China is planning a complex Mars sample return mission

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HELSINKI — China is working on a complex mission to collect Mars rock samples and deliver them to Earth by building on the successes of recent moon and Mars missions.

The mission, likely to be named Tianwen-2, could launch as soon as 2028 with the goal of returning samples around 2030. Such a mission has never before been attempted.

A presentation from Zhang Rongqiao, chief designer of the Tianwen-1 mission, at deep space forum in Shenzhen Oct. 18 indicates a shift in mission profile from a single-launch to using two launches within the same launch window.

Earlier statements on the mission suggested using a single future Long March 9 super heavy-lift rocket. Instead the mission will likely use the established Long March 3B and Long March 5 launch vehicles.

Zhang’s presentation indicates the Long March 3B will launch a lander and ascent vehicle within an aeroshell attached to a propulsion module, with the orbiter and reentry capsule to be launched by the Long March 5. 

China’s ambition to carry out the unprecedented mission has been stated previously and was included in the China National Space Administration’s plans for development across 2021-2025.

The mission is understood to have recently passed a milestone review and could, potentially, deliver to Earth the first samples of rock sampled from Mars. Such a mission would have tremendous scientific value, providing insights in the composition and geology of Mars and possibly even evidence of life such as fossils or biosignatures.

However there is a leading competitor in what could be seen as a race to Mars and back.

NASA and ESA are already collaborating to conduct a Mars sample return mission. The Perseverance rover touched down on Mars in February and in September collected the first samples for potential later delivery to Earth. 

Launches of a NASA-led rover and European Space Agency rover, to pick up the samples and send them into orbit around Mars, and an ESA-led orbiter for the return to Earth, are to launch no earlier than 2026, with samples returning in 2031.

China’s mission builds on the capabilities developed for and demonstrated by two flagship missions. In July 2020 China launched its first independent interplanetary mission which involved the successful landing of the solar powered Zhurong rover on Mars. The rover demonstrated crucial entry, descent and landing technologies including an aeroshell, supersonic parachute, sensor systems and retropulsion needed for a soft landing on Mars.

The Chang’e- 5 mission launched in November 2020 and just over three weeks later delivered fresh lunar samples to Earth. The mission proved the ability to scope and drill for samples, launch unaided from the moon, and an automated rendezvous and docking in lunar orbit. 

A Mars sample return will need to combine and even improve on these capabilities while also operating independently while hundreds of millions of kilometers away from Earth. 

Zhang said in a post-Zhurong landing press conference in May that big technological challenges lie ahead. “We need about two to three years to tackle the core technologies before conducting engineering development,” he said. 

Zhang Rongqiao said in a June CNSA press conference that technologies required for taking off from Mars are closer to those needed to takeoff from Earth rather than from the moon, as demonstrated by Chang’e-5. 

China’s mission will use a lander to extract samples and not include a rover. The use of a rover in the NASA and ESA mission adds complexity but allows for a greater range of samples to be collected. 

Missing the late 2028 launch window would mean a delay of 26 months until the next opportunity to launch. Given the challenges involved in such a mission, such delays are possible for both the Chinese and NASA-ESA missions.

Before attempting its unprecedented Red Planet mission China will attempt to collect material from near-Earth asteroid Kamoʻoalewa using two separate sampling methods before delivery to Earth. 

That mission, set for launch in 2024 and tentatively named after Ming dynasty admiral and explorer Zheng He, will then head for a main-belt comet 311P/PANSTARRS after dropping off samples on Earth. 

The mission could provide China further expertise and experience of sampling and deep space exploration operations ahead of the ambitious Mars sample return attempt.