Dienstag, 5. April 2016 - 18:15 Uhr
Top Chinese aerospace engineer Ye Peijian on the sidelines of China's parliamentary sessions in Beijing in March 2014. (Photo: Andrew Jones, gbtimes)
Ye Peijian is the chief designer of the ongoing Chinese Lunar Exploration Program, chief engineer at the China Academy of Space Technology (CAST) and a senior figure within China's space program.
On the sidelines of China's recently concluded annual parliamentary sessions in Beijing, Ye Peijian answered questions on China's future space exploration, including a 2020 Mars mission, lunar far side and sample return missions, as well as the possibilities for outer planet missions and future international cooperation.
What can you tell us about the development of China’s Mars 2020 mission?
We considered and proposed an earlier Mars exploration, but for a number of reasons it didn’t happen and became something of a regret. We had the possibility to become the first in Asia, but India’s Mangalyaan has already reached Mars. While it could be considered that the technological level and function of Mangalyaan is limited, we still congratulate our Asian neighbours for reaching Mars for the achievement itself, and India talks about reaching Mars ahead of us.
Luckily, our researchers didn't give up preparations and continued the work concerning key technical problems and designing solutions. We created a deep space exploration team building on our lunar exploration program. Therefore, after Chang’e-3 completed its mission, the Chang’e-3 team turned their focus to Mars exploration. The hard work has paid off. Now I think Mars exploration has gained the same awareness at the national level and from the State Administration of Science, Technology and Industry for National Defence. The work is ongoing intensively.
In terms of reaching Mars, we already lag behind India. Since we now have accumulated experience of Chang’e-1, -2, and -3, and soon will have experience in Chang’e-5 [sample return], plus experience of Chang’e-4, [first far side landing] we are capable of stepping forward with Mars exploration. Although we might lag behind in time, we can standout higher in standard. I think we possibly can launch the probe in 2020 when the two planets are best positioned, based on our hard work, accumulated experience, and everyone’s support.
To realise two 100 year anniversary goals, we should be able to launch a probe to Mars 100 years after the founding of the CCP. It will be a great Chinese contribution to the world. We are late in terms of time but we will perform at a high level. Up to now, there have been many different kinds of Mars probe. India’s Mangalyaan orbits around the Martian equator, which is relatively easy to achieve, while the Mars Global Surveyor probe was very complex, not easy. While some other countries also launched probes and landed on Mars, we would like to realise all of these in one step – that is, reach Mars orbit and land in one step.
In the meantime, we want our probe be able to land on Mars from orbit, and the rover be able to explore Mars. If we can realise these ways to explore Mars and combine them, it will be an international first. By doing this, our Mars exploration could suddenly reach the advanced world-class level. There are a lot technical challenges, regarding how to reach and land on Mars.
We have landed on Moon, but it’s different on Mars, involving hundreds of millions of kilometres of TT&C [telemetry, tracking, and command] communication, losing radio communication due to the position of the Sun, how to conduct autonomous flight and control over several months. It will greatly improve the entire development of space technology. In the meantime, we will conduct many scientific investigations of the environment on Mars, as the aims set out. Through our hard work, aerospace researchers can realise this Mars exploration on an original basis and with everyone’s support.
Landing on Mars, with high velocity, a thin atmosphere and different gravity is very challenging. Will this be done with parachutes and thrusters, building on experiences from Chang’e-3?
Landing a probe on Mars and Chang’e-3 has similarities, but there are more differences. There are several key issues. Because the Moon is the Earth's natural satellite, going to the moon involves reaching the first cosmic velocity of 7.9 km per second, and reducing velocity to land. A Mars mission involves the second cosmic velocity of 11.2 km per second [Earth escape velocity], and there are many difficulties related to this point. While the moon has no atmosphere, there is a thin atmosphere on Mars.
Another factor is that the lunar surface is dead, while the surface of Mars is very active, especially with dust storms. The Moon is also much closer, at only 400,000 km, while Mars can be up to 400 million kilometres away. Landing procedures differ a lot in terms of control and monitoring conditions, as the communication time with the Moon is seconds, but up to 20 minutes with Mars.
In the case of an emergency rescue and changing instructions it takes a very long time, and therefore more autonomy is needed. For these reasons, a Mars landing will be more difficult, but we believe we have mastered the technical aspects, including large parachutes, reverse thrust engines and an airbag.
China will attempt the world’s first soft landing on the far side of the Moon in 2018, which is very exciting for the world. What do you hope to learn from the Chang’e-4 mission?
First, a landing on the far side of the Moon will be a great achievement, because so far no country has done this. Our understanding of the far side has come from long-distance observation…but this time we can descend to make close-up, direct observations, including soil analysis, and so on. We will utilise a relay satellite, which will be the world's first such lunar relay, which is hoped to have long life span.
Someone asked why China is going to the far side of the moon but other countries have not. In fact, it is not that others do not want to, but that the situation previously has not been as conducive now, and it is because that China is combining several tasks of the Chang’e lunar exploration programme. As far as I know, the United States and other countries also have plans to go to the lunar far side, but it may be later than us. If they attempt this sometime soon after, I hope the Chinese relay satellite can serve their missions.
The back-up to Chang’e-3, which soft-landed on the Moon, will attempt to land on the far side of the Moon. Is it possible the back-up to the Chang’e-5 lunar sample return could try to bring back samples from the far side of the Moon?
Chang’e-5 will return samples from the near side of the Moon, and in the future we'll consider a series of plans for robotic lunar exploration. The Chang’e-6 mission has not been decided on and is still being discussed.
Looking to the decade beyond the 13th Five Year Plan, what exploration priorities does China have, along with the Mars program? Can we expect missions to asteroids, and inner and outer solar system planets?
Scientists have studied and developed proposals for exploring other planets, but there are no plans at present. We are very pleased however that the 13th Five-Year Plan specifically mentions deep space exploration. As the state has named deep space exploration as one of the major projects, we hope that within this wide field we can realise a lot of our scientists’ many ideas, including missions to asteroids and the giant gas planets.
China and the European Space Agency (ESA) have been working together on a number of projects. How beneficial is this relationship, and what do you hope to achieve together? Could China get involved in the ESA Director-General’s vision for a ‘Moon Village’?
There is only one Earth, only one universe, for all humanity. If we can cooperate and support each other technically and learn from each other on the ground with each other’s public facilities, the knowledge gained to serve humanity will be immensely valuable. So we hope for cooperation in all sectors, but some individual countries do not cooperate with us.
There are many within Europe that do cooperate, and in fact in the Chang’e project we have had a lot of cooperation with the European Space Agency, for example in ground control and also in our other satellite projects in the past such as the Double Star program. In the future, Europe will cooperate with us a lot, such as in the solar wind detection [SMILE] probe and so on.
In the Chang’e project, we also hope to have cooperation in two aspects. One is in scientific objectives of concern to humans, and if we have the level of scientific instruments in this respect as with others, we feel that there will be great benefits. The other is ground control. Ground-based monitoring stations in China are still relatively sparse, while Europe has a distributed network of monitoring stations around the world. If these monitoring stations are use, then this is beneficial to our entire control operations, because more monitoring stations means more information is available, meaning greater security.
There is no substantive progress regarding participation in the ‘Moon Village’. Moreover, Europe’s idea of a Moon Village exists so far only on paper, there’s no practical action.