The second of three high-profile Mars missions is poised for takeoff as early as Thursday, an ambitious attempt by China to send a sophisticated orbiter, lander and rover to the red planet in a major demonstration of the nation's growing space prowess.
China did not announce the launch date in advance. But based on a notice to mariners in the offshore launch danger zone, liftoff of the Tianwen-1 spacecraft atop a powerful Long March 5 rocket at the Wenchang Satellite Launch Center on Hainan Island was expected between 12 a.m. and 3 a.m. EDT Thursday.
The flight comes on the heels of the successful launch of a United Arab Emirates Mars orbiter, called Hope, from Japan on Tuesday. Next up will be the launch of NASA's $2.4 billion Perseverance Mars rover from Cape Canaveral on July 30.
An artist's impression of the Tianwen-1 lander and rover on the surface of Mars.
China Global Television Network
All three missions are taking advantage of a relatively short Mars launch opportunity that comes around once every 26 months when Earth and Mars are in favorable positions to permit direct flights by existing rockets. All three spacecraft are expected to reach their target next February.
NASA's Perseverance rover got its name from a Virginia seventh grader who won a NASA contest open to school kids across the nation. Hope refers to the UAE's drive to develop a high-tech "knowledge-based" economy while inspiring the youth of the Middle East to pursue careers in math and science.
Tianwen-1's name comes from an ancient Chinese poem and means, appropriately enough, "questions to heaven."
If all goes well, the Long March 5 booster will place the 11,000-pound Tianwen-1 on a seven-month-long trajectory to Mars. Using its on-board thrusters, the spacecraft will brake into an elliptical orbit next February.
The orbiter is equipped with seven instruments, including high- and medium-resolution cameras; a ground-penetrating radar; a mineralogy spectrometer; a magnetometer; and two charged particle detectors. Its planned orbit around the martian poles will carry it within about 165 miles of the surface and as far away as 7,450 miles.
After mapping the world below for several months, the orbiter will release a landing craft that will descend to a rocket-powered touchdown on a broad, 2,000-mile-wide plain known as Utopia Planitia, the same general region where NASA's Viking 1 lander touched down in 1976.
The 530-pound six-wheel rover will ride down atop the lander and then roll off extendable ramps to the surface. The rover is equipped with six instruments, including a multi-spectral camera, a terrain camera, a ground-penetrating radar, magnetic field detector, meteorology sensors and others.
The rover is designed to receive commands and beam back data to Earth using the Tianwen-1 orbiter as a relay station.
"A successful landing would put China among elite company," Mason Peck, an aerospace engineer at Cornell University, told the journal Science.
China has successfully sent two rovers to the moon, including one that landed on the never-before-visited far side. An attempt to send an orbiter to Mars in 2011, hitchhiking on a Russian rocket, ended in failure when the Zenit booster malfunctioned.
The all-Chinese Tianwen-1 mission is the nation's most ambitious attempt yet at interplanetary exploration.
"Tianwen-1 is going to orbit, land and release a rover all on the very first try, and coordinate observations with an orbiter," mission managers wrote in the journal Nature Astronomy. "No planetary missions have ever been implemented in this way. If successful, it would signify a major technical breakthrough."
The solar-powered rover is designed to operate for at least 90 days while the design life of the orbiter is a full martian year, the equivalent of two Earth years.
NASA has successfully landed eight spacecraft on the martian surface: two Vikings in 1976; the Mars Pathfinder rover in 1997; the twin Mars Exploration Rovers, Spirit and Opportunity, in 2004; the stationary Phoenix lander in 2008; the nuclear-powered Curiosity rover in 2012; and the stationary InSight lander in 2018.
InSight and Curiosity are still operational, as are three NASA orbiters.
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Perseverance, which is a near twin of Curiosity and four times heavier than its Chinese cousin, is the most advanced rover of them all. It is equipped with state-of-the-art cameras and instruments to search for signs of past or even present microbial life.
It also will deploy a small experimental helicopter — a first on Mars — and collect rock and soil samples for eventual return to Earth by a joint NASA-European Space Agency mission at the end of the decade.
The Chinese say they're also planning a Mars sample return mission around 2030.