Leonard David's INSIDE OUTER SPACE

Image credit: CCTV/Inside Outer Space screengrab

China is ready to loft the uncrewed Tianzhou-7 supply ship to the country’s space station – but adopting a first-time rapid rendezvous and docking plan.

According to China Global Television Network (CGTN), the cargo ship will make a three-hour trek to the orbiting complex. Two-hour and six-and-a-half-hour rapid rendezvous and docking plans have been practiced on previous missions to the station.

Liftoff of the supply ship is reportedly expected to occur on January 17, with rocket control engineers working to ensure a successful launch of the Tianzhou-7 cargo craft.

Image credit: CCTV/Inside Outer Space screengrab

The combination of the Tianzhou-7 cargo spacecraft and a Long March-7 Y8 carrier rocket was vertically transferred to the launching area on Monday.

Manual ignition

“For this mission, we’ll use manual ignition for the first time to launch the Long March-7 rocket,” said Yu Peng, an engineer at the Wenchang Spacecraft Launch Site in south China’s Hainan Province.

“This optimizes the control system’s pre-launch emergency handling procedures, but at the same time places higher demand on the operators, Yu told China Central Television (CCTV). “All the operations prior to ignition must be performed punctually and precisely, and meanwhile, the ignition error must be controlled within one second.”

Although manual ignition helps to improve the flexibility of procedures on the launching day, to minimize errors, the rocket control engineers have developed over 300 plans to address potential faults, according to CCTV.

Image credit: CMSA

Minimize risks, potential hazards

“In case of potential malfunctions during manual ignition, we have conducted simulations for over 130 possible fault scenarios, and accordingly developed more than 300 response measures with an aim to ensure the rocket’s punctual ignition,” said Da Yongbo, an engineer.

“To guarantee flawless operations, the engineers responsible for various systems have carried out simulations and reviews every day, aiming to minimize risks and potential hazards to the greatest extent. Throughout the testing process, we uphold stringent quality control measures to ensure that both the launching process and results are satisfactory,” said Liao Guorui, another engineer.

China’s Tianzhou-7 cargo craft is assigned three major missions when in orbit.

• it will form an assemblage with the space station after its successful rendezvous and docking with the space station.
• the cargo ship will carry seven tons of supplies to the space station. It will also support many on-orbit scientific experiments.
• it will assist with waste disposal and handle the complex’s attitude and orbit control.

Improve cargo cabin

According to CCTV, in contrast to the two-hour and 6.5-hour programs that were previously implemented, the three-hour program will provide a more efficient way to transport supplies to the space station and reduce pressure on various systems during the mission.

Yin Rui, deputy commander-in-chief of the astronaut system of the Astronaut Center of China.
Image credit: CCTV/Inside Outer Space screengrab

Tianzhou-7 carry with it the spare parts and maintenance kits for space station equipment, samples for experiments, and station propellant.

The spacecraft adopts an improved cargo cabin, reports CCTV, and the original unsealed rear cone has been transformed into a sealed section, so as to expand the loading space and improve cargo capacity.

“The one-meter-long rear cone gives us more space to load supplies. The parcels are in special shapes. And several sets of special shaped parcels could perfectly fit with each other in this section to save space and improve loading capacity,” said Yin Rui, deputy chief commander of the Astronaut System with the CMSA.

Parcel delivery

All those parcels are placed in an orderly way allowing astronauts to easily get the items they need. Different colored labels are used to differentiate between goods.

High-definition images of China’s space station were taken by the departing Shenzhou-16 crew last October 30.
Image credit: CMS

“We use labels of different color to mark different goods. For example, the green label suggests the goods inside the parcel are food, dark blue for environmental control supplies for space station, light blue for crew outfit, and purple for space application system and experimental supplies. Each parcel has a QR code, and astronauts will know what is inside of the parcel after scanning the QR code,” said Yin.

So far, all parcels have been loaded into the spacecraft except the two refrigerated consumable packages which contain temperature-sensitive experimental consumables and samples. Those two parcels will be loaded into the Tianzhou-7 on launch day.

Precision resupply

The Tianzhou-7 cargo spacecraft is the inaugural mission of China’s human space program this year.

With an increase in the payload capacity of the cargo spacecraft and based on the principle of “precision resupply,” the launch frequency of the cargo spacecraft will be optimized from twice a year to three times every two years, further saving costs in space transportation, reports CCTV.

Tianzhou-7 will deliver about nearly 200 pounds (90 kilograms) of fruits, daily essentials for the now orbiting Shenzhou-17 crew and the future Shenzhou-18 astronauts as well as supplies for environmental control and life support system to China’s Tiangong space station.