Indian Space Programme Discussion

rsingh · Post by **rsingh** » 10 Jul 2015 20:37

DD works on Chrome just fine. Actually I find DD to be far better then all other unditv etc. Who is Mark Lynn?

Comer · Post by **Comer** » 10 Jul 2015 20:40

live webcast started on the ISRO link. Beautiful sight in the night

member_28108 · Post by **member_28108** » 10 Jul 2015 20:42

I can't see it on DD live whereas I am geting spotty transmission from ISRO website.Any mirrors ?

juvva · Post by **juvva** » 10 Jul 2015 20:43

http://24framesdigital.com/isro/webcast/100715/live.asx

working: streaming to windows media player.

sooraj · Post by **sooraj** » 10 Jul 2015 20:49

http://www.isro.gov.in/pslv-c28-dmc3-mi ... ve-webcast

Gagan · Post by **Gagan** » 10 Jul 2015 20:50

This time DD is focussing more on the Mission director!
Love it.
You get to see exactly how busy the MD is!.
Wish the stoooopid commentator will keep quiet onlee

Comer · Post by **Comer** » 10 Jul 2015 21:00

DD is yet to telecast it but NDTV has picked up the feed.

chaanakya · Post by **chaanakya** » 10 Jul 2015 21:07

successful launch of heaviest commercial mission of ISRO

congrats. isro

Comer · Post by **Comer** » 10 Jul 2015 21:22

Performance naarmal. Three satellites placed in orbit.
Congrats ISRO!
EDIT : all satellites placed in orbit . Mission accomplished!

Gagan · Post by **Gagan** » 10 Jul 2015 21:26

Everything is Naarmal !!!

A Nandy · Post by **A Nandy** » 10 Jul 2015 21:26

Congrats ISRO on a copybook launch yet again!

brat · Post by **brat** » 10 Jul 2015 21:27

Congrats ISRO

rsingh · Post by **rsingh** » 10 Jul 2015 21:31

ISRO ko badhaiyan. This British experimental sat could be used as weapon to de-orbit an enemy sat.

Supratik · Post by **Supratik** » 10 Jul 2015 21:32

congrats

SwamyG · Post by **SwamyG** » 10 Jul 2015 21:34

awww. sucks I missed it. Congrazulations onlee.

member_28108 · Post by **member_28108** » 10 Jul 2015 21:38

Congrats

member_28108 · Post by **member_28108** » 10 Jul 2015 21:42

juvva · Post by **juvva** » 10 Jul 2015 21:44

And now let's brace for the whining about the British aid.....

SwamyG · Post by **SwamyG** » 10 Jul 2015 21:46

Good report here. All the material - photos, graphs, charts, pictures itiyadi would be from ISRO, yet the guys packaged the report in a good to read mode. ISRO has mastered rockets, should hire some good writers next. ANTRIX should be doing all this narration business onlee.

http://www.nasaspaceflight.com/2015/07/ ... atellites/

member_28108 · Post by **member_28108** » 10 Jul 2015 22:05

SwamyG wrote:Good report here. All the material - photos, graphs, charts, pictures itiyadi would be from ISRO, yet the guys packaged the report in a good to read mode. ISRO has mastered rockets, should hire some good writers next. ANTRIX should be doing all this narration business onlee.

http://www.nasaspaceflight.com/2015/07/ ... atellites/

Have you seen the professional brochure that ISRO has released ?

Gagan · Post by **Gagan** » 10 Jul 2015 22:17

So GSAT-6 mil comms satellite will launch on a GSLV mark2 in August
Astrosat in Sept

Bade · Post by **Bade** » 10 Jul 2015 22:52

Now they can take our subsidized launch costs and pay their bills !

akashganga · Post by **akashganga** » 10 Jul 2015 22:55

Congratulations ISRO for another success. Waiting eagerly for gslv launch. Cheers.

SriKumar · Post by **SriKumar** » 11 Jul 2015 05:11

prasannasimha wrote:One question , how are 3 satellites in LEO spaced 120 deg apart able to provide pan earth monitoring ? I thought for near complete observation we need to keep it at GSO orbit and even there we will not be able to see extreme polar regions needing additional polar /sun synchronous orbits or Molniya orbits.

They were launched in a sun-synchronous orbit i.e. going polar, and not in an east-west orbit that geo-stationary obits are. The other aspect of the claim (observe any part of the earth) is the key phase: is able to image any spot every day...this is mentioned in the brochure. Between their polar orbit and the earth rotating below them, and the orbital period (around 90 minutes? or thereabouts) the 3 satellites should be able to image the earth between the three of them...though not all at the same time. It is sequential, as I understand it, because, as you pointed out, 650+ km altitude is way too low to observe 1/3rd of the earth in one shot.

Bade · Post by **Bade** » 11 Jul 2015 05:29

If one plots the orbital swath footprint of each satellite one may see that the coverage is full earth for 24 hours, as the swaths do not overlap entirely. Usually the standard IRS type of satellite in similar orbit, have a exact orbit repeat period of a 3-4 days, so it will take that many days to image every corner of earth.

Shreeman · Post by **Shreeman** » 11 Jul 2015 05:29

. China’s Twenty First Century Aerospace Technology Company (21AT) will lease all three spacecraft under a seven-year arrangement providing finance for the program.

SriKumar · Post by **SriKumar** » 11 Jul 2015 05:40

Bade wrote:If one plots the orbital swath footprint of each satellite one may see that the coverage is full earth for 24 hours, as the swaths do not overlap entirely. Usually the standard IRS type of satellite in similar orbit, have a exact orbit repeat period of a 3-4 days, so it will take that many days to image every corner of earth.

What is the orbit height (altitude) of the IRS?

Talking about swaths, the brochure mentions the imaging swath as 23.3 km.....which seems quite small. Perhaps they are going for hi-res or something like that.
http://www.isro.gov.in/sites/default/fi ... LV-C28.pdf

The other thing that is interesting is that the 3 DMC satellites seem to have been 'ejected' pretty much simultaneously (see the launch protocol table in the brochure), within 0.5 seconds of each other. It seems like these three satellites are marching together in close vicinity (within metres) of each other if you see the altitude at release.

ADded later: I guess one could calculate the orbital altiude given the information of 'exact orbit repeat period' of 3-4 days, but I is lazy today, as it is Fridin.

arun · Post by **arun** » 11 Jul 2015 05:54

Per the BBC, the entire capacity of the trio of the DMC Satellites launched by PSLV C-28 have been leased to a company based in the People’s Republic of China:

The capacity on the DMC-3 satellites has been leased to a company from China - 21st Century Aerospace Technology Ltd (21AT) - to help them survey the fast-growing Asian nation.

From here:

Five UK satellites go into orbit on Indian rocket

Bade · Post by **Bade** » 11 Jul 2015 05:55

They can change the orbit parameters after launch in any case. See even geostationary launches are not straight to the final orbit...there are intermediate stages via Hohmann transfer. Salvi has tools to plot the orbits and swath I believe. So in due course he will post on this perhaps.

23km swath width is narrow. Most imaging satellites in orbit ~ 800 km above have swath widths of ~ 1000km or more by factor of 2-3. It depends on on board memory and bandwidth to downlink (flush out) all the data captured before the next cycle begins. Limited by design and money and infra on the ground. Narrow swaths are used for high resolution imaging, so the same number of pixels on your focal plane will get mapped to a smaller footprint on the ground increasing your resolution using the same hardware kind of...as there is only so much a payload can carry in terms of dimensions...it has to fit inside the vehicle....power constraints etc. All these are engineering issues, no science as such.

Bade · Post by **Bade** » 11 Jul 2015 06:00

What is the orbit height (altitude) of the IRS?

One will have to look it up as each of them will vary based on mission profile. But must be in the 800-900 km range as a good guess.

vasu raya · Post by **vasu raya** » 11 Jul 2015 07:15

The 3 DMC sats aren't the entire constellation, more were launched before and all are still active only the tech was getting better. Chinese already had trio sats parked closely, this one is different?

I think it was Dr.Venkateswaran in the DD commentary who mentioned that Antrix got the deal because ISRO's credibility went up with the successful Mars mission.

Bade · Post by **Bade** » 11 Jul 2015 08:33

Not really the complete story, though each success helps the cause. The Chinese have been launching left and right year after year with success. The issue is perhaps like the US which has officially barred companies to use Chinese launchers for its payloads, it is quite possible that UK also has similar concerns. This was after the fall out of the Hughes fiasco where critical launch improvement technology was shared with PRC apparently. With India such concerns are less clearly, though the US would not launch its payload using Indian launchers. The latest co-development of InSAR mission may be the game changer, where we will see more collaborative missions. Chandrayaan was the other, where payloads were shared on the same bus, but not co-developed as I understand.

SSridhar · Post by **SSridhar** » 11 Jul 2015 09:04

Antrix has orders for sending 28 satellites - The Hindu

Antrix Corporation, the commercial arm of ISRO, has already signed service contracts for launching 28 satellites for various countries in the next two years.

“Of the 28, the next launch would be before the end of this year for Singapore,” Antrix Corporation chairman and managing director V.S. Hegde said.

The satellites vary from nano, micro and normal, which can be launched by a PSLV rocket, he said.

Antrix which recorded over Rs. 1,600 crore revenue during 2013-14, got a revenue of Rs. 1,850 crore during 2014-15. While the cost for launching smaller satellites would be calculated on its weight (cost per kg), Antrix would follow different norms in case of big satellites.

Singha · Post by **Singha** » 11 Jul 2015 10:56

Ariane seems to have locked itself into the high and heavy category via its massive ariane5 variants.
if India can improve the rate of PSLV launches to some 10 per year, it can pickup some of this large number of smaller sats going into orbit.
with the PSLV being mature tech , it can be the cash cow businesses need to invest in the next light launcher and also help the gslv program.

Singha · Post by **Singha** » 11 Jul 2015 10:58

spaceX and cheen(once its rehabilitated as a munna) will be formidable threats at the light end.

I see the russian space pgm as fading away due to lack of sustained funding.

soko and japan could be serious players too if they want.

Pratyush · Post by **Pratyush** » 11 Jul 2015 12:32

Yet another routine launch of the pslv. I hope to see, similar routine launches of the gslv as well.

member_28108 · Post by **member_28108** » 11 Jul 2015 13:23

^^^ Thanks SSSalvi and others. So it means that they will be able to return to image the same spot daily rather than continuously. Clarifies things.

Vivek K · Post by **Vivek K** » 11 Jul 2015 19:29

ISRO males us all proud, yet again!! Congrats ISRO.

member_28108 · Post by **member_28108** » 11 Jul 2015 19:49

Any news about the fate of the satellites can't see anything on their websites

rrao · Post by **rrao** » 11 Jul 2015 21:10

http://www.sstl.co.uk/News-and-Events/2 ... the-DMC3-T