Five rovers have successfully explored the surface of Mars, but by next week it could be six. The Chinese spacecraft Tianwen-1, which is currently in orbit around the Red Planet, is about to launch a lander and rover – completing the most dangerous phase of its ten-month mission.
It is China’s first mission to Mars, and if successful, will make the nation only the third – after Russia and the United States – a spacecraft landing on the planet. The mission “is a big leap for China, as they take a single step in what NASA has taken for decades,” said Roberto Orosei, a planetary scientist at the Institute of Radio Astronomy in Bologna, Italy.
The Chinese National Space Agency (CNSA) remains tense exactly when its rover named Zhurong – after the Chinese mythological god of fire – touches.
If he succeeds, he will join several other active missions on Mars. Rover NASA Perseverance, which arrived on February 18, is several hundred kilometers from a possible landing site, while NASA’s Curiosity Curiosity has been orbiting the planet since 2012. Several spacecraft are also orbiting Mars, including the United Arab Emirates. I hope the orbiter, which also arrived in February. “The more on Mars,” says David Flannery, an astrobiologist at Queensland University of Technology in Brisbane, Australia.
Scientists say that during China’s first voyage to Mars, engineering to get there took precedence over science, but the mission could still uncover new geological information. They are particularly excited about the possible detection of permafrost in Utopia Planitia, the area in the northern hemisphere of Mars where Zhurong will land (see “Landing Site”).
So far the biggest test
Tianwen-1 includes an orbiter, lander and rover – the first mission to send all three elements to the planet. The spacecraft left Earth in July 2020 and arrived on Mars in February 2021, but the landing will be the greatest test to date in China’s emerging deep space capabilities.
The rover could arrive in a matter of days, but the CNSA revealed several details. And scientists in China involved in the mission did not respond Naturerequests for pre-landing interviews; other scientists argue that the reason for this is likely to be a high risk of failure.
Landing on Mars is notoriously difficult, not least because engineers back on Earth have no real-time control over it and must play pre-programmed instructions. Many missions were lost or crashed on arrival.
In 1997, NASA’s Mars Pathfinder sent its first rover called Sojourner to a rocky region of the planet. “We haven’t gained much amazing science from this mission, but it has paved the way for much more capable autonomous rovers, and now we’re reaping the benefits of these missions,” said Flannery, who is working on Perseverance. NASA’s fifth Mars rover.
What to expect
On the day of landing, the orbiter releases the landing module and the vehicle, which will throw toward the surface protected by the heat shield. As the spacecraft approaches Mars, it releases the parachute to slow its progress, then uses rocket boosters to brake and hover above the ground, while a laser-guided system evaluates space for obstacles such as boulders before landing.
Utopia Planitia, a designated landing site, is a wide, flat area in a large, feature-free basin that formed when a smaller object struck Mars billions of years ago.
The surface of the basin is mostly covered with volcanic material, which could be modified by newer processes, such as repeated freezing and thawing of ice. Orosei says studies of the region from the orbit of Mars suggest that a layer of permafrost could be hidden just below the surface.
In 1975, NASA’s Viking 2 mission also landed on Utopia Planitia, but further north from where it is planned to touch Zhurong. “It’s a good place for the first landing,” explains Flannery. The low altitude, clear terrain and potential for finding ice in the subsurface plane also mean that future missions there could be able to collect samples and that the region could be a good landing site for manned missions, he says.
West of Zhurong’s landing area, Perseverance moves around the Lake crater and could even see a new visitor if it lands within 200 kilometers and at night, Flannery says.
Zhurong is equipped with six tools for exploring the Martian environment (see “Zhurong”). Two cameras are mounted on the mast, which take pictures of nearby rocks, which are at rest, and which will be used to plan the trips that are needed. A multispectral camera placed between these two navigation sensors detects the minerals present in these rocks.
Like Perseverance, Zhurong has radar penetrating the ground. When traversing a river basin, it reveals the geological processes that led to the formation of the areas through which it passes. With any luck, Zhurong can detect a thin horizon that marks any permafrost, says Orosei. He knew how deep this lie and its general characteristics could offer a glimpse of recent climate change on Mars and reveal the fate of ancient water that could once soak a surface, he says.
If he’s really lucky, he could even find some very old rocks that could offer a window into the Earth’s own history, where most of the evidence was destroyed by plate tectonics, says Joseph Michalski, a planetary scientist at the University of Hong Kong.
Zhurong’s spectrometer incorporates laser technology that can switch stones and study their makeup. It will also be the first rover equipped with a magnetometer to measure the magnetic field in its vicinity. The device could provide insight into how Mars lost its strong magnetic field, an event that turned the planet into a cold, dry place, harmless to life.
From orbit, Tianwen-1 will communicate Zhurong’s observations to Earth. But the orbiter will also provide its own scientific contributions with its seven instruments, including cameras, ground-penetrating radar and a spectrometer.
The magnetometer and particle analyzers will study the boundary between the atmosphere of higher Mars and the solar winds to better understand how its magnetic field works today. Combined with data from other orbits studying the planet’s upper atmosphere, it will offer scientists “a much better picture of what is happening around Mars,” says Orosei.
A successful landing on Mars could lead to more advanced Chinese missions, including a planned return of samples by 2030.