Spaceflight Insider

Long March 3B sends BeiDou-3 satellite duo into space

Long March 3B rocket lifts off with two BeiDou-3 satellites on July 29, 2018

Long March 3B rocket lifts off with two BeiDou-3 satellites on July 29, 2018. Photo Credit: Xinhua/Liang Keyan

Lifting off from the Xichang Satellite Launch Center in China’s Sichuan Province, a Long March 3B booster orbited a pair of BeiDou-3 spacecraft for the country’s homegrown satellite navigation system.

Thundering off the launch pad at 9:48 p.m. EDT July 28 (01:48 GMT July 29), 2018, the rocket powered its way to a medium-Earth orbit (MEO). The flight lasted more than four hours in order to place the dual payload into its targeted orbital spot.

An graphic of the BeiDou navigation constellation. Image Credit:

An graphic of the BeiDou navigation constellation. Image Credit:

“China on Sunday sent twin satellites into space via a single carrier rocket, entering a period with unprecedentedly intensive launches of BeiDou satellites,” The Xinhua press agency confirmed nearly seven hours after liftoff.

Originally planned to launch on March 29, 2018, the flight was postponed to June 23 and then to July 29. What was behind the delays remains unknown as Beijing has not disclosed why those decisions were made.

The Long March 3B rocket flew in a configuration with a Yuanzheng-1 upper stage, as was the case with previous BeiDou-3 launches. The stage’s YF-50D engine is capable of firing twice in a time period of up to 6.5 hours and was used to deploy the navigation satellites into MEO at an altitude of some 13,360 miles (21,500 kilometers) with an inclination of approximately 55.5 degrees.

As usual the details about the mission were shrouded in secrecy. China keeps information about its BeiDou launches under tight wraps, not informing the public about pre-launch preparations and not revealing exact mission timelines.

What is known is that the passengers of Sunday’s flight were designated BeiDou-3 M5 and M6. Both spacecraft are based on a newly-developed dedicated satellite bus and each weigh about one metric ton. They have two deployable solar arrays and are designed to be operational for about 12 years.

Belonging to the third phase of the BeiDou satellite navigation system, the two spacecraft are the 33rd and 34th satellites of the program. Named after the Chinese term for the Big Dipper, the project was formally launched in 1994 and the first satellite was orbited in 2000. By 2012, a regional network had begun to take shape, which provided positioning, navigation, timing, and short message services in China and several other Asian countries.

If everything goes according to plan, the BeiDou-3 constellation should consist of some 27 BeiDou-3M satellites in MEO, five BeiDou-3G satellites in a geostationary orbit, and three BeiDou-3I satellites in an inclined geosynchronous satellite orbit. The first BeiDou-3 satellite was launched in March of 2015.

According to Xinhua, the BeiDou satellite navigation system currently covers more than 50 countries with a total population of more than three billion. By 2020, BeiDou is expected to have more than 30 operational satellites in orbit.

The three-stage Long March 3B rocket is 180 feet (55 meters) tall and capable of sending up to 12 metric tons of payload into low-Earth orbit or five metric tons of cargo into a geostationary transfer orbit. For some launches, this rocket can be equipped with a Yuanzheng-1 upper stage.

Sunday’s liftoff marked the 281st flight of the Long March rocket series and the 21st mission carried out by China in 2018. Beijing’s next orbital launch is scheduled for July 31, when a Long March 4C booster is slated to launch with Gaofen 11 Earth-observing satellite.

Video courtesy of SciNews



Tomasz Nowakowski is the owner of Astro Watch, one of the premier astronomy and science-related blogs on the internet. Nowakowski reached out to SpaceFlight Insider in an effort to have the two space-related websites collaborate. Nowakowski's generous offer was gratefully received with the two organizations now working to better relay important developments as they pertain to space exploration.

⚠ Commenting Rules

Post Comment

Your email address will not be published. Required fields are marked *