On 23 July, a CZ-5 launcher took off from the Wenchang Space Centre carrying Tianwen-1. This Chinese probe includes an orbiter, intended to orbit Mars from February 2021, and a rover to explore the planet’s surface.
With a slightly superior performance to Ariane 5, the CZ-5 launcher (Chang Zheng or Long March) has proved essential to the ambitious space projects envisaged by the Chinese CNSA agency, whether for manned flights (the future China Space Station in particular), exploration of the Moon or Mars. 27 December 2019 thus marked the return of CZ-5 to flight after the failure of its second mission in 2017. After enabling the automatic test flight of a new manned craft in May 2020, CZ-5 was consequently called on again to send Tianwen-1 to the red planet.
Despite its importance, the launch of Tianwen-1 on 23 July 2020 was not the subject of an official video from CNSA. The agency confirmed a flight by press release at 12.41 p.m. local time from the Wenchang base on the island of Hainan and the successful start of a seven-month journey towards Mars.
This flight confirms the date of 23 July which was suggested by many observers of the Chinese space effort. This is also the second take-off for Mars this year after the United Arab Emirates probe, Hope, (which used the Japanese H-IIA launcher on the night of 19 to 20 July). The third will be NASA’s Perseverance rover on 30 July (follow it live at Cité de l’espace). Remember that every 26 months, the positions of Earth and Mars in their respective orbits present a favourable “launch window” to reach the fourth planet. For 2020, the ideal window is from mid-July to mid-August. As the journey lasts for seven months, the probes sent in this Martian window of summer 2020 will arrive in February 2021.
TIANWEN-1: A DUAL-PURPOSE MISSION
This will obviously be the case for Tianwen-1 which is scheduled to be placed in orbit around Mars between 11 and 24 February 2021. It should be noted that this is not the first Chinese mission to the red planet. In November 2011, the small Yinghuo-1 probe weighing around 100 kilos was a “passenger” of Phobos-Grunt, the Russian mission to explore Mars which, unfortunately, burnt up in the Earth’s atmosphere after a malfunction.
With Tianwen-1, the rationale is very different, since China is working independently. The ambitions are also of a different order since the total mass of Tianwen-1 is almost five tons. The ship sent on 23 July is, in fact, “dual-purpose”: it includes an orbiter and a lander with a rover.
In February 2021, Tianwen-1 will enter orbit around Mars. The orbiter section includes several scientific instruments with cameras, a spectrometer and a magnetometer. In April 2021, the orbiter will release the capsule housing a landing platform with the task of taking a 240 kg rover into the Utopia Planitia region. By revisiting a similar design to NASA’s Viking Programme of the 1970s (an orbiter from which a lander subsequently detaches itself), China is showing serious ambitions for its first independent mission.
It should be emphasised however, that Viking included a lander without potential mobility, while Tianwen-1 has a rover.
The Tianwen-1 rover houses six instruments, including a radar designed to probe underground, cameras, a weather station and equipment to analyse the surface. CSNA has planned at least 90 days of operations in the difficult Martian environment.