China's space probe Tianwen-1 is expected to enter Mars' orbit next month after traveling more than 400m km since its launch on July 23 last year. The probe has flown in space for 163 days and is currently around 8.3m km from Mars, according to the China National Space Administration. The flight marks the start of the country's independent planetary exploration mission. "The probe is flying faster and faster as it gets out of the influence of heliocentric gravity," explained Li Zhencai, the deputy commander of the project. "At present, the speed is basically stable at around 22km per second relative to Earth." That means that the probe is covering about 1.8km per day. The spacecraft consists of an orbiter, a lander, and a rover. It's expected to touchdown on Mars in May 2021, about three months after arriving in the red planet's orbit. The distance between Mars and Earth changes periodically, from 50 million kilometers at its nearest and 400 million kilometers at its farthest. China has apparently chosen a primary landing site for its Tianwen-1 Mars rover ahead of the spacecraft's arrival at the Red Planet in February 2021. China has already stated that the rover will attempt to land in a designated area of Utopia Planitia, a huge basin formed by a large impact far back in Mars' history. The area is to the south of NASA's Viking 2 landing site and northwest of the spot where the American space agency's Mars InSight lander touched down in November 2018. However information published in an article (in Chinese) in the official China Space News publication following launch in July provides a specific primary landing site. The article reported landing coordinates of 110.318 degrees east longitude and 24.748 degrees north latitude, within the southern portion of Utopia Planitia. Online versions of the article have since been edited to remove the coordinates; however, these remain published by sources citing the article. The area appears to provide a relatively safe place for a landing attempt but is also of great scientific interest, according to Alfred McEwen, director of the Planetary Image Research Laboratory at the University of Arizona and the principal investigator of the powerful HiRISE camera aboard NASA's Mars Reconnaissance Orbiter. McEwen described the site as typical southern Utopia Planitia, adding that it is "mostly flat and smooth but with craters, aeolian [wind-sculpted] ridges, and a few boulders." The area has been "interpreted as covered by mud flows by some scientists, so ancient deep groundwater may have existed, and this could be an interesting location to study with a rover," McEwen told Space.com. McEwen added that he's not aware of any evidence suggesting that there may be water ice at or near the surface of the Tianwen-1 landing site. The Mars rover will also analyze surface material composition and characteristics of the Martian climate and environment on the surface. China has twice landed on the moon, with Chang'e 3 in 2013 and Chang'e 4 on the far side in 2019. However Tianwen-1 is China's first independent interplanetary mission, and landing on Mars, with its thin atmosphere, remoteness and different gravity field, presents new and greater challenges. If it lands successfully, the Tianwen-1 rover is expected to be in operation for about 90 Martian days, or sols. The Tianwen-1 orbiter will provide a relay communication link to the rover while performing its own scientific observations for one Martian year. — Agencies
