China gets closer to Jupiter mission by bringing Nasa’s StarNAV concept to life

Chinese researchers have demonstrated a novel navigation technique for spacecraft in deep space, bringing a NASA-funded concept to life and setting the stage for China's ambitious Jupiter mission slated for 2030. This innovative method, called stellar aberration navigation, relies on minute shifts in the relative positions of stars to calculate a probe's velocity and direction, enabling autonomous real-time navigation without the need for continuous Earth-based tracking and commands.

In January, a Tianhui-7 satellite conducted a low-Earth-orbit experiment, utilizing this technique to pinpoint its position to within approximately 5km (3.1 miles), comparable to NASA's antenna-based Deep Space Network. Jupiter's vast distance from Earth, reaching up to 900 million kilometers, makes real-time intervention from ground control impossible due to the significant time delay of radio signals.

The Chinese Academy of Space Technology, China's primary spacecraft manufacturer, noted in a forthcoming paper in the Journal of Deep Space Exploration that while China can monitor spacecraft as far as Jupiter, achieving the same precision as NASA or the European Space Agency remains a challenge.

The Tianwen-4 mission, China's maiden endeavor to explore the Jupiter system and scrutinize the giant planet and its moons, including their evolutionary history, environment, and internal structures, will harness this stellar navigation technology. Launched on December 30, 2025, aboard a Long March 4B rocket from Jiuquan Satellite Launch Centre in northwest China, Tianhui-7 carried three highly precise star cameras and an infrared sensor to test this navigation method for 20 hours in orbit, with the planet serving as a stand-in for Jupiter.

The cameras captured various sky patches, while the infrared sensor monitored Earth. By combining these measurements, the satellite determined its own position and speed, which researchers subsequently validated against GPS data to assess the technique's accuracy.

Stellar aberration, the phenomenon observed by English astronomer James Bradley over 300 years ago, arises as stars seem to shift slightly in the sky due to Earth's orbital motion around the sun. Much like the apparent slanting of raindrops through a moving car's windshield, this effect is minuscule yet predictable. Initially, researchers had to account for it when measuring star positions.

However, later, they harnessed this effect for navigation purposes. By analyzing the degree of star shifts, they could compute the spacecraft's velocity and direction. In 2020, NASA funded the StarNAV project, aiming to achieve the extraordinary precision needed to navigate solely by starlight. The star cameras aboard Tianhui-7 achieved an accuracy of about 50 milliarcseconds, equivalent to the apparent width of a rice grain seen from 500km away.

To enhance reliability, the Chinese team integrated an optical reference system that monitored the cameras' minor movements due to launch vibrations and temperature fluctuations. During the 20-hour test, the navigation system's error margin for position and velocity measured around 5km and 5 meters per second, respectively, surpassing GPS data.

Following systematic error corrections, these figures further improved to better than 4km and 4 meters per second. Nevertheless, the researchers cautioned that the conditions around Jupiter would differ significantly, and the reliability of this technique in the gas giant's orbit needed further testing. Additionally, China is advancing the development of more precise milliarcsecond-level star cameras.

A prototype has been constructed and subjected to ground tests, as reported in a 2025 article on the China Aerospace Science and Technology Corporation website.