"Preliminary data showed the rocket placed the spacecraft in an orbit with a high point of 12,807 miles, a low point of 176 miles and an inclination of 19.2 degrees."
Maybe I'm reading this wrong, but this appears to be a very elliptical orbit with a the difference between the high and the low being more than 70x.
Does someone here know what the purpose of such an orbit is? Obviously it states navigation but I guess that's not enough for me to understand why they would pick such an orbit.
Geostationary satellites have a circular equatorial orbit, at 35,786 km above the Earth. Launch vehicles can only place satellites in an elliptical orbit with some degree of inclination from equator. So, geostationary satellites are placed in elliptical "geostationary transfer orbits". And, satellite's onboard propulsion system is used to:
1) Gradually raise the apogee
2) Transform elliptical orbit into circular orbit
3) Reduce inclination to zero degree with respect to equator.
Orbit's apogee is raised by firing onboard motor at perigee. Circular transformation is done by firing onboard motor at apogee.
It is Geosynchronous Transfer Orbit I assume(http://en.wikipedia.org/wiki/Geostationary_transfer_orbit) (but wiki article's suggested apogee doesn't match) as there 5 more orbit manoeuvres remaining which will put it to final position.
From what I know, this is dues to lower capacity of PSLV which was used for this launch. GSLV being developed has more power but it is not as dependable as PSLV yet.
As an indian citizen I've never understood how these technologies ever reach me. I know GPS is by the US government, is any one commercializing these technologies in India?
"Indian officials say the independent navigation service will aid marine traffic, emergency response officials, vehicle tracking applications, mobile communications, mapping, and civilian drivers."
IRNSS wiki page[1] sums up nicely, on why indigenous navigation system is required:
The requirement of such a navigation system is driven by the fact that access to foreign government-controlled global navigation satellite systems is not guaranteed in hostile situations.
Two more IRNSS satellites will be launched by the end of 2014, and remaining three will be launched by mid 2015. So, the 7 satellite constellation will be ready by 2015. IRNSS receivers (akin to GPS receivers) can be tested by 2014 itself (4 satellites are sufficient for determining position). I've come across few vendors who already have industrial/commercial grade IRNSS receivers[2]. So, it's only a matter of time until we start seeing IRNSS receiver chips in consumer electronic devices.
Missiles use satellite navigation to determine their targets. So, relying on external navigation systems is undesirable.
Even if it doesn't become popular for civilian use because of the overwhelming popularity of GPS software and hardware, precise location fixes for military purposes is a no-brainer in 2014.
E.g., Imagine every solider fitted with a receiver/transmitter so that their location is known with a resolution of a few feet. Think that'll make it easier to save the wounded during operations?
It's supposed to cost $250 million (approx $25 million per year since it lasts 10 years). Cost seems wildy reasonable considering just the military benefits.
[+] [-] ljd|12 years ago|reply
Maybe I'm reading this wrong, but this appears to be a very elliptical orbit with a the difference between the high and the low being more than 70x.
Does someone here know what the purpose of such an orbit is? Obviously it states navigation but I guess that's not enough for me to understand why they would pick such an orbit.
[+] [-] swatkat|12 years ago|reply
1) Gradually raise the apogee
2) Transform elliptical orbit into circular orbit
3) Reduce inclination to zero degree with respect to equator.
Orbit's apogee is raised by firing onboard motor at perigee. Circular transformation is done by firing onboard motor at apogee.
[+] [-] amitamb|12 years ago|reply
From what I know, this is dues to lower capacity of PSLV which was used for this launch. GSLV being developed has more power but it is not as dependable as PSLV yet.
[+] [-] swatkat|12 years ago|reply
[+] [-] dalek2point3|12 years ago|reply
"Indian officials say the independent navigation service will aid marine traffic, emergency response officials, vehicle tracking applications, mobile communications, mapping, and civilian drivers."
[+] [-] swatkat|12 years ago|reply
Missiles use satellite navigation to determine their targets. So, relying on external navigation systems is undesirable.
[1] http://en.wikipedia.org/wiki/Indian_Regional_Navigational_Sa...
[2] http://gpsworld.com/novatel-supplies-reference-receivers-for...
[+] [-] singlecomment17|12 years ago|reply
E.g., Imagine every solider fitted with a receiver/transmitter so that their location is known with a resolution of a few feet. Think that'll make it easier to save the wounded during operations?
It's supposed to cost $250 million (approx $25 million per year since it lasts 10 years). Cost seems wildy reasonable considering just the military benefits.
[+] [-] KumarAseem|12 years ago|reply