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China’s Zhu Rong rover has been roaming the red planet for more than a year. Photo: Xinhua

China Science

Did Nasa imitate China’s Mars robot? Scientists say rovers share ‘inchworm’ design

Artemis programme’s VIPER appears to borrow from award-winning rover Zhu Rong
The Chinese device draws inspiration from the movement of a common moth caterpillar

Science

Stephen Chenin Beijing

Published: 2:00pm, 2 Nov 2022

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Nasa’s latest moon rover appears to borrow from the design of a Chinese robot on Mars, according to scientists familiar with the projects – a twist in a space rivalry in which China has long been accused of being the copycat.

Zhu Rong, a robotic rover named after the Chinese god of fire, has been roaming the red planet for more than a year. It features an active suspension system that simulates the movement of an inchworm, allowing it to pull its wheels free when they become stuck in rocks or sand. The unprecedented design significantly increases the rover’s mobility and chance of survival in rough terrain.

But Zhu Rong may soon have an imitator “inching” its way over extraterrestrial surfaces. The Volatiles Investigating Polar Exploration Rover (VIPER), under development at Nasa’s Ames Research Centre in California, will also “inchworm – or move its wheels in a special, caterpillar-like coordinated way that helps the rover get itself unstuck”, according to Nasa’s website.

Zhu Rong’s inchworm-inspired suspension system allows it to move around the rough terrain of Mars without getting stuck in sand or rocks. Photo: Beijing Institute of Spacecraft System Engineering

In July, a VIPER prototype with this feature completed a ground test at Nasa’s Glenn Research Centre in Cleveland. The rover is expected to be deployed during a 2024 mission to find water at the moon’s south pole as part of the Nasa-led Artemis programme.

“This is a copy of the Chinese design,” said a Beijing-based space scientist who has been closely monitoring the projects.

Though the VIPER uses four wheels, the working principle of its suspension system is the same as that of the six-wheeled Zhu Rong’s “brave design [that] has not appeared in any previous space missions”, said the researcher, who requested anonymity because of the sensitivity of the issue.

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The US has long accused China of stealing space technology. The White House and Congress forbid Nasa from collaborating with Chinese organisations or individuals because of concerns over intellectual property theft.

Last year, a senior Nasa scientist with the Ames Research Centre was sentenced to a month in prison for unreported collaboration with China.

In recent years, China’s space programme has achieved several breakthroughs including quantum satellites, hypersonic weapons and landing its Chang’e 4 spacecraft on the far side of the moon. These projects have been driven in part by new technology not yet developed or used by the United States.

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“Nasa is a great agency with many good ideas and innovations. But they have suffered budget cuts, increasing conservatism and other problems that have hindered the adoption of new technologies,” said a senior researcher involved in the Zhu Rong rover programme in an interview on Friday.

Adapting Zhu Rong’s design for VIPER could be “just the beginning”, he said. “Lots of new, exciting technologies are under development here [in China]. They may need to copy from us more in the future.”

The Post contacted Nasa for comment last week.

01:35

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The US has sent five robotic vehicles to Mars. These rovers used a passive suspension system known as rocker-bogie suspension.

The arms of a rocker-bogie system respond passively to bumps on the ground. When they get stuck, the rover must use the sheer force of its electric motor to pull its wheels from the trap by rocking back and forth.

When Sojourner, the first rover on Mars, got stuck on a rock in 1997, it took the mission team days to rescue it.

Nearly all Nasa Mars rovers have run into similar troubles on the rough terrain of the red planet. The Spirit rover, for instance, was trapped in soft sand for months and eventually lost contact with Earth in 2010.

Scientists around the world have attempted to design active suspension systems for space rovers. These proposals have usually required many extra components that would increase the complexity, cost and risk of a rover mission.

China’s rover finds evidence of water on Mars more recently than thought

The team in Beijing drew their inspiration from the inchworm, a type of moth caterpillar commonly found in forests and gardens. The inchworm moves by anchoring its front legs to a surface, raising the middle section of its body and then dragging its hind legs forward. This not only helps the inchworm bypass obstacles on leaves or twigs, but also allows it to stretch into various shapes to camouflage itself from predators.

Using computer simulations and experiments, Chinese researchers found it was possible to build a rover that could imitate the sophisticated movements of an inchworm by adding just one component to a passive suspension system. They shared their idea with space researchers from other countries at academic conferences.

The Chinese team estimated that the inchworm-inspired suspension would have a slight impact on the rover’s top speed, but it could increase traction by more than 80 per cent, allowing it to escape from a sand trap. Zhu Rong’s performance on Mars proved the effectiveness of their design.

China’s first Mars mission, named Tianwen 1, employed other new technologies such as smart materials and artificial intelligence to put Zhu Rong on the red planet without any first-hand data for mission planning.

In September, during a global gathering of space scientists and engineers in Paris, the Tianwen 1 team won the International Astronautical Federation World Space Award, which recognises exceptional contributions to space exploration.

The VIPER mission has an important role in the Artemis programme because it could produce the first map of strategic resources, including water, in a permanently shadowed lunar crater, according to Nasa.

The golf cart-sized rover is expected to cover a distance of 20km (12.4 miles) over about three months to locate the most accessible ice. The water and other resources could support long-term activities of astronauts on the lunar surface.

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The Artemis programme aims to take American astronauts back to the moon by late 2025 and stay there.

The mission comes as US competition with space rival China heats up. In July, Nasa administrator Bill Nelson warned of a Chinese takeover of the moon during an interview with a German newspaper.

China also plans to look for ice at the moon’s south pole and build an international research station there with Russia.

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In addition to sending rovers, Chinese scientists and engineers are building a hopping device designed to take off and land repeatedly on the lunar surface.

The device could significantly increase the chance of finding ice and other resources in the vast lunar crater, according to Chinese space authorities. It would be the first time for the device to be used in a space mission.

“We don’t mind colleagues in other countries using our ideas at all,” said the researcher with the Zhu Rong team.

“Competition can be healthy. But we should compete as teammates, not enemies.”