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China’s Mars probe enters orbit, scoring another first

For the second time this week, a spacefaring nation put its first robotic probe in Martian orbit.

Today it was China’s turn: After a seven-month, 300 million-mile cruise, China’s Tianwen-1 probe executed a 15-minute firing of its main engine, putting it into an elliptical orbit that comes as near as 250 miles (400 kilometers) to the surface of Mars every 10 days.

Tianwen-1’s success came less than 24 hours after the United Arab Emirates’ Hope spacecraft began orbiting the Red Planet.

Both nations have sent probes into space before, and China has put three probes on the surface of the moon. One of China’s moon probes even returned lunar samples to Earth. But these were the first successful Mars missions for each country. Only four other spacefaring powers — the United States, Russia, the European Space Agency and India — have put spacecraft into Martian orbit. Officials at NASA and ESA were among those tweeting their congratulations today.

The arrivals of the two probes came so close together because they were launched so close together last July, during a favorable alignment of Earth and Mars that occurs only every 26 months.

A third probe, NASA’s Perseverance rover, was launched during the same time frame and is due to land in Mars’ Jezero Crater on Feb. 18. Unlike this week’s orbital insertions, Perseverance’s planned trajectory goes directly through Mars’ atmosphere — with a heat shield, parachutes and rocket thrusters coming into play during the descent.

Eventually, Tianwen-1 will send down a lander-rover combination using similar technologies. Over the course of the next couple of months, the spacecraft will adjust its orbit and make detailed observations of potential landing zones. The lander’s descent is currently scheduled for the May-June time frame, which is somewhat later than previously expected.

Tianwen-1’s science objectives include high-resolution mapping of the Red Planet from above, plus studies of its atmosphere, magnetosphere and ionosphere. The orbiter and the rover have ground-penetrating radar systems that could identify underground pockets of water.

Although Tianwen-1’s mission managers haven’t yet revealed the precise landing site, they’re expected to pick a spot in Utopia Planitia. Based on past radar readings, scientists suspect that region contains enough frozen water to fill a lake, distributed in the soil across an area wider than the state of New Mexico.

Such reservoirs could be the best places to look for traces of microbial life — or the best places for converting water ice into drinkable H2O plus hydrogen fuel and breathable oxygen for future Mars settlers.

By Alan Boyle

Mastermind of Cosmic Log, contributing editor at GeekWire, author of "The Case for Pluto: How a Little Planet Made a Big Difference," president of the Council for the Advancement of Science Writing. Check out "About Alan Boyle" for more fun facts.

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