China is racing to make the 2020 launch window to Mars

Teams in China are working urgently to ready their first independent mission to the Red Planet. “We are aiming to use the launch window of 2020,” says Dr Wu Ji, director-general of the National Space Science Centre (NSSC) in Beijing. “If we miss that window, it will be 2022. So it is quite urgent.”
The NSSC is managing the development and integration of all the science payloads for China’s Mars Mission, which will, ambitiously, combine an orbiter, lander and a rover.
This effectively means China will be integrating two steps into one. For its Moon exploration program, the Chinese first launched orbiters before attempting, successfully, to soft-land its Chang’e-3 probe on the lunar surface.
Wu, speaking to gbtimes about China’s space science ambitions, revealed that the orbiter will have on board space particle detectors and cameras capable of detecting methane, the presence of which may indicate biological processes occurring on Mars.
The orbiter will also have radar sensor equipment allowing it to observe the Martian surface and ionosphere. Down on the surface the rover will carry a ground-penetrating radar that could reveal a lot about the past and present of Mars.
The same instrument allowed China’s Yutu rover to image around 400m below the lunar surface, making intriguing discoveries about the composition and history of the Moon, such as evidence of volcanic floods. Other scientific payloads will include particle detectors to measure radiation and may involve international cooperation.
As well instruments, China has less than five years remaining to develop and master the technologies required for deep space travel and communications, landing, power and navigation and locomotion on the Martian surface.
The minimum-energy launch windows for a Martian expedition, which allow the largest mass payload for least energy needed, occur at intervals of approximately two years and two months due to the respective orbits of Earth and Mars around the Sun. Thus even small delays on the ground can result in long waits.
The launch vehicle, likely a new Long March 5 heavy lift rocket which is set to debut this year, and the spacecraft will be developed by the China Aerospace Science and Technology Corporation (CASC) and subsidiaries.
Notably however, while China’s 2020 Mars mission is bold, it will amount to a demonstration of technology needed for even more ambitious outlined deep space projects, including a ground-breaking Mars sample return mission around 2030.
China succeeded in soft-landing on the Moon in 2013, becoming only the third country to do so, but Mars presents another challenge altogether. The country will be attempting its first independent interplanetary mission, requiring months of travel through deep space before attempting orbital insertion around Mars.
The lander and rover will then face a thin but significant atmosphere that does not much allow parachutes to slow craft, but could destroy them. What awaits then is a unique gravitational and surface environment.
Pietro Baglioni, manager of the ExoMars mission rover at the European Space Agency (ESA), notes that while there are a number of ways it can be attempted, the challenges of landing and operating on Mars are significant.
“After the atmospheric entry with the heat shield protection and the use of parachutes necessary to slow down to acceptable descent speeds, one can choose different landing techniques, depending also on the mass and configuration of the module you need to land and to the levels of residual acceleration required at touch down.
"For the final approach, you can land by use of a first parachute of course to slow down the entry phase, and then using thruster’s engines that are fired few seconds before the final touchdown to decrease the shock at landing.”
“Or you can land with a system of airbags as NASA did for the Spirit and Opportunity Rovers. Or finally, you can also use the innovative Sky Crane system which is what NASA has used for Curiosity.”
Scientific instruments and supporting equipment sent to Mars needs in general, thermally conditioned and environmental protected to deal with temperatures from minus 120 degrees at night to 20 degrees plus during the day.
“They landed a rover on the Moon not so long ago, so they must have acquired some experience, some know-how also about the operational philosophy that they can somehow apply also to a mission to Mars,” says Baglioni, referring to the Chinese mission.
“[But] landing on Mars is different because there is an atmosphere, there is a different gravity, so the mission scenarios are different.”
China’s first attempt to get to Mars was with its Yinghuo-1 probe, which piggybacked on the ill-fated Russian Phobos-Grunt mission that did not get beyond Earth orbit.
This, along with Japan’s earlier failure with its Nozomi orbiter, left the path clear for India to become the first Asian country to get to Mars with its Mars Orbiter Mission in 2014, sparking a strong reaction in China.
Phobos-Grunt was not an isolated failure, as half of all missions to Mars have failed for a variety of reasons and at different stages, underlining the difficulty and complexity of the tasks ahead.
Interest in Mars is blooming, with a range of missions looking to build on previous discoveries and search for evidence that we are, or were, not alone in the solar system.
Ahead of China’s visit to Mars, ESA’s ExoMars mission will, in collaboration with Russia’s Roscosmos State Corporation and Nasa, search for evidence of traces of past life or even present life.
Split into two missions, the first will consist of the Trace Gas Orbiter, including a cutting-edge camera, and the ‘Schiaparelli’ lander, which will demonstrate the technology required to land on Mars.  
ExoMars 2016 will launch next month, and will use a landing technology with a radar Doppler altimeter and dedicated software for the timely activation and parachute and thruster systems.  
The scheduled ExoMars 2018 mission will then use a Russian-built descent module and landing platform system which will make use of European technology derived from that tested with Schiaparelli to finally deliver the rover on the Martian surface.  
The ExoMars rover will carry a drill which can retrieve samples from two metres below the Martian surface where, shielded from the harsh radiation, traces of past or even present life may be found.