Launch azimuth for PSLV, 180 deg (i.e. due south). No dogleg.

Amber G.
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Re: Indian Space Program: News & Discussion - Sept 2016

Postby Amber G. » 25 Dec 2018 09:38

^^^ Thanks. And where is site in Gujarat suggested.
For Kulasekharapatnam looking at the map it looks like azimuth 40 degrees on both sides of south direction is available for launch.

This means that any inclination inclination of 50 degrees or higher (both for retrograde or prograde orbits) can be easily reached.
(For those who want to see a simple formula :
(launch_azimuth = most optimal direction to launch (without dogleg etc) = arcsin (cos(i)/cos(L)))
(where L is latitude of the site, and i is the inclination you want to achieve).

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

Postby prasannasimha » 25 Dec 2018 10:01

PratikDas wrote:
prasannasimha wrote:Thr video will be of least interest other than for PR. Its the telemetry data and voice transmission they will be worried about. Any higher speed video transmissions will be when they are ovuserhead. I watched Apollo and even for ISS video transmission is selective. IDSS is to reduce download to nonIndian ground stations . These has far reaching repercussions wrt many things. Just as a sample when we did MOM we needed ship based telemetry. We often have periods of loss of lelemetry during some launches. Others need not be mentioned

Excuses. If video is only for PR then is anyone waiting for PR from 1969? Answer that question first.

If it is only good for PR then PR like it’s 2019, or else don’t bother.

They should be aiming higher.

Did I say that it is only for PR ? Your bandwith is more usefully used for real time telemetry data rather than 24×7 video transmission at a high rate. Easy to say aim high. Why will anyone waste bandwith for relatively less useful information that can be downloaded when it is directly overhead. Even the ISS is unable to do it. See
https://www.nasa.gov/multimedia/nasatv/iss_ustream.html
Wishes can be horses but practical reality ,expense etc will always triumph. The real need for IDSS is for out of sight telemetry of our rocket launches and HSP apart from other uses

Amber G.
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Re: Indian Space Program: News & Discussion - Sept 2016

Postby Amber G. » 25 Dec 2018 10:04

Here is one nice picture which makes a few things clear to visualize. (I took the picture from a blog from planetary dot org)
Image
The Launch site is Vandenberg Air Force base in California. (Latitude = 34 degrees - west cost of USA)

The white orbit is retrograde, inclination = 123 degree orbit.
The green orbit shows a technically retrograde, polar orbit of inclination = 97 degrees.
Red represents a true polar orbit of 90 degrees.
And we also have blue orbit, inclination = 34 degree orbit which is crossing the United States.

On each orbit, the dot on the orbit represents when the first stage finished burning and the sat has inserted into an orbit.

Now:
Blue orbit is most efficient, it is launched exactly towards East. Launch azimuth = 90 degrees. (This might be a GSO transfer orbit). Obviously this route will NOT be allowed (it is going over US populated area) and so for such orbits Florida is used where there is ocean on the east side.

(But important point here is: An easterly launch will begin drifting south until it passes through the equatorial plane, continuing until it reaches the matching latitude of the launch site below the equator, whereupon it will start heading northward again) (When it is farthest south one can make a correction if one wants to achieve an orbit whose inclination is less than 34 degrees)

The first orbit (123 degrees) can be reached by launching from Florida too but it will go over Cuba so without dogleg they are not going to allow it.

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

Postby Shrinivasan » 25 Dec 2018 10:46

Kulasekaranpattinam also has an additional advantage for being pretty close to Mahendragiri and Thumba and Tiruvanathapuram.. my only worry is, it is in deep evangelicals country... they tried to derail Kudangulam... sterlite... whatit they do the same to ISRO.

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

Postby SaiK » 25 Dec 2018 11:45

In Photos: India's Amazing Launch of the GSAT-7A Communications Satellite

https://www.space.com/42801-india-gsat- ... hotos.html

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

Postby arun » 25 Dec 2018 23:38

Another success for ISRO: Brazil’s Amazonia-1 satellite to be launched on board PSLV in 2020 :

Financial Express

Methinks a PSLV CA will be used as this is not a piggy back launch and this Earth Observation Satellite is just 500 kg. Amazonia 1 was originally to have been launched by Brasil's own VLS but that launcher is yet to notch up a sucessfull launch.

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

Postby jaysimha » 26 Dec 2018 15:36

Prof. U. R. Rao page in The Space & Satellite Professionals International website
( posting for records,,,,, MBD-if-RP)
https://www.sspi.org/cpages/hof-rao
https://youtu.be/YzUUktiA3Iw



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