(天问一号), is nearing Mars and expected to enter
orbit around the Red Planet (that’s greyscale above…) on Wednesday, Feb. 10, sandwiched between UAE’s Hope orbiter (arriving Feb. 9
) and NASA’s Perseverance rover (arriving, landing Feb. 18).
On Feb. 5 CNSA released a first image of Mars at a distance of 2.2 million km (above). A fourth trajectory correction manoeuvre was also carried out at 12:00 UTC Feb. 5.
China has not revealed the timing of the braking burn that will aim to put the Tianwen-1 spacecraft into an elliptical orbit. However amateur radio operators tracking the spacecraft estimate Tianwen-1 will reach periapsis at ~12:00 UTC/7 am Feb. 10 following a long braking burn. Keep in mind this is an estimate.
The braking burn should start n the 20 minutes or so before this, then there will be loss of signal as Tianwen-1 goes behind Mars, and reacquisition of signal will come maybe 30 minutes later. Remember also that there is a light-time delay of 10.5+ minutes as Mars is currently around 190,000,000 km away, so we might not get news until ~13:00 UTC.
This is China’s independent interplanetary mission and orbit insertion is due a day before Chinese New Year’s eve. The feat will, all being well, be paraded in the traditional CCTV Spring Festival Gala, though likely not on a high-stakes live webcast (CGTN
& CCTV (weibo
) may be in play if there is coverage). While the space program is a symbol of national progress, leadership are keen to limit the potential damage of a high-profile failure (and have the means to withhold information).
Tianwen-1 consists of an orbiter and rover. However the entry, descent and landing (EDL) of the rover however is not expected until around May. It will target a primary site
in a southern portion of Utopia Planitia, to the south of Viking 2 and northwest of InSight
The orbiter carries 7 payloads: high- and medium-resolution cameras, a sounding radar, a magnetometer, mineralogy spectrometer, ion and neutral particle analyser and energetic particle analyzer. Objectives include surveying the ionosphere and interplanetary environment, detecting subsurface water ice, soil characteristics and surface structures, and Martian topography, surface compositon and geomorphology.
Tianwen-1’s planned initial highly elliptical orbit (400 x 180,000 km) may be related to use a Chang'e orbiter heritage 3000N engine being required to slow a larger, interplanetary spacecraft. The spacecraft will reduce this elongated orbit over time into a planned science observation orbit and for the rover EDL attempt.
The cameras will likely return images shortly after insertion. The Hi-res camera is capable of better than 0.5 metre resolution (greyscale) imagery from an altitude of 265 km, so these should be impressive shots. Colour images will be around 2 metre at nadir at similar altitude.