Rocket arrives as China targets July for Tianwen-1 Mars mission launch

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HELSINKI — China is gearing up to launch its Tianwen-1 Mars mission following the delivery of a Long March 5 launch vehicle to Wenchang launch center.

The rocket components arrived at Wenchang May 24 following delivery to Hainan island via Yuanwang 21 and 22 cargo ships. The spacecraft arrived at the launch center April 10, after air delivery to Haikou airport. 

Space officials at China’s ongoing annual political sessions in Beijing confirmed launch of the combined orbiter and rover mission for July. The specific launch date was not announced.

Previous Long March 5 launch campaigns have taken two months, meaning launch can be expected late July. The launch window is likely similar to the July 17 – Aug. 5 window for NASA’s Perseverance rover. 

A successful landing would make China only the second country to land and operate a spacecraft on Mars after the United States.

The biggest challenge is the ‘seven minutes of terror’, said Bao Weimin, chief of China Aerospace Science and Technology Corporation (CASC) science and technology commission, at the political sessions. The phrase is borrowed from NASA Jet Propulsion Laboratory engineers to describe the entry, descent and landing (EDL) process.

During this time the landing segment for the rover is required to reduce speed from 20,000 kilometers per hour (12,427 mph) to zero, according to Bao. The Tianwen-1 rover is expected to attempt EDL from orbit, whereas Perseverance will land on arrival at Mars. 

The landing segment will utilize heat shielding and parachute technology derived from the Shenzhou spacecraft.  Propulsion will draw from the Chang’e lunar landers.

Deep space network upgrades

Upgrades and updates to China’s deep space network facilities are underway to support the mission. 

A 70-meter-diameter antenna was hoisted in Tianjin April 25 to support mission communications. Antennas in Miyun District, Beijing and Kunming, southwest China, will also receive data from Mars, which can be as far as 400 million kilometers distant.

The Yutu-2 Chang’e-4 rover is expected to remain stationary for the ongoing 18th lunar day on the lunar far side mission due to the upgrades.

Yuanwang 6, a space tracking ship, left port Wednesday to test new equipment and antennas for tracking and supporting the Tianwen-1 mission. 

The mission will fly on the fourth Long March 5, a heavy-lift rocket which had a successful return-to-flight in December. The second launch failed in 2017, grounding the rocket for more than 900 days.

China’s Tianwen-1 Mars rover undergoing thermal vacuum testing.
China’s Tianwen-1 Mars rover undergoing thermal vacuum testing. Credit: CCTV/frame grab

Tianwen-1 landing site

The Tianwen-1 spacecraft will arrive at Mars in February 2021 and enter orbit. The EDL attempt may not take place until weeks or months afterwards

Two landing areas have been outlined, with a candidate landing site in Utopia Planitia. The landing ellipse is understood to be around 100 x 40 kilometers.

The Tianwen-1 orbiter will be equipped with a high-resolution camera comparable to HiRise on board NASA’s Mars Reconnaissance Orbiter. It also carries a medium-resolution camera, subsurface radar, mineralogy spectrometer, neutral and energetic particle analyzers and a magnetometer. The orbiter will also play a relay role for the mission rover.

The roughly 240-kilogram solar-powered rover is nearly twice the mass of China’s lunar rovers. It will carry a ground-penetrating radar, multispectral camera and a Laser Induced Breakdown Spectroscopy instrument. Other payloads will analyze the climate and magnetic environment. 

China’s Mars exploration program suffered a loss May 21 with the death of its chief scientist following illness. Wan Weixing, 61, was a researcher at the Chinese Academy of Sciences.

Tianwen-1 will be followed by a Mars sample return mission around 2030. Single and two-launch mission profiles have been proposed, using either a Long March 9, or Long March 5 and Long March 3B launches.

The July mission will be China’s first independent interplanetary mission. The country’s Yinghuo-1 orbiter piggybacked on the Russian Phobos-Grunt mission in 2011, but the spacecraft failed to leave Earth orbit.