China, with Tianwen-1, begins tenure at Mars with successful orbital arrival

by Chris Gebhardt

The Tianwen-1 orbiter, lander, and rover mission to Mars from the People’s Republic of China has successfully arrived at the Red Planet following an approximately 15 minute Mars Orbit Insertion burn that placed the craft into orbit.

The arrival capped a seven-month cruise to Mars and marks the start of a multi-pronged scientific mission that will include dispatching a lander and rover to the surface in April.

Arrival at Mars

As with most things in the Chinese space program, much of what is known about the Mars orbit arrival for Tianwen-1 came not from Chinese officials or the mission team but instead from Chinese observers as well as those around the world monitoring the mission’s radio signal returns.

From those independent trackers, the signal confirming the start of the Mars Orbit Insertion burn arrived at Earth at 12:03:30 UTC (07:03:30 EST), with the craft’s signal lost at an Earth Receive Time of 12:13:50 UTC — as expected as Tianwen-1 passed behind Mars and out of range of listening stations on Earth.

The communications blackout ended with signal reacquisition at 12:48 UTC (07:048 EST).

Given current light travel time between Earth and Mars, it took 641 seconds (or just under 10 minutes) for transmissions from the craft to reach Earth.

(Credit: CCTV News)

 

An anticipated timeline (pre -burn) of Mars Orbit Insertion events — based on information gathered — can be found here on the NASASpaceflight forums.

Compiling a precise timeline ahead of the events was difficult as unlike Al-Amal’s arrival on 9 February 2021 and the pending 18 February 2021 arrival of NASA’s Perseverance rover, China did not provide information regarding the mission plan in any large public manner.

The Tianwen-1 mission

The mission follows the failed Fobos-Grunt flight, a joint partnership between China and Russia, which included the Yinghuo-1 craft that was to be China’s first Mars orbiter.

The mission came to an end after Fobos-Grunt itself failed to perform the Trans Mars Injection burn to send itself on its way to Mars from Earth parking orbit.  The entire mission reentered and burned up in Earth’s atmosphere in January 2012.

After that, Chinese authorities began an independent Mars program, and Tianwen-1 was formally approved in 2016 as a three-pronged approach that included an orbiter, lander, and rover.

Artist’s impression of the three spacecraft China will send to Mars. ( Credit: Nature Astronomy, CNSA)

The three-parts launched and have made the journey to Mars as an integrated stack and will remain together through Mars orbit insertion and the first two months of orbital operations. 

The trio were developed by the China Aerospace Science and Technology Corporation while the overall mission is managed by the National Space Science Center in Beijing and launched from the Wenchang Spacecraft Launch Center in Wenchang, Hainan, People’s Republic of China, on 23 July 2020 at 04:41 UTC using a Chang Zheng 5 carrier rocket, the nation’s heavy-lift vehicle.

With a successful Mars Orbit Insertion, the craft has entered a highly eccentric, equatorial capture orbit of the planet, and controllers will now spend two months undertaking initial activations and checkouts in Martian orbit for the primary science mission while altering the craft’s orbit from equatorial to polar.

In April 2021, the lander, with the rover inside, will detach from the orbiter and prepare for Entry, Descent, and Landing.  Prior to launch, 23 April 2021 was given as the target landing date.

The landing location is within Utopia Planitia and will — if the orbit insertion burn is completed successfully — utilize a combination of aerobraking, parachute descent, retrorocket firing, and airbag deployments to achieve a soft touchdown on the Martian surface.

After landing, the rover will be deployed — ideally on the same day — to begin a planned 90 Sol (Martian day) mission to categorize the local environment.

Tianwen-1 en route to Mars. (Credit: Xinhua)

The rover will be powered by solar panels and will perform both radar and chemical analyses of the Martian surface, specifically looking for biomolecules and biosignatures that would indicate the presence of past or current life on the Red Planet.

A paper by Zhou, et al. presented at the 16th International Conference on Ground Penetrating Radar in 2016 revealed the overall mission objectives for the flight.

  1. Search for evidence of current or past life,
  2. Produce Martian surface maps,
  3. Characterize Martian soil composition and water ice distribution, and
  4. Examine the Martian atmosphere.

Additionally, Tianwen-1 serves in part as a technology demonstration for a proposed Chinese Mars sample-return mission in the 2030s.

To accomplish the mission’s objectives, the orbiter carries both medium and high-resolution cameras capable of discerning objects to within 100 meters and 2 meters, respectively, from a 400 km orbit.

The orbiter also carries a Mars Magnetometer, a Mars Mineral Spectrometer, an Orbital Subsurface Radar, and a Mars Ion and Neutral Particle Analyzer.

For surface operations, the rover is outfitted with Ground Penetrating Radar capable of seeing 100 meters below the Martian surface, a Mars Surface Magnetic Field Detector, a Mars Meteorological Measurement Instrument, a Mars Surface Compound Detector, a Multi-Spectrum Camera, and a Navigation and Topography Camera. 

Tianwen-1 launches from Wenchang, People’s Republic of China on 23 July 2020 on a Chang Zheng 5 carrier rocket.

While Tianwen-1 is a China-led mission, it is not a solo enterprise and enjoys a range of international support and cooperation.

The European Space Agency’s Estrack ground stations provided telemetry and communications support during launch, as did the Comisión Nacional de Actividades Espaciales (CONAE), the space agency of Argentina.

CONAE is also assisting with long-range and deep space tracking of Tianwen-1 as one of China’s deep space telemetry dishes is within Argentina.

Meanwhile, the Austrian Research Promotion Agency, which includes the Austrian Space Agency, partially designed and built the magnetometer on the Orbiter, and the Centre national d’études spatiales (CNES) of France provided build and development support for the spectroscopy camera instrument on the rover.

Lead image: The lander and orbiter separate in Martian orbit ahead of a planned April 2021 landing. (Credit: Mack Crawford for NSF/L2)

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