China appears to be on the cusp of launching the Shijian-13 high-speed telecommunications satellite atop their heavy-lift Long March 3B rocket. Though no solid launch window has been announced, it has been reported that the China Academy of Space Technology (CAST) stated that April 2017 is the targeted timeframe, and data seems to be coalescing around an April 12, 2017, date.
image: http://www.spaceflightinsider.com/wp-content/uploads/2017/04/LongMarch3B-387x655.png
File photo of China’s Long March 3B on the pad at the Xichang Satellite Launch Center. Photo credit: Chinanews.com
As with other geosynchronous orbit-bound missions, it will launch from the Xichang Satellite Launch Center in southwestern China.
HIGH-SPEED COMMUNICATIONS FOR HIGH-SPEED TRAVELERS
The new satellite will provide high-bandwidth – greater than 20 gigabits per second – communications and Internet service to China’s air and rail passengers, and will continue the trend of using domestically sourced hardware wherever possible.
The satellite, built on the indigenous DFH-3B spacecraft bus, is estimated to tip the scales at 10,141 pounds (4,600 kilograms), fully fueled. Shijian-13 will use an electric engine to boost its orbit to its slot 22,236 miles (35,786 kilometers) above the equator at 110.5 degrees East longitude. It marks the first Chinese satellite to use electric propulsion.
Beyond providing commercial telecommunications services, the satellite will also host experimental space-to-ground laser communication hardware.
RELIABLE ROCKET TO TAKE FLIGHT ONCE MORE
China’s workhorse Long March 3B has been tapped to deliver the 4.6-metric-ton spacecraft to geosynchronous transfer orbit (GTO). The rocket has launched 38 times – notching 36 successes, 1 partial failure, and 1 total failure – across both its standard (3B) and enhanced (3B/E) configurations.
While it’s not clear which version of the 3B will be used for the mission, the 3B has not been used since the launch of twin BeiDou navigation satellites on July 25, 2015. The following 11 launches have all been on the Long March 3B/E variant.
The rocket is a three-stage launch vehicle, with four supplemental liquid-fueled strap-on boosters. Outfitted in the more likely enhanced configuration, the rocket is capable of lofting 12,100 pounds (5,500 kilograms) to GTO.
At liftoff, the first stage’s YF-21C engine and the supplemental power supplied by the single YF-25 on each of the four boosters provide 1,331,600 pounds-force (5,923.2 kilonewtons) of sea-level thrust. The boosters operate for 140 seconds, with the first stage lasting nearly 20 seconds longer.
The second stage is powered by a YF-24E propulsion package, consisting of a single YF-22E engine and four YF-23C vernier thrusters. In total, the YF-24E provides 177,419 pounds-force (789.2 kilonewtons) of thrust and operates for slightly more than three minutes.
Like its first stage and booster siblings, the second stage’s YF-24E burns a relatively inefficient mixture of nitrogen tetroxide and unsymmetrical dimethylhydrazine (UDMH).
The 3B/E’s third stage is outfitted with a single YF-75 engine, producing 37,850 pounds-force (167.17 kilonewtons) of vacuum thrust and burning a mixture of liquid hydrogen and liquid oxygen. This stage can operate for nearly eight total minutes across two ignitions.
This will mark China’s fourth launch of this year (2017).