China launches Tianzhou-1 cargo spacecraft on space station refueling test flight
With the launch of the Tianzhou-1 automated cargo ship, China has taken a significant step in being able to support a long-term crewed presence in space. The spacecraft, mounted atop China’s Long March 7 carrier rocket, lifted off at 7:40 a.m. EDT (11:40 GMT) April 20, 2017, from the Wenchang Satellite Launch Center (WSLC) on Hainan Island.
For this mission, the unpiloted 28,700 pounds (13,000 kilograms) Tianzhou-1 spacecraft will rendezvous with the Chinese Tiangong-2 space station, which launched in September of last year (2016). It will dock with the unoccupied module at least three times over three months. Each time it will demonstrate its ability to transfer fuel into the laboratory’s tanks.
Tianzhou-1 is 34.8 feet (10.6 meters) long and 11.2 feet (3.4 meters) wide. It has a payload capacity of 14,330 pounds (6,500 kilograms), which includes 4,400 pounds (2,000 kilograms) of transferable propellant.
When the launch countdown reached zero, the Long March 7 carrier rocket’s six YF-100 engines roared to life, allowing the vehicle to lift off the pad a couple seconds later.
Rising on a pillar of flame, the byproduct of a combined 1.6 million pounds-force (7,200 kilonewtons) of thrust from the combustion of highly refined kerosene (RP-1) and liquid oxygen (LOX), the 174-foot (53.1-meter) tall Long March 7 cleared the tower seconds after liftoff.
With all six power plants functioning nominally, the rocket continued to build speed as it climbed skyward and began arcing out over the South China Sea.
Approximately three minutes into the flight, the four strap-on boosters consumed their propellant and were jettisoned. Nearly ten seconds later, the core stage followed suit after its RP-1 and LOX were depleted.
After separating from the spent the first stage, the second stage’s quartet of YF-115 engines were ignited and continued the task of delivering Tianzhou-1 to orbit.
The four vacuum-optimized engines produced a combined 161,880 pounds-force (720 kilonewtons) of thrust in order to deliver the nearly 29,000-pound (13,000-kilogram) Tianzhou-1 to low-Earth orbit.
Nearly ten minutes after launch, Tianzhou-1 separated from the second stage and was readied to begin orbital maneuvers to catch up with the Tiangong-2 space laboratory, orbiting at an altitude of about 235 by 230 miles (378 by 370 kilometers).
Importance of logistical support
Beyond simply giving China the ability to bring supplies to an orbiting outpost, Tianzhou-1 will be used to demonstrate the capability to do so without the need for human intervention. Additionally, without the means to refuel on-orbit spacecraft, supporting such crewed operations would be fiscally difficult – if not impossible – to maintain.
The launch of Tianzhou-1 marks China’s fifth successful mission of 2017. Next up on their manifest is the launch of the Hard X-Ray Modulation Telescope (HXMT) on a Long March 2D, tentatively scheduled for May 2017.
According to NASA Spaceflight, the next Tianzhou cargo spacecraft will launch in 2019. It will dock with the core module of China’s next space station, Tiangong-3, which is scheduled to launch sometime next year.
This article was edited on April 22, 2017 to reflect the correct launch date of the Tiangong-2 space station.
Video courtesy of Space Videos
Curt Godwin has been a fan of space exploration for as long as he can remember, keeping his eyes to the skies from an early age. Initially majoring in Nuclear Engineering, Curt later decided that computers would be a more interesting - and safer - career field. He's worked in education technology for more than 20 years, and has been published in industry and peer journals, and is a respected authority on wireless network engineering. Throughout this period of his life, he maintained his love for all things space and has written about his experiences at a variety of NASA events, both on his personal blog and as a freelance media representative.