December 21, 2017 - China Launches Communication Satellite

On December 21, 2017, you can trace China's launch of a high-throughput communication satellite aboard a Long March rocket, delivering the payload into geostationary transfer orbit. The mission capped a record-breaking year of 18 Chinese orbital launches — a 28% jump from 2016. The satellite carried 20 Gbps capacity across Ka-band beams, supporting broadband, telemedicine, and emergency services. If you keep going, you'll uncover the full story behind this milestone mission.

Key Takeaways

• On December 21, 2017, China launched a communication satellite aboard a Long March 3C rocket into geostationary transfer orbit.
• The satellite, designated TJS-3, achieved clean orbital insertion with no reported anomalies during ascent or payload deployment.
• The launch was either China's 17th or 18th mission of 2017, reflecting a 28% increase over 2016's 14 launches.
• The satellite was positioned at 110.5° East geostationary orbit, supporting communications services including internet access and emergency communications.
• The mission contributed to China's broader strategic goal of integrating military, commercial, and scientific objectives within its space program.

What China Launched on December 21, 1917?

On December 21, 1917, China didn't launch a communication satellite—that's a modern achievement. Instead, China was navigating complex wartime diplomacy with Allied powers. You'd find Chinese officials offering staggering military contributions: between 100,000 and 200,000 troops, potentially exceeding one million personnel.

Unlike the fallen Qing dynasty's era of isolation, China's 1917 government actively sought engagement in World War I. However, their participation came with clear conditions—Allied nations had to provide military assistance, armaments, and financial support.

China also proposed Chinese labor contributions as part of its wartime role. Without secured funding and weapons provisions, China couldn't mobilize effectively.

These negotiations reflected China's strategic attempt to gain international recognition and leverage through active Allied partnership during the war's critical final years. Decades later, China would dramatically shift its global standing when it detonated its first nuclear device at Lop Nur Test Ground on October 16, 1964, yielding 22 kilotons. That transformation continued into the space age when China launched its first satellite, Dongfanghong-1, aboard a Long March 1 rocket on April 24, 1970.

The Communication Satellite Behind the December 21 Mission

Launched from Xichang Satellite Launch Center on December 21, 2017, the Shijian-18 (SJ-18) was China's experimental geostationary communications satellite, built by the China Academy of Space Technology (CAST) on a DFH-4S platform.

Weighing approximately 4,600 kg, it carried cutting-edge laser payloads and used ion engines for precise orbital maneuvers.

Here's what made SJ-18 significant:

1. High-throughput capacity — 20 Gbps across 26 Ka-band user beams
2. Laser communication terminal — experimental space-to-ground optical links
3. Electric propulsion — ion engines enabling efficient station-keeping at 110.5° East
4. Broad service coverage — internet access, telemedicine, and emergency communications over China

You're looking at a satellite designed for a 15-year lifespan, later operating as ChinaSat-18 (ZX-18). The mission was launched aboard a CZ-3B/G2 rocket from the Xichang Space Center in Sichuan, China. Much like the modular assembly philosophy used in designing commercial space station modules, SJ-18's architecture was built with expandable capability in mind, allowing successive upgrades to its communication and propulsion systems. China's later Queqiao-2 relay satellite, launched in 2024, was built on the CAST-2000 bus by the same DFH Satellite Company and designed to support lunar far-side communications for multiple missions over an 8–10 year lifespan.

Which Long March Rocket Carried the Payload?

The Long March 11 rocket carried the Hongyun broadband test satellite into orbit on December 21, 2017, lifting off from the Jiuquan space center in northwest China at 2351 GMT. You'll find this rocket's solid fueled design and rapid launchability features particularly notable, as they distinguish it from China's liquid-fueled launch vehicles.

Developed by the China Academy of Launch Vehicle Technology, the Long March 11 stands approximately 68 feet tall and nearly 7 feet in diameter. This December mission marked the rocket's fifth flight since its September 2015 maiden launch and its third flight within 2017 alone. That growing launch cadence reflects the program's increasing reliability, with another mission already planned for January 2018, demonstrating China's commitment to expanding its launch capabilities. The Long March family, operated by China Aerospace Science and Technology Corporation, has performed more than 600 launches in total, making it the third most active rocket family among those currently in operation. Unlike its liquid-fueled counterparts, the Long March 11 uses solid propellant rockets, which require no separate tanks for propellant and oxidizer and burn to completion once ignited.

Why the Long March Was China's Trusted Rocket by 2017

By 2017, China's Long March rocket family had earned its trusted status through decades of accumulated success. You can trace its credibility through these milestones:

1. 100 successful launches completed by June 2007, proving operational redundancy across multiple rocket variants
2. 251 flights logged by September 2017, with 15–25% of global launches annually since 2010
3. Propulsion evolution from hypergolic fuels to liquid oxygen and liquid hydrogen, boosting Long March 5's LEO capacity to 51,000 pounds
4. Rapid failure recovery, as engineers redesigned Long March 5's fuel pump after July 2017's setback, restoring confidence within months

China's Long March didn't just survive setbacks—it grew stronger from them, becoming the undisputed backbone of China's space transport system. The family's range of launch destinations spans low Earth orbit, Sun-synchronous orbit, geostationary transfer orbit, and even trans-lunar and trans-Mars injection, reflecting the breadth of capability built over decades. Furthering this breadth, the Long March 2 family alone accounted for roughly half of all Chinese launches, underscoring its central role within the broader rocket program. This sustained launch infrastructure positioned China to later expand into advanced technology sectors, including the rollout of commercial 5G networks across 50 cities simultaneously in October 2019.

Where China Launched From and What Orbital Path Was Used

Nestled amid mountains in Sichuan province, southwestern China, Xichang Satellite Launch Center served as the departure point for this mission—a military facility with established infrastructure purpose-built for geostationary transfer orbit (GTO) deliveries via Long March 3B heavy-lift rockets.

From the Xichang launchpad, the rocket climbed vertically before pitching and rolling southeast across the Chinese mainland. Boosters and the first stage separated roughly two-and-a-half minutes after liftoff, dropping over Chinese territory as the vehicle continued downrange over the Pacific Ocean. A key drawback of launching from Xichang is that spent stages fall on inhabited areas of the Chinese mainland, a hazard that future vehicles launching from coastal sites aim to eliminate.

Approximately thirty minutes into flight, the reignitable cryogenic third stage completed its burn, inserting TJS-2 into a Geostationary Transfer orbit—a highly elliptical path that would allow the satellite to maneuver itself into its final geosynchronous operational altitude. China's newer Wenchang Satellite Launch Center, located in Hainan province at a lower latitude, was constructed specifically to improve payload capacity and reduce the inclination change needed to reach geosynchronous orbit. Much like the United Kingdom's Calder Hall, which pioneered commercial nuclear power by connecting to the National Grid in 1956, China's space launch infrastructure reflects how national programs often blend military objectives with broader civilian and technological ambitions.

Did the December 21 Launch Succeed?

China's December 21 launch of TJS-3 aboard a Long March 3C rocket succeeded without incident, achieving clean orbital insertion into a geostationary transfer orbit.

You'll find this mission notable for several reasons:

1. No anomalies occurred during ascent or payload deployment
2. Military implications remain significant, as TJS-3 carries inferred dual-use communications capabilities
3. Launch economics benefited from Long March's proven reliability, keeping costs predictable
4. 94% success rate defined China's 2017 orbital launch record across 18 attempts

This mission contrasted sharply with the Long March 3B anomaly from June 2017, requiring zero onboard propulsion corrections. The Long March family has recorded 620 successful launches out of 640 total attempts as of April 2026.

TJS-3 contributed cleanly to China's successful launch tally, reinforcing confidence in the Long March family's operational consistency throughout that year. That same year saw 466 satellites attempted across global launch campaigns, reflecting an unprecedented surge in orbital activity. This growth in satellite communications echoes the foundational work of Bell Laboratories, whose hexagonal cell and frequency reuse concepts first established the theoretical groundwork for scalable wireless coverage as early as 1947.

Where December 21 Ranked in China's 18-Launch 2017 Manifest

The December 21 TJS-3 launch rounded out China's 2017 manifest as either the 17th or 18th mission of the year, placing it among a concentrated cluster of year-end deployments. China's launch sequencing throughout 2017 reflected deliberate orbital logistics planning, with the final quarter absorbing multiple satellite operations to meet priority objectives before year's end.

You can see how China's Long March 3B dominated communication satellite assignments, making it the natural vehicle choice for TJS-3's geostationary insertion. The December positioning wasn't accidental — it aligned with both orbital mechanics windows and programmatic planning cycles. Across 18 missions, China demonstrated a consistent cadence that balanced commercial, strategic, and scientific payloads, with communication satellites representing a substantial share of the overall manifest. The Long March 3B relies on hypergolic propellants, specifically unsymmetrical dimethylhydrazine and dinitrogen tetroxide, in its main stages and liquid boosters.

China's broader space program advances under a whole-of-nation approach that integrates military, commercial, and scientific objectives to achieve dominance in cutting-edge technologies and high-tech sectors. This strategic integration ensures that communication satellite deployments like TJS-3 serve not only civilian purposes but also the CCP's overarching ambitions for global technological preeminence. In contrast, commercial competitors like SpaceX were simultaneously driving down launch costs through reusable rockets, with the Falcon 9 reducing the price to orbit to approximately $2,500 per kilogram, undercutting traditional expendable launch vehicles by roughly 75%.

How December 21 Advanced China's Communication Satellite Network

Launching on December 21, 2017, the Chinasat communication satellite expanded China's geosynchronous infrastructure by adding broadband multimedia capacity, radio and television broadcasting coverage, and enterprise communication services to an already active orbital network.

Its DFH-4 platform delivered reliable broadband expansion and strengthened network redundancy across civilian and governmental sectors.

Here's what this launch contributed:

1. Broadband access — Extended high-throughput multimedia transmission nationwide
2. Broadcasting coverage — Reinforced radio and TV distribution demands
3. Network redundancy — Backed military, emergency, and enterprise communication reliability
4. Service diversification — Supported e-governance and distance education applications

You can see how each addition built upon China's existing Chinasat fleet, pushing its geosynchronous communication network toward greater operational resilience. The ChinaSat 18 satellite, also launched aboard a Long March 3B/E and valued at US$250 million, had previously been declared a total loss after malfunctioning following separation from its launch vehicle. The DFH-4 platform itself traces its lineage to Project 331, a communications satellite program initiated on March 31, 1975, that gave rise to the first-generation Dong Fang Hong 2 satellites led by Sun Jiadong. China's geosynchronous strategy reflects the broader principle, demonstrated by INTELSAT's global architecture, that just three evenly spaced geostationary satellites can provide continuous coverage across the entire globe.

What the December 21 Mission Signaled About Long March Cadence

Beyond its contribution to China's communication network, the December 21 launch fits into a broader pattern worth examining — what China's late-2017 mission cluster revealed about Long March rocket cadence. You can see this clearly when you look at 2017's numbers: 18 successful Long March missions, up 28% from 2016's 14. December alone featured two launches, capping a year that hit three missions in August alone.

That launch tempo wasn't accidental. It reflected deliberate infrastructure scaling, with Jiuquan handling roughly 40% of 2017's launches and the Long March-2D completing its 20th flight by year's end. These aren't isolated milestones — they're signals. China was building toward 2018's record 39 Long March missions, demonstrating it could sustain 2-3 launches monthly without compromising reliability. The rocket family's name itself carries historical weight, referencing the Chinese Red Army's retreat of 1934–1935, a grueling 10,000-kilometer march that became central to the founding narrative of the People's Republic of China. That original Long March began with roughly 86,000 troops departing from southeastern China, yet only about 8,000 survivors completed the journey to northern Shaanxi, a staggering attrition that nonetheless cemented Mao Zedong's leadership of the Chinese Communist Party. This kind of institutional perseverance through extreme cost and logistical hardship echoes earlier infrastructure ambitions, much as British banks financed the Grand Trunk Pacific's mountain section construction at approximately $105,000 per mile through some of Canada's most rugged terrain.