NASA's Perseverance rover may have company on the Red Planet. China intends to jump to the top in planetary exploration with an ambitious mission to Mars, its first independent bet to reach the planet. Tianwen-1, "Search for Heavenly Truth," consists not only of an orbiter, but also of a lander and scout vehicle, a trifecta that no other nation has accomplished in its first offer to Mars. "A successful landing would place China among the elite companies," says Mason Peck, an aerospace engineer at Cornell University.
Due to the July launch, the mission, if successful, would mark dramatic progress for China's space program. In recent years, it has deployed several lunar landers, but has only made one attempt on Mars, an orbiter that overlapped on a failed 2011 Russian mission to the Martian moon Phobos.
A landing on Mars is one of the most challenging feats in space flight. Unlike the Moon, Mars has an atmosphere, which means that landers need protection from the heat generated during the descent. But its air is too thin for a parachute to only slow down the landing; Retrorockets are also required. And the entire sequence should run autonomously. Of the 18 landing or rover missions to Mars, only 10 have been successful. Nine of those 10 were NASA missions. A Russian probe landed successfully, but almost immediately lost communications.
Scientists involved in Tianwen-1 said they did not have permission from the China National Space Administration (CNSA) to speak to the press and that the agency did not respond to questions. Although the state media has published stories about the mission, there is nothing quite like the fanfare that accompanies a landing at NASA on Mars. Several sources within China's space community believe the agency is silencing advertising to moderate expectations for a risky mission.
China has yet to announce which of the two candidate landing sites it prefers. Both are flat, smooth plains, not too far from where NASA's Viking 1 and Viking 2 landers landed in 1976. Low spots give the parachute more time to work. Although scientists may have preferred a more rugged site at higher elevations with a more interesting geology, "I speculate. [CNSA engineers] they're particularly looking to demonstrate a safe landing, "says Jim Bell, a planetary scientist at Arizona State University, Tempe, and a veteran of several Mars rover missions.
However, landing is not the only objective. "Our goal is to explore and gather as much scientific data as possible," CNSA chief mission architect Zhang Rongqiao said during a mission conference in July 2019. The orbiter aims to study the Martian magnetic field. and the atmosphere. With a high resolution camera, it will map the surface and characterize its geology.
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The 240-kilogram rover, still unnamed, the size of a small golf cart and a quarter the weight of Perseverance, carries six scientific instruments. Among them is a ground penetrating radar (GPR) which, along with one in Perseverance, will be the first such devices on Mars, capable of mapping the characteristics of the subsoil that orbiting radars only faintly see. "You can really investigate the layers, the structures, and the presence of permafrost or ice," says Elena Pettinelli, a geophysicist at Roma Tre University, who has helped analyze the GPR data from the Chang'e 3 and 4 missions to the Moon in China.
It will take 7 months for Tianwen-1 to reach Mars, and it will take several more months before the orbiter launches the lander, according to a 2017 document describing the mission in Science Technology Sciences of China. After exiting a ramp on the lander, the solar-powered rover is expected to run for at least 90 Martian days, using the orbiter as a communications relay. The orbiter will continue for about a Martian year, or about 23 months.
Dean Cheng, a China policy expert at the Heritage Foundation, a conservative think tank in the United States, says that beyond demonstrating technological prowess, China wants to contribute "to the global body of knowledge." He believes that "great powers are also scientific powers," he says.
Tianwen-1 is not the only upcoming demonstration of those ambitions. Later this year, China plans to launch its Chang'e 5 mission, which would return the first moon rocks since the last Soviet mission to the Moon in 1976; It will probably attempt a sample return mission from the far side after that.
CNSA officials have suggested that if Tianwen-1 and Chang'e 5 go well, China could try to return samples from Mars starting around 2030. That timeline puts it immediately behind the sample return mission from NASA-European Space Agency, but not much.
With reports from Bian Huihui.
