Some of those questions are definitely heavenly in nature: How are reservoirs of potentially precious water ice distributed beneath the Martian surface? Where are the best places to find traces of past life, or to shelter future explorers?
But the biggest question about Tianwen-1 is more down to Earth: Can the Chinese actually pull this off?
“Tianwen-1 is going to orbit, land and release a rover all on the very first try, and coordinate observations with an orbiter. No planetary missions have ever been implemented in this way,” mission team leaders wrote last week in Nature Astronomy. “If successful, it would signify a major technical breakthrough.”
The mission’s start looked auspicious, although it lacked the level of official reportage that Western space enthusiasts are used to.
A video stream from Douyu.com showed China’s Long March 5 rocket sending the 5-ton probe skyward from Wenchang Satellite Launch Center on Hainan Island at 12:41 p.m. local time July 23 (9:41 p.m. PT July 22). China’s official Xinhua news agency confirmed the launch in a bulletin issued a couple of minutes later.
The plan calls for Tianwen-1 to make a seven-month cruise to Mars and enter a polar elliptical orbit next February.
Tianwen-1 is one of three Mars probes being launched this summer to take advantage of a favorable celestial alignment that comes around only every 26 months. The other two spacecraft are the United Arab Emirates’ Hope orbiter, which was launched earlier this week; and NASA’s Perseverance rover, which is due for liftoff next week.
NASA’s recent Mars missions may make the interplanetary trip look easy. But over the past five decades, trips to the Red Planet have been so fraught with risks that mission managers used to joke darkly about a “Great Galactic Ghoul” who gobbled spacecraft bound for Mars.
Only NASA and the Soviet Union have successfully landed probes on Mars, and the Soviet Mars 3 lander lasted just 110 seconds on the ground before giving up the ghost in 1971.
Several NASA probes have gone astray, including Mars Observer in 1993 as well as Mars Climate Orbiter and Mars Polar Lander in 1999. China has fallen victim to the ghoul’s grip as well: Its first Mars probe, a piggyback orbiter known as Yinghuo-1, was lost when the Russian spacecraft it was riding on, Phobos-Grunt, failed to get out of Earth orbit after its launch in 2011 and eventually fell into the Pacific.
Since that failure, China’s robotic space program has had much more success: The Chang’e-3 mission put a rover on the lunar surface in 2013, and a little more than five years later, Chang’e-4 became the world’s first mission to explore the moon’s far side at ground level.
Tianwen-1’s agenda is similarly ambitious: The orbiter is meant to conduct a global high-resolution survey of Mars over the course of a full Martian year, or nearly two Earth years. Two or three months after entering Martian orbit, a lander will unhook from the orbiter, descend through the atmosphere and make a soft landing in Utopia Planitia with the aid of a parachute, retrorockets and airbags.
If that touchdown is successful, the lander will disgorge a 500-pound rover that’s bristling with six scientific instruments — including two cameras, a meteorology station, a magnetometer, a surface composition analyzer and a ground-penetrating radar that could map those hidden concentrations of subsurface water ice.
Mars’ reservoirs of water ice would be crucial for sustaining human exploration and settlement of the Red Planet. In the past, Chinese experts have talked about sending astronauts there sometime after 2040. But that’s an issue for another day. In the meantime, China — and the rest of the world’s spacefaring nations — will have to deal with lots of slightly less lofty heavenly questions.
Update for 1:25 a.m. PT July 23: NASA Administrator Jim Bridenstine wished Tianwen-1 safe travels in a tweet:
With today’s launch, China is on its way to join the community of international scientific explorers at Mars. The United States, Europe, Russia, India, and soon the UAE will welcome you to Mars to embark on an exciting year of scientific discovery. Safe travels Tianwen-1!
— Jim Bridenstine (@JimBridenstine) July 23, 2020