DRO-A and B lifted off atop a Long March 2C from the Xichang Satellite Launch Centre at 8.51pm on Wednesday. The rocket’s first and second stages worked normally, but its Yuanzheng-1S upper stage did not, the official Xinhua news agency reported a day later.
“The satellites have not been inserted into their designated orbit, and work is under way to address this problem,” Xinhua said in a brief statement.
The plan was for the duo to head towards the moon and enter a so-called distant retrograde orbit, or DRO. From there they would fly in formation and work with DRO-L – a third satellite that was successfully placed into low Earth orbit by a Jielong 3 rocket last month – to test laser-based navigation technologies between the Earth and the moon, known as cislunar space
The DRO orbit is at a high altitude about tens of thousands of kilometres above the lunar surface. It is highly stable, allowing spacecraft to remain on track for a long time without using fuel, and is an advantageous waypoint for research and exploration, according to Chinese scientists.
US military and amateurs who monitor objects in space do not know the current orbit of DRO-A and B, according to Jonathan McDowell, a Harvard astronomer who tracks rocket launches and space activities.
“It often takes the US Space Force a long time to find objects that are in unexpected orbits, particularly high orbits,” he told the South China Morning Post in an email on Thursday.
The Xinhua announcement made it seem like the satellites were “indeed in an orbit around the Earth, just not one that is high enough to let them reach the moon”, he said.
Yuanzheng-1S probably suffered an engine failure on Wednesday, according to a Beijing-based rocket engineer who spoke with the Post on the condition of anonymity.
“Technically, there’s still a chance for the satellites to use their own propellant to climb to higher orbits, though that’ll significantly reduce the mission’s lifetime,” the engineer said.
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All three DRO satellites were developed by the Innovation Academy for Microsatellites which is under the Chinese Academy of Sciences (CAS) in Shanghai although little technical detail is known about it.
A Chinese paper published in the domestic Journal of Deep Space Exploration last year proposed a possible scenario to achieve high-precision relative navigation in deep space, based on the communications between two satellites placed in lunar DRO and a third in low Earth orbit using laser beams.
The DRO mission was designed to verify key technologies for deep-space laser communications and data transmission, a CAS researcher said.
DRO is increasingly important for China because the country planned for its next-generation space station in lunar orbit to allow a crewed moon landing and material delivery between the moon and Earth, said the researcher who declined to be named because he was not authorised to speak to the media.
In the meantime, Nasa plans to use a different orbit, known as the near-rectilinear halo orbit or NRHO, to build its lunar Gateway station and support missions to the moon’s surface, Mars and beyond.