Thousands of years ago, Chinese poet Qu Yuan wrote the poem Tianwen, meaning Quest for Heavenly Truth. He came up with a series of questions about the sky, stars, nature and the world around us. The poem showed his spirit of finding the truth.

Inspired (激励) by the great poet, China named its latest series of planetary exploration missions (行星探测任务) after the poem in 2020. The first one in the series — a Mars exploration mission — has been named Tianwen 1, the China National Space Administration (CNSA) said on April 24^th, 2020, China’s Space Day. This shows China’s wish to explore the universe.

China has made great progress in space exploration. In 1970, China sent its first man-made Earth satellite (卫星), becoming the fifth country in the world to send a man-made satellite independently. Since 2003, China has carried out six Shenzhou manned missions. China’s moon exploration missions — the Chang’e series — started in 2007. In December 2018, China became the first country to send the probe (探测器) Chang’e 4 to the moon’s far side.

The Tianwen series will follow the Shenzhou and Chang’e series and move further into space. The first step is to send a Mars probe this year, which will mean the start of China’s exploration of the red planet. The probe is planned to circle around, land on and explore Mars in one mission. If it succeeds, it will be the first to finish all of these tasks in one mission. The Long March 5 rocket will send the probe to Mars.

After this mission, China plans to visit Mars again in 2028, aiming to collect soil from the ground of the planet and bring it to Earth. Around 2030, China will explore Jupiter and several small planets.

Have you ever seen the auroras (极光) in the sky? Cosmic radiation (宇宙辐射) creates these pretty lights in the North and South Pole areas. It seems that cosmic radiation is a beautiful gift from space. But for some people, it can be dangerous.

A 53-year-old fight attendant in South Korea, who spent about 1,022 hours flying each year, passed away due to cancer. A South Korean court connected his death to great exposure (暴露) to cosmic radiation. During his career, nearly half of his flights crossed the areas in and around the North Pole, where cosmic radiation is extremely strong.

①       Cosmic radiation from space is hitting Earth nonstop, coming from both the sun and other stars in the Milky Way.

②       Earth’s magnetic field (磁场) and atmosphere (大气层) protect us from most cosmic radiation. The magnetic field is strongest near the equator and weakest at the poles. People living at higher latitudes (纬度), like in Heilongjiang province, are exposed to a little bit more cosmic radiation than those living at lower latitudes, like in Hainan province. Also, when you go higher in an airplane, the thin atmosphere increases exposure to cosmic radiation.

③      For flight attendants crossing polar areas and for astronauts in space, cosmic radiation can create health risks. NASA reported that the radiation exposure faced by astronauts spending six months in space is the same as having 1,000 chest X-rays.

④      However, what makes cosmic radiation dangerous also makes it useful. The light speed and energy of cosmic radiation have provided wonderful ideas for treating tumors (肿瘤). Scientists can now produce man-made radiation similar to cosmic radiation. Compared to the present ways of treating tumors, it can kill tumors better with less damage to healthy parts of the body around them.

What will astronauts eat when a space trip takes years?

“Lots of fresh vegetables,” says Dr. Janet Williams, whose team have spent the last 10 years learning how to grow plants in a space station. And it’s a good thing that she has already started her work, because space gardening can be really hard.

As usual, astronaut George White looked into the closed plant room. He had planted Dr. Williams’s quick-growing seedlings none of the stems were showing. He opened the room to check and found the problem. The stems weren’t growing upward and the roots weren’t growing downward. On Earth, gravity (重力) helps a plant’s stems and in it, but roots (根) to find “up” and “down”. However, in the space station, there was almost no gravity.

Dr. Williams suggested a method: give the plants more light, as plants also use sunlight to find their way. And it worked. When the plants had more light, the stems turned up and the roots went down.

Now Dr. Williams was free to worry about the next problem: Would her baby plants live to flower? Can we grow food on a space journey?

Many plants died in the space station. Dr. Williams thought she knew why: the space plants were hungry for air. Plants live by taking up CO₂ from the air. Since a plant uses it up in the air around, the plant needs moving air to bring more CO₂ close to its surface! On Earth, the air is always moving. Gravity pulls down cold air, and warm air rises. And with these air movements, plants get enough CO₂.

Many earlier experiments (实验) with plants in space had used closed rooms. Dr. Williams tried a new greenhouse that had a fan (电扇) to keep the air move. The plants loved it. They flowered and even produced more seeds. Using Dr. Williams’s method, astronaut George completed the first seed-to-seed experiment in space, and moved one plant closer to a garden in space.

“And this,” says Dr. Williams, “is good news for long-term space travel.”