Nottingham Trent University astronomy lecturer Dr Daniel Brown tells us what to expect from the two new arrivals to Mars.
How times have changed since the Apollo era. Within the space of a few days, two space missions from China and the United Arab Emirates (UAE) will have reached Mars.
The UAE’s Hope mission entered Mars orbit yesterday. Today (10 February), the Chinese Tianwen-1 mission – an orbiter and lander – will swing into orbit, with a predicted landing date some time in May.
It is a very big moment for both countries. Hope is the first interplanetary mission by an Arab nation ever. And if China succeeds, it will be the first country ever to visit and land on Mars on its first try. The odds are stacked against them, with nearly half of all Mars missions failing. China already lost a Mars orbiter mission, Yinghuo-1, back in 2011.
Before Mars missions can start doing science, tense moments await. As they arrive at the planet, they need to trigger a burn of their engines just at the right time to slow the probes down so they can be captured by Mars’ gravitational field. Given the large distance from Earth, this needs to be carried out automatically by the probe.
These busy times for all interested in Mars exploration have been kicked off by two relative newcomers in the treacherous business of Martian exploration, bringing a welcome, fresh perspective. And if you haven’t had enough seeing these missions arriving, then sit back for a few days until 18 February, when NASA’s Perseverance rover will join them.
One Martian year of Hope
The Hope mission is the UAE’s first ever interplanetary mission arriving at Mars at the same time as the UAE is celebrating its 50th anniversary of formation. This mission blasted off from Japan in July 2020 using the same launch window to reach Mars as the Chinese and NASA missions.
Hope is set to orbit Mars for one Martian year – nearly two Earth years. From distances of 22,000km up to 44,000km, it will explore the Martian atmosphere in more detail.
The Hope mission will investigate Mars’ global weather, its links to the upper atmosphere and how this can explain the changing abundance of hydrogen and oxygen there. This will help us understand how Mars is gradually losing its atmosphere as well as the role that dust plays in the Martian weather – important information for those who want to settle on Mars one day.
China’s questions to Mars
If all goes well, the orbiter Tianwen (which means ‘questions to heaven’) and the yet-unnamed rover will attempt to measure Mars’ ionosphere, a layer of electrically charged particles surrounding the planet.
This work might also help to understand how Mars is losing its atmosphere. It will also support future crewed missions to Mars by exploring its surface and mapping its shape, geology and internal structure.
The Tianwen orbiter is packed with cameras, a magnetometer (used to measure magnetic fields) and various particle analysers. It will also act as a relay station to stay in communication with the rover.
The rover, the size of a small car, is just a little bit smaller than the NASA Perseverance rover, which is also approaching Mars. Due to land on 18 February, Perseverance sports a similar look to the Chinese rover, with a six-wheel drive, large solar panels and a pole with cameras attached.
What makes China’s mission even more fascinating is that the rover contains a ground-penetrating radar. During the rover’s estimated lifespan of 90 Martian days (a Martian day being nearly 38 minutes longer than ours) it can explore the sub-surface structure and search for water deposits below the ground. Evidence of underground saltwater lakes was found using radar in 2018 but never followed up with measurements from the surface.
The Tianwen-1 rover will not visit these specific sites but could find similar conditions at the proposed landing site, which we know used to be covered by mudflats. There’s huge interest in such deposits as they represent a resource for future astronauts on the planet. We also can’t rule out the possibility that the lakes could host some form of life.
China has already used the radar technology with great success on its recent Yutu-2 rover to identify separate unique layers of water ice up to 40m below the surface on the Moon.
The Chinese National Space Administration stated that the Tianwen-1 rover will land in the region known as Utopia Planitia, the largest known impact basin in the solar system. In its first three months, the orbiter will survey and identify the precise location.
Curiously, after the successful launch of the Tianwen-1 mission, the official China Space News publication initially indicated the intended coordinates within Utopia Planitia, but these were later removed. This could have been done to ensure the early report does not contradict a later slight alteration, or with political motivation. Speaking to Space.com, Dr Alfred McEwen, director of the Planetary Image Research Laboratory at the University of Arizona, said the intended landing area is safe and scientifically very interesting.
China’s first Mars rover will need to go through the so-called seven minutes of terror: the automated decent of any lander through the Martian atmosphere. The craft will have to successfully decelerate and land in one piece, all without any active communication with an orbiter or ground control. To achieve this, it will do an initial deceleration using a conical aeroshell. This is a protective shield that causes aerodynamic drag (resistance) but will also heat up immensely. It will be followed by a parachute and then the firing of retrorockets to allow a soft touch down.
Daniel Brown is a lecturer in astronomy at Nottingham Trent University. He is also responsible for the NTU observatory, where he develops astronomy-related outreach activities for the general public and schools. His areas of research interest include cultural astronomy, astronomy outreach and heritage, light pollution, stellar evolution and stellar wind.