Indian Space News and Discussion

[Arun_S]

From the ISRO released [url="http://isro.org/pslv-c17/pdf/pslv-c17-brochure.pdf#PSLV-C17"]PSLV-C17 brochure[/url], few interesting observations:

1. The GSAT carries about 900 kg fuel for orbit raising and station keeping.
2. Given that this is a stretched PSLV with stretched XL strap on booster for higher payload impulse, it inserts the GSAT to 21,000 Km altitude instead of 36k Km, (only marginally less efficient insertion altitude) , and lets the LAM do the rest
3. Also note that the small station keeping thrusters ( 10 and 22 N thrust) are bi-propellant type (and not mono-propellent type used many years ago), the ISP is much better.

[url="http://isro.org/pslv-c17/PSLV-C17.aspx"]Polar Satellite Launch Vehicle (PSLV-C17)[/url],

in its nineteenth flight, launches India's communication satellite GSAT-12 from the Second Launch Pad of Satish Dhawan Space Centre, SHAR, Sriharikota, India. PSLV-C17 measuring 44.5 m height, with a lift off weight of 320 tonnes has four stages of solid and liquid propulsion systems alternately. In its XL Version, PSLV-XL uses six extended solid strap-on motors wherein each strap-on carries 12 tonnes of solid propellant. This is a second time such a configuration is being flown, earlier one being the PSLV-C11/Chandrayaan-I mission.



Salient feature of PSLV-C17/GSAT-12 Mission:

• For the first time, use of indigenously designed and developed On-Board computer (OBC) with Vikram 1601 processor in both primary and redundant chains of the vehicle. The OBC performs the functions of Navigation, Guidance and Control processing for the vehicle.
• Use of extended solid strap-on configuration

Note that Kalpana was also inserted in GTO. Standard PSLV's payload limit is of about 1050 Kg. The PSLV-XL is more capable with its larger strapons and also CIP improvements. -XL Was used for Chandrayaan. Now for the first time we have data to quantify its performance improvement versus standard configuration. An improvement from 1050 Kg to about 1350 Kg (correcting for lower insertion apogee).

PTI reports

May 25, 2011

GSAT- 8 Satellite Placed in Geosynchronous Orbit

India's advanced communication satellite, GSAT-8, launched on May 21, 2011 has reached Geosynchronous orbit with an orbital period of 23 hours 45 minutes. The satellite's orbit has a perigee of 35,543 km, apogee of 35,770 km and an orbital inclination of 0.04 deg with respect to the equatorial plane. The solar arrays on both sides of the satellite have been deployed and they are tracking the Sun and generating electrical power. These solar arrays are designed to generate 6,240 W of electrical power. Two large dual grid Ku-band antennae have been opened and are pointing towards the Earth.



Today, the satellite has been put into the final orbital configuration pointing towards the Earth continuously. GSAT-8 is presently located at 47 deg East longitude and is being moved towards its final orbital position of 55 deg East where it will be co-located with INSAT-3E satellite.



In Orbit Testing (IOT) of 24 Ku-band transponders of GSAT-8 is scheduled to begin on June 1, 2011 and the satellite is expected to be ready for service in about a month. Testing of the GAGAN navigational payload will be conducted from the new Navigation Control Centre at Kundanahalli near Bangalore.

Good job ISRO and all its suppliers!