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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 s
by swatkat 13y ago
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.
- 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...