The first launch of the Long March 5 (Chang Zheng 5, or CZ-5) rocket was originally scheduled for 18:00 CST (10:00 UTC) on 3 November 2016, but a string of technical glitches on the new rocket including liquid oxygen leaks, propellant tank cooling failure, and flight control problems caused four holds during the launch countdown. The launch time was postponed twice to 20:40 CST. The launch vehicle eventually lifted off at 20:43:13, slightly later than the originally scheduled launch window of 18:00—20:40.
Long March 5 Flight Profile
The Long March 5 (Y1) launch vehicle was launched from Launch Complex 101 at the Wenchang Space Launch Site, on Hainan Island. Carried onboard the launch vehicle was a spacecraft complex consisting of a YZ-2 (Yuanzheng-2, or Expedition 2) upper stage and a technology experimental satellite named Shijian 17 (SJ-17).
Shortly after clearing the tower, the launch vehicle pitched over towards downrange at 17 seconds into the flight. The four strap-on boosters were shut down and jettisoned at T plus 2 minutes and 53 seconds, while the core vehicle continued to fly along an ascent trajectory.
The two-piece payload fairing was jettisoned at T plus 4 minutes and 45 seconds, followed by the main engine shut down and the separation of the first-stage at T plus 7 minutes 55 seconds.
The second-stage of the launch vehicle was shut down at T plus 13 minutes and 50 seconds seconds. The vehicle continued unpowered flight for another 10 minutes, before re-staring its engine at T plus 23 minutes and 42 seconds. The second-stage engine finally shut down at T plus 29 minutes and 25 seconds.
The separation of the second-stage took place at T plus 29 minutes 43 seconds, placing the payload complex into a highly ecliptic (Apogee: 35,836 km. Perigee: 225 km) parking orbit inclined at 19.5 degrees to the Equator.
About two minutes after the stage separation, the hypergolic-fuelled YZ-2 upper stage fired its engine for 47 seconds to move to a high orbit.
Nearly six hours into the flight, the YZ-2 upper stage fired its engine for a second orbit elevation burn, which lasted about 18 minutes. The satellite entered its intended position on GEO about 6 hours 15 minutes from launch.
Long March 5 Development History
The Long March 5 is the most critical element in China’s space programme in the early 21st century, designed as a heavy-lift orbital launcher to place large spacecraft into orbit. The concept of a heavy-lift launch vehicle was first envisaged under the 863 Programme (China’s high-tech research and development initiative) in 1986, though the actual development of the launch vehicle did not begin until a decade later in 2006. It then took the Chinese space industry nearly a decade to develop the launcher from scratch.
The launch vehicle also features a number of breakthroughs in design and technology, from design philosophy, computer-aided design and manufacturing (CAD/CAM), rocket engines, airframe materials, special welding technology, to digitised flight control. Almost 100% of the onboard systems are newly developed, which posed significant technical challenges to Chinese aerospace engineers. In particular, the development of the three cryogenic rocket engines encountered some serious difficulties, including a number of failed attempts in ground static firing tests. The first launch of the Long March 5 was originally scheduled for 2014, but had to be pushed back due to delays in development.
The Long March 5 represents a significant leap in China’s space capability. With a maximum payload capability of 25 tonnes to LEO, or 13 tonnes to GTO, the launch vehicle is on a par with the like of Delta IV Heavy, Ariana 5, and Energia. The launch vehicle will be used to launch China’s Chang’e 5 lunar sample return mission in 2017 and the Mars probe mission in 2020. A LEO variant of the launch vehicle, named Long March 5B, will place the various modules of China’s Tiangong space station between 2018 and 2022.
In the Long March 5 programme, China has not only obtained a new rocket, but also established a whole new set of spaceflight R&D and launch infrastructure. New rocket and spacecraft fabrication facilities have been built in the costal city of Tianjin, which allows rocket segments and large spacecraft modules to be transported by sea to its launch site on Hainan Island in southern China. The new space launch facility at Wenchang, Hainan Island allows orbital launches to be conducted from a location nearer to the Earth Equator ((19° N), which gives additional payload performance from Earth’s rotational speed. The flight path from the launch site is entirely over water, which allows used rocket stages to be dumped directly into the sea.
The launch mission is also the debut flight of the YZ-2, a new upper stage specifically designed for use on the Long March 5. Developed by China Academy of Launch Vehicle Technology (CALT), the upper stage serves as a “space tug” to deliver spacecraft vehicles and satellites directly into their intended orbit without the need to use their own propulsion.
The upper stage is 5.2 m in diameter and weighs 1.8 t, with multiple re-ignitions and precision control capabilities. With its own propulsion, navigation and control systems, the YZ-2 upper stage is capable of flying a complex mission profile autonomously, performing a series of orbital manoeuvres to deploy its payloads at different altitudes and on different orbital planes.
Shijian 17 is a technology experimental satellite designed and built by China Academy of Space Technology (CAST). Despite claims that the satellite was based on the DFH-4S satellite bus, it appears that Shijian 17 is based on an improved DFH-3B satellite bus, which has also been used by the LaoSat 1 telecommunications satellite launched in 2015.
Operating from Geostationary Earth Orbit (GEO), Shijian 17 was designed to demonstrate a variety of new technologies, including spacecraft propulsion, solar array cells, guidance, navigation and control (GNC), and space-based optical observation of space debris.