Mon. Sep 26th, 2022
A Long March 4B launch vehicle takes off from the Taiyuan Satellite Launch Center in Taiyuan in northern China's Shanxi province in April 2019.
enlarge A Long March 4B launch vehicle takes off from the Taiyuan Satellite Launch Center in Taiyuan in northern China’s Shanxi province in April 2019.

Xinhua/Liu Qiaoming via Getty Images

On Monday, a Long March 4B rocket was launched from China’s Taiyuan Satellite Launch Center with a remote-sensing satellite. This 50-year-old spaceport is located in northern China, about 500 km southwest of Beijing.

As often happens with early stages of Chinese rockets launched from the inland Taiyuan facility, the spent Long March 4B booster fell downstream from the spaceport. In this case, it landed near a school, creating a predictably large cloud of poisonous gas.

Unlike most spaceports in the world, several of China’s launch sites are in inland locations rather than near water to avoid such hazards. For security reasons, China built three of its major launch centers away from water during the Cold War, amid tensions with both America and the Soviet Union.

In recent years, China has begun experimenting with lattice fins to send its rockets back to Earth — and eventually to potentially land boosters, as SpaceX does with its Falcon 9 rocket. However, this project seems driven more by a desire to master reuse technology than to protect the population, as China has been launched from Taiyuan since 1968 with seemingly little regard for local residents.

The problem of dropping the first rocket stages in the surrounding countryside is further complicated by the fact that China continues to use toxic hydrazine fuel for its first stages. Hydrazine, two nitrogen atoms bonded together by hydrogen atoms, is an efficient fuel that can be stored. But it is also highly corrosive and toxic.

When a Crew Dragon spacecraft exploded during a test in April 2019, it produced large clouds of poisonous orange gas that could be seen for miles on Florida beaches. These reddish clouds were caused by nitrogen tetroxide, the oxidizer that burns with hydrazine fuel. This spacecraft — and many others in the past, including the space shuttle — used propellants that can be stored for operations in space. NASA has been working to find “green” propellants that would prevent the use of hydrazine even for space operations.

For rockets, however, it’s a different story. The use of hydrazine as a fuel for launch vehicles has been phased out for most of the world. The last major US missile to use hydrazine was the United Launch Alliance’s Delta II missile, which used the toxic fuel in its second stage. This rocket was retired in 2018. The Russian workhorse Proton rocket uses hydrazine for the first and second stages.

Still, the bulk of China’s launch fleet is powered by hydrazine fuel and nitrogen tetroxide oxidizer. This includes the human-rated Long March 2F rocket and the widely used Long March 4 family. All of these missiles, with their poisonous first stages, launch over land and have caused numerous incidents over the years. These fuels are cheap and relatively easy to use, and it would have been obvious for China to use them in the 1980s and 1990s when these boosters were developed. But its use continues unabated today.

China is slowly changing. The new family of large rockets, the Long March 5 fleet, is powered by liquid oxygen and kerosene, like SpaceX’s Falcon 9 rocket. Paradoxically, however, the Long March 5 rockets usually launch from the Wenchang Spacecraft Launch Site – above the ocean.

By akfire1

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