On clear April nights, Zhu Jin, director of the Beijing Planetarium, retreats into the city's quiet, mountainous suburbs and aims a telescope at the sky.

"Dongfanghong-1," Zhu whispered as a dim light passed across his lens on his most recent trip. "Amazing, huh? Seeing it still up there after all these years."

Launched on April 24, 1970, Dongfanghong-1, or The East is Red 1, marked China's entry into a new epoch of space exploration. Forty-six years later, it is still circling the Earth, and should continue to do so for centuries -- long after the passing of the scientists who gave it life.

"I turned five the day Dongfanghong took to the sky," Zhu said. "Somehow, I have felt connected to it ever since."

On Sunday, every Chinese is likely to feel a stronger connection to that magical days in 1970. The State Council recently designated April 24 as Space Day, scheduling annual celebrations for the anniversary of China's first satellite launch.

Behind the achievement is the story of how China developed its own space technology during impoverished and turbulent times.

GREAT LEAP FORWARD

In 1957 and 1958, the Soviet Union and the United States each launched their first satellites, officially starting a space race. Mao Zedong was quick to pronounce, "We too shall make satellites."

Members of the Chinese Academy of Sciences scrambled to turn those words into reality. They aimed to launch their first probe in 1960.

Publicly, few at the time deemed the goal far-fetched.

But it was the Great Leap Forward, a period of exaggerated agricultural and industrial ambitions. Ordinary Chinese talked of "launching high-yield satellites" in a reference to officials reporting fictitiously high crop yields or industrial output. A satellite launch was harder to fabricate.

In the autumn of 1958, geophysicist Zhao Jiuzhang led a Chinese delegation to the Soviet Union to study space technology, only to be given the cold shoulder. "We have only ourselves to rely on [to develop a satellite]," Zhao said after the trip.

Young Chinese scientists worked day and night for three months and produced models of the satellite and the launch rocket, which would become known as Long March-1. However, they lacked knowledge of basic satellite theory and computing methods. Their first attempt was abandoned.

Realizing that China did not yet have what it would take to develop and launch a satellite, senior scientists decided to instead focus on sounding rockets, designed to take measurements on sub-orbital flights.

On February 19, 1960, the T-7M sounding rocket soared into the air from the suburbs of Shanghai, reaching 8 km above the ground.

The nation that invented the primitive rocket 800 years before had launched its first modern one.

NEW SATELLITE PLAN

Suspension of the satellite plan did not stifle Chinese scientists' space dreams.

In 1964, China successfully tested its first ballistic missile and atomic bomb. That rekindled consideration of satellite research.

Qian Xuesen, later deemed the father of China's space program, and Zhao Jiuzhang suggested the central government put the satellite back on the agenda. It was approved.

In the autumn of 1965, scientists met for 42 consecutive days to discuss the satellite plan. The launch was scheduled for 1970.

Finally, everything seemed to be on the right track, but then came the Cultural Revolution.

In early 1967, many scientists, including Wang Xiji, chief designer of Long March-1, were denounced and sidelined.

Rocket expert Yao Tongbin was beaten to death in the doorway of his home. Zhao Jiuzhang committed suicide rather than endure more persecution. Qian Ji, who drafted the launch plan, was identified as a "reactionary academic authority."

"It was a chaotic time," said Qi Faren, who took part in the Dongfanghong-1 mission and went on to head up China's Shenzhou-5 manned space program.

"Many people made outstanding contributions [to Dongfanghong-1] but were sidelined, some even persecuted. They should not have been treated like this," Qi said.

As scientific research ground to a halt in almost every field, then Premier Zhou Enlai and Vice Premier Nie Rongzhen decided to act to keep the satellite mission alive. They established the China Academy of Space Technology as an arm of the military under the Communist Party's leadership.

JOINING THE SPACE CLUB

The time could not have been more hostile, but Chinese scientists still hoped the country's first satellite could turn out to be more advanced than those of other countries.

He Zhenghua, chief designer of the Dongfanghong-1 program, suggested the satellite be equipped to transmit a recording of "Dongfanghong," the folk song lauding Chairman Mao.

The government approved the idea. The scientists' enthusiasm was mixed with stress, for the mission was about far more than just science. What if the music was out of tune or failed to work in space? It could be a political disaster.

Countless tests were conducted to rule that scenario out.

"We worked till 2 or 3 a.m. almost every day back then. Sometimes we ate only once a day," said Song Qingyuan, who helped calculate the orbits of Dongfanghong-1 and Long March-1.

"We had computers, but they were slow and unstable. Plotting a single trajectory could take us two to three hours," she recalled. "Not exactly Tony Stark in Iron Man."

Their hard work eventually paid off.

When Dongfanghong-1 was sent into orbit on top of Long March-1, China became the fifth nation to achieve independent launch capability.

Streets around the country were filled with cheering crowds when Xinhua News Agency reported the news.

NO PROBLEM UNSOLVABLE

Zhou Zhicheng was 7 years old when the Dongfanghong-1 launch took place. "I heard the 'The East is Red' played on the radio. When the satellite passed over China, the grownups were all so thrilled," he said.

Now director of the communications satellite department of the China Academy of Space Technology, Zhou has helped develop a range of satellites in the Dongfanghong series.

He was central to the Dongfanghong-3 research program and chief designer of Dongfanghong-4 in 2000.

"China has won high recognition in the global market," Zhou added. It has launched 14 Dongfanghong-4 satellites, and is planning five more this year. A number of new Dongfanghong-5 satellites will be sent into space in 2018.

For Chinese space scientists, the working conditions have changed immeasurably since those 1960s days of rudimentary computers and political strife, but one thing has never changed, according to Zhou.

"The spirit of hard work, persistence and commitment continues, making us believe that no problem is unsolvable," he said.