China's Tianwen-1 Mars spacecraft: Everything we know about the daring mission
Sometime in late July (or early August, perhaps) a Long March 5 rocket will blast off from China's Wenchang Satellite Launch Center on Hainan Island, in the South China Sea. It will be carrying three robotic explorers, designed and engineered by China's space agency, on a historic voyage to Mars. The mission is known as Tianwen-1, taken from the poem of the same name and loosely translated as "questions to Heaven."
But with only days before launch, some of the biggest questions are around the mission itself. China has been tight-lipped about the mission's major milestones and information has been hard to come by.
"In the months running up to a major mission, there's close to radio silence, which is frustrating," says Andrew Jones, a journalist who reports on China's space program for SpaceNews.com. "We didn't get anything for Chang'e-4 until landing success was confirmed."
The Chang'e-4 mission to the moon is one of the crowning achievements of the Chinese space exploration program. In Jan. 2019, China was able to deliver a rover to the lunar far side -- the first time a nation had achieved such a feat. Unlike the recent NASA and SpaceX mission to the International Space Station, the launch of Chang'e-4 was not broadcast across the globe in real-time. There was no livestream for launch and no shots of Chinese mission control celebrating when the scientists and engineers learnt of their success.
We know where Tianwen-1 will launch, but the exact details of when remain a mystery. On July 14, China Daily reported the spacecraft had been transported to the launch facility ready for lift-off. An expected date of July 23 has long been proposed, but never confirmed.
"We should see the rocket rolled out onto the pad on the 17th (or maybe 16th) if the July 23rd date is true," says Jones, noting this sort of time frame has been used in previous launches of the Long March 5 rocket.
On the English language version the China National Space Administration (CNSA) website, there are no updates about the Tianwen-1 mission. CNSA did not immediately respond to a request for comment.
On Chinese social media network Weibo, it's a different story. Quanzhi Ye, an astronomer at the University of Maryland, says the Tianwen-1 hasthag on Weibo has generated 29,000 tweets and 150 million reads as of July 15.
Ye notes it's not unusual for China to be quiet before the mission, but also says he has observed an improvement in the communication over the last decade, noting "nowadays you can see scientists discussing mission concepts on media outlets and lots of discussion on the Chinese space program happening on Weibo."
What we know about Tianwen-1
Landing on the moon is difficult -- and landing on its far side even more so -- but Mars is a whole different kettle of cosmic fish. The red planet will be at its closest point to Earth in late July, at around 36 million miles (58 million kilometers), but Tianwen-1 will still have to navigate a much greater distance to land on Mars' surface sometime in April 2021. That requires a good deal of navigational accuracy and a terrifying descent to the surface. As the US and Russia are well aware, Mars is notoriously good at killing off robotic explorers. Over 50% of the missions sent to the red planet fail.
The Chinese mission will kick the difficulty up a few more notches. Tianwen-1 is a triple threat: It contains an orbiting spacecraft, a lander and a rover.
"Tianwen-1 is going to orbit, land and release a rover all on the very first try, and coordinate observations with an orbiter," the mission's chief scientist wrote in a short article for the journal Nature Astronomy on July 13. "No planetary missions have ever been implemented in this way."
Will we be able to follow the historic launch live? Potentially. Quanzhi Ye points to rumours circulating on Weibo that Tianwen-1's launch will be livestreamed via China Central Television.
Scientific objectives of Tianwen-1
With three spacecraft headed to Mars, China hopes to provide a "global and extensive survey of the entire planet" while using the rover to examine locations on the surface with high scientific interest.
As detailed by the article in Nature on July 13, there are five core science objectives which were first laid out in 2018:
Create a geological map of MarsExplore the characteristics of the Martian soil and potentially locate water-ice depositsAnalyze the surface material compositionInvestigate the Martian atmosphere and climate at the surfaceUnderstand the electromagnetic and gravitational fields of the planet
The orbiter is equipped with seven instruments. It contains two cameras, a subsurface penetrating radar, a spectrometer to reveal the mineral composition of the surface and instruments to analyze charged particles in the Martian atmosphere.
The rover, which is about twice the mass of China's lunar Yutu-2 rover at around 240 kilograms (530 pounds), contains six instruments and also includes two cameras, as well as radar and three detectors which can be used to understand the soil composition and magnetic fields of Mars.
The landing site for the rover has been the subject of speculation, but the Nature article confirms it will be somewhere in Utopia Planitia, a vast plain in Mars' northern latitudes and the same place NASA's Viking 2 mission landed in the 1970s. The expected touchdown date is approximately two to three months after Tianwen-1 arrives in Mars orbit so, if all goes to plan, we can expect it sometime in April or May 2021.
Mars is the place
July and August look to be an impressively busy time for Mars.
Not only will China launch Tianwen-1, but the United Arab Emirates will have sent their own Martian explorer to the red planet: an orbiter named Hope. The orbiter will examine and analyze the thin atmosphere on Mars to try and expound why it's so unusual.
NASA, too, is getting in on the Earth exodus. The space agency aims to launch its Perseverance rover no earlier than July 30. The next-gen rover will also be carrying a helicopter known as Ingenuity, a tech demonstration that aims to become the first vehicle to fly across the surface of another planet.
Photo: © Provided by CNET An artist's impression of the three spacecraft China will send to Mars in the coming weeks. Nature Astronomy
