China's Mars probe travels over 400 million km
Updated 13:41, 03-Jan-2021

The probe of China's first Mars mission Tianwen-1 had traveled more than 400 million kilometers by Sunday morning and is expected to enter Mars orbit next month, according to the China National Space Administration (CNSA).

The probe is in stable condition at a distance of around 130 million kilometers from Earth and 8.3 million kilometers from the red planet after 163 days of flight, said CNSA.

The distance between Mars and Earth varies periodically, from about 50 million kilometers to over 400 million kilometers. 

The probe is traveling at a speed of 23 kilometers per second, covering about 2 million kilometers a day. It flies at a speed of 21 kilometers per second relative to Earth's velocity, which means it is moving roughly 1.8 million kilometers away from Earth while 200,000 kilometers towards Mars every day, according to Li Zhencai, deputy commander of the Mars probe under China Academy of Space Technology.

When the probe approaches Mars, it would have flown 470 million kilometers and be 190 million kilometers away from Earth.

Prepare for 'braking'

The Mars probe will perform a critical "braking" maneuver to slow down before being captured into the orbit around Mars.

The long distance makes it a highly challenging task, as the communication will delay for over 10 minutes, leading to no real-time control or intervention from the ground crew.

Usually, the ground team gives instruction to start up the engine, said Li, while "this time, the probe will do that automatically, and the ground team will only know about the status from telemetry data nearly an hour later."

A fourth orbital correction may be implemented in order to obtain relevant orbital parameters of the point where the probe will be captured, Li added.

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