4 ms·
"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 deg
by ljd 13y ago
"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.
- amitamb 13y agoIt is Geosynchronous Transfer Orbit I assume(http://en.wikipedia.org/wiki/Geostationary_transfer_orbit 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.
- swatkat 13y agoGeostationary 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.
- swatkat 13y agoIf a launch vehicle can place satellite in a geostationary transfer orbit with calculated apogee of 35, 786 km itself, the the apogee raising operation (i.e. perigee firing) is not required. Satellite can just start firing at apogee to transfrom elliptical orbit to circular orbit. ISRO's PSLV-XL placed IRNSS-1B at an apogee of 20,630 km. So, ISRO needs to do apogee raising before transforming into circular orbit.
- swatkat 13y agoISRO's bigger rocket GSLV Mk2 can launch satellites directly to geostationary transfer orbit (calculated apogee of 35,786 km), so there's no need to do orbit raising manoeuvres.
- swatkat 13y agoHere's an article from Planetary Society blog about getting geostationary satellites to geostationary orbits: http://www.planetary.org/blogs/jason-davis/20140116-how-to-get-a-satellite-to-gto.html http://www.planetary.org/blogs/jason-davis/20140116-how-to-g...