China Joins the Mars Club

China Joins the Mars Club

Today China became the sixth member of the group of countries and space agencies to successfully place a spacecraft into orbit around Mars. Tianwen-1 entered orbit less than 24 hours after the United Arab Emirates’ (UAE’s) Hope probe did the same thing. Getting into orbit is only the first step for Tianwen-1, however. In a few months, it will detach a lander/rover to descend to the surface of Mars, a perilous journey. The United States is the only country to land successfully and its next attempt, with Mars Perseverance, is just a week away.

The United States, Soviet Union/Russia, European Space Agency, India and the UAE are the other members of the Mars club.

Tianwen-1 is China’s first planetary exploration probe. China has launched five probes to the Moon so far, including two landers/rovers and a sample return mission whose main spacecraft is now on an extended journey into interplanetary space, but Tianwen-1 is its first dedicated deep space mission.

Tianwen-1, which means Questions to Heaven, is one of three missions arriving at Mars right now. That is not a coincidence, but the result of celestial mechanics. The orbital positions of Earth and Mars are favorably aligned only every 26 months, creating limited opportunities for making the trip.  UAE’s Hope got there yesterday, Tianwen-1 today, and NASA’s Perseverance will arrive on February 18.

Hope is an orbiter. Perseverance is a rover.

Tianwen-1 is an orbiter, lander and rover, an ambitious first planetary exploration attempt for China. It will wait several months before attempting the landing unlike Perseverance, which will plunge directly into the Mars atmosphere next Thursday for its “Seven Minutes of Terror” entry-descent-and-landing sequence similar to that of its cousin Curiosity in 2012.

Curiosity was the eighth successful U.S. Mars lander and Perseverance hopefully will be the ninth, but NASA stresses how challenging it is and a 1999 failure was a lesson learned. Efforts by the Soviet Union and Europe did not have happy endings. The world will be watching when Tianwen-1 makes the attempt in May or June.

Launched on a Long March 5 rocket on July 23, 2020, Tianwen-1 fired its braking rockets this morning beginning at 6:52 am Eastern Standard Time (7:52 pm Beijing Time). Unlike the UAE yesterday, China did not provide live coverage of the orbital insertion. Tweets from amateur radio satellite (AMSAT) enthusiasts using a 20-meter antenna at the Bochum Observatory in Germany to track the Doppler shift in the spacecraft’s signals back to Earth were the only way for the public to keep track.

China’s CGTN news service tweeted news of the success after the fact.

Tianwen-1 has 13 scientific instruments.  The orbiter is equipped with a medium-resolution and a high-resolution camera, a Mars-orbiting Subsurface Exploration Radar, a minerology spectrometer, a magnetometer, an ion and neutral particle analyzer and an energetic particle analyzer.

The lander/rover’s destination is Utopia Planitia, a large plain where the U.S. Viking 2 lander also set down. Viking 2 was stationary, however. Tianwen-1’s 240 kilogram solar-powered rover will roll off the lander like Yutu and Yutu-2 to explore the surrounding area.

The rover is equipped with a suite of instruments that includes a ground-penetrating radar to search for pockets of subsurface water. It also has a multispectral camera, a terrain camera, a surface composition detector, a magnetic field detector, and a meteorology monitor.

China has experience with lander/rover combinations having placed two on the Moon already. Chang’e-3 and its Yutu rover arrived in 2013 and Chang’e-4 and Yutu-2 in 2019. Chang’e-4 is the first spacecraft to land on the far side of the Moon. China also successfully landed Chang’e-5 on the Moon, collected soil samples, lifted off, rendezvoused with the mother spacecraft in lunar orbit, and returned the samples to Earth last year.  Chang’e is China’s mythological goddess of the Moon.  Yutu is her pet Jade Rabbit.

Getting to the surface of Mars is more challenging than the Moon, however.  Tianwen-1 will use aerodynamics, parachutes and retrorockets for the soft landing.

China is already talking optimistically about its next Mars mission, a sample return, as well as exploration of asteroids and the Jovian system.


This article has been updated.

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